DE112023002637T5 - Device for switching between electrical power sources, vehicle control device and method for switching between electrical power sources - Google Patents

Abstract

A device for switching between electrical power sources is provided, which is capable of preventing damage to a semiconductor switch even when the output voltages of a first and a second power supply source differ. The device (1) for switching between electrical power sources comprises a first semiconductor switch (3a) connected to a first power supply source (2a), a second semiconductor switch (3b) connected to a second power supply source (2b), and a switch control device (7) designed to control the drive voltages (Vga, Vgb) of the first and second semiconductor switches. When switching from one of the first power supply source (2a) and the second power supply source (2b) to the other, the switch control device (7) provides an intermediate state in which the semiconductor switch connected to the power supply source configured to supply electric power after switching is maintained in an unsaturated state, and changes the holding time of the intermediate state according to the difference between the voltages (Va, Vb) output from the first and second power supply sources.

Description

Technical area

The present invention relates to an apparatus for switching between electric power sources, a vehicle control apparatus and a method for switching between electric power sources, and more particularly to a technology for protecting a circuit for switching between electric power sources during the supply of electric power.

Technical background

In recent years, with the advancement of electric vehicles and autonomous driving, components such as conventional hydraulic and mechanical systems have become increasingly electric. Therefore, there is a need to improve on-board power supply systems to reduce the number of wiring harnesses used for power supply and increase the reliability (redundancy) and efficiency of power systems. On-board power supply systems traditionally controlled the power supply using mechanical switches such as relays and fuses. However, in recent years, power control systems using semiconductor switches have been widely used. Semiconductor switches have a faster switching speed than relays and can prevent temporary power interruption when the electrical power source is changed. Furthermore, because they do not have mechanical contacts, semiconductor switches are very durable, and the limitations on the number of switching operations have been significantly relaxed.

Conventional technologies for the power supply systems using semiconductor switches described above are disclosed in Patent Literature 1 and Patent Literature 2. Patent Literature 1 discloses a protection technology for preventing a reverse current from flowing from a second power supply to a first power supply without increasing the size and cost of a control circuit.

In contrast, Patent Literature 2 discloses a configuration including a first pair of switches for selectively connecting a first power supply node to an output node, a second pair of switches for selectively connecting a second power supply node to the output node, and a switch control circuit. The switch control circuit operates to connect only one of the first and second power supply nodes to the output node at any given time.

Quotation list

Patent literature

• Patent Literature 1: Unexamined Japanese Patent Application Publication No. 2002-061736
• Patent Literature 2: Unexamined Japanese Patent Application Publication (Translation of PCT Application) No. 2019-514328

Summary of the invention

Technical problem

When a drop in the main power supply occurs, the technology described in Patent Literature 1 disconnects the main power supply to prevent reverse current from flowing from a sub-power supply to the main power supply. This technology performs switching operations only when the main power supply fails, and it cannot selectively supply electric power during normal use by utilizing the main power supply and the sub-power supply.

The technology described in Patent Literature 2 is capable of selectively connecting the first and second power sources to the output node. However, this technology is designed to connect only one of the first and second power sources to the output node. Therefore, a temporary power outage may occur when switching the electric power source. Furthermore, if the supply voltages of the first and second power sources differ due to, for example, individual differences or deterioration of the power supplies, an overcurrent due to an inrush current or a discharge current during switching may flow through a semiconductor switch, thus damaging the semiconductor switch. Furthermore, because the inrush current during switching depends on the current capacity of a connected load, it is generally necessary to estimate the maximum current under worst-case conditions where all connected loads are operating and select a semiconductor switch that meets these conditions. This leads to an increase in the cost of the semiconductor switch.

Under the above circumstances, a need has arisen for a method capable of preventing damage to the semiconductor switch even when the output voltages of the first and second power supply sources differ.

Solution to the problem

To solve the above problem, according to one aspect of the present invention, there is provided an apparatus for switching between electrical power sources, comprising a first semiconductor switch, a second semiconductor switch, and a switch control device. The first semiconductor switch is arranged between a load device and a first power supply source configured to supply electrical power to the load device. The second semiconductor switch is arranged between the load device and a second power supply source configured to supply electrical power to the load device. The switch control device controls the drive voltages of the first and second semiconductor switches.

When switching from one of the first and second power sources to the other, the switch control device provides an intermediate state in which the semiconductor switch connected to the power source configured to supply electric power after switching is maintained in an unsaturated state, and changes the holding time of the intermediate state according to the difference between the voltages output from the first and second power sources.

Advantageous effects of the invention

In at least one aspect of the present invention, the holding time of the intermediate state of a semiconductor switch connected to the power supply that supplies electric power after switching is changed according to the voltage difference between the output voltages of the first power supply and the second power supply. This can prevent damage to the semiconductor switch due to an overcurrent even when the output voltages of the first power supply and the second power supply differ.

Objects, configurations and effects different from those mentioned above will be understood from the description of the following embodiments.

Brief description of the drawings

• 1 ein schematisches Diagramm eines Beispiels, bei dem mehrere elektrische Stromquellen mit einer an einem Fahrzeug montierten Fahrzeugsteuervorrichtung verbunden sind.
• 2 ein Diagramm eines Beispiels der Konfiguration einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß einer ersten Ausführungsform der vorliegenden Erfindung,
• 3 ein Diagramm eines Beispiels des Betriebs einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der ersten Ausführungsform der vorliegenden Erfindung,
• 4 ein Diagramm eines Beispiels der Konfiguration einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß einer zweiten Ausführungsform der vorliegenden Erfindung,
• 5 ein erklärendes Diagramm, das zeigt, wie die Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der zweiten Ausführungsform der vorliegenden Erfindung einen Einschaltstrom beim Wechsel der elektrischen Stromquelle unter Verwendung von Lastinformationen schätzt,
• 6 ein Diagramm eines Beispiels des Betriebs einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der zweiten Ausführungsform der vorliegenden Erfindung,
• 7 ein Diagramm eines Beispiels der Konfiguration einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß einer dritten Ausführungsform der vorliegenden Erfindung,
• 8 ein Diagramm eines Beispiels der Konfiguration einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß einer vierten Ausführungsform der vorliegenden Erfindung,
• 9 ein Diagramm eines Beispiels des Betriebs einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der vierten Ausführungsform der vorliegenden Erfindung,
• 10 ein erklärendes Diagramm, das vorteilhafte Wirkungen zeigt, die erhalten werden, wenn ein Überlappungszeitraum für die Gate-Spannungen des ersten und des zweiten Halbleiterschalters in der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der vierten Ausführungsform der vorliegenden Erfindung bereitgestellt ist,
• 11 ein Diagramm eines Beispiels der Konfiguration einer Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß einer fünften Ausführungsform der vorliegenden Erfindung,
• 12 ein Diagramm eines ersten Beispiels der Konfiguration zum Einschalten eines Halbleiterschalters in der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß einer sechsten Ausführungsform der vorliegenden Erfindung,
• 13 ein Diagramm eines Beispiels des Betriebs des Halbleiterschalters beim ersten Beispiel der Konfiguration der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der sechsten Ausführungsform der vorliegenden Erfindung,
• 14 ein Diagramm eines zweiten Beispiels der Konfiguration zum Einschalten eines Halbleiterschalters in der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der sechsten Ausführungsform der vorliegenden Erfindung,
• 15 ein Diagramm eines Beispiels des Betriebs des Halbleiterschalters beim zweiten Beispiel der Konfiguration der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der sechsten Ausführungsform der vorliegenden Erfindung,
• 16 ein Diagramm eines dritten Beispiels der Konfiguration zum Einschalten eines Halbleiterschalters in der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der sechsten Ausführungsform der vorliegenden Erfindung,
• 17 ein Diagramm eines Beispiels des Betriebs des Halbleiterschalters beim dritten Beispiel der Konfiguration der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß der sechsten Ausführungsform der vorliegenden Erfindung und
• 18 ein Blockdiagramm eines Beispiels der Hardwarekonfiguration eines Computers, der in der Vorrichtung zum Schalten zwischen elektrischen Stromquellen gemäß jeder Ausführungsform der vorliegenden Erfindung enthalten ist. Beschreibung von Ausführungsformen

They show:

