DE102019209654A1 - Vehicle electrical system - Google Patents

Abstract

A vehicle electrical system (FB) is equipped with a DC voltage charging connection (GA), an accumulator (AK), a galvanically isolating DC voltage converter (GW), and an electric drive (I, M). The accumulator (AK) is connected to a connection point (VP) via a first switch (S1). The DC voltage charging connection (GA) is connected to the connection point (VP) via a second switch (S2). The connection point (VP) is connected to the electrical drive (I, M) via the galvanically isolating DC voltage converter (GW). The electric drive (I, M) is connected to the connection point (VP) via a third switch (S3). There is a connection between the connection point (VP) and the DC voltage converter (GW). This connection is connected to the electric drive (I, M) via the DC voltage converter (GW).

Description

Vehicles with an electric drive have an accumulator that can supply the electric drive with energy. It is known that the vehicles have a corresponding charging connection for charging the accumulator (“plug-in vehicles”). The functions of charging and supplying the electric drive are implemented by a vehicle electrical system, with various requirements resulting, as shown below.

To control the electric drive, semiconductor switches are operated in a clocked manner, which causes interference. In the case of the electric drive (or also in other, clocked-controlled electrical components of the vehicle electrical system), a filter capacity is therefore used to suppress the interference. In particular, Cy capacitors are used, which essentially consist of a capacitor between vehicle ground and a supply potential. These capacitors divert interference signals, which result from the clocked operation of the semiconductor switches, to ground. However, these capacitors are an obstacle to the charging function, since it must be ensured that the energy stored in the capacitors does not lead to a high contact voltage at the charging connection.

It is therefore an object of the invention to show a possibility with which a vehicle electrical system can be formed in a simple manner, with which both disturbances resulting from a clocked operating mode can be suppressed and excessively high contact voltages can be avoided.

This object is achieved by the vehicle electrical system according to claim 1. Further properties, features, embodiments and advantages emerge from the dependent claims, the description and the figure.

A vehicle electrical system is proposed which has a DC voltage charging connection, an accumulator and a galvanically isolating DC voltage converter. The vehicle electrical system also includes an electric drive. The accumulator is connected to the connection point via a first switch. This results in a simple connection between the accumulator and the converter or other components. The connection point is connected to the DC voltage charging connection via a second switch. Furthermore, the connection point is connected via a switch to the electric drive and the DC voltage converter connected therein. Another connection exists between the connection point and the DC voltage converter, but with one side of the DC voltage converter which is opposite to the electric drive. The connection point and the converter are thus connected to one another via the third switch on the one hand and via the connection on the other. Both sides of the transducer are connected to the connection point via different paths, one side being connected to the connection point via the third switch and the other side being connected to the connection point via said connection. The connection can be switchable.

As a result of this arrangement, the accumulator is connected to the remaining on-board network only via a single switch. However, the second switch enables the DC voltage charging connection to be connected to the accumulator or targeted disconnection (for example when driving). The electric drive can be operated directly from the accumulator via the first and the third switch (or energy can be transferred in the opposite direction during recuperation), while the second switch can disconnect the connection point from the DC charging connection when driving. The electric drive can also be supplied with energy from the accumulator via the connection (instead of via the third switch), the accumulator then being supplied via the first switch and the connection and via the galvanically isolating DC voltage converter.

The DC voltage converter can also be used during charging by supplying the DC voltage converter via the second switch and the connection, which in turn can supply additional components during charging, such as components such as an electrical heater and / or a low-voltage on-board network branch.

There are therefore various options for charging or supplying components (including the electric drive), and these can also be set differently for different battery voltages, for example. During charging, the DC voltage connection can be connected directly to the accumulator, whereby on the one hand the third switch and on the other hand the galvanically isolating DC voltage converter ensure that filter capacitances in the electric drive or in other components cannot affect the DC voltage charging connection. This provides protection against excessively high contact voltage. At the same time, it is possible that only a single connection is necessary to connect the accumulator (or the first switch) to the remaining vehicle electrical system, so that only one connection is required for maintenance minimum number of connections must be disconnected or connected.

