JP5547603B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply apparatus that controls an output by changing a switching frequency.

In recent years, due to increasing awareness of global environmental conservation, high efficiency is required for power supply devices, and resonant converters that can suppress switching loss are used. Further, in order to cope with the higher functionality of the power supply device, digital control of the power supply device is being promoted instead of the analog control method that has been used for a long time.
In the resonant converter, a rectangular wave voltage is generated by a switching circuit, and the output power is adjusted by changing the frequency while maintaining the high time rate of the rectangular wave voltage at 50%. In order to slightly change the output power of the resonant converter, it is necessary to increase the modulation resolution of the frequency of the rectangular wave voltage, and it is necessary to slightly change the period of the rectangular wave voltage. In order to slightly change the period of the rectangular wave voltage, the frequency of the clock signal is usually increased. A method for reducing the change in the period of the rectangular wave voltage without increasing the clock frequency is disclosed in Patent Document 1.

JP 2004-194484 A

However, the method of increasing the frequency of the clock signal in order to change the output power of the resonant converter minutely causes an increase in power consumption and an increase in cost.
In addition, the method disclosed in Patent Document 1 requires a multiplier, which causes a problem of increasing costs.

  Therefore, the present invention solves such problems, and an object of the present invention is to provide a power supply device that can reduce cost and power consumption while finely controlling output power.

In order to solve the above-described problems and achieve the object of the present invention, the present invention is configured as follows.
That is, between a DC circuit where a DC power supply is connected between the DC terminals and a rectangular wave voltage is output between the AC terminals, and a current input between the AC terminals is rectified and a DC load and a smoothing capacitor are connected in parallel. A primary winding connected between the AC terminals of the switching circuit and a secondary winding connected between the AC terminals of the rectifying circuit, and the primary winding and the The transformer that magnetically couples the secondary winding, the resonant capacitor and the resonant inductor connected in series with the primary winding and / or the secondary winding, and the switching so that the frequency of the rectangular wave voltage changes. Control means for controlling a switching element included in the circuit, the power supply apparatus supplying power of the DC power supply to the DC load, wherein the control means is a Hi of the rectangular wave voltage while maintaining the h time constant within a predetermined range positive and negative symmetrical operation is allowed, and wherein the changing the period of the rectangular wave voltage by one clock cycle of the clock signal provided in the said control means.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device which reduced cost and power consumption can be provided, controlling output power finely.

It is a circuit diagram which shows the structure of the power supply device of 1st Embodiment of this invention. It is a figure explaining the circuit operation | movement of the AC-DC converter 2 in 1st Embodiment of this invention. It is a figure which shows the state of the mode A explaining the circuit operation | movement of the DC-DC converter 3 in 1st Embodiment of this invention. It is a figure which shows the state of the mode B explaining the circuit operation | movement of the DC-DC converter 3 in 1st Embodiment of this invention. It is a figure which shows the state of the mode C explaining the circuit operation | movement of the DC-DC converter 3 in 1st Embodiment of this invention. It is a figure which shows the state of the mode D explaining the circuit operation | movement of the DC-DC converter 3 in 1st Embodiment of this invention. FIG. 3 is a waveform diagram of a rectangular wave voltage that is an operation waveform of the DC-DC converter 3 in the first embodiment of the present invention. It is a block diagram which shows the outline | summary of the power supply system of the electric vehicle in 2nd Embodiment which employ | adopted the power supply device of this invention.

Embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a circuit diagram showing a configuration of a power supply device 1 according to the first embodiment of the present invention. The power supply device 1 is provided between the AC power supply 5 and the DC load 6, and supplies power from the AC power supply 5 to the DC load 6.
Power supply 1 receives the AC power of the AC power supply 5, the supply and the AC-DC converter 2 that outputs a DC link voltage V _LINK, the DC power to the DC load 6 while insulating the link voltage V _LINK and power And a control means 4 for controlling the AC-DC converter 2 and the DC-DC converter 3.

In the AC-DC converter 2, the AC voltage of the AC power supply 5 is full-wave rectified by bridge-connected rectifier diodes D11 to D14. The full-wave rectified voltage is input to a boost chopper circuit 7 including a smoothing inductor L1, a boost switching element Q10, a boost diode D10, and a link capacitor C1. The voltage between both ends of the link capacitor C1 becomes the link voltage V _LINK of the output of the AC-DC converter 2.