• 1 a schematic diagram of an example in which multiple electrical power sources are connected to a vehicle control device mounted on a vehicle.
• 2 a diagram showing an example of the configuration of an apparatus for switching between electric power sources according to a first embodiment of the present invention,
• 3 a diagram showing an example of the operation of an apparatus for switching between electric power sources according to the first embodiment of the present invention,
• 4 a diagram showing an example of the configuration of an apparatus for switching between electric power sources according to a second embodiment of the present invention,
• 5 an explanatory diagram showing how the apparatus for switching between electric power sources according to the second embodiment of the present invention estimates an inrush current when changing the electric power source using load information,
• 6 a diagram showing an example of the operation of an apparatus for switching between electric power sources according to the second embodiment of the present invention,
• 7 a diagram showing an example of the configuration of an apparatus for switching between electric power sources according to a third embodiment of the present invention,
• 8 a diagram showing an example of the configuration of an apparatus for switching between electric power sources according to a fourth embodiment of the present invention,
• 9 a diagram showing an example of the operation of an apparatus for switching between electric power sources according to the fourth embodiment of the present invention,
• 10 an explanatory diagram showing advantageous effects obtained when an overlap period is provided for the gate voltages of the first and second semiconductor switches in the apparatus for switching between electric power sources according to the fourth embodiment of the present invention,
• 11 a diagram of an example of the configuration of a device for switching between electric power sources according to a fifth embodiment of the present invention,
• 12 a diagram of a first example of the configuration for turning on a semiconductor switch in the apparatus for switching between electric power sources according to a sixth embodiment of the present invention,
• 13 a diagram showing an example of the operation of the semiconductor switch in the first example of the configuration of the apparatus for switching between electric power sources according to the sixth embodiment of the present invention,
• 14 a diagram of a second example of the configuration for turning on a semiconductor switch in the apparatus for switching between electric power sources according to the sixth embodiment of the present invention,
• 15 a diagram showing an example of the operation of the semiconductor switch in the second example of the configuration of the apparatus for switching between electric power sources according to the sixth embodiment of the present invention,
• 16 a diagram of a third example of the configuration for turning on a semiconductor switch in the apparatus for switching between electric power sources according to the sixth embodiment of the present invention,
• 17 a diagram showing an example of the operation of the semiconductor switch in the third example of the configuration of the apparatus for switching between electric power sources according to the sixth embodiment of the present invention; and
• 18 a block diagram of an example of the hardware configuration of a computer included in the apparatus for switching between electric power sources according to each embodiment of the present invention. Description of Embodiments

Examples of modes for implementing the present invention (hereinafter referred to as "embodiments") will now be described with reference to the accompanying drawings. In this document and the accompanying drawings, components that are identical or have substantially the same functions are denoted by the same reference numerals and will not be described redundantly. Furthermore, if multiple components having the same or similar functions are used, different subscripts may be appended to the same reference numerals for explanatory purposes. Furthermore, the subscripts may be omitted from the description if it is not necessary to distinguish between multiple components.

<First Embodiment>

First, with reference to 1 an example of a vehicle provided with a device for switching between a plurality of electrical power sources is described.

1 is a schematic diagram showing an example in which multiple electric power sources are connected to a vehicle control device mounted on a vehicle. As shown in 1 As shown, the vehicle 100 includes a vehicle control device 110, sensors 120, actuators 130, a first power supply source (“first power supply” in 1 ) 2a and a second power supply source (“second power supply” in 1 ) 2b. The vehicle control device 110 is connected to the sensors 120, the actuators 130, the first power supply source 2a, and the second power supply source 2b.

The vehicle control device 110 includes a device 1 for switching between electric power sources and a controller 111. The controller 111 receives detection signals from the sensors 120 via a signal line d1 and controls the vehicle 100 by sending control signals to the actuators 130 via a control line s1. The controller 111 analyzes the detection signals received from the sensors 120 and generates control signals for controlling the operations of the actuators 130 according to the analysis results. The controller 111 can be configured using, for example, an ECU (electronic control unit). The sensors 120 and the actuators 130 are load devices that consume electric power supplied from the first power source 2a or the second power source 2b.

The device 1 for switching between electrical power sources switches a power supply source between these power sources according to the supply voltages of the first power supply source 2a and the second power supply source 2b. The device 1 for switching between electrical power sources receives electrical power supplied from the first power supply source 2a via a power supply line p1 and receives electrical power supplied from the second power supply source 2b via a power supply line p2. The device 1 for switching between electrical power sources performs the electric current received from the first power supply source 2a or the second power supply source 2b to the sensors 120 via a power supply line p3 and to the actuators 130 via a power supply line p4.

At the in 1 In the configuration described in the example shown, the electric power source switching device 1 is incorporated into the vehicle control device 110. Alternatively, however, the electric power source switching device 1 may be separate from the vehicle control device 110. Further, an alternative configuration may be used to allow the control device 111 to control the electric power source switching device 1. For example, a terminal used by, for example, a mechanic may be connected to the control device 111 so that the control device 111 can control the turning on/off of a first semiconductor switch 3a and a second semiconductor switch 3b according to commands from the terminal.

Next, a configuration of the device 1 for switching between electric power sources according to the first embodiment of the present invention will be described with reference to FIG. 2 described.

2 1 is a diagram showing an example of the configuration of the electric power source switching device 1 according to a first embodiment of the present invention. The electric power source switching device 1 is connected to the first power source 2a and the second power source 2b. For example, the first power source 2a and the second power source 2b are connected to an onboard battery and a power converter such as a DC-DC converter. The electric power source switching device 1 includes the first semiconductor switch 3a, the first semiconductor switch 3b, and a switch control device 5.

The first semiconductor switch 3a is located between load devices 4a to 4c and the first power supply source 2a, which supplies electric power to the load devices 4a to 4c. The electric power from the first power supply source 2a is supplied to a plurality of load devices 4a to 4c through the first semiconductor switch 3a. For example, the first semiconductor switch 3a includes a field-effect transistor M. The field-effect transistor M included in the first semiconductor switch 3a is configured such that a body diode (also referred to as a "parasitic diode") formed between the drain and source electrodes of the first semiconductor switch 3a is connected in the opposite direction to the direction of the power supply from the first power supply source 2a. That is, the anode of the body diode is connected to the source electrode of the field-effect transistor M, and the cathode is connected to the drain electrode of the field-effect transistor M.

The second semiconductor switch 3b is located between the load devices 4a to 4c and the second power supply source 2b, which supplies electric power to the load devices 4a to 4c. The electric power from the second power supply source 2b is supplied to a plurality of load devices 4a to 4c through the second semiconductor switch 3b. For example, the second semiconductor switch 3b includes the field-effect transistor M. The field-effect transistor M included in the second semiconductor switch 3b is configured such that a body diode formed between the drain and source electrodes of the second semiconductor switch 3b is connected opposite to the direction of the power supply from the second power supply source 2b. That is, the anode of the body diode is connected to the source electrode of the field-effect transistor M, and the cathode is connected to the drain electrode of the field-effect transistor M.

The load devices 4a to 4c are configured to supply electric power from either the first power source 2a or the second power source 2b according to the control of the first semiconductor switch 3a and the second semiconductor switch 3b. An output terminal of the first semiconductor switch 3a and an output terminal of the second semiconductor switch 3b are electrically connected, and the plurality of load devices 4a to 4c are connected to the output terminals.

The load devices 4a to 4c are actuators 130 such as electric motors mounted on the vehicle 100, and solenoids or sensors 120 such as cameras. Furthermore, according to the present embodiment, the number of connected load devices is assumed to be three. However, the number of connected load devices is not limited to three. An alternative configuration in which two or more load devices are connected may be used. In the following description, the load devices 4a to 4c are referred to as "load devices 4" when it is not necessary to distinguish between them.

The switch control device 5 outputs control signals (gate voltages) to the first semiconductor switch 3a and the second semiconductor switch 3b to switch the power supply. The switch The gate control device 5 has a voltage comparator 7 and a gate voltage control circuit 6.

The voltage comparator 7 monitors a voltage Va output from the first power source 2a and a voltage Vb output from the second power source 2b and detects a voltage difference Vd (= Va - Vb). The voltage difference Vd is output to the gate voltage control circuit 6.

According to the voltage difference Vd, the gate voltage control circuit 6 generates and outputs a gate voltage Vga of the field-effect transistor M used as the first semiconductor switch 3a and a gate voltage Vgb of the field-effect transistor M used as the second semiconductor switch 3b. When the gate voltage Vga of the first semiconductor switch 3a goes to the high level, the first semiconductor switch 3a is turned on.

When the gate voltage Vgb of the second semiconductor switch 3b goes high, the second semiconductor switch 3b is turned on. In the following description, the first semiconductor switch 3a and the second semiconductor switch 3b are referred to as "semiconductor switch 3" unless it is necessary to distinguish between them.

In 2 An N-channel MOS field-effect transistor is used as the field-effect transistor M. However, a P-channel MOS field-effect transistor or another field-effect transistor may alternatively be used. Alternatively, the semiconductor switches 3 may be designed using a bipolar transistor.

An example of the operation of the device 1 for switching between electric power sources according to the present embodiment will now be described with reference to 3 described.

3 is a diagram showing an example of the operation of the device 1 for switching between electric power sources. The upper part of 3 shows a voltage profile of the gate voltage Vga during switching from the first power supply source 2a to the second power supply source 2b, the middle part of 3 shows a voltage profile of the gate voltage Vgb, and the lower part of 3 shows a current I2 flowing through the second semiconductor switch 3b. In 3 the horizontal axis represents time t.

