JP3602708B2 - Power supply - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power supply device that can be used as, for example, a vehicle auxiliary power supply device or a similar power supply device.
[0002]
[Prior art]
Conventionally, a power supply device used as a vehicle auxiliary power supply device has a configuration shown in FIG. This conventional power supply device includes first and second capacitors 101 and 102 for dividing a DC input voltage, and a self-extinguishing type semiconductor element, and the voltage is divided by the first and second capacitors 101 and 102, respectively. First and second converters 103 and 104 for generating a high-frequency rectangular wave voltage from the applied DC voltage, and first and second transformers 105 for insulating output voltages of the first and second converters 103 and 104, respectively. , 106, first and second rectifiers 107, 108, whose output terminals are connected in series, for rectifying high-frequency rectangular wave voltages output from the first and second transformers 105, 106, respectively. And a smoothing reactor 109 and a filter capacitor which are inserted to remove a ripple with respect to the DC voltage output of the series-coupled second rectifiers 107 and 108. 10 and is connected to a filter capacitor 110, and a smoothing reactor 109 and smoothed by the filter capacitor 110, an inverter 110 for converting the DC voltage of the first and second rectifier into an AC voltage.
[0003]
A control circuit for switching control of the converters 103 and 104 detects the voltage 116 of the filter capacitor 110 and compares the error with respect to the reference voltage 115 with the sawtooth wave 114, and the output of the comparator 117. , A PWM circuit 113 for supplying a switching signal 112 to the self-extinguishing semiconductor elements of the first and second converters 103 and 104 so that the voltage 116 of the filter capacitor 110 becomes constant.
[0004]
In this conventional power supply device, a DC input voltage is divided into two by first and second capacitors 101 and 102, and a high-frequency rectangular wave voltage is generated by first and second converters 103 and 104 connected respectively. . FIGS. 6A and 6B show waveforms of high-frequency rectangular wave voltages generated by the first and second converters. In this conventional example, the switching timings of the first and second converters 103 and 104 are made the same to make the phases of the rectangular wave voltages uniform. However, the purpose is to reduce the voltage ripple and reduce the inductance of the smoothing reactor 109. There is also known one that performs control for shifting the phase of the switching timing of the first and second converters 103 and 104 by 90 degrees.
[0005]
The rectangular wave voltages output from the first and second converters 103 and 104 are insulated and transformed by the first and second transformers 105 and 106, respectively, and further rectified by the first and second rectifiers 107 and 108. After that, they are connected in series and output as one DC voltage to the smoothing reactor 109 and the filter capacitor 110 (in the related art, the output sides of the first and second high-frequency transformers are connected in series, It is also known that only one rectifier is used).
[0006]
Since the combined voltage is a voltage including a ripple as shown in FIG. 6C, it is smoothed by the smoothing reactor 109 and the filter capacitor 110 to form a voltage waveform as shown in FIG. It is input to inverter 110.
[0007]
[Problems to be solved by the invention]
However, in such a conventional power supply, since the voltage rectified by the rectifier includes an unavoidable amount of ripple, a filter circuit including a smoothing reactor and a filter capacitor is necessarily required. There is a problem that the weight and weight are inevitable.
[0008]
The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a power supply device capable of reducing the size and weight of the device by eliminating the need for a smoothing reactor.
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a power supply device comprising: a first and a second capacitor for dividing a DC input voltage by two; And a second converter, first and second high-frequency transformers for insulating output voltages of the first and second converters, and after insulation output from the first and second high-frequency transformers The first and second rectifiers, whose output sides are connected in parallel, rectify the high-frequency rectangular wave voltage of the above, and the parallel output of the first and second rectifiers via a filter capacitor and without a smoothing reactor. An inverter connected to convert the DC voltage of the first and second rectifiers into an AC voltage; and a control circuit for switching control of the first and second converters, wherein the control circuit Comparing a reference voltage with a sawtooth wave and outputting a pulse-wide signal having a fixed duty factor of 50% or more, and a 90-degree phase shift with respect to the pulse-wide signal from this comparator The control circuit outputs the pulse-wide signal output from the comparator as a switching signal of the first converter as it is, and outputs a pulse shifted by 90 degrees through the phase shift circuit. By outputting the wide signal to the second converter as a switching signal, the first and second converters are each shifted by 90 degrees, and each is switched at a fixed duty ratio of 50% or more. Switching control is performed so that
[0010]
In the power supply device according to the present invention, the DC input voltage is divided into two by the first and second capacitors, and the first and second capacitors are used as input filters by the first and second converters. A high-frequency rectangular wave voltage is generated for each of the pressed DC input voltages. The output voltages of the first and second converters are insulated and transformed by first and second high-frequency transformers, and the high-frequency rectangular wave voltages are respectively rectified by first and second rectifiers. The rectified outputs of the first and second rectifiers are connected in parallel to form a DC voltage. Then, the parallel-coupled DC voltage is input to an inverter, converted into an AC having a desired number of phases, frequency and voltage, and output as an AC power supply.