The control means 4 controls the step-up switching element Q10 made of an N-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) of the step-up chopper circuit 7. The main purpose of including the smoothing inductor L1 and the step-up switching element Q10 is to control the step-up switching element Q10 by the control means 4 so that the input current from the AC power source 5 is made into a sinusoidal waveform that is substantially similar to the AC voltage of the AC power source 5. It is to be. By this control, the power factor between the AC voltage of the AC power supply 5 and the input current is improved. Details of this control will be described later with reference to FIG.
The control means 4 also controls the DC-DC converter 3 described later.

  The DC-DC converter 3 includes a switching circuit 8 including switching elements Q1 to Q4 connected in a full bridge, a winding N1 in which a resonance capacitor Cr1 and a resonance inductor Lr1 are connected in series, and a winding N2. T1, bridge-connected diodes D21 to D24, and a smoothing capacitor C2.

Here, the resonant inductor Lr1 may be omitted depending on the leakage inductance or wiring inductance of the transformer T1.
Further, a switching element Q1 and a switching element Q2 connected in series are referred to as a first switching leg, and a switching element Q3 and a switching element Q4 are connected in series as a second switching leg.

  The switching elements Q1 to Q4 that are connected in a full bridge configuration that constitutes the switching circuit 8 are controlled to be opened and closed by the control unit 4, whereby a rectangular wave voltage is generated between the nodes Nd1 and Nd2. This rectangular wave voltage is applied to the series connection body of the resonance capacitor Cr1, the resonance inductor Lr1, and the winding N1, and a resonance current is caused to flow through the winding N1. The current induced in the winding N2 magnetically coupled to the winding N1 is rectified by the bridge-connected diodes D21 to D24, smoothed by the smoothing capacitor C2, and supplied to the DC load 6. Details of this control and operation will be described later with reference to FIG.

  Although the diodes D21 to D24 are described as being fully bridged, a more specific configuration is as follows. The anode of the diode D21 and the cathode of the diode D22 are connected, and the diode D21 and the diode D22 are connected in series to form a first diode leg. In addition, the anode of the diode D23 and the cathode of the diode D24 are connected, and the diode D23 and the diode D24 are connected in series to form a second diode leg.

The first diode leg and the second diode leg are connected in parallel, and both terminals of the first diode leg and the second diode leg are between the DC terminals. The series connection point of the diode D21 and the diode D22 and the series connection point of the diode D23 and the diode D24 are between the AC terminals. The DC terminals between both terminals of the first diode leg and the second diode leg are connected to the smoothing capacitor C2 and the DC load 6 as described above.
The AC terminal between the series connection point of the diode D21 and the diode D22 and the series connection point of the diode D23 and the diode D24 is connected to the winding N2.

  In addition, diodes D1 to D4 are connected to the switching elements Q1 to Q4 in parallel and in the reverse direction (reverse parallel), respectively. Here, when a MOSFET is used as the switching elements Q1 to Q4, a parasitic diode of the MOSFET can be used as the antiparallel diodes D1 to D4.

In addition, the power supply device 1 includes a voltage sensor 21 that detects an input voltage, a voltage sensor 22 that detects a link voltage V _LINK , and a voltage sensor 23 that detects an output voltage. In addition, the power supply device 1 includes a current sensor 24 that detects an input current and a current sensor 25 that detects an output current.
The voltage sensors 21 to 23 and the current sensors 24 and 25 are connected to the control unit 4, and the control unit 4 refers to the information on the voltages and currents detected by the voltage sensors 21 to 23 and the current sensors 24 and 25. I have control.

As described above, the boosting switching element Q10 and the switching elements Q1 to Q4 are digitally controlled by the control means 4. For this purpose, FIG. 1 shows a state in which control signal lines are connected from the control means 4 to the respective gate terminals of the step-up switching element Q10 and the switching elements Q1 to Q4. However, this shows the relation of control, and the control signal voltage converted into the voltage necessary for control is supplied to the actual control signal line.
For example, the control means 4 operates with a power supply of approximately 12V, and a DC voltage of approximately 380V is applied across the link capacitor C1. Therefore, when switching elements Q1 and Q3 are turned on, it is necessary to apply a voltage 12V higher than 380V to the gates (Q1) and (Q3) of switching elements Q1 and Q3. Since such a high voltage cannot be supplied directly from the control means 4, the gates (Q1) and (Q3) of the switching elements Q1 and Q3 are converted into a high signal voltage via a conversion circuit (not shown). To supply.