The voltages Va, Vb output from the first power supply 2a and the second power supply 2b vary due to, for example, the individual difference between the on-board battery and the DC-DC converter, the state of charge, the length of the wiring, and the deterioration of the on-board battery and the power supply wiring. The following describes an example in which the power supply is switched from the first power supply 2a generating a low output voltage to the second power supply 2b generating a high output voltage, assuming that the voltage Va of the first power supply 2a is 13 V and the voltage Vb of the second power supply 2b is 14 V.

As in 3 As shown, when electric power is supplied from the first power supply source 2a to the load devices 4a to 4c (the first power supply S1), the gate voltage Vga of the first semiconductor switch 3a is at a high level and the gate voltage Vga of the second semiconductor switch 3b is at a low level.

When the power supply is to be switched from the state of the first power supply S1 to the second power supply 2b, the gate voltage control circuit 6 first sets the gate voltage Vga of the first semiconductor switch 3a to the low level. Then, the gate voltage control circuit 6 increases the gate voltage Vga to an intermediate voltage Vm between the low level and the high level simultaneously with this voltage setting or after the gate voltage Vgb of the second semiconductor switch 3b starts to rise, and holds the intermediate voltage Vm for a holding time Tm (intermediate state S2).

It should be noted that a certain period of time (rise time) is required for the gate voltage control circuit 6 to increase the gate voltage from the low level to the intermediate voltage Vm. Therefore, it can be said that the time during which the gate voltage is actually held at the intermediate voltage Vm is shorter than the holding time Tm, which starts at the moment the 3 However, because the rise time is shorter than the time during which the gate voltage is held at a constant value of the intermediate voltage Vm, the hold time Tm is considered to be the period between the start of the gate voltage rise and the start of the voltage rise to the next voltage level. For example, the next voltage level in 3 the high level and is in 13 the intermediate voltage of the second stage, as described later.

Subsequently, the gate voltage control circuit 6 increases the gate voltage Vgb of the second semiconductor switch 3b to the high level. This completely switches the power supply from the first power supply 2a to the second power supply 2b (second power supply S3).

As described above, the voltage levels of the gate voltages Vga, Vgb according to the present embodiment exist in three different states: the high level, the low level, and the intermediate voltage. The high level represents a voltage at which the on-resistance of the field-effect transistors serving as the first semiconductor switch 3a and the second semiconductor switch 3b is minimized, for example, a voltage at which the gate-source voltage is 10 V or higher. The low level represents a voltage at which the output characteristics (ID-VDS characteristics) of a field-effect transistor are in a blocked region, for example, a voltage at which the gate-source voltage is 0 V. At the intermediate voltage, the output characteristics of a field-effect transistor are in an unsaturated region, and the source-drain resistance depends on the gate voltage.

The holding time Tm is dynamically set according to the voltage difference Vd between the voltages output from the first power supply 2a and the second power supply 2b. When the voltage difference Vd is small, the holding time Tm is shortened, and when the voltage difference Vd is large, the holding time Tm is lengthened. That is, the gate voltage control circuit 6 changes the holding time Tm to be longer than a predetermined reference time when the voltage difference Vd is greater than a predetermined value, and the gate voltage control circuit 6 changes the holding time Tm to be shorter than the predetermined reference time when the voltage difference Vd is less than or equal to the predetermined value.

According to the present embodiment, a state in which the gate voltage of the semiconductor switch is between the low level and the high level is defined as an "intermediate state." In the conventional device for switching between electric power sources, the voltage profile remains unchanged until the gate voltage Vgb in the intermediate state increases from the low level to the high level, as shown by the thin solid line in the middle part of 3 The holding time limits the inrush current that flows through the semiconductor switch when the electrical power source is switched, and it can also be referred to as the "current limiting time."

When switching is performed between power sources with different voltage values, for example, when switching the power source from the first power source 2a (voltage Va = 13 V) to the second power source 2b (voltage Vb = 14 V) as described in connection with the present embodiment, the inrush current corresponding to the voltage difference Vd between the two power sources occurs. In conventional configurations, a large inrush current exceeding an allowable current indicated by the dot-dash line flows through the second semiconductor switch 3b.

The current I2 flowing through the second semiconductor switch 3b when switching from the intermediate state S2 to the second power supply S3 in the configuration according to the present embodiment will be described below. As shown in the lower part of 3 As shown, a first peak current flows when the gate voltage Vgb of the second semiconductor switch 3b rises to the intermediate voltage Vm, and then, after the first peak current has decreased, a second peak current flows when the gate voltage Vgb rises to the high level.

As described above, the present embodiment is configured to gradually increase the gate voltage Vgb of the second semiconductor switch 3b without abruptly increasing from the low level to the high level. Therefore, a peak current can be dispersed so that the current I2 (peak current) flowing through the second semiconductor switch 3b when switching the electric power source does not exceed the allowable current. Furthermore, the present embodiment is configured to change the power source according to the voltage difference Vd between the output voltages of the first power source 2a and the second power source 2b. Therefore, switching from one power source to another can be performed without exceeding the allowable current. Conventionally, there has been no configuration for changing the holding time Tm of the intermediate voltage Vm in the intermediate state when switching the electric power source according to the voltage difference Vd. Therefore, conventionally, as the voltage difference Vd increases, the peak current of a semiconductor switch increases accordingly and may exceed the allowable current. However, this problem is solved by the present embodiment.

As described above, the electric power source switching device (electric power source switching device 1) according to the first embodiment includes a first semiconductor switch (first semiconductor switch 3a), a second semiconductor switch (second semiconductor switch 3b), and a switch control device (switch control device 5). The first semiconductor switch (first semiconductor switch 3a) is located between the load devices (4a to 4c) and a first power supply source (first power supply source 2a) configured to supply electric power to the load devices (4a to 4c). The second semiconductor switch (second semiconductor switch 3b) is located between the load devices and a second power supply source (second power supply source 2b) configured to supply electric power to the load devices. The switch control device (switch control device 5) controls the drive voltages of the first semiconductor switch and the second semiconductor switch.

When switching from one of the first and second power sources to the other, the switch control device provides an intermediate state in which the semiconductor switch (the second semiconductor switch 3b) connected to the power source (for example, the second power source 2b) configured to supply electric power after switching is maintained in an unsaturated state, and changes the holding time (holding time Tm) of the intermediate state according to the voltage difference (voltage difference Vd) between voltages output from the first and second power sources.

With the above-described configuration of the present embodiment, the holding time (current limiting time) of the intermediate state of a semiconductor switch connected to the power supply that supplies electric power after switching is changed according to the voltage difference between the output voltages of the first power supply and the second power supply. Therefore, even if the output voltages of the first power supply and the second power supply differ, damage to the semiconductor switch due to overcurrent can be prevented, and the power supply can be smoothly switched without interrupting the power supply.

<Second Embodiment>

Next, the electric power source switching device according to a second embodiment will be described. The second embodiment is an example of a configuration in which the first semiconductor switch 3a and the second semiconductor switch 3b are controlled by taking into account the voltage difference Vd between the output voltages of the first power source 2a and the second power source 2b, as well as information related to the load devices 4 (load information). The following description of the electric power source switching device according to the second embodiment focuses on the differences from the first embodiment.

First, the configuration of the apparatus for switching between electric power sources according to the present embodiment will be described with reference to 4 described.

4 1A is a diagram showing an example of the configuration of an electric power source switching device 1A according to the present embodiment. The electric power source switching device 1A includes a switch control device 5A instead of the switch control device 5 of the electric power source switching device 1 according to the first embodiment. Specifically, the electric power source switching device 1A includes the first semiconductor switch 3a, the second semiconductor switch 3b, and the switch control device 5A.

The switch control device 5A outputs control signals to the first semiconductor switch 3a and the second semiconductor switch 3b to switch the power supply. The switch control device 5A includes the voltage comparator 7, a gate voltage control circuit 6A, and load information 8A.

The gate voltage control circuit 6A generates and outputs the gate voltage Vga of the first semiconductor switch 3a (field-effect transistor M) and the gate voltage Vgb of the second semiconductor switch 3b (field-effect transistor M) according to the voltage difference Vd output by the voltage comparator 7. Furthermore, the gate voltage control circuit 6A generates and outputs the gate voltages Vga, Vgb according to the load information 8A based on the equivalent electrical resistance and the equivalent capacitance of the load devices 4a to 4c. The load information 8A is stored, for example, in a memory. The gate voltage control circuit 6A accesses the memory in which the Load information 8A is stored and generates the gate voltages Vga, Vgb.

The present embodiment is characterized in that the gate voltages Vga, Vgb are generated and output in addition to the voltage difference Vd according to the load information 8A. The load information 8A is a parameter based on the equivalent circuit model of the load devices 4a to 4c as shown in 4 The load devices 4a to 4c can be based on an equivalent circuit with the equivalent electrical resistance and the equivalent capacitance, as shown in 4 The load information 8A is based on the equivalent electrical resistance and the equivalent capacitance of the plurality of load devices 4a to 4c. According to the present embodiment, it is desirable that the information representing the electrical characteristics of the load devices include at least the equivalent electrical resistance and the equivalent capacitance. Although the electrical resistance and capacitance of the load devices 4 are given as examples of the electrical characteristics, a reactance component, for example, may be additionally considered.

