JP2001086771A - Power supply having power converting circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power supply having a power converting circuit comprising a bridge of switches, in which the switches in the power converting circuit are protected against being applied with a high voltage from a filter circuit. SOLUTION: A controller 13 for controlling the switches in a power converting circuit 5 is arranged to turn off switches Fu, Fv constituting the upper side of a switch simultaneously, when the main current of the power converting circuit 5 is interrupted and a current is fed by conducting both switches Fu, Fv, when energy stored in the coils L1, L2 constituting a filter circuit 6 is released. Since the energy stored in the coils L1, L2 is released quickly, voltage rise across the coils L1, L2 is prevented, and each switch in the power converting circuit 5 is protected against application of a high voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device having a power conversion circuit formed by connecting switches in a bridge.

[0002]

2. Description of the Related Art As a power supply device using a generator driven by an internal combustion engine as a power source, an AC voltage obtained from the generator is once rectified and converted into a DC voltage, and then converted to an AC voltage having a constant frequency by an inverter circuit. What is converted is used. This type of power supply device includes, for example, a multi-pole magnet generator driven by a prime mover, a rectifier for rectifying the output of the magnet generator, and a switch that is turned on in response to a drive signal. A bridge-type power conversion circuit (inverter circuit) having a lower side configured to receive an output of the rectifier between DC input terminals, a flywheel diode connected in anti-parallel to each switch of the power conversion circuit, A control device for turning on / off each switch of the power conversion circuit so as to perform PWM control of a main current flowing through a pair of switches at diagonal positions of a bridge of the conversion circuit, a load connection terminal to which a load is connected, and a power conversion circuit And an LC filter circuit connected between the output terminal and the load connection terminal.

In the above power supply device, an AC voltage output from a multi-pole magnet generator is converted into a constant DC voltage by a rectifier, and the DC voltage is input to a power conversion circuit.
The control device applies a drive signal to the switches so as to simultaneously turn on a pair of switches at diagonal positions of the bridge circuit forming the power conversion circuit for a desired half cycle of the sine wave, and supplies a drive signal to the switches. By turning on / off the upper or lower switch at a duty ratio proportional to the instantaneous peak value of each sine wave, an AC voltage having a waveform similar to a sine wave is generated from the power conversion circuit. After the voltage approximated to the sine wave output from the power conversion circuit is passed through a low-pass filter circuit including a coil and a capacitor, harmonics are removed and the voltage is converted to a smooth sine wave voltage. It is given to the load through the connection terminal.

A sine wave voltage applied to a load is detected by a load voltage detection circuit and fed back to a control device. The control device compares each instantaneous magnitude of the output voltage with each instantaneous value (set value) of the desired sine wave voltage, and when the instantaneous value of the output voltage is lower than the instantaneous value of the desired sine wave voltage,
The duty ratio of the WM control is increased, and when the instantaneous value of the output voltage becomes higher than the instantaneous value of the desired sine wave voltage, PW
The duty ratio of the M control is controlled to be small, and a sine wave voltage having a desired magnitude is generated between the load connection terminals.

[0005] The switch control means also stops outputting a drive signal to be given to the switch of the power conversion circuit when the load current detected by the load current detection circuit exceeds a set value (when an overcurrent is detected). Perform overcurrent control. With this overcurrent control, the output of the power conversion circuit is stopped when an overcurrent flows, thereby protecting the switches constituting the power conversion circuit.

In this type of power supply device, a DC voltage output from a rectifier can be converted into an AC voltage having an arbitrary frequency by controlling a power conversion circuit. In addition, an AC voltage having a desired frequency can be obtained at the load connection terminal.

In the bridge type power conversion circuit, a drive signal is given to a switch at a diagonal position of the bridge, and one of the switches at the diagonal position is turned on / off at a predetermined duty ratio, thereby providing an arbitrary switch. Size (average value)
Can be obtained.

[0008]

In the power supply device as described above, a coil and a capacitor are connected between the output terminal of the power conversion circuit and the load connection terminal in order to remove harmonic components from the output of the power conversion circuit. Is inserted. Therefore, in the PWM control, when the main current flowing through the switch at the diagonal position of the bridge of the power conversion circuit is cut off, the energy stored in the coil of the filter circuit and the energy stored in the coil included in the load are cut off. Must be open.