<Circuit operation of AC-DC converter>
Next, the circuit operation of the AC-DC converter 2 will be described with reference to FIG. Here, the case of one polarity on one side when the voltage of the AC power source 5 is inverted between positive and negative by AC will be described. The operation in the case where the voltage of the AC power supply 5 is inverted and has the opposite polarity on the other side can be easily inferred only by having the opposite polarity.
2A and 2B, “a mode a” in which the switching element Q10 is turned on (ON) and “mode b” in which the switching element Q10 is turned off (OFF). The circuit operation in “ In FIGS. 2A and 2B, the direction and path of current flow are indicated by broken lines with arrows.

≪Mode a≫
In mode a shown in FIG. 2A, the switching element Q10 is in the on state. The voltage of the AC power supply 5 is applied to the smoothing inductor L1 via the diode D11 and the diode D14, and the energy of the AC power supply 5 is accumulated in the smoothing inductor L1.

≪Mode b≫
The mode b is shown in FIG. When the switching element Q10 is turned off (off), the mode b is entered. In mode b, the energy stored in the smoothing inductor L1 is released to the link capacitor C1 via the diode D11, the diode D14, and the boost diode D10.

Thereafter, mode a and mode b are repeated.
The AC power supply 5 has a commercial power supply frequency of 50 Hz to 60 Hz, whereas the switching element Q10 is generally switched at 20 KHz to 100 KHz. Therefore, in FIG. 2, the switching element Q10 repeats switching from several hundred times to several thousand times while the polarity of the AC power supply 5 does not change as shown.
In addition, as described above, the case where the polarity of the AC power supply 5 is inverted is not illustrated, but when the polarity is inverted, the same thing as described above is performed via the diode D12 and the diode D13.

<Circuit operation of DC-DC converter>
Next, the circuit operation of the DC-DC converter 3 will be described with reference to FIGS. 3A to 3D. 3A to 3D show circuit operations in “mode A” to “mode D”, respectively.

≪Mode A≫
FIG. 3A shows the mode A state. In mode A, the switching elements Q1 and Q4 are in the on state. A voltage V _LINK of the link capacitor C1 is applied between the nodes Nd1 and Nd2 so that the node Nd1 is in a positive direction. A resonance current from the link capacitor C1 by the resonance capacitor Cr1 and the resonance inductor Lr1 flows through the winding N1. The current induced in the winding N2 flows to the smoothing capacitor C2 and the output DC load 6 via the diodes D21 and D24. In FIG. 3A, a broken line with an arrow indicates a current flow direction and a path.

Although it is described as a resonance current by the resonance capacitor Cr1 and the resonance inductor Lr1, strictly speaking, it is a current of a resonance circuit including a leakage inductance and an excitation inductance of the transformer T1. Hereinafter, it is simply expressed as “resonance by the resonant capacitor Cr1 and the resonant inductor Lr1” as appropriate.
Further, in the transformer T1 having the winding N1 on the primary side and the winding N2 on the secondary side, an AC voltage substantially proportional to the winding ratio (N2 / N1) of the AC voltage on the primary side is induced on the secondary side. The

≪Mode B≫
FIG. 3B shows the state of mode B. When the electric current accumulates in the resonance capacitor Cr1 due to the flowing current and the resonance current by the resonance capacitor Cr1 and the resonance inductor Lr1 finishes flowing, the mode B is entered. In mode B, the exciting current of the transformer T1 flows through the winding N1. The voltage of the winding N2 is lower than the voltage of the output smoothing capacitor C2, and no current flows through the winding N2 because of the diodes D21 and D24.

≪Mode C≫
FIG. 3C shows the mode C state. When the switching elements Q1 and Q4 are turned off, the mode C is entered. In mode A, if switching elements Q1 and Q4 are turned off before the resonance current ends, mode B may be omitted. In mode C, the current of the resonant inductor Lr1 that has flowed through the switching elements Q1 and Q4 flows through the diodes D2 and D3 and flows to the link capacitor C1. At this time, the voltage of the link capacitor C1 is generated between the nodes Nd1 and Nd2 in the positive direction of the node Nd2.
Next, before switching to the mode D, the switching elements Q2 and Q3 are turned on.

