JP6322565B2 - Power supply device and power supply control method - Google Patents

Description

  The present invention relates to a power supply device and a power supply control method.

  In recent years, a power supply device including a DC / DC converter that is supplied with power from three-phase alternating current and performs current mode control is known (see Patent Document 1).

Japanese Patent Laid-Open No. 11-113256

  However, in the power supply apparatus described above, when a full bridge type DC / DC converter (hereinafter referred to as a full bridge converter) is used, it is difficult to perform current mode control. In a power supply apparatus including a full bridge converter, It is common to perform phase shift control. Therefore, in a power supply device including a full bridge converter, the peak value of the input current of each converter in each phase supplied from multiphase AC cannot be made uniform, and the conversion efficiency of the power supply may be reduced. In the power supply device described above, the response of the switching element may be delayed.

  The present invention has been made to solve the above problems, and an object thereof is to provide a power supply device and a power supply control method capable of improving the conversion efficiency of the power supply and improving the response of the switching element. is there.

  In order to solve the above problem, one aspect of the present invention is a power supply device including a full-bridge DC / DC converter, wherein the DC / DC converter includes a first switching element, a second switching element, A full bridge circuit having a third switching element and a fourth switching element, and the full bridge circuit is connected to the primary side coil, and a rectifier circuit for rectifying the output from the secondary side coil is provided in the secondary side coil. The transformer to be connected and the first switching element and the second switching element connected to the first end of the primary coil of the transformer are controlled by a predetermined fixed duty, and the primary coil A control unit for controlling the third switching element and the fourth switching element connected to the second end in a current mode; A power supply and wherein the obtaining.

  According to another aspect of the present invention, in the power supply device described above, the control unit controls the first switching element and the second switching element by pulse width modulation at a light load, and the third switching element. The switching element and the fourth switching element are controlled to be in a non-conductive state.

  Further, according to one aspect of the present invention, in the power supply device, the control unit controls the first switching element and the second switching element with a predetermined fixed duty, and the third switching element and The fourth switching element is controlled by pulse width modulation.

  According to another aspect of the present invention, the power supply apparatus includes a plurality of the DC / DC converters, and the plurality of DC / DC converters have the same current peak value of a current waveform flowing through the primary coil. In addition, the third switching element and the fourth switching element are controlled in a current mode.

  According to one embodiment of the present invention, in the above power supply device, the first switching element and the third switching element are connected to a first power supply line, and the second switching element and the fourth switching element are connected. The switching element is connected to a second power supply line, and the control unit controls the first switching element to be in a conductive state with the predetermined fixed duty in a first period when the load is not light. In addition, the fourth switching element is controlled to be in a conductive state by current mode control, and in the second period, the second switching element is controlled to be in a conductive state with the predetermined fixed duty. The switching element is controlled to be in a conductive state by current mode control.

  One embodiment of the present invention is a power supply device including a full-bridge DC / DC converter, wherein the DC / DC converter includes a first switching element, a second switching element, a third switching element, And a full bridge circuit having a fourth switching element, a transformer in which the full bridge circuit is connected to the primary side coil, and a rectifier circuit that rectifies the output from the secondary side coil is connected to the secondary side coil; When the load is light, the first switching element and the second switching element connected to the first end of the primary coil of the transformer are controlled by pulse width modulation, and the second end of the primary coil is And a control unit that controls the third switching element and the fourth switching element to be connected to a non-conductive state. It is a power supply that.

  Another embodiment of the present invention is a power supply control method for a power supply apparatus including a full-bridge DC / DC converter, wherein the DC / DC converter includes a first switching element, a second switching element, and a third switching element. A full bridge circuit having a switching element and a fourth switching element, and the full bridge circuit is connected to the primary coil, and a rectifier circuit for rectifying the output from the secondary coil is connected to the secondary coil. And a control unit that controls conduction and non-conduction states of the first switching element, the second switching element, the third switching element, and the fourth switching element included in the full bridge circuit. The control unit includes a first end of the primary coil of the transformer and a first power line in the first period. The first switching element connected to the first switching element is controlled to be conductive by a predetermined fixed duty, and the fourth switching is connected between the second end of the primary coil and the second power supply line. The element is controlled to be in a conductive state by current mode control, and the second switching element connected between the first end of the primary coil and the second power supply line is fixed in a predetermined period in the second period. And controlling the third switching element connected between the second end of the primary coil and the first power supply line to a conductive state by current mode control. It is a power supply control method characterized.