For example, the load device 4a is represented as an equivalent circuit in which an equivalent electrical resistance R _L 1 is connected in parallel with an equivalent capacitance C1 and an equivalent electrical resistance R _S 1 connected in series. Similarly, the load device 4b is represented as an equivalent circuit in which an equivalent electrical resistance R _L 2 is connected in parallel with an equivalent capacitance C2 and an equivalent electrical resistance R _S 2 connected in series. In addition, the load device 4c is represented as an equivalent circuit in which an equivalent electrical resistance R _L 3 is connected in parallel with an equivalent capacitance C3 and an equivalent electrical resistance R _S 3 connected in series. The equivalent circuits of the load devices 4a to 4c are connected to a power supply line at one end and to ground at the other end.

An example of the procedure for determining a gate voltage profile according to the above-described load information 8A according to the present embodiment will now be described with reference to FIG. 5 and 6 described.

5 is an explanatory diagram showing how the device 1A for switching between electric power sources estimates the inrush current when changing the electric power source using the load information 8A. In 5 The vertical axis represents the current I2 flowing through the second semiconductor switch 3b, and the horizontal axis represents time t. For example, if switching is performed from the first power source 2a to the second power source 2b, the current I2 flowing through the second semiconductor switch 3b can be predicted by the following equation (1).

[Equation 1] $$I2\left(t\right)=i_c+i_R=\frac{V_d}{R_s}{e}^{\frac{1}{C{R}_s}t}+\frac{V_b}{R_L}$$

Here, "ic" is the capacitance charging current of the current I2 flowing through the second semiconductor switch 3b. "i _R " is the DC component of the current I2 flowing through the second semiconductor switch 3b. "t" is the time elapsed since the gate voltage Vgb was applied to the second semiconductor switch 3b. "Vd" is the difference between the voltages output from the first power supply source 2a and the second power supply source 2b (hereinafter also referred to as "supply voltage difference"). "Rs" is the combined parallel resistance of the electrical resistors (Rs1 to Rs3 in 4 ). "C" is the combined parallel capacitance of the equivalent capacitances (C1 to C3) of each load device 4. "Vb" is the output voltage of the second power supply source 2b. " _RL " is the combined parallel resistance of the equivalent electrical resistances ( _RL1 to _RL3 ) of each load device 4.

Based on the above equation (1), the peak current of the inrush current flowing through the second semiconductor switch 3b when switching the electric power source is estimated. If the peak current exceeds the allowable current, the following equation (2) is used, taking into account the source-drain resistance Rsd of the second semiconductor switch 3b, to calculate the value of the source-drain resistance Rsd without exceeding the allowable current.

[Equation 2] $$I2\left(t\right)=i_c+i_R=\frac{V_d}{R_s+R_{sd}}{e}^{-\frac{1}{C\left(R_s+R_{sd}\right)}t}+\frac{V_b}{R_L}$$

After the source-drain resistance Rsd is calculated using equation (2), the gate voltage Vgb at which the source-drain resistance is equal to Rsd is determined based on the electrical characteristics of the field-effect transistor M included in the second semiconductor switch 3b. The gate voltage Vgb can be determined, for example, using the drain current-gate-source voltage characteristics (Id-V _GS characteristics). The value of the gate voltage Vgb determined here is the intermediate voltage value in the intermediate state according to the present invention (intermediate voltage Vm in 6 ).

Next, an example of the operation of an apparatus 1B for switching between electric power sources according to the present embodiment will be described with reference to FIG. 6 described. 6 is a diagram showing an example of the operation of the device 1B for switching between electric power sources. The upper part of 6 shows the voltage profile of the gate voltage Vgb generated by the gate voltage control circuit 6, and the lower part of 6 shows the current I2 of the second semiconductor switch 3b. In 5 the horizontal axis represents time t.

First, the gate voltage control circuit 6 increases the gate voltage Vgb after the electric power source changes from a low level to the intermediate voltage Vm determined as described above. The holding time Tm at the intermediate voltage Vm is determined by the following equation (3) according to the equivalent electrical resistance Rs and the equivalent capacitance C of the load devices 4 and the source-drain resistance Rsd of the field-effect transistor.

[Equation 3] $$Tm=kC\left(R_s+R_{sd}\right)$$

In equation (3), "k" is a constant. When the gate voltage Vgb is increased to the high level after the gate voltage Vgb is maintained in the intermediate state for a period of the holding time Tm, the second semiconductor switch 3b is fully turned on. The current at this voltage profile is I2, the first peak current flows when the gate voltage Vgb is changed to the intermediate voltage Vm, and the second peak current flows when the gate voltage Vgb subsequently rises to the high level. The present embodiment is designed so that the peak current is dispersed into the first peak current and the second peak current according to the voltage difference Vd and the electrical characteristics of the load devices 4. Therefore, the peak current can be changed without exceeding the allowable current.

In the above-described example according to the present embodiment, the holding time Tm is determined from the equivalent electrical resistance and the equivalent capacitance in the manner described above. However, the holding time Tm can be optimized by multiplying the time constant (= C (Rs + Rsd)) in equation (3) by a predetermined coefficient k. That is, the rising curve (rise rate) of the gate voltage Vgb can be varied as needed by the value of k to change the holding time Tm. For example, if the second peak value of the current I2 has a margin for the allowable current, k < 1 can be set so that the holding time Tm is shorter than the time constant, and if the second peak value of the current I2 has no margin for the allowable current, k > 1 can be set so that the holding time Tm is longer than the time constant. In other words, the gate voltage Vgb can be optimized by using the hold time Tm and the source-drain resistance Rsd of the field-effect transistor M of the second semiconductor switch 3b as parameters.

Furthermore, in the above-described example of the present embodiment, the gate voltage Vgb (intermediate voltage Vm) maintained in the intermediate state has a single value. Alternatively, however, multiple voltage values may be set to increase the gate voltage Vgb in two or more steps. These voltage profiles are design parameters and are appropriately set according to, for example, the load devices 4 and the characteristics of the semiconductor switches 3.

As described above, the switch control device (switch control device 5A) according to the second embodiment is configured to change the holding time Tm of the intermediate state according to the voltage difference Vd between the voltages output from the first power source 2a and the second power source 2b and the information representing the electrical characteristics of the load devices 4a to 4c (load information 8A).

In the above-described configuration of the present embodiment, the gate voltage control circuit 6 sets the voltage profile of the gate voltage of the semiconductor switches 3 according to the information relating to the load devices 4 (load information 8A) in addition to the voltage difference Vd. Even if the inrush current changes during the change of the electric power source due to the addition or update of a load device 4, the above-described configuration makes it possible to prevent failure and deterioration of the semiconductor switches 3, which might occur due to the inrush current when the load information changes. In other words, changes in the load devices 4 can be accommodated without replacing the semiconductor switches 3. For example, if the number of connected loads or the current capacity is changed as a result of a later addition, such changes can be handled by a software modification without having to replace the semiconductor switches 3.

In the above description of the present embodiment, the equivalent electrical resistance and equivalent capacitance of the load devices 4 are indicated as load information 8A. However, the load information 8A is not limited to this equivalent electrical resistance and equivalent capacitance. For example, the intermediate voltage Vm and the holding time Tm may be predetermined based on the characteristics of the inrush current flowing through the semiconductor switch 3 and stored in a memory as load information 8A. That is, the advantageous effects of the present invention can be obtained as long as the load information 8A can appropriately change the parameters (Tm, Vm) that determine the voltage profile of the gate voltage depending on the electrical characteristics of the connected load devices 4, and the voltage profile of the gate voltage and the holding time of the intermediate state can be changed.

<Third Embodiment>

Next, the device for switching between electric power sources according to a third embodiment will be described. The third embodiment is an example in which the gate voltage of the semiconductor switches 3 is controlled according to the information representing the electrical characteristics of an activated one of the load devices 4.

The configuration of the apparatus for switching between electric power sources according to the present embodiment will be described with reference to 7 described.

7 1B is a diagram showing an example of the configuration of the electric power source switching device 1B according to the present embodiment. The electric power source switching device 1B is configured substantially the same as the electric power source switching device 1A according to the second embodiment, and the following description of the electric power source switching device 1B focuses on the differences from the second embodiment.

The electric power switching device 1B includes a switch control device 5B instead of the switch control device 5A of the electric power switching device 1 according to the second embodiment. That is, the electric power switching device 1B includes the first semiconductor switch 3a, the second semiconductor switch 3b, and the switch control device 5B. The switch control device 5B includes the voltage comparator 7, a gate voltage control circuit 6B, and the load information 8A.

In addition to the components included in the second embodiment, the present embodiment includes load switches 9a to 9c and a load switch control device 10. The load switches 9a to 9c are located on the supply lines of the load devices 4a to 4c. The load switch control device 10 controls the activation/deactivation of the load switches 9a to 9c according to external commands. The load switch control device 10 can be integrated into the control device 111 of the 1 The vehicle control device 110 shown may be installed. The external commands specify whether the connected load devices 4a to 4c are to be controlled or not.