≪Mode D≫
FIG. 3D shows the mode D state. In the mode D, the current in the winding N1 is inverted. In mode D, since the switching elements Q2 and Q3 are on, when all the energy of the resonant inductor Lr1 is discharged in the final stage of mode C, a current, that is, energy flows from the link capacitor C1 to the resonant inductor Lr1.

In mode D, the voltage V _LINK of the link capacitor C1 is applied between the nodes Nd1 and Nd2 so that the node Nd2 is in the positive direction. A resonance current from the link capacitor C1 by the resonance capacitor Cr1 and the resonance inductor Lr1 flows through the winding N1. However, the current flowing direction and the path indicated by the broken line with the arrow are opposite to those in the mode A.
The current induced in the winding N2 flows to the smoothing capacitor C2 and the output DC load 6 via the diodes D22 and D23.

This mode D is a symmetrical operation of mode A. Therefore, in the mode A described above, the switching elements Q1 and Q4 may be the switching elements Q2 and Q3, and the diodes D21 and D4 may be the diodes D22 and D23.
Thereafter, modes B and C are symmetrically operated, and then the mode A is returned again. In addition, illustration and description of a symmetrical operation are omitted.

  As described above, in the power supply device 1, the DC-DC converter 3 is a resonant converter, and the switching frequency of the switching elements Q1 to Q4 is changed, and the frequency of the rectangular wave voltage generated between the nodes Nd1 and Nd2 is changed. Control the output.

<Method for generating rectangular wave voltage>
Next, a method for generating a rectangular wave voltage between the nodes Nd1 and Nd2 will be described with reference to FIGS. The items shown in FIGS. 4A to 4C are (1) a basic clock signal in the control means 4, and (2) gates Q1 and Q1, which are the gate waveforms of the switching elements Q1 and Q4, respectively. Q4, (3) Gates that are the gate waveforms of the switching elements Q2, Q3: Q2, Q3, (4) A rectangular wave voltage between the nodes Nd1-Nd2. The horizontal axis is the elapsed time.

<< (a) 10 clock cycles >>
FIG. 4A shows a rectangular wave voltage between the clock signal, the gate signals of the switching elements Q1 to Q4, and the nodes Nd1 to Nd2. The switching elements Q1 to Q4 have an on time of 4 clock cycles and an off time of 6 clock cycles, and all of Q1 to Q4 are off between Q1 and Q4 on state and Q2 and Q3 on state. A dead time of 1 clock cycle is provided. As a result, the rectangular wave voltage has a high (high potential, positive, 1) time and a low (low potential, negative, 0) time of 5 clock cycles, a high time rate of 50%, and a cycle of 10 clock cycles. Yes.

<< (b) 9 clock cycles >>
Next, FIG. 4B shows a waveform when the frequency of the rectangular wave voltage is increased by one gradation in order to reduce the output power a little compared with FIG. 4A. The on-time of the switching elements Q1 and Q4 is shortened to 3 clock cycles, and the off-time of the switching elements Q2 and Q3 is shortened to 5 clock cycles. Thus, the high time of the rectangular wave voltage is 4 clock cycles, the low time is 5 clock cycles, the high time rate is 44%, and the cycle is 9 clock cycles.

≪ (c) 8 clock cycles≫
FIG. 4C shows a waveform when the frequency of the rectangular wave voltage is set higher by one gradation than that in FIG. 4B. The switching elements Q1 to Q4 have an on-time of 3 clock cycles and an off-time of 5 clock cycles, and the rectangular wave voltage has both a high time and a low time of 4 clock cycles, a high time rate of 50%, and a cycle of 8 clocks. It is a cycle.

As described above, in this embodiment, the high time of the rectangular wave voltage is shortened by one clock period from FIGS. 4A to 4B, and the low time of the rectangular wave voltage is changed from FIG. 4B to FIG. 4C. One clock cycle is shortened. Accordingly, in order to gradually reduce the output power from FIG. 4A to FIG. 4C, the period of the rectangular wave voltage can be shortened by one clock period.
In this example, “basically to a predetermined value” is “basically to 50%”, but this is an example, and the value can be changed within a range where the effect of the invention is exerted.