A vehicle electrical system is therefore proposed which comprises a DC voltage charging connection, an accumulator, a galvanically isolating DC voltage converter and an electric drive. The accumulator is preferably a high-voltage accumulator. The accumulator is connected to a connection point via a first switch (of the vehicle electrical system). The DC charging connection is connected to the connection point via a second switch (of the vehicle electrical system). The first and the second switch are thus located on different sides of the connection point.

The connection point is connected to the electrical drive via the galvanically isolating DC voltage converter. This can be referred to as the first connection path. The electric drive is also connected to the connection point via a third switch. This can be referred to as the second connection path. The connection point is thus connected to the electric drive via two different connection paths, one of the paths (the first connection path) leading via the DC / DC converter (and thus including it), and the other path (i.e. the second connection path) being converter-free.

There is also a connection between the connection point and the DC / DC converter. The connection is part of the first connection path. Thus, the connection point (in the following order) is connected to the electric drive via the connection and the DC voltage converter. This connection between the connection point and the DC voltage converter and the DC voltage converter itself connect the connection point to the electric drive. The first and second connection paths both start from the connection point. The first and the second connection path are connected to different sides of the DC-DC converter. The connection point is connected to a first side of the DC voltage converter via the connection. This is the side of the DC / DC converter that is opposite to the electric drive. The connection point is also connected to the second side of the DC-DC converter via the third switch. This side is the side of the DC / DC converter connected to the electric drive.

The DC voltage converter is set up to transmit and convert a DC voltage between the two sides. The first and second connection paths meet at the connection point, the second switch (and thus also the DC voltage connection via the second switch) being connected to the connection point, and the accumulator also being connected to the connection point (via the first switch).

The vehicle electrical system described here is preferably a high-voltage electrical system. The prefix “high voltage” here means a nominal voltage of the relevant component of at least 60 volts, in particular of at least 400 volts, 600 volts, 800 volts or 1000 volts. The DC voltage charging connection can be configured in accordance with a standard for cable-based charging of electric vehicles (plug-in vehicles). The DC voltage charging connection is preferably equipped as a contact group of a plug connection device (for example a socket), which can also have contacts for AC voltage transmission and thus contacts of an AC voltage charging connection). The mentioned connections and connections are preferably two-pole / two-wire and comprise a first and a second supply potential, for example a negative pole and a positive pole.

The galvanically isolating DC voltage converter has, in particular, a transformer which has galvanically isolated windings. The DC / DC converter includes in particular a chopper and a rectifier, which are connected to different sides of the transformer.

The switches are in particular electromechanical switches, but can also be designed as semiconductor switches. The switches are two-pole and thus comprise a first switching element and a second switching element, the two switching elements being assigned to two different supply potentials. This results in complete separation when the respective switch is opened. H. a separation of both supply potentials (when the relevant switch is open).

The first switch can be connected to the connection point via a first battery connection device and a second battery connection device. A line connects the battery connection device to one another. The battery connection devices are in particular plug-in devices, for example sockets. The line includes connecting conductors and connecting elements such as plug-in elements that can be connected to the battery connection device. The line comprises in particular two high-voltage conductors, namely a first high-voltage conductor for the positive supply potential and a second conductor for the negative supply potential. In particular, the line is two-core (at least in relation to the high-voltage conductor). It signal lines can also be provided and / or shielding. In particular, the accumulator is connected to the rest of the vehicle electrical system (via the first switch) only via the battery connection devices. The connection between the accumulator and the remaining vehicle electrical system or the accumulator and the first switch on the one hand and the remaining vehicle electrical system provides only two supply potentials, in particular in the form of a two-wire line. The line is therefore also preferably two-core; the battery connection devices in particular comprise only two high-voltage wires.