  Another embodiment of the present invention is a power supply control method for a power supply apparatus including a full-bridge DC / DC converter, wherein the DC / DC converter includes a first switching element, a second switching element, and a third switching element. A full bridge circuit having a switching element and a fourth switching element, and the full bridge circuit is connected to the primary coil, and a rectifier circuit for rectifying the output from the secondary coil is connected to the secondary coil. And a control unit that controls conduction and non-conduction states of the first switching element, the second switching element, the third switching element, and the fourth switching element included in the full bridge circuit. And the control unit has a first end of the primary side coil of the transformer in a first period at a light load. The first switching element connected to the first power supply line is controlled to be conductive by pulse width modulation, and the third switching element connected to the second end of the primary coil and the first switching element The second switching element is connected between the first end of the primary coil of the transformer and the second power supply line in the second period at the time of the light load. And the third switching element connected to the second end of the primary side coil and the fourth switching element are controlled to be in a non-conductive state. This is a power control method.

  According to the present invention, since the third switching element and the fourth switching element are controlled in the current mode, the peak values of the currents of the respective converters in each phase AC can be made uniform. Therefore, the conversion efficiency of the power source can be improved and the response of the switching element can be improved.

It is a block diagram which shows an example of the power supply device by this embodiment. It is a block diagram which shows an example of the DC / DC converter by this embodiment. It is a time chart which shows an example of control of the DC / DC converter by this embodiment. It is a block diagram which shows an example of the control part by this embodiment. It is a time chart which shows an example of the current mode control by this embodiment. It is a time chart which shows an example of the three-phase current mode control by this embodiment. It is a time chart which shows an example of the control at the time of the light load of the DC / DC converter by this embodiment. It is a block diagram which shows an example of the three-phase collective control by this embodiment.

Hereinafter, a power supply device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating an example of a power supply device 1 according to the present embodiment.
As shown in this figure, the power supply device 1 is a power supply device that outputs a predetermined DC voltage from a three-phase AC power supply (R, S, T). The power supply apparatus 1 includes PFC (Power Factor Correction) units 2-1 to 2-3 and DC / DC converters 10-1 to 10-3.

The PFC unit 2-1 is a U-phase PFC circuit, the PFC unit 2-2 is a V-phase PFC circuit, and the PFC unit 2-3 is a W-phase PFC circuit. In this figure, the PFC unit 2-1, the PFC unit 2-2, and the PFC unit 2-3 have the same configuration, and indicate any PFC unit included in the power supply device 1, or do not particularly distinguish between them. Will be described as the PFC unit 2.
The PFC unit 2 is a power factor correction circuit, removes high-frequency current components, converts input AC power into DC power, and outputs the DC power.

The DC / DC converter 10-1 converts the DC power converted from the U phase supplied from the PFC unit 2-1 into a predetermined DC voltage and outputs it. Further, the DC / DC converter 10-2 converts the DC power converted from the V phase supplied from the PFC unit 2-2 into a predetermined DC voltage and outputs it. Further, the DC / DC converter 10-3 converts the DC power converted from the W phase supplied from the PFC unit 2-3 into a predetermined DC voltage and outputs it.
In this figure, the DC / DC converter 10-1, the DC / DC converter 10-2, and the DC / DC converter 10-3 have the same configuration, and any DC / DC converter included in the power supply device 1 is used. The DC / DC converter 10 will be described when it is shown or not particularly distinguished.
The DC / DC converter 10 is, for example, a DC-DC conversion circuit that converts DC power supplied from the PFC unit 2 into a predetermined DC voltage. The DC / DC converter 10 is a full-bridge DC / DC converter. Here, a configuration example of the DC / DC converter 10 will be described with reference to FIG.