The resonance frequency due to the excitation inductance of the resonance capacitor Cr1, the resonance inductor Lr1, and the transformer T1 is set lower than the switching frequency of the switching elements Q1 to Q4. Basically, the output power of the DC-DC converter 3 increases as the resonance frequency and the switching frequency are closer.
In the cases shown in FIGS. 4A to 4C, as the clock period of the rectangular wave voltage is changed from 10 clock periods to 9 clock periods and then to 8 clock periods, the frequency is the reciprocal and gradually increases. Get higher. Therefore, since the switching frequency moves away from the resonance frequency, the output power decreases. That is, the output power is gradually reduced.

As described above, conventionally, when the frequency of the rectangular wave voltage is changed by one gradation, both the high time and the low time of the rectangular wave voltage are changed by one clock period, so the period of the rectangular wave voltage is 2 clock periods. It was changing gradually.
On the other hand, in the present invention, when the frequency of the rectangular wave voltage is changed by one gradation, the rectangular wave voltage cycle is set to 1 by alternately changing the High time and Low time of the rectangular wave voltage by one clock cycle. The clock cycle can be changed. Thereby, since the modulation resolution of the frequency of the rectangular wave voltage is doubled, the output voltage and the output current can be finely controlled.

It is desirable that the high time rate of the rectangular wave voltage is 50%, that is, the interval between the high time and the low time of the rectangular wave voltage is equal. In order to keep the operations of the switching elements Q1, Q4 and the switching elements Q2, Q3 ideally symmetrical, the waveforms of the gates Q1, Q4 and the gates Q2, Q3 in FIG. 4 need to be symmetrical. For this reason, it is desirable that the high time rate of the rectangular wave voltage is 50%.
In FIG. 4B, the high time rate of the rectangular wave voltage is a little different from 50%, but if the difference is less than this level, there is often no practical problem.

  As described above, the control means 4 is connected to the voltage sensor 23 that detects the output voltage and the current sensor 25 that detects the output current. The control means 4 can control the output at a constant voltage by adjusting the switching frequency so that the detected output voltage matches the target value, and can output if the switching frequency is adjusted so that the detected output current matches the target value. The constant current can be controlled.

Further, if the constant voltage control and the constant current control are appropriately selected, the output can be controlled at a constant current and a constant voltage.
As described above, in the power supply device 1 according to the first embodiment of the present invention, the switching frequency can be finely adjusted by changing the high time and the low time of the rectangular wave voltage alternately by one clock period. Voltage control and constant current control can be performed.

  In the first embodiment of FIG. 1, the AC-DC converter 2 has been described as means for obtaining DC power from an AC power supply. However, when a DC power supply (DC power supply) has already been provided and DC power can be obtained. The AC-DC converter 2 is not an essential element of the present invention.

(Second Embodiment)
Next, a second embodiment is shown.
FIG. 5 is a configuration diagram showing an outline of a power supply system of an electric vehicle 110 that employs the power supply device 1 according to the present invention. The power supply device 1 is connected to a plug-in charging connector 108 connected to an AC power source 109 and a secondary battery 105.
The secondary battery 105 is connected to a DC-DC converter 100 that supplies power to the auxiliary battery 106 to which the electrical equipment 101 is connected.
The secondary battery 105 is connected to a DC-DC converter 102 that supplies power to an inverter 103 that drives a power motor 104.
Further, the secondary battery 105 is connected to a quick charge connector 107 for charging the secondary battery 105 by connecting an external DC power source such as a quick charger.

The power supply device 1 charges the secondary battery 105 using the power of the AC power supply 109 connected to the plug-in charging connector 108 while controlling the output of the DC power at constant current and constant voltage. In the second embodiment, by using the power supply device 1, the secondary battery 105 can be charged while finely controlling current and voltage.
The power supply device 1 can also be applied to an electric vehicle other than a hybrid vehicle or an electric vehicle.

(Other embodiments)
In the resonance type DC-DC converter 3 described above, a combination of a circuit in which switching elements are full-bridge connected by four elements and a circuit in which diodes are bridge-connected by four elements is used. A similar effect can be obtained by a circuit system combining a center tap circuit.

  The switching element Q10 (including Q1 to Q4) has been described as a MOSFET, but may be an IGBT (Insulated Gate Bipolar Transistor).

  Further, when the switching elements Q1 to Q4 are not configured by MOSFETs, diodes D1 to D4 are added in parallel and in the reverse direction (reverse parallel) to the switching elements Q1 to Q4, respectively. Note that the antiparallel diodes D1 to D4 may be provided even when the switching elements Q1 to Q4 are configured by MOSFETs.