Therefore, in the conventional power supply device with a power conversion circuit, when interrupting the current flowing through the switch at the diagonal position of the bridge of the power conversion circuit, one of the two switches constituting the upper side of the bridge is cut off. Only the ON state, and the flywheel diode and the filter circuit and the load connected in parallel to the one switch and the other switch release the energy stored in the coil of the filter circuit and the coil of the load. By configuring a closed circuit and passing current through this closed circuit,
The energy stored in the coil was released.

However, when the energy stored in the coil of the filter circuit and the coil of the load increases, the energy cannot be released quickly in the closed circuit described above, so that the voltage across the coil constituting the filter circuit increases. However, there has been a problem that a high voltage is applied to the switches constituting the power conversion circuit. For this reason, in the conventional power supply device, it is necessary to use an expensive switch having a high withstand voltage as a switch constituting the power conversion circuit, which inevitably increases the cost.

When a load is not connected to the power supply device or when the load is capacitive, the current flowing through the diagonal switch of the bridge of the power conversion circuit is small, and the inductance of the coil of the filter circuit is small. Is reduced, the capacitor of the filter circuit is charged to a high voltage. However, since the charge of this capacitor cannot be discharged by the above-described closed circuit including one switch constituting the upper side of the bridge and the flywheel diode, the switching duty of the power conversion circuit is small. However, the voltage at both ends of the capacitor rises, and this voltage causes a waveform of the voltage between the load connection terminals to be a waveform close to a rectangular wave, which causes a problem that the distortion rate of the waveform of the output voltage increases. .

An object of the present invention is to enable the energy stored in a filter circuit and a load to be quickly released when a main current flowing through a power conversion circuit is cut off.
An object of the present invention is to provide a power supply device with a power conversion circuit capable of preventing a high voltage from being applied to a switch of a power conversion circuit and preventing a waveform of an output voltage from being distorted.

[0013]

SUMMARY OF THE INVENTION The present invention provides a bridge-type power conversion circuit comprising two switches, each of which is turned on in response to a drive signal on each of an upper side and a lower side of the bridge; A flywheel diode connected in anti-parallel to each switch of the circuit, a control device for turning on / off the switches of the power conversion circuit so that the main current flowing through the switch at the diagonal position of the bridge of the power conversion circuit is PWM controlled, Related to a power supply unit with a power conversion circuit, comprising a load connection terminal to which a load is connected, a filter circuit including a coil and a capacitor, and connected between an output terminal of the power conversion circuit and the load connection terminal. It is.

In the present invention, at least two switches constituting the upper side of the bridge of the power conversion circuit are composed of switch elements having a characteristic that current can flow in both directions when in an ON state. The control device is configured to generate a period during which the two switches forming the upper side of the bridge of the power conversion circuit are simultaneously turned on when the main current of the conversion circuit is cut off.

With the above configuration, the two switches constituting the upper side of the bridge of the power conversion circuit constitute a closed circuit for releasing the energy stored in the filter circuit. The capacity can be increased. Therefore, it is possible to easily release the energy stored in the coil of the filter circuit, and to prevent the voltage across the coil of the filter circuit from rising.

Further, with the above configuration, the electric charge accumulated in the capacitor of the filter circuit can be discharged by the closed circuit, so that the voltage at both ends of the capacitor of the filter circuit is prevented from rising, and the output is prevented. Voltage waveform distortion can be reduced.

In this specification, the ON state of a switch means a state in which a current can flow through a main current path of the switch when a voltage is applied to both ends of the switch.

[0018]

FIG. 1 shows an example of the configuration of a power supply device 1 to which the present invention is applied. In FIG.
The phase magnet type alternator 3 is an internal combustion engine that drives the magnet type alternator 2. The magnet-type alternator 2 includes a magnet rotor (not shown) having a multi-pole structure and a stator having three-phase star-connected generator coils 2u to 2w. Is mounted on the crankshaft of the internal combustion engine 3.

Reference numeral 4 denotes diodes Du to Dw and Dx to
A rectifier in which Dz is connected in a three-phase bridge, the three-phase output terminals of the generator 2 are connected to the three-phase AC input terminals 4u to 4w of the rectifier 4, respectively, and the DC output terminals 4a, 4
A smoothing capacitor Cd is connected between b.

5 is a MOSFET Fu as a switch.
, Fv and Fx and Fy are bridge-connected, and flywheel diodes Dfu and Dfv and Dfx and Dfy are connected in anti-parallel between the drain sources of MOSFETs Fu and Fv and Fx and Fy, respectively. (Towards the source side of the corresponding FET). In this example, M as a switch
The upper side of the bridge circuit is constituted by OSFETs Fu and Fv, and the lower side of the bridge circuit is constituted by MOSFETs Fx and Fy. The flywheel diodes Dfu, Dfv, Dfx, and Dfy form a feedback current conduction path.