A separate battery housing is provided for the accumulator. Another housing, namely a converter housing, is provided for the DC / DC converter. This optional arrangement of the accumulator and the DC-DC converter in different housings enables a modular topology, and in particular a simple exchange and a simple design of an accumulator device which comprises the accumulator. The first switch and the accumulator can be arranged in the battery housing. The first switch is preferably the only switch (the only high-voltage switch) in the battery housing. Furthermore, the battery housing does not include a further converter, but can have safety measures such as a fuse and / or a battery management unit. Further signal connections on the battery housing are possible.

The DC / DC converter and the second and third switches are arranged in the converter housing. Further switches can also be provided in the converter housing. The switch-related functionality is thus focused on the converter housing. The converter housing can form a converter module with the DC voltage converter located therein. In the same way, the accumulator and the first switch, together with the battery housing, can form a battery module. Both modules are connected to one another via the line and the relevant first and second battery connection devices. The first battery connection device can be part of the battery housing or of the battery module. The second battery connection device can be part of the converter housing or of the converter module. The line then connects the battery module to the converter housing.

The electric drive is preferably connected to the DC voltage converter via a drive connection. The drive connection can be part of the converter housing or the converter module. The drive connection is provided in particular on an outside of the converter housing. Furthermore, a component connection and / or a low-voltage connection can be provided, which are arranged on the converter housing and thus form part of the converter module. The component connection and / or the low-voltage connection are connected to the side of the DC voltage converter to which the electric drive is also connected. In other words, the component connection and / or the low-voltage connection are connected to the third switch, in particular to the side of the third switch that is connected to the DC voltage converter. The drive connection and the component connection and / or the low-voltage connection can be part of the same plug-in device, in particular the same socket. This allows the contacts of the connections to be accommodated in the same connection device. When connecting, several connections can be connected at once. This particularly applies to plug connections. The drive connection, the component connection and / or the low-voltage connection can jointly form a connection module or be part of a common connection module.

The electric drive is preferably connected to the DC voltage converter via a drive connection. In this case, the drive connection is connected directly to the DC voltage converter, in particular to the side facing the third switch or is directly connected to it. As a result, the converter housing forms a module to which other components such as the electric drive can be connected (via the drive connection or other connections).

The drive connection and the DC voltage charging connection are arranged on an outside of the converter housing. The connections are accessible from the outside, so that in particular a plug connection can be plugged into the connections mentioned. The DC voltage charging connection and the drive charging connection can each be part of different connection modules. These are preferably arranged on the converter housing and in particular can be accessed from outside the converter housing. The drive connection and the DC voltage charging connection can be provided on the same side of the converter housing. If an AC voltage charging connection is provided, this can also be provided on the outside of the converter housing. If there is an AC voltage charging connection, it is preferably provided in the same connection module together with the DC voltage charging connection. The electric drive is preferably provided in another connection module. The DC voltage charging connection and the AC voltage charging connection can be provided in the same socket device or in the same electromechanical connecting device.

Furthermore, the vehicle electrical system can have a low-voltage electrical system branch. This can be connected via an additional DC / DC converter to the side of the DC / DC converter that is connected to the third switch. In particular, the low-voltage electrical system branch is connected to the same potential as the electric drive. Alternatively or in combination with this, at least one electrical component can also be provided in the on-board network branch. This at least one component can be a high-voltage component. The at least one component is connected to the side of the DC / DC converter that is connected to the third switch or to the electric drive. The low-voltage on-board network branch and / or the electrical component are thus preferably connected to the second side of the DC voltage converter. The electrical component can in particular be a heating element, in particular a heating element of a cooling circuit or an exhaust system, in particular of a catalytic converter, or it can be an electric drive of a demo compressor. As mentioned, the vehicle electrical system branch can have a component connection or a low-voltage connection for this purpose. This is directly connected to the second side of the DC / DC converter, ie to the side of the DC / DC converter that is (directly) connected to the third switch. The low-voltage on-board network branch or the at least one electrical component are connected to the DC voltage converter via the relevant connections. The component connection and / or the low-voltage connection are provided on the converter housing, in particular on its outside.