  Further, in the rectifier circuit including the diodes D21 to D24 in FIG. 1, a first voltage dividing capacitor and a second voltage dividing capacitor can be substituted for the diode D23 and the diode D24, respectively. Further, the diode D21 and the diode D22 may be replaced.

  Further, instead of the resonant capacitor Cr1 in FIG. 1, the switching element Q3 and the switching element Q4 can be replaced with a resonant capacitor. At this time, resonance occurs between the resonant capacitor replaced with the switching elements Q3 and Q4 and the resonant inductor Lr1. Note that the switching elements Q1 and Q2 may be replaced.

  Further, in FIG. 1, the resonance capacitor Cr1 and the resonance inductor Lr1 are provided in the circuit on the primary side of the transformer T1, but may be provided in the circuit on the secondary side of the transformer T1. Further, both the primary side and secondary side circuits of the transformer T1 may be provided.

  Further, in FIG. 1, the configuration of only the primary side winding and circuit of the transformer T1 and the configuration corresponding to the secondary side may be magnetically coupled. For example, if the power supply device of the present invention is used in an IH (Induction Heating) system, the heat generation amount of the heated conductor can be finely controlled.

  In addition, as described above, in FIG. 4B, the high time rate of the rectangular wave voltage is slightly different from 50%, and it has been described that there is no problem if the difference is less than this level. Therefore, the same effect as described above can be obtained even when the High time is 5 clock cycles, the Low time is 4 clock cycles, the High time rate is 56%, and the cycle is 9 clock cycles.

4A to 4C, the dead time (the switching elements Q1 to Q4 are all off) is digitally generated from the clock signal. However, the dead time is analogly generated from the digitally generated signal from the clock signal. A gate signal can also be obtained by generating time.
In this case, the rise and fall of the gate signal are not synchronized with the clock signal, but the high time and low time of the rectangular wave voltage are the same as those in FIGS. 4A to 4C in that they are integral multiples of the clock cycle. The above-described method of changing the high time and the low time alternately by one clock cycle can be applied.

  Furthermore, in order to improve the apparent frequency modulation resolution, it may be used in combination with dithering generated by alternately repeating the period of the rectangular wave voltage at different periods. For example, if the period of 10 clocks shown in FIG. 4A and the period of 9 clocks shown in FIG. 4B are alternately repeated, a rectangular wave voltage having an apparent period of 9.5 clocks And an intermediate output between FIGS. 4A and 4B can be obtained.

<Comparison with comparative circuit example>
If the 10 clock cycle of FIG. 4A and the 8 clock cycle of FIG. 4C are alternately repeated by dithering, a rectangular wave voltage having an apparent cycle of 9 clock cycles can be generated.
However, in this case, pulsations of 18 clock cycles, which is twice the 9 clock cycles, are superimposed on the output. In general, dithering superimposes subharmonics on the output.
On the other hand, in the case of the rectangular wave voltage having a cycle of 9 clocks in FIG. 4B of the present embodiment described above, an output in which the subharmonic is not superimposed can be obtained.

(This embodiment, supplement of the present invention)
As described above, the power supply apparatus according to the present embodiment finely controls the output power by improving the frequency modulation resolution while maintaining the high time rate of the rectangular wave voltage at about 50% by the control means 4 in the DC-DC converter 3. A power supply device can be provided.
Since the clock frequency is not increased and the multiplier is not used, a power supply device that realizes low power consumption at low cost can be provided.
In addition, the power supply device of the present embodiment can be widely applied to systems that control the output by flowing a resonance current with a rectangular wave voltage and digitally changing the frequency. For example, as described above, if the power supply device of this embodiment is used in an IH (induction heating) system, the amount of heat generated by the heated conductor can be finely controlled.

DESCRIPTION OF SYMBOLS 1 Power supply device 2 AC-DC converter 3 DC-DC converter 4 Control means 5 AC power supply 6 DC load 7 Boost chopper circuit 8 Switching circuit 21, 22, 23 Voltage sensor 24, 25 Current sensor 101 Electrical equipment 100, 102 DC-DC Converter 103 Inverter 104 Motor for power 105 Secondary battery 106 Auxiliary battery 107 Quick charge connector 108 Plug-in charge connector 109 AC power supply 110 Electric vehicle.
C1 Link capacitor C2 Smoothing capacitor Cr1 Resonant capacitor D1 to D4 Diode, antiparallel diode D10 Boost diode D11 to D14 Diode, Rectifier diode D21, D22 Diode (first diode leg)
D23, D24 Diode (second diode leg)
L1 Smoothing inductor Lr1 Resonant inductor N1, N2 Winding Nd1, Nd2 Node Q1, Q2 Switching element (first switching leg), gate, gate waveform Q3, Q4 Switching element (second switching leg), gate, gate waveform Q10 switching element, the boosting switching element T1 transformer V _LEAK link voltage, the voltage V _O output voltage