The switch control device 5B receives a load switch change command input from an electronic control unit (ECU) of a power management system. For example, when faults (or indications of faults) are detected in the load device 4, the load switches 9a to 9c are switched to interrupt the use of the load devices 4 or restrict their functions.

Semiconductor switches comprising a field-effect transistor or mechanical switches such as relays can be used as load switches. The power supply to the load devices 4a to 4c is controlled by the load switches 9a to 9c. In the following description, the load switches 9a to 9c are referred to as "load switch 9" unless it is necessary to distinguish between them.

The load information 8A is based on the equivalent electrical resistance and the equivalent capacitance of the load devices 4a to 4c. However, the load information 8A according to the present embodiment is generated according to switching information related to the load switches 9a to 9c (“switch information” in 7 ) transmitted from the load switch control device 10, namely information relating to the activated load devices 4a to 4c connected to the power supply line.

Alternatively, the load information 8A may include information representing the electrical characteristics of all load devices 4a to 4c, and the load information 8A may be updated and stored in a memory based on the switch information corresponding to the electrical characteristics of a driven load device 4 (the electrical characteristics of the equivalent circuit model).

The gate voltage control circuit 6B has the same function as the gate voltage control circuit 6A according to the second embodiment. The gate voltage control circuit 6B accesses the memory in which the load information 8A is stored and generates the gate voltages Vga, Vgb in the same way as in the second embodiment.

Furthermore, in a case where information regarding the electrical characteristics of the load devices 4a to 4c has been included in the load information 8A, the gate voltage control circuit 6B can extract only information regarding the electrical characteristics of an activated load device 4 from the load information 8A according to the switch information and generate a gate voltage based on the extracted information regarding the electrical characteristics of the activated load device 4. The gate voltage control circuit 6B can obtain the switch information before changing the electric power source by periodically communicating with the load switch control device 10. For example, in 7 Only the load switch 9a is activated, and the load device 4a is connected to the supply line and is thereby driven. The gate voltage control circuit 6B generates a gate voltage corresponding to the load information 8A based on the electrical characteristics of the load device 4a.

The inrush current flowing through the semiconductor switches 3 during the switching of the electric power source is determined by a currently driven load device 4. Therefore, the present embodiment makes it possible to more accurately estimate the inrush current flowing through the semiconductor switches 3 during the switching of the electric power source and to generate an optimal gate voltage.

Furthermore, before switching from one power source to another, the switch control device 5B can interrupt the power supply to one of the load devices 4a to 4c and change the intermediate state holding time Tm according to information representing the electrical characteristics (e.g., equivalent electrical resistance and equivalent capacitance) of an activated load device 4. For example, multiple load devices 4 can be classified in advance as critical devices and non-critical devices, and the non-critical devices can be turned off during the electric power source switch. This makes it possible to reduce the number of load devices 4 connected during the electric power source switch and to reduce the inrush current flowing through the semiconductor switches 3 during the electric power source switch. For example, the critical devices are brake lights, headlights, windshield wipers, and other load devices important for the safe driving of motor vehicles. Non-critical devices are audio devices, air conditioners, power windows, and other load devices that do not affect the safe driving of motor vehicles if they are temporarily deactivated.

After switching the electric power source, the load switch control device 10 supplies electric power to the load devices 4 whose power supply has been interrupted. In the above case, the load switch control device 10 activates the load switches 9 connected to the load devices 4 whose power supply has been interrupted without exceeding the allowable current of the semiconductor switches 3, and thus drives the load devices 4. For example, the load switch control device 10 drives multiple stopped load devices 4 sequentially instead of driving them simultaneously. Alternatively, the load switch control device 10 may prevent load devices 4 with high inrush currents (equivalent capacities) from being activated simultaneously to prevent the allowable current of the semiconductor switches 3 from being exceeded. Conversely, power can be supplied to multiple load devices 4 simultaneously as long as the allowable current of the semiconductor switches 3 is not exceeded.

As described above, the switch control device (switch control device 5B) according to the third embodiment is configured to change the holding time Tm of the intermediate state according to information (load information 8A) representing the electrical characteristics of an activated one of the plurality of load devices 4a to 4c.

In the above-described configuration of the present embodiment, the holding time of the intermediate state of a semiconductor switch connected to the power source that supplies electric current after switching is adjusted according to the voltage difference The difference between the output voltages of the first power supply and the second power supply and the connected load device is changed. This prevents the power switches from being damaged by overcurrent even when the output voltage difference between the first and second power supply sources varies, and the power supply source can be easily changed without interrupting the power supply. In addition, the cost of the semiconductor switches can be reduced because it is not necessary to design under the worst-case current capacity conditions of a load device connected to the device for switching between electrical power sources.

<Fourth Embodiment>

Next, the device for switching between electric power sources according to a fourth embodiment will be described. The fourth embodiment is an example configured to prevent reverse current from flowing from the load devices 4 to the first power source 2a and the second power source 2b, and to prevent through current from flowing between the first power source 2a and the second power source 2b.

First, the configuration of the apparatus for switching between electric power sources according to the present embodiment will be described with reference to 8 described.

8 1C is a diagram showing an example of the configuration of an electric power source switching device 1C according to the present embodiment. The electric power source switching device 1C is configured substantially the same as the electric power source switching device 1A according to the second embodiment, and the following description of the electric power source switching device 1C focuses on differences from the second embodiment. The biggest difference between the electric power source switching device 1C and the electric power source switching device 1A according to the second embodiment is that the electric power source switching device 1C includes a first semiconductor switch 3c and a second semiconductor switch 3d instead of the first semiconductor switch 3a and the second semiconductor switch 3b.

The device 1C for switching between electric power sources includes the first semiconductor switch 3c, the second semiconductor switch 3d, and a switch control device 5C. The electric power from the first power source 2a is supplied to a plurality of load devices 4a to 4c through the first semiconductor switch 3c. The first semiconductor switch 3c includes a plurality of field-effect transistors M1, M2 connected in series so that their body diodes point in opposite directions.

The electric current from the second power source 2b is supplied to a plurality of load devices 4a to 4c through the second semiconductor switch 3d. The second semiconductor switch 3d includes a plurality of field-effect transistors M3, M4 connected in series so that their body diodes point in opposite directions.

The switch control device 5C switches the power supply by outputting control signals (gate voltages) to the field-effect transistors M1, M2 of the first semiconductor switch 3c and the field-effect transistors M3, M4 of the second semiconductor switch 3d. The switch control device 5C includes the voltage comparator 7, a gate voltage control circuit 6C, and the load information 8A.

According to the voltage difference Vd between the output voltages of the first and second power sources 2a, 2b, which is detected by the voltage comparator 7, the gate voltage control circuit 6C generates and outputs a gate voltage Vga1 of the field-effect transistor M1, which is the first semiconductor switch 3c, and a gate voltage Vga2 of the field-effect transistor M2. According to the voltage difference Vd, the gate voltage control circuit 6C generates and outputs a gate voltage Vgb1 of the field-effect transistor M3 used as the second semiconductor switch 3d and a gate voltage Vgb2 of the field-effect transistor M4.

Moreover, the gate voltage control circuit 6C can generate and output the gate voltages Vga1, Vga2 and the gate voltages Vgb1, Vgb2 according to the load information 8A based on the equivalent electrical resistance and the equivalent capacitance of the load devices 4a to 4c in addition to the voltage difference Vd.

According to the present embodiment, as shown in 8 As shown, two field-effect transistors in both the first and second semiconductor switches 3c, 3d are connected back-to-back. The back-to-back connection is a connection configuration in which the body diodes of two field-effect transistors are connected in series opposite each other. This allows to block a reverse current from the load devices 4 to the first and second power supply sources 2a, 2b and to prevent a through current from flowing in the first and second power supply sources 2a, 2b.

Next, an example of the operation of the electric power source switching device 1C according to the present embodiment will be described with reference to FIG. 9 described.

9 is a diagram showing an example of gate voltages Vga1, Vga2, Vgb1, Vgb2 generated by the gate voltage control circuit 6C as an example of the operation of the electric power source switching device 1C. The upper part of 9 shows a voltage profile of the gate voltages Vga1, Vga2 during switching from the first power supply source 2a to the second power supply source 2b, the middle part of 9 shows a voltage profile of the gate voltages Vgb1 and Vgb2, and the lower part of 9 shows a current I2 flowing through the second semiconductor switch 3d. In 9 the horizontal axis represents time t.

As in the case of the first embodiment, in the following description of the present embodiment, it is assumed that the voltage Va of the first power supply source 2a is 13 V and that the voltage Vb of the second power supply source 2b is 14 V, and it refers to an example in which the power supply source is switched from the first power supply source 2a, which generates a low output voltage, to the second power supply source 2b, which generates a high output voltage.

As in 9 As shown, when electric power is supplied from the first power supply source 2a to the load devices 4a to 4c (the first power supply S1), the gate voltages Vga1 and Vga2 of the first semiconductor switch 3c are at a high level and the gate voltages Vgb1 and Vgb2 of the second semiconductor switch 3d are at a low level.