As shown in FIG.
When an FET is used, the flywheel diode Dfu,
MOSFETs Fu, F are used as Dfv and Dfx, Dfy.
A parasitic diode formed between v and the drain and source of Fx and Fy may be used.

The pair of input terminals 5a and 5 of the power conversion circuit 5
b is connected to output terminals 4a and 4b of the rectifier 4, and a pair of output terminals 5u and 5v of the power conversion circuit 5 are connected to a pair of load connection terminals 7u and 7v through a filter circuit 6 comprising coils L1 and L2 and a capacitor C1, respectively. It is connected to the. A load 9 is connected to the load connection terminals 7u and 7v through a well-known connector 8 composed of an outlet and a plug.

Reference numeral 11 denotes a load current detection circuit for detecting a current supplied from the power conversion circuit 5 to the load. Reference numeral 12 denotes an operational amplifier OP1 and resistors Ru and Rv connecting the input terminals of the operational amplifier to the load connection terminals 7u and 7v. The output of the load current detection circuit 11 and the output of the load voltage detection circuit 12 are input to the control device 13.

The control device 13 includes a comparator 13a for comparing the output of the load current detection circuit 11 with a reference signal, an A / D converter 13b for converting the output of the load voltage detection circuit 12 into a digital signal, a RAM and a CPU. And a microcomputer 13c having
ET The drive signal G is applied to the gates of Fu, Fv, Fx and Fy.
drive signal output circuit 13 for providing u, Gv, Gx and Gy
d, and an A / D converter 13e for converting a detection value of the output voltage of the rectifier 4 into a digital signal.

The voltage between the output terminals of the rectifier 4 is applied to the input terminal of the operational amplifier 14, and the output of the operational amplifier 14 is input to the A / D converter 13e in the control device 13.

The control device 13 controls the power conversion circuit so as to compensate for the decrease in the output current of the power conversion circuit due to the decrease in the output voltage of the rectifier 4 when the load current increases and the output voltage of the rectifier 4 decreases. By increasing the on-duty ratio of one of the switches at the diagonal positions of the bridge circuit constituting the above, the current supplied from the generator 2 to the power conversion circuit 5 through the rectifier 4 is adjusted to be substantially constant.

The control device 13 also includes a load current detection circuit 1
1 is compared with an overcurrent determination value by the comparator 13a, and when the detected value of the current exceeds the determination value, the switch of the power conversion circuit 5 (in the illustrated example, FET F
u, Fv, Fx, and Fy), the overcurrent control for stopping the output of the power conversion circuit 5 by stopping the supply of the drive signal to the power conversion circuit 5 is performed.

In the power supply device 1 shown in FIG. 1, a three-phase AC voltage output from the generator 2 is converted into a DC voltage by the controller 4 and input to the power conversion circuit 5. Control device 1
Reference numeral 3 denotes drive signals Gu, Gy such that the pair of FETs Fu, Fy and Fv, Fx at diagonal positions of the bridge circuit constituting the power conversion circuit are simultaneously turned on for a desired half cycle of a sine wave. And Gv, Gx, the drive signal given to the lower-stage FET is turned on and off at a duty ratio proportional to the instantaneous peak value of each sine wave, thereby turning the lower-stage FET on and off. Apply PWM control. The voltage output from the power conversion circuit 5 is passed through the filter circuit 6 to remove harmonic components and is converted into a smooth sine wave voltage, and then applied to the load 9 through the load connection terminals 7u and 7v.

The sine wave voltage applied to the load 9 is detected by the load voltage detection circuit 12 and fed back to the control device 13. The CPU 13c of the control device 13 compares each instantaneous magnitude of the output voltage with each instantaneous value (set value) of the desired sine wave voltage, and determines that the instantaneous value of the output voltage is greater than the instantaneous value of the desired sine wave voltage. When it is low, the duty ratio of the PWM control is increased, and when the instantaneous value of the output voltage becomes higher than the instantaneous value of the desired sine wave voltage, the duty ratio of the PWM control is controlled to be small. 7v
A desired sine wave voltage is generated in between.