FIG. 2 is a block diagram illustrating an example of the DC / DC converter 10 according to the present embodiment.
As shown in FIG. 2, the DC / DC converter 10 includes a current detection unit 11, a voltage detection unit 12, a control unit 13, a full bridge circuit 20, a driver unit 40, a smoothing capacitor (Ci, Co), and the like. , Transformer TL1, series reactor L1, diodes (D5, D6), rectifier diodes (D7, D8), and choke coil L2. The full bridge circuit 20 includes switching elements Q1 to Q4, a resonance capacitor C5, parasitic capacitances C1 to C4, and body diodes D1 to D4.

  The smoothing capacitor Ci is connected between the input power supply line VI (first power supply line) and the power supply line GND1 (second power supply line), and smoothes the input voltage.

  The switching element Q1 (an example of the first switching element) has a drain terminal connected to the power supply line VI, a source terminal connected to the node N1, and a gate terminal connected to the signal line of the drive signal G1. That is, the switching element Q1 is connected between the power supply line VI and a first end of a primary coil TL11 described later. Further, the switching element Q1 has a parasitic capacitance C1 and a body diode D1 between the drain terminal and the source terminal.

  The switching element Q2 (an example of the second switching element) has a drain terminal connected to the node N1, a source terminal connected to the power supply line GND1, and a gate terminal connected to the signal line of the drive signal G2. That is, the switching element Q2 is connected between the power supply line GND1 and a first end of a primary side coil TL11 described later. Further, the switching element Q2 has a parasitic capacitance C2 and a body diode D2 between the drain terminal and the source terminal.

  Switching element Q3 (an example of a third switching element) has a drain terminal connected to power supply line VI, a source terminal connected to node N2, and a gate terminal connected to a signal line for drive signal G3. That is, the switching element Q3 is connected between the power supply line VI and a second end (node N3) of a primary side coil TL11 described later. Further, the switching element Q3 has a parasitic capacitance C3 and a body diode D3 between the drain terminal and the source terminal.

  The switching element Q4 (an example of the fourth switching element) has a drain terminal connected to the node N2, a source terminal connected to the power supply line GND1, and a gate terminal connected to the signal line of the drive signal G4. That is, the switching element Q4 is connected between the power supply line GND1 and a second end (node N3) of a primary side coil TL11 described later. Further, the switching element Q4 has a parasitic capacitance C4 and a body diode D4 between the drain terminal and the source terminal.

The transformer TL1 has a primary side coil TL11 and a secondary side coil TL12 with a center tap, converts power supplied to the primary side coil TL11, and outputs it to the secondary side coil TL12.
The primary coil TL11 is connected to the full bridge circuit 20. For example, the primary side coil TL11 has a first end connected to the switching element Q1 and the switching element Q2 via the resonance capacitor C5. In other words, the first end of the primary coil TL11 is connected to the node N1 via the resonance capacitor C5. The primary coil TL11 has, for example, a second end connected to the node N3, and a second end connected to the switching element Q3 and the switching element Q4 via the series reactor L1. That is, the second end of the primary side coil TL11 is connected to the node N2 via the series reactor L1.
The series reactor L1 is connected in series with the primary side coil TL11, and realizes ZVS (Zero Voltage Switching) operation of the switching elements Q1 to Q4 by resonance with the parasitic capacitances C1 to C4 and the wiring capacitance.

  Secondary coil TL12 has a first end connected to node N4 and a second end connected to node N5. The secondary coil TL12 has a center tap, and the center tap is connected to the node N6. The center tap is connected to the choke coil L2. The secondary coil TL12 is connected to a rectifier circuit 30 described later.

The diode D5 has an anode terminal connected to the node N3 that is the first end of the primary coil TL11, and a cathode terminal connected to the power supply line VI. The diode D5 functions as a clamp diode.
The diode D6 has an anode terminal connected to the power supply line GND1 and a cathode terminal connected to the node N3 that is the first end of the primary coil TL11. The diode D5 functions as a clamp diode.