When the power supply source is to be switched from the state of the first power supply S1 to the second power supply source 2b, the gate voltage control circuit 6C first sets the gate voltages Vga1, Vga2 of the first semiconductor switch 3c to the low level.

In the above case, the gate voltage control circuit 6C increases the gate voltage Vgb1 of the second semiconductor switch 3d to the intermediate voltage Vm immediately before the gate voltages Vga1, Vga2 reach the low level. As shown in the middle part of 9 As shown, the present embodiment is configured to provide an overlap period Po in which the gate voltage Vga1 and the gate voltage Vgb1 are simultaneously higher than the low level. When switching from one power supply source to the other during the overlap period Po, the gate voltage control circuit 6C of the switch control device 5C exercises control in which the field effect transistor (for example, the field effect transistor M3) related to the power supply from the other power supply source is placed in the intermediate state before the power supply from the one power supply source is cut off. The advantageous effect of the overlap period will be described later. The gate voltage control circuit 6C maintains the gate voltage Vgb1 at the intermediate voltage Vm (intermediate state S2) during the hold period Tm.

Subsequently, the gate voltage control circuit 6C increases the gate voltage Vgb1 from the intermediate voltage Vm to the high level, and then increases the gate voltage Vgb2 from the low level to the high level. This completely switches the power supply from the first power supply 2a to the second power supply 2b (second power supply S3).

As in the first embodiment, the holding time Tm is dynamically set according to the voltage difference Vd between the voltages output from the first power supply 2a and the second power supply 2b. When the voltage difference Vd between the output voltages of the first and second power supplies 2a, 2b is small, the holding time Tm is shortened, and when the voltage difference Vd is large, the holding time Tm is lengthened. According to the present embodiment, a state in which the gate voltage Vgb1 of the second semiconductor switch 3d of the field-effect transistor M3 is between the low and high levels is defined as an "intermediate state."

The current flowing through the second semiconductor switch 3d as a result of the above-described control of the switching of the power supply is in the lower part of 9 represented as current I2. At time t0, the gate voltage Vgb1 begins to rise from the low level. The first peak current flows when the gate voltage Vgb1 rises to the intermediate voltage Vm (time t1), and then, after the first peak current has decreased, the second peak current flows when the gate voltage Vgb1 rises to the high level (time t2). Subsequently, a third peak current flows when the gate voltage Vgb2 rises to the high level (time t3). When the gate voltage voltages Vgb1, Vgb2 are both at the high level (time t4), the power supply source is switched entirely to the second power supply source 2b.

As described above, the switch control device (switch control device 5C) according to the fourth embodiment provides the intermediate state in which the field effect transistor (for example, the field effect transistor M3) whose body diode is oriented opposite to the direction of the power supply during switching from one power source to another is maintained in the unsaturated state, and ends the holding time of the intermediate state according to the voltage difference Vd between the voltages output from the first and second power sources 2a, 2b.

Alternatively, the switch control device (switch control device 5C) according to the present embodiment may be configured to provide the intermediate state in which the field-effect transistor (for example, the field-effect transistor M3) whose body diode is oriented opposite to the power supply direction during switching from one power source to another is maintained in the unsaturated state, and change the holding time of the intermediate state according to the information representing the electrical characteristics of the load devices 4a to 4c. Another alternative is to change the holding time Tm of the intermediate state according to the voltage difference Vd and the information representing the electrical characteristics of the load devices 4a to 4c.

As described above, the present embodiment makes it possible to disperse the peak current so as to prevent the current I2 (peak current) flowing through the second semiconductor switch 3d from exceeding the allowable current indicated by the dashed line. Furthermore, the present embodiment is configured so that the power supply source can be changed according to the voltage difference Vd between the output voltages of the first power supply source 2a and the second power supply source 2b. Therefore, switching from one power supply source to another can be performed without exceeding the allowable current.

The advantageous effect of providing the overlap period Po for the gate voltages Vga1, Vgb1 of the first and second semiconductor switches 3c, 3d will now be described with reference to 10 described.

10 is an explanatory diagram showing the advantageous effect of providing the overlap period Po for the gate voltage Vga1 of the first semiconductor switch 3c and for the gate voltage Vgb1 of the second semiconductor switch 3d.

The example from 10 shows the operations of the field effect transistors M1 to M4 contained in both the first and second semiconductor switches 3c, 3d during switching from the first power supply source 2a to the second power supply source 2b.

As in 10 As shown, when electric power is supplied to the load devices 4a to 4c from the first power supply source 2a (first power supply S1), the field-effect transistors M1, M2 of the first semiconductor switch 3c are turned on, while the field-effect transistors M3, M4 of the second semiconductor switch 3d are turned off. When electric power is supplied to the load devices 4a to 4c from the second power supply source 2b (second power supply S3), the field-effect transistors M1, M2 of the first semiconductor switch 3c are turned off, while the field-effect transistors M3, M4 of the second semiconductor switch 3d are conversely turned off.

During the overlap period Po, field-effect transistors M1 and M3 are turned on, while field-effect transistors M2 and M4 are turned off. This means that field-effect transistors M2 and M4 are placed in a state where a current flows through each of the body diodes, forming a parallel diode circuit.

Conversely, the present embodiment allows the switching operation to be performed without interrupting the power supply. Furthermore, according to the present embodiment, the body diodes between the first power supply 2a and the second power supply 2b are in a reverse-biased configuration. Therefore, the through current between the first and second power supply sources 2a, 2b can be interrupted.

According to the present embodiment, the holding time Tm and the intermediate voltage Vm are set according to the voltage difference Vd between the output voltages of the first and second power sources 2a, 2b. However, these parameters may also be set according to the voltage difference Vd and the load information 8A, as in the case of the second embodiment. Moreover, the device 1C for switching between electric power sources according to the present embodiment may be provided with the third embodiment, in which the information relating to an activated one of the load devices 4 is used.

Although the overlap period Po has been described in connection with the present embodiment, the overlap period is not an essential requirement for the present embodiment. However, the configuration of the electric power switching device 1C in which the overlap period Po is provided for the gate voltages between the first and second semiconductor switches 3c, 3d cannot be applied to the first to third embodiments. This is because the first to third embodiments do not have a reverse-biased configuration formed by two field-effect transistors such as the first semiconductor switch 3c and the second semiconductor switch 3d. Therefore, when the overlap period is provided for the gate voltages of the first and second semiconductor switches 3a, 3b according to the first to third embodiments, the through current flows between the first power supply source 2a and the second power supply source 2b.

<Fifth Embodiment>

Next, the electric power source switching device according to a fifth embodiment will be described. The fifth embodiment is an example in which the electric power source switching device forming a parallel diode circuit when switching the electric power source is configured to suppress an increase in voltage drop and electric power loss due to the forward voltage of a body diode.

The configuration of the apparatus for switching between electric power sources according to the present embodiment will be described with reference to 11 described.

11 1D is a diagram showing an example of the configuration of an electric power source switching device 1D according to the present embodiment. The electric power source switching device 1D is configured substantially the same as the electric power source switching device 1C according to the fourth embodiment, and the following description of the electric power source switching device 1D focuses on differences from the fourth embodiment. The biggest difference between the electric power source switching device 1D and the electric power source switching device 1C according to the fourth embodiment is that the electric power source switching device 1C has ideal diode control circuits 11a, 11b.

The electric power switching device 1D includes a first semiconductor switch 3e, a second semiconductor switch 3f, and a switch control device 5D. The electric power from the first power source 2a is supplied to a plurality of load devices 4a to 4c through the first semiconductor switch 3e. As in the case of the first semiconductor switch 3c according to the fourth embodiment, the first semiconductor switch 3e is configured such that the field-effect transistor M1 and the field-effect transistor M2 are oppositely connected. However, the fifth embodiment differs from the fourth embodiment in that the gate voltage of the field-effect transistor M2 is input from the ideal diode control circuit 11a.

The electric power from the second power source 2b is supplied to a plurality of load devices 4a to 4c through the second semiconductor switch 3f. As with the second semiconductor switch 3d according to the fourth embodiment, the second semiconductor switch 3f is configured such that the field-effect transistor M2 and the field-effect transistor M4 are connected in opposite directions. However, the fifth embodiment differs from the fourth embodiment in that the gate voltage of the field-effect transistor M4 is input from the ideal diode control circuit 11b.

The switch control device 5D switches the power supply by outputting control signals (gate voltages) to the field-effect transistor M1 of the first semiconductor switch 3e and the field-effect transistor M3 of the second semiconductor switch 3f. The switch control device 5D includes the voltage comparator 7, the gate voltage control circuit 6A, and the load information 8A. The switch control device 5D may have the same configuration as the switch control device 5A according to the second embodiment. Furthermore, the switch control device 5D may have the same configuration as the switch control device 5A according to the first embodiment, without referring to the load information 8A.