Claims (14)

A switching circuit in which a DC power source is connected between the DC terminals and a rectangular wave voltage is output between the AC terminals;
A rectifying circuit that rectifies current input between AC terminals and outputs between DC terminals in which a DC load and a smoothing capacitor are connected in parallel;
A primary winding connected between the alternating current terminals of the switching circuit and a secondary winding connected between the alternating current terminals of the rectifying circuit, and the primary winding and the secondary winding are magnetically A transformer to be combined,
A resonant capacitor and a resonant inductor connected in series with the primary winding and / or the secondary winding;
Control means for controlling the switching element of the switching circuit so that the frequency of the rectangular wave voltage changes;
A power supply device that supplies power of the DC power supply to the DC load,
The control means maintains the high time rate of the rectangular wave voltage within a predetermined range in which positive and negative symmetrical operations are allowed, and sets the period of the rectangular wave voltage by one clock period of the clock signal included in the control means. A power supply device characterized by being changed. 2. The power supply device according to claim 1, wherein “within the predetermined range” means that a high time ratio of the rectangular wave voltage is within a range of 44% to 56%. The power supply device according to claim 1 or 2 , further comprising an AC-DC converter,
An AC power supply is connected between input terminals of the AC-DC converter, and an output terminal is connected between DC terminals of the switching circuit. 4. The power supply device according to claim 1 , wherein the control unit alternately changes a high time and a low time of the rectangular wave voltage for each clock cycle of the clock signal. 5. . In any one of claims 1 to 4, wherein, the power supply apparatus characterized by varying the power supplied to the DC load by varying the frequency of the rectangular wave voltage. In any one of claims 1 to 5, wherein the rectifier circuit includes first, a first diode leg in which the second diode connected in series, the third, the fourth diode connected in series, and A second diode leg connected in parallel to the first diode leg, and between both ends of the first diode leg as a direct current terminal, the series connection point of the first and second diodes and the first diode leg 3. A power supply device characterized in that a portion between the series connection points of the fourth and fourth diodes is an AC terminal. 7. The power supply device according to claim 6 , wherein the third and fourth diodes are replaced with first and second voltage dividing capacitors, respectively. In any one of claims 1 to 7, wherein the switching circuit includes first, a first switching leg, third, a fourth switching element connected in series with a second switching element connected in series And a second switching leg connected in parallel to the first switching leg, wherein both ends of the first switching leg are between DC terminals, and a series connection point of the first and second switching elements. A power supply device characterized in that the AC terminal is between the first and third switching elements connected in series. 9. The power supply device according to claim 8 , wherein the resonance capacitor is a first or second resonance capacitor in which the third and fourth switching elements are replaced. According to claim 8 or claim 9, the power supply apparatus characterized by comprising a reverse parallel diode in each of the first to fourth switching elements. In any one of claims 1 to 10, wherein, the power supply device, characterized in that the constant-current constant-voltage controls the output of the power supply. A switching circuit in which a DC power source is connected between the DC terminals and a rectangular wave voltage is output between the AC terminals;
A winding connected between AC terminals of the switching circuit;
A resonant capacitor connected in series with the winding;
Control means for controlling a switching element included in the switching circuit so as to change the frequency of the rectangular wave voltage;
With
A power supply device that induction-heats a heated conductor that is magnetically coupled to the winding by the power of the DC power source,
The control means maintains the high time rate of the rectangular wave voltage within a predetermined range in which positive and negative symmetrical operations are allowed, and sets the period of the rectangular wave voltage by one clock period of the clock signal included in the control means. A power supply device characterized by being changed. 13. The power supply device according to claim 12, wherein the predetermined range is a high time ratio of the rectangular wave voltage within a range of 44% to 56%. The power supply device according to claim 12 or 13 , further comprising an AC-DC converter,
An AC power supply is connected between input terminals of the AC-DC converter, and an output terminal is connected between DC terminals of the switching circuit.

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