The rectifier diode D7 has an anode terminal connected to the output power line GND2, and a cathode terminal connected to the node N4 that is the first end of the secondary coil TL12. The rectifier diode D8 has an anode terminal connected to the output power line GND2 and a cathode terminal connected to the node N5 that is the second end of the secondary coil TL12.
The rectifier diode D7 and the rectifier diode D8 are included in the rectifier circuit 30 and function as a double-wave rectifier circuit.

The choke coil L2 has a first end connected to the node N6 connected to the center tap of the secondary coil TL12, and a second end connected to the output power line VO. The choke coil L2 is used for smoothing the DC power output from the DC / DC converter 10 together with a smoothing capacitor Co described later.
The smoothing capacitor Co is connected between the output power supply line VO and the power supply line GND2, and smoothes the output voltage.
Here, the load RL indicates a load that consumes DC power output from the DC / DC converter 10.

The current detection unit 11 detects a current input to the primary coil TL11. The current detection unit 11 outputs the detected current to the control unit 13 as a signal Vi converted into a voltage.
The voltage detector 12 detects the output voltage of the DC / DC converter 10 and outputs it to the controller 13 as a signal Vo that is a feedback voltage signal. The voltage detector 12 converts the level of the output voltage of the DC / DC converter 10 to compare with the reference voltage Vref, and outputs a signal Vo.

  The control unit 13 is a processor including, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and the like, and includes a switching element Q1, a switching element Q2, a switching element Q3, and a switching element Q4 included in the full bridge circuit 20. It controls the ON state (conducting state) and the OFF state (non-conducting state). The control unit 13 receives the drive signal G1, the drive signal G2, the drive signal G3, and the drive signal G4 that control the voltage at the gate terminals of the switching element Q1, the switching element Q2, the switching element Q3, and the switching element Q4. Output via.

Further, the control unit 13 controls, for example, the switching element Q1 and the switching element Q2 with a predetermined fixed duty during a normal load (when not light), and controls the switching element Q3 and the switching element Q4 in the current mode. Control. That is, the control unit 13 controls the switching element Q1 and the switching element Q2 with a predetermined fixed duty, and controls the switching element Q3 and the switching element Q4 with PWM (pulse width modulation).
The control unit 13 controls the switching element Q1 and the switching element Q2 by PWM (pulse width modulation) and controls the switching element Q3 and the switching element Q4 to be in an OFF state at a light load. Details of control of switching element Q1, switching element Q2, switching element Q3, and switching element Q4 by control unit 13 will be described later.

  The driver unit 40 converts the control signal for the switching element Q1, the switching element Q2, the switching element Q3, and the switching element Q4 output from the control unit 13 into a voltage for driving each switching element, so that each switching element Supply to the gate terminal of the device. The driver unit 40 includes drivers 41 to 44, for example.

The driver 41 supplies a drive signal G1 for driving the switching element Q1 to the gate signal of the switching element Q1 based on the control signal of the switching element Q1 output from the control unit 13.
The driver 42 supplies a drive signal G2 for driving the switching element Q2 to the gate signal of the switching element Q2 based on the control signal of the switching element Q2 output from the control unit 13.
The driver 43 supplies a drive signal G3 for driving the switching element Q3 to the gate signal of the switching element Q3 based on the control signal of the switching element Q3 output from the control unit 13.
The driver 44 supplies a drive signal G4 for driving the switching element Q4 to the gate signal of the switching element Q4 based on the control signal of the switching element Q4 output from the control unit 13.

Next, with reference to FIG. 3, the control of the switching element Q1, the switching element Q2, the switching element Q3, and the switching element Q4 during a normal load by the control unit 13 will be described.
FIG. 3 is a time chart showing an example of control of the DC / DC converter 10 according to the present embodiment.
In this figure, the waveforms of the waveforms W1 to W4 indicate the voltage waveforms of the drive signals G1 to G4 in order from the top. In this figure, the horizontal axis indicates time, and the vertical axis indicates the logical level.