[0011]
The power conversion control for converting the DC input voltage into a predetermined AC voltage and outputting the converted AC voltage is performed by a control circuit. The control circuit shifts the phases of the first and second converters by 90 degrees, respectively, to provide a 50% or more communication. Switching control is performed so that switching is performed at the flow rate.
[0012]
Therefore, when the high-frequency AC voltages output by the first and second converters are rectified through the first and second high-frequency transformers and the first and second rectifiers, are coupled in parallel, and are output as DC voltages, This DC voltage does not include ripple. For this reason, it is possible to directly input the signal from the rectifier to the inverter via the filter capacitor without passing through the reactor for smoothing, and the circuit configuration is reduced in size and weight because no smoothing reactor is required. Becomes possible.
[0013]
According to a second aspect of the present invention, there is provided a power supply device comprising: first and second converters connected in parallel to a DC input voltage to generate a high-frequency rectangular wave voltage; and an output voltage of each of the first and second converters. First and second high-frequency transformers to be insulated, and first and second output-side parallel-coupled rectifying high-frequency rectangular wave voltages after insulation output from the first and second high-frequency transformers. 2 rectifier and the parallel output of the first and second rectifiers are connected via a filter capacitor without a smoothing reactor, and convert the DC voltage of the first and second rectifiers into an AC voltage. An inverter; and a control circuit for controlling switching of the first and second converters, wherein the control circuit compares a reference voltage with a sawtooth wave, and has a fixed ON period longer than an OFF period. And a switching signal inverter circuit for determining the phase of the pulse-wide signal from the comparator, wherein the control circuit outputs the pulse-wide signal from the comparator. By outputting the pulse-wide signal as it is as a switching signal of the first converter and outputting the pulse-wide signal whose phase has been inverted through the switching signal inverter circuit to the second converter as a switching signal, Switching the converter to switch at a fixed duty factor with an on-period longer than the off-period and to switch the second converter at a phase opposite to the on / off phase of the first converter; It is characterized by the following.
[0014]
According to the power supply device of the present invention, the DC input voltage is converted into a high-frequency rectangular wave voltage by the first and second converters connected in parallel, and the output voltage of each of the first and second converters is converted. It is insulated and transformed by the first and second high-frequency transformers, and further rectified by the first and second rectifiers. The outputs rectified by the first and second rectifiers are connected in parallel to form a DC voltage, which is input to an inverter, converted into an AC having a desired number of phases, frequency and voltage, and output as an AC power supply.
[0015]
The power conversion control for converting the DC input voltage to a predetermined AC voltage and outputting the converted AC voltage is performed by a control circuit. The control circuit switches the first converter at a fixed duty ratio and switches the second converter. Switching control is performed so that ON switching is performed only when the voltage output from the first converter is OFF.
[0016]
Therefore, when the high-frequency AC voltages output by the first and second converters are rectified through the first and second high-frequency transformers and the first and second rectifiers, are coupled in parallel, and are output as DC voltages, The dent that appears in the AC voltage corresponding to the off-switching timing of the first converter is covered by the AC voltage corresponding to the on-switching timing of the second converter, and the final output DC voltage includes a ripple. There is no. For this reason, it is possible to directly input the signal from the rectifier to the inverter via the filter capacitor without passing through the reactor for smoothing, and the circuit configuration is reduced in size and weight because no smoothing reactor is required. Becomes possible.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a circuit configuration of the first embodiment of the present invention. The power supply device according to the first embodiment includes first and second capacitors 1 and 2 for dividing a DC input voltage into two, and a self-extinguishing type semiconductor element such as an IGBT. The first and second converters 3 and 4 for generating a high-frequency rectangular wave voltage from the DC voltage divided by the capacitors 1 and 2, respectively, and insulate the output voltages of the first and second converters 3 and 4, respectively. The first and second high-frequency transformers 5 and 6 rectify high-frequency rectangular wave voltages output from the first and second high-frequency transformers 5 and 6, respectively. 2 rectifiers 7, 8 and a DC voltage connected to the parallel-connected DC voltage outputs of the first and second rectifiers 7, 8 via only the filter capacitor 9 without passing through the smoothing reactor. The desired number of phases (eg, Phase), and an inverter 10 for converting the alternating current frequency and voltage.