The vehicle electrical system can have an AC voltage charging connection. In particular, the vehicle electrical system can have an AC voltage charging connection and a rectifier device. The AC voltage charging connection is connected to the connection point, in particular via the rectifier device. The rectifier device can be a single-phase or polyphase rectifier device. The rectifier device can be designed as a BnC or BnU bridge, where n corresponds to twice the number of phases. In the case of three phases, n is equal to 6, in the case of one phase, n is equal to 2. The rectifier device is, in particular, a full-wave rectifier device. The rectifier device can also be designed as a power factor correction filter (in particular as a Vienna filter), this having a function that converts DC voltage in addition to the rectifier function.

The rectifier can be connected to the AC voltage connection via a fourth switch. The AC voltage connection can in particular be designed as three-phase. The AC voltage charging connection and the DC voltage charging connection can be formed in the same plug device unit or in the same socket device.

It can be provided that the vehicle electrical system comprises a fourth switch, via which the AC charging connection is connected to the rectifier device. As a result, the AC voltage connection can be disconnected from the rest of the vehicle electrical system (in particular if the charging device is not in a charging mode or in a feedback mode. The rectifier device can be bidirectional or unidirectional.

The rectifier device is connected to the DC / DC converter, in particular to its first side. The rectifier device is connected to the connection point through the connection. A fifth switch can be provided which can be located between the rectifier or the DC voltage converter on the one hand and the connection point on the other hand, in particular within the connection.

The connection between the connection point and the DC voltage converter can thus be switchable. The connection can have a fifth switch. The third switch and the fifth switch connect the connection point to different sides of the transducer (in a switchable manner). The connection is provided between the rectifier (and thus the AC voltage connection) and the DC voltage connection (or the second switch), it being possible for the fifth switch to be located between these two elements. The accumulator is thus connected to the DC voltage converter via the first switch and the fifth switch and is connected to the DC voltage converter via the first switch and the third switch, but to a different side of the DC voltage converter. The fifth switch connects the connection point to the DC / DC converter. The fifth switch connects the connection point with the rectifier (and thus with the downstream fourth switch or the AC voltage connection).

The vehicle electrical system can also have a controller that is connected to the switches in a driving manner. As an alternative or in addition, the control can be provided to be connected to the DC voltage converter in a driving manner, in particular also to the rectifier, if this is designed as a controlled rectifier. In a DC voltage charging mode, the controller is designed to close the second switch and to open the third switch, as well as to close the first switch. In the loading mode, the Controller be set up to control the DC-DC converter according to an active state. This allows the connected components or the low-voltage on-board network branch to be supplied with voltage. In an AC voltage charging mode, the controller can be configured to close the fourth switch, to open the second switch and to close the first switch. In the AC voltage charging mode, the controller is set up to control the DC voltage converter in an active state. In a driving or recuperation mode, the controller can be set up to control the fourth and the second switch in the open state. Either the third switch can be closed in order to connect the electric drive directly to the accumulator, or the third switch can be opened and the fifth switch can be closed in order to activate the electric drive by means of the accumulator via the then actively provided DC voltage converter supply. In a recuperation mode, either the third switch can be open and the fifth switch closed, or the fifth switch can be open and the third switch can be closed.

The vehicle electrical system is preferably an electrical system that is intended for traction. The accumulator is preferably a high-voltage accumulator and the electric drive is in particular a high-voltage drive. The electric drive is in particular a traction drive of the vehicle in which the vehicle electrical system is provided.