  At time T1, the control unit 13 first sets the drive signal G1 of the switching element Q1 and the drive signal G4 of the switching element Q4 to the H (High) state. In this case, the control unit 13 maintains the drive signal G2 for the switching element Q2 and the drive signal G3 for the switching element Q3 in the L (Low) state. Thereby, the switching element Q1 and the switching element Q4 are turned on, and the switching element Q2 and the switching element Q3 are turned off. As a result, a current flows from the power supply line VI through the path of the switching element Q1, the resonance capacitor C5, the primary side coil TL11, the series reactor L1, and the switching element Q4. As a result, power is generated from the primary side coil TL11 to the secondary side coil TL12. The secondary side coil TL12 rectifies this power via the rectifier circuit 30, and smoothes it via the choke coil L2 and the smoothing capacitor Co. The converted DC voltage is output to the power supply line VO.

  The control unit 13 maintains the switching element Q4 on until the current value detected by the current detection unit 11 reaches a predetermined value so that the output signal Vo of the voltage detection unit 12 and the reference voltage Vref match. To do. Further, the control unit 13 maintains the ON state of the switching element Q1 so that the ON state period (turn-on period) of the switching element Q1 becomes a predetermined duty (predetermined fixed duty).

  At time T2, the current value detected by the current detection unit 11 reaches a predetermined value, and the control unit 13 sets the drive signal G4 to the L state and turns off the switching element Q4. The period DT2 in which the switching element Q4 is ON varies depending on the output signal Vo and the current consumption of the load RL. That is, the control unit 13 performs PWM (pulse width modulation) by current mode control, and controls the period DT2 of the ON state of the switching element Q4.

At time T3, the ON state period of the switching element Q1 reaches a predetermined duty, and the control unit 13 sets the drive signal G1 to the L state and turns the switching element Q1 to the OFF state. Here, the predetermined duty is, for example, a ratio (for example, 50%) of the on-state period DT1 in the period TT1, and a predetermined conduction time (period DT1) per one period (period TT1). It is a time ratio indicating a ratio (DT1 / TT1 × 100). In this embodiment, the predetermined duty is assumed to be about 50%.
As described above, the control unit 13 controls the switching element Q1 to be in the ON state with a predetermined fixed duty in the first period (for example, the period DT1) when the load is not light, and the switching element Q4 is made current. Control to ON state by mode control.

  Next, at time T4, the control unit 13 sets the drive signal G2 for the switching element Q2 and the drive signal G3 for the switching element Q3 to the H state. In this case, the control unit 13 maintains the drive signal G1 of the switching element Q1 and the drive signal G4 of the switching element Q4 in the L state. Thereby, switching element Q2 and switching element Q3 are turned on, and switching element Q1 and switching element Q4 are turned off. As a result, a current flows from the power line VI through the switching element Q3, the series reactor L1, the primary coil TL11, the resonance capacitor C5, and the switching element Q2. As a result, power is generated from the primary side coil TL11 to the secondary side coil TL12. The secondary side coil TL12 rectifies this power via the rectifier circuit 30, and smoothes it via the choke coil L2 and the smoothing capacitor Co. The converted DC voltage is output to the power supply line VO.

  The control unit 13 turns on the switching element Q3 until the current value detected by the current detection unit 11 reaches a predetermined peak value so that the output signal Vo of the voltage detection unit 12 matches the reference voltage Vref. maintain. Further, the control unit 13 maintains the ON state of the switching element Q2 so that the ON state period (turn-on period) of the switching element Q2 becomes a predetermined duty (predetermined fixed duty).

  At time T5, the current value detected by the current detection unit 11 reaches a predetermined value, and the control unit 13 sets the drive signal G3 to the L state and turns off the switching element Q3. The period DT4 of the ON state of the switching element Q3 varies depending on the output signal Vo and the current consumption of the load RL. That is, the control unit 13 performs PWM (pulse width modulation) by current mode control, and controls the period DT4 in which the switching element Q3 is in the ON state.

At time T6, the ON state period of the switching element Q2 reaches a predetermined duty, and the control unit 13 sets the drive signal G2 to the L state and turns the switching element Q2 to the OFF state.
Thus, the control unit 13 controls the switching element Q2 to be in the ON state with a predetermined duty during the second period (for example, the period DT3) when the load is not light, and controls the switching element Q3 in the current mode. To control the ON state.