According to the voltage difference Vd between the output voltages of the first and second power supply sources 2a, 2b, which is detected by the voltage comparator 7, the gate voltage control circuit 6A generates a gate voltage Vga1 of the field effect transistor M1 as the first semiconductor switch 3e and a gate Voltage Vgb1 of field-effect transistor M3 as the second semiconductor switch 3f and outputs it. Furthermore, the gate voltage control circuit 6A can generate and output the gate voltage Vga1 of field-effect transistor M1 and the gate voltage Vgb1 of field-effect transistor M3 according to the load information 8A based on the equivalent electrical resistance and equivalent capacitance of the load devices 4a to 4c in addition to the voltage difference Vd.

With reference to 11 Note that the gate voltage Vga2 of the field-effect transistor M2 in the first semiconductor switch 3e is controlled by the ideal diode control circuit 11a. In the second semiconductor switch 3f, the gate voltage Vgb2 of the field-effect transistor M4 is controlled by the ideal diode control circuit 11b.

The ideal diode control circuit 11a includes operational amplifiers 12a, 13a, and a transistor 14a. The operational amplifiers 12a, 13a detect the direction of an electric current according to the drain voltage and source voltage of the field-effect transistor M2. The transistor 14a adjusts the gate voltage Vga2 according to the outputs of the operational amplifiers 12a, 13a.

The power supply of the operational amplifiers 12a, 13a is not shown. In the example from 11 A bipolar transistor is used as transistor 14a. However, the present invention is not limited to the use of a bipolar transistor.

The operational amplifier 12a applies a high-level signal to the gate of transistor 14a when the current flowing through the field-effect transistor M2 is reverse-biased (reverse biased with respect to the body diode). For example, when the second semiconductor switch 3f is turned on and the output voltage of the second power supply 2b is higher than that of the first power supply 2a, the current flowing through the field-effect transistor M2 is reverse-biased. When the current flowing through the field-effect transistor M2 is reverse-biased, the operational amplifier 12a turns on the transistor 14a and pulls down the gate voltage Vga2 to immediately turn off the field-effect transistor M2.

The operational amplifier 13a applies a high-level signal to the gate of the field-effect transistor M2 when the current flowing through the field-effect transistor M2 is forward-biased (forward-biased with respect to the body diode). Operating on a boosted power supply, the operational amplifier 13a sets the gate voltage Vga2 to the high level to activate the field-effect transistor M2 when the current flowing through the field-effect transistor M2 is forward-biased.

The above-described configuration of the ideal diode control circuit 11a enables diode operation with a reduced voltage drop. The ideal diode control circuit 11b has a similar configuration.

The ideal diode control circuit 11b includes operational amplifiers 12b, 13b, and a transistor 14b. The operational amplifiers 12b, 13b detect the direction of an electric current according to the drain voltage and source voltage of the field-effect transistor M4. A transistor 14b adjusts the gate voltage Vgb2 according to the outputs of the operational amplifiers 12b, 13b.

The operational amplifier 12b applies a high-level signal to the gate of transistor 14b when the current flowing through a field-effect transistor Mf is reverse-biased (reverse biased with respect to the body diode). For example, when the first semiconductor switch 3e is turned on and the output voltage of the first power supply 2a is higher than that of the second power supply 2b, the current flowing through the field-effect transistor M4 is reverse-biased. When the current flowing through the field-effect transistor M4 is reverse-biased, the operational amplifier 12b turns on the transistor 14b and pulls down the gate voltage Vgb2 to immediately turn off the field-effect transistor M4.

Operational amplifier 13b applies a high-level signal to the gate of field-effect transistor M4 when the current flowing through field-effect transistor M4 is forward-biased (forward-biased with respect to the body diode). Operating on a boosted power supply, operational amplifier 13b sets the gate voltage Vgb2 to a high level to activate field-effect transistor M4 when the current flowing through field-effect transistor M4 is forward-biased.

As described above with respect to a plurality of field-effect transistors included in the semiconductor switch connected to one power supply source and provided with body diodes oriented in the forward direction with respect to the direction of the power supply (for example, field-effect transistors M2) and a plurality of field-effect transistors included in the semiconductor switch connected to the other power supply source, the switches control device (switch control device 5D) in the device for switching between electric power sources (device 1D for switching between electric power sources) according to the fifth embodiment, the field-effect transistors (field-effect transistors M2, M4) turn off when the current flowing through the field-effect transistors (for example, field-effect transistors M2, M4) whose body diodes are oriented in the forward direction with respect to the direction of the power supply is oriented opposite to the direction of the output supply.

According to the fourth embodiment described above, a parallel diode circuit is formed using the body diodes of the field-effect transistors M2, M4 when switching the electric power source. However, such a configuration has a problem in that the forward voltage of the body diodes causes an increase in the voltage drop and the loss of electric power. In contrast, the present embodiment is designed to use field-effect transistors with a low on-resistance to provide a function similar to a diode. This can prevent damage caused by the through current flowing between the first and second power sources 2a, 2b and reduce the voltage drop and the loss of electric power.

<Sixth Embodiment>

Next, the device for switching between electric power sources according to a sixth embodiment will be described. The first and second embodiments were described with reference to an example in which the gate voltages Vga, Vgb during turn-on of the first and second semiconductor switches 3a, 3b are controlled by a two-stage voltage profile indicating a period in which the gate voltages Vga, Vgb are maintained at the intermediate voltage. However, the present invention is not limited to such a configuration. For example, the configuration for turning on the first semiconductor switch 3 may be as indicated in the following examples of the first to third configurations.

(First configuration example for switching on the semiconductor switch)

First, the first configuration for turning on the semiconductor switch 3 is described below with reference to the 12 and 13 The first configuration is an example in which the gate voltage generated by a voltage source is increased in three or more steps according to a voltage profile.

12 1 is a diagram showing an example of the first configuration for turning on the semiconductor switch 3 of the electric power source switching device according to the present embodiment. In the first configuration example, electric power is supplied to the load device 4 from the power source 2 when the field-effect transistor M of the semiconductor switch 3 is turned on according to the gate voltage generated by a voltage source 15.

13 is a diagram showing an example of the operation of the semiconductor switch 3 in the first example of the configuration of the electric power source switching device according to the present embodiment. 13 the vertical axis represents the gate voltage of the field effect transistor M and the horizontal axis represents the time t. 13 shows an example of the voltage profile, indicating that the gate voltage, when rising from the low to the high level, rises in three stages, passing through a first intermediate state S21 and a second intermediate state S22. 13 Additionally, an example shows where the gate voltage (intermediate voltage) is maintained at a higher value in the first and second intermediate states S21, S22, as indicated by the dashed lines. In addition to the values of the intermediate voltages in the first and second intermediate states S21, S22, the holding time Tm in each of the first and second intermediate states S21, S22 can also be appropriately changed.

(Second configuration example for switching on the semiconductor switch)

Next, the second configuration for turning on the semiconductor switch 3 will be described below with reference to the 14 and 15 The second configuration is an example in which the gate voltage is controlled by a current source using the electrical resistance component and the capacitance component of an external circuit connected to the gate of the field-effect transistor.

14 is a diagram showing an example of the second configuration for turning on the semiconductor switch 3 of the electric power source switching device according to the present embodiment. In the example of the second configuration, a power source 16 is connected to the gate of the field effect transistor M of the semiconductor switch 3 via an electric resistor 17. Further, a capacitor 18 is connected at one end to the connection center between between the gate of the field-effect transistor M and the electrical resistor 17, and the other end is grounded. The electrical resistor 17 and the capacitor 18 form a so-called CR circuit. The current output from the current source 16 passes through the CR circuit, is input to the gate, and then turns on the field-effect transistor M of the semiconductor switch 3. Consequently, electric current is supplied to the load device 4 from the power source 2. The CR circuit described above can be used to adjust the value of the gate voltage in the intermediate state (at the intermediate voltage) and the holding time Tm.

15 is a diagram showing an example of the operation of the semiconductor switch 3 in the second example of the configuration of the electric power source switching device according to the present embodiment. As shown in 15 As shown, the time constant of the CR circuit can be adjusted to change the speed at which the gate voltage rises from the low level to the high level (corresponding to the hold time Tm). For example, the time constant of the CR circuit can be adjusted to increase the gate voltage more quickly, thereby shortening the intermediate state (the hold time Tm). Furthermore, as the amount of electric current supplied from the power source 16 is increased, the gate voltage rises to the high level more quickly. That is, the amount of electric current supplied from the power source 16 can be adjusted to adjust the hold time Tm during which the gate voltage is within the range of the intermediate voltage (in the intermediate state). In this case, the gate voltage in the intermediate state is not maintained at a constant value, as was the case with the intermediate voltage Vm described above.

(Third configuration example for switching on the semiconductor switch)

Next, the third configuration for turning on the semiconductor switch 3 will be described below with reference to the 16 and 17 The third configuration is an example in which a PWM (pulse width modulation) generator is provided to apply a PWM waveform to the gate as an intermediate state. Also in this configuration, the intermediate state can be provided in the semiconductor switch to obtain the same advantageous effects as those provided by the above-mentioned configuration examples.