The first switch can be referred to as a battery disconnect switch, as it controllably connects or disconnects the battery. The second switch can be referred to as a DC voltage connection switch, since it connects or disconnects the DC voltage connection. The third switch can be referred to as a drive switch, since the connection between the accumulator or the first switch and the electric drive can be separated or established via the third switch. The fourth switch can be referred to as an AC voltage connection switch, since it can be used to switch the AC voltage connection or to switch it on. The fifth switch can also be referred to as a converter switch, as it can be used to control the switch connected to or disconnected from the connection point.

The 1 serves to exemplify the vehicle electrical system described here. In the 1 is a vehicle electrical system FB shown that via a charging interface LS with an AC voltage source WQ and / or a DC voltage source GQ can be connected. The charging interface LS an AC voltage connection and a DC voltage connection. The AC voltage connection is optional. On the station side are the sources, ie the alternating voltage source WQ and the DC voltage source GQ , via the respective isolating switch T1 , T2 with the charging interface LS connected. The AC voltage connection WA and the DC voltage connection are considered part of the vehicle electrical system.

The vehicle electrical system has an accumulator AK who has a first switch S1 with a first battery connection device B1 connected is. This can be designed as a socket, in particular as a socket with two contacts (each contact being assigned to one of two different supply potentials). One line L. connects the first switch S1 with a second battery connection device B2 . The line can have a two-phase design, that is to say two-phase with regard to high-voltage lines, wherein at least one signal conductor and / or a shield can also be provided.

The second battery connector B2 is with a connection point VP connected. This connection point VP is via a second switch S2 with the DC voltage connection GA connected. Furthermore is the connection point VP via a third switch with a galvanically isolating DC voltage converter W1 connected. The side of the third switch, the one with the DC / DC converter W1 is also connected to the drive connection EA , with a component connection KA and a low-voltage connection N / A connected. The drive connection EA is connected to an electrical machine M via an inverter I. The component connection KA is with one component K connected, such as a high-voltage heating element and / or an electric drive of an air conditioning compressor. The low-voltage connection N / A is via an additional DC voltage converter with a low-voltage on-board network branch NV connected. The additional DC voltage converter W2 can be designed as a galvanically isolating DC voltage converter, in particular as a step-down converter. It can thus be provided an on-board network branch BZ, the electrical drive (with the inverter I and the electrical machine M), the component K and / or the low-voltage electrical system NV as well as the additional DC voltage converter W2 includes.

The AC charging port WA is also via a fourth switch S4 with a rectifier GR connected. Its DC voltage side is with the DC voltage converter W1 or with the connection point VP connected. The DC / DC converter W1 is also about a fifth switch S5 with the connection point VP connected. Between the connection point VP and the DC / DC converter W1 there is thus a connection, in particular by means of the fifth switch S5 is switchable. A first connection path results from the connection point VP Via the fifth switch to the DC voltage converter W1 , in particular to a first side of the DC-DC converter W1 . There is also a second connection path between the connection point VP via the third switch S3 to a second side of the DC / DC converter W1 . This second side of the DC-DC converter W1 is with the drive connection EA (thus with the connections KA and N / A ) connected. The two connection paths connect the connection point VP with different sides of the DC-DC converter W1 .

The accumulator AK and the first switch S1 are in a battery case BG arranged. On this case BG is the first battery connector B1 arranged. Another housing Flat share , ie a converter housing Flat share is with the second battery connector B2 fitted. One line L. connects the two battery connection devices B1 and B2 . The converter housing and the battery housing are thus spatially separated from one another.

The connection point is provided in the converter housing, as well as the second switch, the third switch, the fourth switch and the fifth switch, as well as the DC voltage converter W1 and the rectifier GR . There are also on the converter housing Flat share the drive connection, the component connection KA and the low-voltage connection N / A arranged, preferably on the same side. Furthermore, the converter housing has the AC voltage charging connection WA and the DC charging port GA on. These can also be arranged on the same side. The connections EA , KA and N / A can be integrated in a common connection module. The connections WA and GA can be provided in a further charging connection module. The two connection modules are preferably separate from one another and can be on different sides of the converter housing Flat share be provided.