  The subsequent processing from time T7 to time T12 is the same as the processing from time T1 to time T6 described above, and therefore description thereof is omitted here. As described above, the control unit 13 alternately repeats the process of the first period (period DT1) and the process of the second period (period DT3), thereby switching the switching element Q1 and switching element Q2 included in the full bridge circuit 20. The ON state and OFF state of the switching element Q3 and the switching element Q4 are controlled.

  In FIG. 3, the switching element Q3 operates as a ZVS during a period from time T2 to time T4, and the switching element Q4 operates as a ZVS during a period from time T5 to time T7. Further, the switching element Q2 performs ZVS operation during a period from time T3 to time T4, and the switching element Q1 performs ZVS operation during a period from time T6 to time T7. In addition, each of these periods (ΔT) is set in advance by the load current value.

Next, a configuration example of the control unit 13 that performs the above-described control will be described with reference to FIG.
FIG. 4 is a block diagram illustrating an example of the control unit 13 according to the present embodiment.
As shown in FIG. 4, the control unit 13 includes a control signal generation unit 131, comparators (132, 133), an OR (or) circuit 134, and an RS flip-flop 135.
Note that the example shown in this figure describes the configuration for generating the drive signal G1 and the drive signal G4 for the sake of explanation, but the configuration for generating the drive signal G2 and the drive signal G3 is basically the same. The description is omitted here.

  The control signal generator 131 generates various control signals for controlling the drive signal G1 and the drive signal G4. For example, the control signal generator 131 outputs a predetermined voltage value to the control voltage Vc1 in order to turn on the switching element Q1 with a predetermined duty. Further, the control signal generation unit 131 generates the sawtooth wave signal S1 with the above-described cycle (period TT1). The control signal generator 131 outputs the generated control voltage Vc1 and the sawtooth signal S1 as input signals to the comparator 132.

Further, the control signal generation unit 131 generates the control voltage Vc2 for current mode control based on, for example, the reference voltage Vref and the signal Vo that is a feedback voltage signal. The control signal generation unit 131 generates the control voltage Vc2 based on, for example, PID (Proportional-Integral-Derivative) control. The control signal generator 131 changes the voltage value of the control voltage Vc2 so that the signal Vo matches the reference voltage Vref. The control signal generator 131 outputs the generated control voltage Vc2 as an input signal of the comparator 133 (−input terminal input signal).
In addition, the control signal generation unit 131 generates a signal CLK1 that periodically sets an RS flip-flop 135, which will be described later, during current mode control, and the generated signal CLK1 is supplied to the S terminal (set terminal) of the RS flip-flop 135. Output. In addition, the control signal generation unit 131 generates a signal RST that resets the RS flip-flop 135 and outputs the generated signal RST to the OR circuit 134. Note that the control signal generation unit 131 outputs an L state to the signal RST during current mode control.

The control unit 13 controls the switching element Q1 and the switching element Q2 by PWM (pulse width modulation) and controls the switching element Q3 and the switching element Q4 to be in an OFF state at a light load. Therefore, the control signal generation unit 131 generates a control voltage Vc1 for PWM control of the switching element Q1 based on, for example, the reference voltage Vref and the signal Vo that is a feedback voltage signal at a light load. In this case, the control signal generation unit 131 changes the voltage value of the control voltage Vc1 so that the signal Vo matches the reference voltage Vref. Further, the control signal generation unit 131 outputs an H state to the signal RST in order to control the switching element Q4 to be in an OFF state at a light load.
Here, the control signal generation unit 131 determines whether or not the load is light based on the level of the signal Vi. That is, for example, when the signal Vi is maintained at a predetermined value or less (that is, current consumption is small), the control signal generation unit 131 determines that the load is light.

  The comparator 132 has a negative input terminal connected to the signal line of the sawtooth signal S1 and a positive input terminal connected to the signal line of the control voltage Vc1. The comparator 132 compares the voltage of the sawtooth wave signal S1 with the voltage value of the control voltage Vc1, and outputs an H state when the voltage value of the sawtooth wave signal S1 is less than the voltage value of the control voltage Vc1. . The comparator 132 outputs an L state when the voltage value of the sawtooth wave signal S1 is equal to or higher than the voltage value of the control voltage Vc1. The output signal of the comparator 132 is output as the drive signal G1 through the driver 41.