16 is a diagram showing an example of the third configuration for turning on the semiconductor switch 3 of the electric power source switching device according to the present embodiment. 16 The example of the third configuration shown indicates a configuration in which the voltage source 15 is in 12 is replaced by a PWM generator 19. In the example of the third configuration, the field-effect transistor M of the semiconductor switch 3 is turned on according to a PWM signal output from the PWM generator 19. This supplies electric current from the power source 2 to the load device 4. At this time, the intermediate state (intermediate voltage) of the gate voltage is generated by controlling the duty cycle of the PWM signal.

17 1 is a diagram showing an example of the operation of the semiconductor switch 3 in the third example of the configuration of the electric power source switching device according to the present embodiment. The gate voltage in the intermediate state (corresponding to the intermediate voltage Vm) can be adjusted by controlling the duty cycle of the PWM signal. For example, when the duty cycle of the PWM signal is constant, the gate voltage is maintained at the intermediate voltage Vm. Further, the time of application of the PWM signal (the period during which the low and high levels are repeated) corresponds to the holding time Tm of the intermediate state.

[Computer hardware configuration]

A hardware configuration of a computer included in the apparatus for switching between electric power sources in each of the above-described embodiments will now be described with reference to 18 described.

18 is a block diagram showing an example of the hardware configuration of a computer included in the device for switching between electric power sources according to each embodiment. 18 The computing device 20 shown is the hardware used as a so-called computer.

The computing device 20 includes a CPU (central processing unit) 21, a ROM (read only memory) 22, a RAM (random access memory) 23, a non-volatile memory 26, and a network interface 27, all connected to a bus.

The CPU 21 is an example of a processor serving as a computing device. The ROM 22 and the RAM 23 are examples of memories. For example, the load information 8A is stored in the ROM 22 or the non-volatile memory 26.

The non-volatile memory 26 is a non-volatile storage element that has a higher capacity than the memories. A program for implementing the functions of the device for switching between electrical power sources in each of the above-described embodiments is stored in the non-volatile memory 26. The non-volatile memory 26 is an example of a computer-readable non-volatile recording medium. The program may be stored in the ROM 22.

The network interface 27 includes, for example, a communication device that controls communication with other devices (e.g., the ECU) via a network such as a communication line or a CAN. The network interface 27 is an example of an input/output device.

Although an example of the hardware configuration of the computer included in the device for switching between electric power sources is described with reference to 18 described, the hardware configuration of a computer included in the control device 111 may be similar to the hardware configuration described above.

Furthermore, the present invention is not limited to the embodiments described above. It is obvious that the present invention can be applied to various other applications and that various other modifications can be made thereto without departing from the spirit thereof as described in the appended claims. For example, the above embodiments have been described in detail in order to facilitate understanding of the present invention, and the present invention is not necessarily limited to having all of the described configurations. Furthermore, some of the components mentioned above in one embodiment may be replaced with the components in another embodiment. Moreover, the components in one embodiment may be added to the components in another embodiment. In addition, part of the configuration of each of the embodiments may be expanded or exchanged and removed from other configurations.

Furthermore, the aforementioned components, functions, and processing sections may be implemented partially or entirely in hardware, for example, by designing integrated circuits. Processor devices in the general sense, such as an FPGA (field-programmable gate array) or an ASIC (application-specific integrated circuit), may be used as hardware.

Furthermore, control lines and information lines considered necessary for the explanation are indicated in connection with the embodiments described above. Not all of the control lines and information lines relevant to products are indicated. In fact, almost all components can be considered interconnected.

List of reference symbols

1, 1A to 10: Device for switching between electrical power sources, 2a: first power supply source, 2b: second power supply source, 3: semiconductor switch, 3a, 3c, 3e: first semiconductor switch, 3b, 3b, 3f: second semiconductor switch, 4, 4a to 4c: load device, 5, 5A to 5D: switch control device, 6, 6A, 6C: gate voltage control circuit, 7: voltage comparator, 8A: load information, 9a to 9c: load switch, 10: load switch control device, 11a, 11b: ideal diode control circuit, 12a, 12b, 13a, 13b: operational amplifier, 14a, 14b: transistor, 15: voltage source, 16: current source, 19: PWM generator, 100: Vehicle, 110: Vehicle control device, 120: Sensors, 130: Actuators

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2019-514328 [0004]

Claims (13)

A device for switching between electrical power sources, comprising: a first semiconductor switch arranged between a load device and a first power supply source configured to supply electrical power to the load device, a second semiconductor switch arranged between the load device and a second power supply source configured to supply electrical power to the load device, and a switch control device that controls drive voltages of the first and second semiconductor switches. The switch control device, when switching from one of the first and second power supply sources to the other, provides an intermediate state in which the semiconductor switch connected to the power supply source configured to supply electrical current after switching is maintained in an unsaturated state, and changes the holding time of the intermediate state according to the difference between the voltages output by the first and second power supply sources. Device for switching between electrical power sources according to Claim 1 wherein the switch control device changes the holding time to be longer than a reference time when the voltage difference is greater than a predetermined value, and changes the holding time to be shorter than the reference time when the voltage difference is less than or equal to the predetermined value. Device for switching between electrical power sources according to Claim 2 , wherein the switch control device changes the holding time of the intermediate state according to the voltage difference and information representing electrical characteristics of the load device. Device for switching between electrical power sources according to Claim 3 wherein an output terminal of the first semiconductor switch and an output terminal of the second semiconductor switch are electrically connected, and a plurality of load devices are connected to the output terminals. Device for switching between electrical power sources according to Claim 4 , wherein the switch control device changes the holding time of the intermediate state according to the information representing the electrical characteristics of an activated one of the plurality of load devices. Device for switching between electrical power sources according to Claim 5 , wherein the switch control device interrupts the power supply to one of the plurality of load devices before switching from one power supply source to the other, and wherein the switch control device changes the holding time of the intermediate state according to the information representing the electrical properties of an activated one of the plurality of load devices. Device for switching between electrical power sources according to Claim 1 , wherein the first and second semiconductor switches are designed such that a plurality of field-effect transistors are connected in series such that body diodes are oriented in opposite directions, and wherein the switch control device, when switching from one power supply source to the other, provides an intermediate state in which the field-effect transistor, whose body diode is oriented opposite to the direction of the power supply, is held in the unsaturated state, and changes the holding time of the intermediate state according to the difference between the voltages output from the first and second power supply sources. Device for switching between electrical power sources according to Claim 7 wherein the switch control device, when switching from one power supply source to another, provides an intermediate state in which the field effect transistor, whose body diode is oriented opposite to the direction of the power supply, is maintained in the unsaturated state, and changes the holding time of the intermediate state according to the information representing electrical characteristics of the load device. Device for switching between electrical power sources according to Claim 7 or 8 wherein the switch control device, when switching from one power supply source to the other, exercises control such that the other field effect transistor related to the power supply from the other power supply source is placed in the intermediate state before the power supply from the one power supply source is interrupted. Device for switching between electrical power sources according to Claim 7 or 8 , wherein the switch control device with respect to a plurality of field effect transistors included in the semiconductor switch which is connected to a power supply source and is provided with body diodes oriented in the forward direction with respect to the direction of the power supply and a plurality of field-effect transistors included in the semiconductor switch connected to the other power supply source, which disconnects the field-effect transistors when the current flowing through the field-effect transistors, whose body diodes are forward-biased with respect to the direction of the power supply, is oriented opposite to the direction of the output supply. Device for switching between electrical power sources according to Claim 3 or 8 , wherein the information representing the electrical properties of the load device comprises at least an equivalent electrical resistance and an equivalent capacitance. A vehicle control device comprising: a control device that controls a vehicle, and a device for switching between electrical power sources, wherein the device for switching between electrical power sources comprises a first semiconductor switch, a second semiconductor switch, and a switch control device. The first semiconductor switch is arranged between a load device located in the vehicle and a first power supply source configured to supply electrical power to the load device, and the second semiconductor switch is arranged between the load device and a second power supply source configured to supply electrical power to the load device. The switch control device controls the drive voltages of the first and second semiconductor switches. wherein, when switching from one of the first and second power supply sources to the other, the switch control device provides an intermediate state in which the semiconductor switch connected to the power supply source configured to supply electrical power after switching is maintained in an unsaturated state, and changes the holding time of the intermediate state according to the difference between the voltages output from the first and second power sources. A method for switching between electrical power sources used by a device for switching between electrical power sources comprising a first semiconductor switch, a second semiconductor switch, and a switch control device, wherein the first semiconductor switch is arranged between a load device and a first power supply source configured to supply electrical power to the load device, and the second semiconductor switch is arranged between the load device and a second power supply source configured to supply electrical power to the load device, wherein the switch control device controls the drive voltages of the first and second semiconductor switches, the method for switching the electrical power source comprising the steps of: during switching from one of the first and second power supply sources to the other, causing the switch control device to provide an intermediate state in which the semiconductor switch connected to the power supply source configured to supply electrical current after switching is maintained in an unsaturated state, and detecting the difference between the voltages output by the first and second power supply sources, and changing the holding time of the intermediate state according to the Voltage difference.

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