In the conventional power supply device, the power conversion circuit 5
In order to obtain a sine wave AC output voltage from the power conversion circuit 5, the switches (FETs in the illustrated example) of the power conversion circuit 5 Fu, Fv, F
Drive signals Gu, Gy, Gx, and G as shown in FIGS. 2A, 2B, 2C, and 2D are respectively assigned to x and Fy.
v was given. Switches Fu, Fy, Fx and F
v indicates that the drive signals Gu, Gy, Gx and Gv are H
When it is at the level, it is turned on, and the drive signals Gu, G
It is kept off when y, Gx and Gv are at L level.

In this example, the period in which the drive signal Gu holds the H level and the period in which the drive signal Gu holds the L level correspond to a half cycle of one polarity and a half cycle of the other polarity of the AC voltage output from the power conversion circuit, respectively. And the drive signal G
The period during which v holds the L level and the period during which it holds the H level correspond to a half cycle of one polarity and a half cycle of the other polarity of the AC voltage, respectively.

The drive signals Gx and Gy are each turned on and off at a predetermined duty ratio so that the AC output voltage approaches a sine wave.

FIG. 2E shows a switch pattern of the power conversion circuit when a drive signal as shown in FIGS. 2A to 2D is given. In FIG. Is a period in which a pair of switches Fu and Fy at diagonal positions of the bridge circuit are simultaneously turned on,
The period indicated by reference sign B 'is a period in which only one switch Fu forming the upper side of the bridge circuit is in the ON state. During the period indicated by reference numeral C ', the other pair of switches Fv and Fx at the diagonal positions of the bridge circuit are simultaneously turned on, and during the period indicated by reference numeral D', the other switch constituting the upper side of the bridge circuit. Only Fv is turned on.

Here, assuming that the load 9 is an inductive load, during a period A 'shown in FIG. 2E, a pair of switches located at diagonal positions as shown by a solid line in FIG. Fu
The current Io flows through the switch Fu and the flywheel diode Dfv during the period B ', as indicated by the broken line in FIG. 3, and the coils L1, L2 and the coils of the load 9 during the period B'. Is released.

In the period C ', as shown by the solid line in FIG.
Through the main current IL, and during the period D ',
A current flows through the switch Fv and the flywheel diode Dfu, and the energy stored in the coils L1, L2 and the load is released.

As described above, in the conventional power conversion generator, when the current flowing through the pair of switches at the diagonal positions of the bridge of the power conversion circuit is interrupted, the upper side of the bridge of the power conversion circuit 2 Only one of the switches is turned on to form a closed circuit for releasing the energy stored in the coil of the filter circuit and the coil included in the load, but in such a configuration, Since the current carrying capacity of the closed circuit for releasing energy cannot be increased, when the energy stored in the coil is large, the energy cannot be fully released and the voltage at both ends of the coil rises, There is a problem that the voltage applied to each switch of the conversion circuit becomes high.

Further, since the electric charge accumulated in the capacitor C1 of the filter circuit cannot be discharged by the above-mentioned closed circuit, the voltage across the capacitor C1 at no load when the impedance of the coils L1 and L2 of the filter circuit becomes low becomes low. Vc1 rises and this voltage Vc1 is applied to the load connection terminal 7
applied between u and 7v. Therefore, the waveform of the voltage VL between the load connection terminals at the time of no load becomes a waveform close to a rectangular wave as shown by the solid line in FIG. 5, and a waveform far from the sine wave shown by the broken line in FIG. There is a problem that the distortion rate of the output voltage waveform increases.

In order to solve such a problem, in the present invention, the switches Fu, Fx, Fv of the power conversion circuit 5 are used.
The drive signals Gu, Gx, Gv and Gy given to Fy and Fy have, for example, waveforms as shown in FIGS. 6A to 6D, and as shown in FIG. When the two switches constituting the upper side of the bridge are simultaneously turned on at the time of shutting off, these switches are on / off controlled by a switch pattern in which a period occurs.

In the period indicated by the symbol A in FIG. 6E, a pair of switches Fu,
Fy is a period in which the two switches Fu and Fv constituting the upper side of the bridge circuit are both in an on state, and a period indicated by reference numeral B is a period in which both switches are on. The period indicated by the symbol C is a period during which the other pair of switches Fv and Fx at the diagonal positions of the bridge circuit are simultaneously turned on, and the period indicated by the symbol D is also a period forming two upper sides of the bridge circuit. Is a period during which the switches Fv and Fu are simultaneously turned on.