[0018]
Then, a control circuit for switching control of the first and second converters 3 and 4 compares the reference voltage 17 with the sawtooth wave 16 and outputs a pulse-wide signal (50% or more) having a fixed duty ratio. A PW signal (PW signal) 14; a phase shift circuit 13 for shifting the phase of the PW signal 14 from the comparator 15 by 90 degrees; and a PW signal output from the comparator 15. 14 is output as it is as the switching signal 11 of the first converter 3, and the PW signal whose phase is shifted by 90 degrees through the phase shift circuit 13 is output to the second converter 4 as the switching signal 12.
[0019]
Next, the operation of the power supply device according to the first embodiment having the above configuration will be described. The DC input voltage is divided into two by the first and second capacitors 1 and 2, and the first and second converters 3 and 4 connected to each generate a high-frequency rectangular wave voltage. FIGS. 2A and 2B show the waveforms of high-frequency rectangular wave voltages generated by the first and second converters. Since the switching timing of the first and second converters 3 and 4 is shifted by 90 degrees by the operation of the control circuit, the output voltage waveform is also shifted by 90 degrees correspondingly.
[0020]
The rectangular wave voltage output from each of the first and second converters 3 and 4 is insulated and transformed by the first and second high-frequency transformers 5 and 6, respectively, and further by the first and second rectifiers 7 and 8. It is rectified, and after this rectification, it is connected in parallel, converted into one DC voltage, and input to the inverter 10 via the filter capacitor 9. The DC voltage coupled in parallel becomes a DC voltage that hardly includes the ripple voltage as shown in the capacitor voltage waveform of FIG.
[0021]
Therefore, a sufficiently smoothed DC voltage can be input to the inverter 10 without providing a smoothing reactor conventionally required for smoothing a ripple voltage, and the circuit configuration can be downsized by omitting the smoothing reactor. , Weight reduction becomes possible.
[0022]
Next, a power supply device according to a second embodiment of the present invention will be described with reference to FIGS. The power supply device according to the second embodiment is configured by a self-extinguishing type semiconductor element such as an IGBT, which is arranged in parallel and receives a DC voltage through an input filter capacitor 21 to generate a high-frequency rectangular wave voltage. First and second converters 22 and 23, first and second high-frequency transformers 24 and 25 for insulating output voltages of the first and second converters 22 and 23, respectively, and the first and second converters The first and second rectifiers 26 and 27, whose outputs are coupled in parallel, rectify the high-frequency rectangular wave voltage output from the high-frequency transformers 24 and 25, and the parallel of the first and second rectifiers 26 and 27. Inverter connected to the coupled DC voltage output via only the filter capacitor 28 without passing through the smoothing reactor and converting the DC voltage into an AC having a desired number of phases, frequency and voltage. It is equipped with a 9.
[0023]
Then, a control circuit for controlling the switching of the first and second converters 22 and 23 compares the reference voltage 36 with the sawtooth wave 35 and outputs a pulse-width signal (PW signal) 33 having a fixed duty ratio. , And a switching signal inverter circuit (INV) 32 for determining the phase of the PW signal 33 from the comparator 34. The PW signal 33 output from the comparator 34 is the first signal as it is. The PW signal output as the switching signal 30 of the converter 22 and the phase-inverted PW signal via the INV 32 is output to the second converter 23 as the switching signal 31.
[0024]
Next, an operation of the power supply device according to the second embodiment having the above configuration will be described. The DC input voltage is input to the first and second converters 22 and 23 via the input filter capacitor 21, and the first and second converters 3 and 4 generate a high-frequency rectangular wave voltage. FIGS. 4A and 4B show waveforms of a high-frequency rectangular wave voltage generated by the first and second converters. By the operation of the control circuit, the ON period of the switching signal for the first converter 22 is set longer than the OFF period, and the ON period of the switching signal for the second converter 23 is set shorter than the OFF period. Since the on / off phase of the switching signal 30 of the first converter 22 and the switching signal 31 of the second converter 23 are reversed, the output voltage waveform is also corresponding to the first converter 22. At a timing when the voltage output is present, the output voltage of the second converter 23 is 0. Conversely, when the output voltage of the first converter 22 is 0, the second converter 23 has a voltage output.
[0025]
The rectangular wave voltage output from each of the first and second converters 22 and 23 is insulated and transformed by the first and second high-frequency transformers 24 and 25, respectively, and further by the first and second rectifiers 26 and 27. The DC voltage is rectified and, after the rectification, is coupled in parallel to be converted into one DC voltage and input to the inverter 29 via the filter capacitor 28. The parallel-coupled DC voltage is a DC voltage that hardly includes the ripple voltage as shown in the capacitor voltage waveform of FIG.