  The comparator 133 has a negative input terminal connected to the signal line of the control voltage Vc2, and a positive input terminal connected to the signal line of the signal Vi. The comparator 133 compares the voltage value of the signal Vi with the voltage value of the control voltage Vc2, and outputs an L state when the voltage value of the signal Vi is less than the voltage value of the control voltage Vc2. The comparator 133 outputs an H state when the voltage value of the signal Vi is equal to or higher than the voltage value of the control voltage Vc2.

  The OR circuit 134 is an arithmetic circuit that performs an OR logical operation (logical sum operation) on two input signals. The OR circuit 134 is supplied with the above-described signal RST and the output signal of the comparator 133 at two input terminals, and outputs an output signal obtained by ORing the two signals to the R terminal (reset terminal) of the RS flip-flop 135. To do.

  When the signal CLK1 is in the H state, the RS flip-flop 135 changes the output signal Q to the H state and holds the output signal Q in the H state until the R terminal is in the H state. The RS flip-flop 135 changes the output signal Q to the L state when the output signal of the OR circuit 134 is in the H state, and holds the output signal Q in the L state until the S terminal is in the H state. The output signal Q of the RS flip-flop 135 is output as a drive signal G4 via the driver 44.

  Although not shown in the example illustrated in FIG. 4, the control unit 13 generates the drive signal G2 in the same manner as the drive signal G1, and generates the drive signal G3 in the same manner as the drive signal G4.

Next, the operation of the current mode control of the control unit 13 described above will be described with reference to FIG.
FIG. 5 is a time chart showing an example of current mode control according to the present embodiment.
In this figure, the respective signals are, in order from the top, the input signal (S1, Vc1) of the comparator 132, the drive signal G1, the signal CLK1, the input signal (Vi, Vc2) of the comparator 133, the output signal of the comparator 133, and the drive signal. G4 is shown. The waveform W5 indicates the waveform of the sawtooth signal S1, the waveform W6 indicates the waveform of the control voltage Vc1, the waveform W7 indicates the waveform of the drive signal G1, and the waveform W8 indicates the waveform of the signal CLK1. ing. The waveform W9 indicates the waveform of the control voltage Vc2, the waveform W10 indicates the waveform of the signal Vi, the waveform W11 indicates the waveform of the output signal of the comparator 133, and the waveform W12 indicates the waveform of the drive signal G4. ing.

In this figure, the horizontal axis indicates time, the vertical axis indicates the voltage of the input signals (S1, Vc1) and the input signals (Vi, Vc2), and the other signals indicate logic levels. Here, the times T1 to T3, the period TT1, the period DT1, and the period DT2 are the same as those in FIG.
Note that the example shown in this figure describes an example in which the drive signal G1 and the drive signal G4 are generated for the sake of explanation, but basically the same applies to the case where the drive signal G2 and the drive signal G3 are generated. Therefore, the description thereof is omitted here.
In addition, the example shown in this figure is a normal load time (not a light load time), and it is assumed that the control signal generation unit 131 outputs an L state to the signal RST.

  When the sawtooth wave signal S1 becomes 0 V at time T1, the output of the comparator 132 is in the H state, and the driver 41 outputs the H state as indicated by the waveform W7. Note that the control signal generation unit 131 outputs a predetermined voltage value of the control voltage Vc1 (waveform W6) so that the switching element Q1 is in the H state with a predetermined duty (for example, 50%).

At time T1, the control signal generation unit 131 sets the signal CLK1 to the H state for a predetermined period as indicated by the waveform W8. As a result, the RS flip-flop 135 outputs the H state, and the driver 44 sets the drive signal G4 to the H state.
As a result, the switching element Q1 and the switching element Q4 are turned on, and the signal Vi corresponding to the current waveform input to the primary coil TL11 increases.

  Next, when the voltage value of the signal Vi reaches the control voltage Vc2 at time T2, the comparator 133 outputs an H state as indicated by a waveform W11. As a result, the RS flip-flop 135 is reset and outputs the L state, and the driver 44 sets the drive signal G4 to the L state. As a result, the switching element Q4 is controlled to the OFF state.