As described above, when the main current flowing through the pair of switches located at the diagonal positions of the bridge is cut off, the two switches constituting the upper side of the bridge are turned on simultaneously, and the coil of the filter circuit 6 is turned on. If a closed circuit for releasing the energy stored in L1 and L2 is formed, the current carrying capacity of the closed circuit can be increased, so that the energy stored in the coils L1 and L2 and the load 9 can be quickly reduced. To prevent the voltage across the coils L1 and L2 from rising.

When the two switches constituting the upper side of the bridge are simultaneously turned on, the electric charge accumulated in the capacitor C1 of the filter circuit 6 can also be discharged through the above closed circuit. It is possible to prevent the output voltage waveform from being distorted due to an increase in the voltage between the connection terminals 7u and 7v.

The operation of turning on and off the switch of the power conversion circuit 5 in the pattern shown in FIG. 6 in the power supply device shown in FIG. 1 will be described in detail below.
First, assuming that the load 9 is inductive, the switches Fu and Fy at the diagonal positions during the period A during which the drive signals Gu and Gy are both at the H level are turned on, as shown by the solid line in FIG. The main current IL flows. When the switch Fy is turned off for PWM control, the switch Fu is subsequently turned on.
And a period B occurs in which both Fv are on.
The current Io flows as shown by the broken line in FIG. 7 due to the voltage induced in the coils L1 and L2, and the energy stored in the coils L1 and L2 is released. The period A and the period B are alternately repeated to form one half cycle of the AC output voltage appearing between the load connection terminals 7u and 7v.

As described above, in the present invention, when releasing the energy stored in the coils L1 and L2 and the load, the two switches constituting the upper side of the bridge are simultaneously turned on. The current Io flowing when releasing the stored energy flows through both the flywheel diode Dfv and the switch Fv. Therefore, the current carrying capacity of the closed circuit through which the current Io flows can be increased, and the energy stored in the coils L1 and L2 can be quickly released.

In the period C during which the drive signals Gv and Gx are both at the H level, the other switches Fv and Fx at the diagonal positions are turned on, so that the main current as shown by the solid line in FIG. IL flows. When the switch Fx is turned off for PWM control, the switches Fu and F
Since a period D occurs in which both v are on, a current Io flows as shown by the broken line in FIG. 8 and the energy stored in the coils L1 and L2 is released. By alternately repeating the period C and the period D in FIG. 6E, the other half cycle of the AC output voltage is formed.

Next, assuming that the load 9 is capacitive, when the main current IL flowing through the switches Fu and Fy at the diagonal positions of the power conversion circuit is cut off, as shown by a broken line in FIG. Then, the switches Fu and Fv are both turned on, a current Io flows, and the electric charge accumulated in the capacitor C1 and the electric charge accumulated in the load are released.

When the switches Fu and Fv are both turned on after the main current IL flowing through the switches Fv and Fx at the diagonal positions of the power conversion circuit 5 is cut off, the broken line is shown in FIG. As described above, the current Io flows, and the energy stored in the capacitor C1 is quickly released.

In the above example, when the main current flowing through the switch at the diagonal position of the power conversion circuit is cut off, the two switches constituting the upper side of the bridge of the power conversion circuit are simultaneously turned on. However, when the main current flowing through the power conversion circuit is cut off, two switches constituting the lower side of the bridge of the power conversion circuit may be simultaneously turned on.

Further, when the main current flowing through one pair of switches at the diagonal positions of the power conversion circuit is cut off, two switches constituting the upper side of the bridge of the power conversion circuit are simultaneously turned on. Operation and operation of simultaneously turning on two switches forming the lower side of the bridge of the power conversion circuit when interrupting the current flowing through the other pair of switches at the diagonal position of the bridge of the power conversion circuit. May be alternately performed.

In the above description, the case where a sine-wave AC voltage is obtained from the power conversion circuit 5 is taken as an example. However, the present invention is not limited to the case where an AC voltage is obtained from the power conversion circuit. The present invention can also be applied to a case where a DC voltage is obtained by simultaneously providing a drive signal to a pair of switches at diagonal positions of the conversion circuit 5 and intermittently applying a drive signal to one of the switches of the pair. it can.

[0050]

As described above, according to the present invention, when the main current flowing through the power conversion circuit is cut off, two switches forming the upper side of the bridge of the power conversion circuit or the lower side of the bridge are formed. Are turned on at the same time to form a closed circuit for releasing the energy stored in the filter circuit and the energy stored in the load by these switches. By increasing the capacity, the energy stored in the filter circuit and the load can be released quickly.
Therefore, it is possible to prevent the voltage at both ends of the coil of the filter circuit from increasing and a high voltage to be applied to the switch of the power conversion circuit, and prevent the output voltage waveform from being distorted by increasing the voltage between the load connection terminals when no load is applied. There are advantages that can be.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing a configuration example of a power supply device according to the present invention.

