JP2001128452A - Constant power outputting dc power supply unit and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit and a control method thereof, capable of enhancing the availability of a transformer, reducing ripple factors in output voltage, and reducing the sizes of the transformer, a smoothing filter, and a power supply unit. SOLUTION: Two constant power outputting DC power supply units are provided, each of which has a switching converting part outputting a pulse width control wave form, an output transformer, and a rectifying smoothing part for rectifying the output from the output transformer. A switching element is connected between the output negative terminal of one power supply unit and the output positive terminal of the other power supply unit, and a diode is connected between the output positive terminal and the output negative terminal of each of the power supply units with a polarity such that a cathode may be on the output terminal side of one of the power supply units respectively; so that DC constant power is fed from between the output positive terminal of one power supply unit and the output negative terminal of the other power supply unit through a smoothing filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply, and more particularly to a DC power supply for supplying a constant power output and output power control thereof.

[0002]

2. Description of the Related Art Conventionally, a switching power supply having a circuit configuration as shown in FIG. 3 is used for a power supply device such as a film forming apparatus. In FIG. 3, 1 is a switching converter, D0 is a rectifier diode, C1 is a smoothing capacitor, Q1 to Q4 are four power transistors, forming a full bridge.
And D2 are diodes connected in the reverse conduction direction to transistors Q3 and Q4, respectively, 2 is the output transformer of the converter,
Reference numeral 3 denotes a rectifier diode of a transformer output, and reference numerals 4 and 5 denote a reactor and a capacitor for a smoothing filter, respectively.

In order to control a film forming apparatus, constant power control is required. Therefore, the output characteristics of the power supply device are as shown in FIG. In FIG. 5, Vo is the output voltage of the power supply, Io
Is the output current. V1 and I2 are the maximum output voltage and the maximum output current, respectively. V2 and I1 are an output voltage and an output current located at both ends of the constant power characteristic, respectively. Therefore, the range between A and B is a constant power range. In FIG. 5, for example, V1 = 500
V, I2 = 40A, the output capacity of the power supply is 20KW
(V1 × I1). Actually, since the constant power control is performed, the maximum output of this device is I1 × V1 (= I2 × V1).
In 2), if I1 = 20A and V2 = 250V, it becomes 10KW.

Therefore, the output transformer has a capacity of 20 KW, but is used only at 10 KW, and the utilization factor is poor. On the other hand, in the switching section including the transistors Q1 to Q4, the power transistors Q1 to Q4 are configured as a full bridge, and perform a well-known pulse width control (PWM) at a constant cycle T (FIG. 4). . In FIG. 4, the waveforms (a) to (d) indicate that Q1 to Q4 are in the ON state, and the output of the full bridge (primary input of the transformer) has the pulse width t shown in the waveform (e). Pulse output. When the output current of the power supply device reaches the maximum value due to the constant power output, the output voltage decreases, and the pulse width t also decreases. Therefore, when this voltage is rectified (waveform (f)) and smoothed, , The size of the smoothing filter increases. As described above, the conventional control method has disadvantages such as a low transformer utilization rate and a large filter.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and it has been proposed to increase the utilization factor of a transformer, reduce the occurrence of ripples in the output voltage, and reduce the size of the transformer and the smoothing filter. An object of the present invention is to provide a power supply device capable of measuring and further reducing the size of the power supply device and a control method thereof.

[0006]

In order to solve the above-mentioned problem, the invention according to claim 1 includes a switching converter that outputs a pulse width control waveform,
An output transformer, and two constant power output DC power supplies having a rectifying and smoothing unit for rectifying the output of the output transformer,
A switch element is connected between the output negative terminal of one power supply device and the output positive terminal of the other power supply device, and one of the power supplies is connected between the output positive terminal and the output negative terminal of the power supply device, respectively. A diode is connected to the polarity having the output terminal side of the device as a cathode, and a constant DC power is supplied from between the output positive terminal of the one power supply device and the output negative terminal of the other power supply device through a smoothing filter. This configuration makes it possible for each circuit component, especially the transformer, to use 100% of its own capacity, and to reduce the size of the transformer due to its high utilization rate. Since there is little change, the output filter can be downsized. Further, in the configuration of the power supply device, the size of these components having a relatively large ratio of size to weight can be reduced, so that the power supply device can be downsized.

According to a second aspect of the present invention, there is provided a power supply apparatus having the structure of the first aspect, wherein the switching converters are operated synchronously, and the output pulse width is set to a conduction width of 180 °, and At the beginning of each output cycle, the switch elements are turned on to connect the outputs of the power supply units in series to supply power, and after a predetermined time of each output cycle, the switch elements are turned off to turn off the power supply units. This is a control method characterized by connecting the outputs of the transformers in parallel to supply power. With this control, the transformer is always in the 180 ° output state, so that its own capacity can be used 100%. At the beginning of the output cycle of the output, by turning on the switch element, control by the recovery current of the diodes 11, 12 when connecting from series connection to parallel connection or from parallel connection to series connection. It is possible to prevent destabilization.