[0026]
Therefore, it is possible to input a sufficiently smoothed DC voltage to the inverter 29 without providing a smoothing reactor which is conventionally required for smoothing a ripple voltage. , Weight reduction becomes possible.
[0027]
【The invention's effect】
As described above, according to the first aspect of the present invention, the high-frequency AC voltage output from the first and second converters is rectified through the first and second high-frequency transformers and the first and second rectifiers, When output as a DC voltage after being connected in parallel, this DC voltage does not include ripples, so it does not pass through a reactor for smoothing, but directly from the rectifier through a filter capacitor. Since no smoothing reactor is required, the circuit configuration can be reduced in size and weight.
[0028]
According to the second aspect of the present invention, the high-frequency AC voltages output from the first and second converters are rectified through the first and second high-frequency transformers and the first and second rectifiers, and are rectified and connected in parallel. When output as a voltage, the dent that appears in the AC voltage corresponding to the off-switching timing of the first converter is covered by the AC voltage corresponding to the on-switching timing of the second converter, and the DC voltage finally output Since no ripple is included in the rectifier, the rectifier can be directly input to the inverter via the filter capacitor without passing through the smoothing reactor, and the smoothing reactor is not required. In addition, the circuit configuration can be reduced in size and weight.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of a first embodiment of the present invention.
FIG. 2 is a waveform chart showing voltage waveforms at various parts in the embodiment.
FIG. 3 is a block diagram showing an overall configuration of a second embodiment of the present invention.
FIG. 4 is a waveform chart showing voltage waveforms at various parts in the embodiment.
FIG. 5 is a circuit block diagram of a conventional example.
FIG. 6 is a waveform chart showing voltage waveforms at various parts in a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st capacitor 2 2nd capacitor 3 1st converter 4 2nd converter 5 1st high frequency transformer 6 2nd high frequency transformer 7 1st rectifier 8 2nd rectifier 9 Filter capacitor 10 Inverter 11 , 12 switching signal 13 phase shift circuit 14 pulse wide signal 15 comparator 16 sawtooth wave 17 reference voltage 21 input filter capacitor 22 first converter 23 second converter 24 first high-frequency transformer 25 second high-frequency transformer 26 First rectifier 27 Second rectifier 28 Filter capacitor 29 Inverter 30, 31 Switching signal 32 Switching signal inverter circuit 33 Pulse wide signal 34 Comparator 35 Sawtooth wave 36 Reference voltage

Claims (2)

First and second capacitors for dividing the DC input voltage by two,
First and second converters that use the first and second capacitors as input filters and generate a high-frequency rectangular wave voltage;
First and second high-frequency transformers for insulating output voltages of the first and second converters,
First and second rectifiers, whose output sides are connected in parallel, for rectifying the insulated high-frequency rectangular wave voltage output from the first and second high-frequency transformers,
An inverter that is connected to a parallel output of the first and second rectifiers via a filter capacitor without a smoothing reactor, and converts a DC voltage of the first and second rectifiers into an AC voltage;
A control circuit for switching control of the first and second converters,
The control circuit compares the reference voltage with the sawtooth wave and outputs a pulse-wide signal of 50% or more and a fixed duty ratio. And a phase shift circuit for shifting the phase by degrees.
The control circuit outputs the pulse wide signal output from the comparator as a switching signal of the first converter as it is, and outputs the pulse wide signal shifted by 90 degrees through the phase shift circuit to the second converter. by outputting a switching signal, wherein the first and second converters by shifting each 90 degree phase, and switching control to switch from each certain of 50% or more fixed duty ratio And power supply. First and second converters connected in parallel to the DC input voltage to generate a high-frequency rectangular wave voltage;
First and second high-frequency transformers for insulating output voltages of the first and second converters,
First and second rectifiers, whose output sides are connected in parallel, for rectifying the insulated high-frequency rectangular wave voltage output from the first and second high-frequency transformers,
An inverter that is connected to a parallel output of the first and second rectifiers via a filter capacitor without a smoothing reactor, and converts a DC voltage of the first and second rectifiers into an AC voltage;
A control circuit for switching control of the first and second converters,
The control circuit compares a reference voltage with a sawtooth wave, and outputs a pulse-width signal having a fixed duty ratio whose on-period is longer than the off-period; and a pulse-width signal from the comparator. A switching signal inverter circuit for determining the phase,
The control circuit outputs the pulse-wide signal output from the comparator as a switching signal of the first converter as it is, and outputs the pulse-wide signal whose phase has been inverted through the switching signal inverter circuit to the second converter. By outputting as a switching signal, the first converter is switched at a fixed duty ratio in which the ON period is longer than the OFF period , and the second converter is switched with the ON / OFF phase of the first converter. A power supply device that performs switching control so as to perform switching in an opposite phase .

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