FIG. 2 is a timing chart showing an example of a drive signal given to each switch of a power conversion circuit and a switch pattern of a switch of the power conversion circuit in a conventional power supply device similar to the power supply device shown in FIG. 1; It is a chart.

FIG. 3 illustrates a main current of one half-wave flowing in a power conversion circuit and a current flowing when the main current is cut off when a control device has a conventional configuration in the power supply device of FIG. FIG.

FIG. 4 illustrates a main current of the other half-wave flowing in a power conversion circuit and a current flowing when the main current is cut off when the control device has a conventional configuration in the power supply device of FIG. FIG.

FIG. 5 is a waveform diagram showing an output voltage waveform of the conventional power supply device when there is no load.

6 is a timing chart showing an example of a drive signal provided to each switch of the power conversion circuit and a switch pattern of the switch of the power conversion circuit in the power supply device shown in FIG. 1 according to the present invention.

FIG. 7 is a diagram showing the relationship between the main current of one half-wave flowing in the power conversion circuit of the power supply device of FIG. 1 according to the present invention and the current flowing when the main current is cut off when the load is inductive. It is an explanatory view for explaining.

8 is a diagram showing the relationship between the main current of the other half-wave flowing through the power conversion circuit of the power supply device of FIG. 1 according to the present invention and the current flowing when the main current is cut off when the load is inductive. It is an explanatory view for explaining.

9 is a diagram showing the relationship between the main current of one half-wave flowing in the power conversion circuit of the power supply device of FIG. 1 according to the present invention and the current flowing when the main current is cut off when the load is capacitive; It is an explanatory view for explaining.

FIG. 10 is a diagram showing the relationship between the other half-wave main current flowing through the power conversion circuit of the power supply device of FIG. 1 according to the present invention and the current flowing when the main current is interrupted when the load is capacitive. It is an explanatory view for explaining.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power supply device, 2 ... Magnet type alternator, 3 ... Internal combustion engine,
4 rectifier, 5 power conversion circuit, 6 filter circuit, 7
u, 7v: load connection terminal, 9: load, 13: control device.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kaoru Hariba 3744 Ooka, Numazu-shi, Shizuoka Domestic Electric Co., Ltd. F-term (reference) 5H007 CA02 CB05 DA05 DA06 DB01 DB07 DC02 DC05 EA02 FA03

Claims (2)

[Claims] 1. A bridge-type power conversion circuit comprising two switches, each of which is turned on in response to a drive signal on an upper side and a lower side of a bridge, and connected in anti-parallel to each switch of the power conversion circuit. A flywheel diode, a control device for turning on and off a switch of the power conversion circuit so as to perform PWM control on a main current flowing through a switch at a diagonal position of a bridge of the power conversion circuit, and a load connected to the load. A power supply device with a power conversion circuit, comprising: a connection terminal; a filter circuit comprising a coil and a capacitor and connected between an output terminal of the power conversion circuit and the load connection terminal; Switches constituting the upper side of the bridge have a characteristic that current can flow in both directions when in the ON state. The control device is configured to include a switch element, and to interrupt the main current of the power conversion circuit so as to generate a period in which two switches forming the upper side of the bridge of the power conversion circuit are simultaneously turned on. A power supply device with a power conversion circuit. 2. A bridge-type power conversion circuit comprising two switches, each of which is turned on in response to a drive signal on each of an upper side and a lower side of the bridge, and connected in anti-parallel to each switch of the power conversion circuit. A flywheel diode, a control device for turning on and off a switch of the power conversion circuit so as to perform PWM control on a main current flowing through a switch at a diagonal position of a bridge of the power conversion circuit, and a load connected to the load. A power supply device with a power conversion circuit, comprising: a connection terminal; a filter circuit comprising a coil and a capacitor and connected between an output terminal of the power conversion circuit and the load connection terminal; The switch that constitutes the lower side of the bridge is a switch having a characteristic that current can flow in both directions when in the ON state. The control device is configured to generate a period in which two switches constituting the lower side of the bridge of the power conversion circuit are simultaneously turned on when the main current of the power conversion circuit is interrupted. A power supply device with a power conversion circuit.