The device described here enables a simple configuration and thus simple maintenance of a battery module that consists of the battery housing BG , the accumulator and the first switch S1 (as well as the first battery connection device) can assemble. The battery module can also have safety mechanisms, for example a fuse and / or a battery monitoring unit. The second switch, the third switch, the fourth switch and the fifth switch, on the other hand, are part of a converter module which, in addition to the switches mentioned, also includes the DC voltage converters W1 having. In addition to these components, the converter module also provides the converter housing and also includes the connections mentioned EA , KA , N / A as GA and WA . Devices can also be provided which, as in FIG 1 shown, but not via a component connection KA or a component K feature. Furthermore, the low voltage connection N / A , the additional DC voltage converter W2 and the low-voltage electrical system is optional. Further is the rectifier GR , the fourth switch and the AC voltage connection are optional.

The DC / DC converter is based on the fifth switch W1 preferably designed as a step-up DC voltage converter.

Claims (11)

Vehicle electrical system (FB) with a DC voltage charging connection (GA), an accumulator (AK), a galvanically isolating DC voltage converter (GW), and an electric drive (I, M), the accumulator (AK) via a first switch (S1) with a Connection point (VP) is connected, the DC voltage charging connection (GA) is connected to the connection point (VP) via a second switch (S2) and the connection point (VP) is connected to the electrical drive (I, M) via the galvanically isolating DC voltage converter (GW) is connected, which is connected via a third switch (S3) to the connection point (VP), and wherein there is also a connection between the connection point (VP) and the DC voltage converter (GW), this connection to the DC voltage converter (GW) electric drive (I, M) is connected. Vehicle electrical system (FB) according to Claim 1 , the first switch (S1) being connected to the connection point (VP) via a first battery connection device (B1) and a second battery connection device (B2), a line (L) connecting the battery connection devices (B1, B2) to one another. Vehicle electrical system (FB) according to Claim 1 or 2 , wherein the first switch (S1) and the accumulator (AK) are arranged in a battery housing (BG) and the DC voltage converter (GW) and the second and third switch (S2, S3) are arranged in a converter housing (WG). Vehicle electrical system (FB) according to one of the preceding claims, wherein the electric drive (M, I) are connected to the DC voltage converter (W1) via a drive connection (EA). Vehicle electrical system (FB) according to Claim 3 and 4th , wherein the drive connection (EA) and the DC voltage charging connection (GA) are arranged on an outside of the converter housing (WG). Vehicle electrical system (FB) according to one of the preceding claims, which also has a low-voltage electrical system branch (NV), which is connected to the side of the DC voltage converter (W1) connected to the third switch (S3) via an additional DC voltage converter (W2), and which is also connected has at least one electrical component (KA) which is connected to the same side of the DC voltage converter (W1). Vehicle electrical system (FB) according to one of the preceding claims, which has an AC voltage charging connection (WA) and a rectifier device (GR) via which the AC voltage charging connection (WA) is connected to the DC voltage converter (W1). Vehicle electrical system (FB) according to Claim 7 which further comprises a fourth switch (S4) via which the AC charging connection (WA) is connected to the rectifier device (GR). Vehicle electrical system (FB) according to one of the preceding claims, wherein the connection between the connection point (VP) and the DC voltage converter (GW) can be switched and has a fifth switch (S5), the third switch (S3) and the fifth switch (S5) ) connect the connection point (VP) to different sides of the transducer (W1). Vehicle electrical system (FB) according to one of the preceding claims, which also has a controller (ST) which is connected to the switches (S1-S5) and / or to the DC voltage converter in a driving manner. Vehicle electrical system (FB) according to one of the preceding claims, wherein the accumulator (AK) is a high-voltage battery and the electric drive (I, M) is a traction drive of the vehicle in which the vehicle electrical system (FB) is provided.

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