[0008]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.
1-1 and 1-2 are switching converters having the same configuration as the conventional switching converter 1, 6 is an output transformer of the switching converter 1-1, 7 is a rectifier diode of the output of the transformer 6, and 8 is a switching converter. 1-2 output transformers, 9 is a rectifier diode of the output of the transformer 8, 10 is a high-speed switch (for example, a power transistor) connecting the negative side of the output of the rectifier diode 7 and the positive side of the output of the rectifier diode 9, 11 Reference numeral 12 denotes a diode connected so that the outputs of the two conversion circuits can be operated in parallel through them.
Is a reactor with two windings wound on the same iron core, each winding is inserted in each of the positive and negative lines operated in parallel,
A smoothing filter is formed together with the capacitor.

FIG. 2 shows operation waveforms of the circuit shown in FIG. FIG.
, The conversion circuits 1-1 and 1-2 have exactly the same timing,
Operate with maximum control angle (approximately 180 °). Therefore, the waveforms rectified by the rectifier diodes on the respective output sides are exactly the same (FIGS. 2A and 2B). Switch 10
Are not operating, the two outputs are diodes 12,
13, and when the switch 10 is turned on by operating the switch 10, the two outputs are switched by the switch 1.
The state becomes a series operation state via 0, and the output voltage Vo as the power supply device becomes twice the voltage of one circuit output voltage.

The following control is performed using these operation states. As shown in FIG. 2 (c), when the switch 10 is turned on at the beginning of each output cycle, the output voltage V1 of the rectifier diode 7 and the output voltage V2 of the rectifier diode 9 are turned on.
(Where V1 = V2) are connected in series, and the combined output voltage is V1 + V
It becomes 2. After time ts, the switch 10 is turned off at time t1. From that point on, the two circuits are in parallel and the combined output voltage is V1 (= V2), and continues in that state until the end of the output cycle t2 (tp period). A period tr from t2 to the beginning t'0 of the next cycle is an operation time for stably performing the switching operation in the switching converters 1-1 and 1-2, and is an extremely short time. t1 is a controllable time, and the required total output voltage V0 (average value)
Control so that

Accordingly, the combined output voltage is such that t1 is equal to t2.
It becomes the maximum when it becomes equal to V0max = 2V1
(= 2V2), and becomes minimum when t1 becomes t0, and V
0 min = V1 (= V2). Therefore, the output voltage V0
Can be controlled from V1 to 2V1. As shown in Fig. 2 (d), the voltage waveform at the input of the output smoothing filter is based on half of the voltage peak value over the entire output cycle, and the control portion causing the output ripple has a waveform. Overpriced
Since it is 1/2, as can be seen from the waveform (f) in FIG. 4, the waveform is essentially a small ripple component, and therefore the output smoothing filter may be small.

As for the current, since the constant power control as shown in FIG. 5 is performed, when the maximum current flows, the output voltage is minimum, so that the two circuits are in parallel during the entire output cycle, and one circuit has It is sufficient if there is a capacity to share half of the maximum output current (actually, when the output voltage increases,
Maximum required current capacity is about 20% due to the series period
growing). As mentioned above, the transformer is almost always 180
° In the output state, and in that state, up to the maximum current flows, so that 100% of its own capacity can be used.

[0013]

As described above, in the conversion circuit of the DC power supply having the constant power output characteristic, the output power is controlled by the direct / parallel operation of the outputs of the two conversion circuits, whereby each of the two circuits is controlled. Is an operation that always outputs for 180 °, so each component of the circuit, especially the transformer, can use 100% of its own capacity, and the transformer can be downsized due to its high utilization rate. Since the amount of change in the waveform is small, the size of the output filter can be reduced. In the configuration of the power supply device, the size of the power supply device can be reduced by reducing the size of these parts having a relatively large ratio of size to weight.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of the embodiment of the present invention.

FIG. 3 is a conventional circuit diagram.

FIG. 4 is an operation waveform diagram of a conventional circuit.

FIG. 5 is an output characteristic diagram of a constant power DC power supply device.

[Explanation of symbols]

 1-1, 1-2: switching converters 6, 8: output transformer 7, 9: rectifier diode 10: switch element 11, 12: diode 13: reactor 14: capacitor

Claims (2)

[Claims] 1. A constant power output DC power supply device comprising a switching converter for outputting a pulse width control waveform, an output transformer, and a rectifying / smoothing unit for rectifying an output of the output transformer. A switch element is connected between the output negative terminal of the power supply device and the output positive terminal of the other power supply device,
A diode is connected between the positive output terminal and the negative output terminal of each of the power supply devices so that the output terminal side of one of the power supply devices has a cathode, and the output positive terminal of the one power supply device and the other are connected to each other. A constant power output DC power supply device, wherein DC constant power is supplied from between the output negative terminals of the power supply device through a smoothing filter. 2. A constant power output DC power supply having a switching converter for outputting a pulse width control waveform, an output transformer, and a rectifying and smoothing unit for rectifying an output of the output transformer, wherein one of the power supplies is provided. A switch element is connected between the output negative terminal of the power supply device and the output positive terminal of the other power supply device,
A diode is connected between the positive output terminal and the negative output terminal of each of the power supply devices so that the output terminal side of one of the power supply devices has a cathode, and the output positive terminal of the one power supply device and the other are connected to each other. A smoothing filter is provided between the output negative terminals of the power supply device, the switching converters are operated in synchronization with each other, and the output pulse width is set to a conduction width of 180 °, and
At the beginning of each output cycle, the switch elements are turned on to connect the outputs of the power supply units in series to supply power, and
After a predetermined time in each output cycle, turn off the switch element.
A control system for a constant power output DC power supply, wherein power is supplied by connecting the outputs of the power supplies in parallel at least.