Next, when the voltage value of the sawtooth signal S1 reaches the control voltage Vc1 at time T3, the comparator 132 outputs the L state, and the driver 41 sets the drive signal G1 to the L state. As a result, the switching element Q1 is controlled to the OFF state.
As described above, during normal load (when light load is not applied), the control unit 13 controls the switching element Q1 with a predetermined fixed duty, and the switching element Q4 is PWM (pulse width modulation) by current mode control. Control by. Although not shown, the control unit 13 similarly controls the switching element Q2 with a predetermined fixed duty and controls the switching element Q3 with PWM (pulse width modulation) by current mode control.

Next, the three-phase current mode control according to the present embodiment will be described with reference to FIG.
FIG. 6 is a time chart showing an example of three-phase current mode control according to the present embodiment.
In this figure, each signal indicates an input signal (Vi, Vc2) and a drive signal G4 (U phase, V phase, W phase) for the comparator 133 for three phases in order from the top. A waveform W13 indicates the waveform of the control voltage Vc2, and a waveform W14 indicates the waveform of the U-phase signal Vi (the signal Vi of the DC / DC converter 10-1). A waveform W15 shows the waveform of the V-phase signal Vi (signal Vi of the DC / DC converter 10-2), and a waveform W16 shows the waveform of the W-phase signal Vi (signal Vi of the DC / DC converter 10-3). The waveform is shown. A waveform W17 indicates a U-phase drive signal G4 (U), a waveform W18 indicates a V-phase drive signal G4 (V), and a waveform W19 indicates a W-phase drive signal G4 (W). Yes.

In this figure, the horizontal axis indicates time, the vertical axis indicates the voltage of the input signals (Vi, Vc2), and the other signals indicate logic levels.
In addition, although the example shown in this figure has described about an example about the drive signal G4 on description, it is the same also in the case of the drive signal G3 fundamentally, and the description is abbreviate | omitted here.
In addition, the example shown in this figure is a normal load time (not a light load time), and it is assumed that the control signal generation unit 131 outputs an L state to the signal RST.

At time T15, the control signal generation unit 131 of each DC / DC converter 10 sets the signal CLK1 to the H state for a predetermined period. Thereby, each RS flip-flop 135 outputs an H state, and each driver 44 outputs each drive signal G4 (drive signal G4 (U), drive signal G4 (V), The drive signal G4 (W)) is set to the H state.
As a result, the switching element Q4 of each DC / DC converter 10 is turned on, and each signal Vi rises as shown by the waveforms W14 to W15. Here, since the phase of the three-phase alternating current is different between the U phase, the V phase, and the W phase, the rising waveform of each signal Vi is different. Here, the voltage value of the control voltage Vc2 is the same voltage value that is equal in each DC / DC converter 10, as shown by the waveform W13.

  Next, when the voltage value of the U-phase signal Vi reaches the control voltage Vc2 at time T16, the U-phase comparator 133 outputs the H state, and the driver 44 outputs the drive signal as indicated by the waveform W17. G4 (U) is set to the L state. As a result, the switching element Q4 of the U-phase DC / DC converter 10-1 is turned off by the current mode control.

  When the voltage value of the V-phase signal Vi reaches the control voltage Vc2 at time T17, the V-phase comparator 133 outputs an H state, and the driver 44 outputs the drive signal G4 as indicated by the waveform W18. (V) is set to the L state. As a result, the switching element Q4 of the V-phase DC / DC converter 10-2 is turned off by the current mode control.

  At time T18, when the voltage value of the W-phase signal Vi reaches the control voltage Vc2, the W-phase comparator 133 outputs an H state, and the driver 44 outputs the drive signal G4 as indicated by the waveform W19. (W) is set to the L state. As a result, the switching element Q4 of the W-phase DC / DC converter 10-3 is turned off by the current mode control.

  Thus, in the case of the three-phase current mode control according to the present embodiment, the DC / DC converter 10 (10-1, 10-2, 10-3) has each current peak value of the current waveform flowing through the primary coil TL11. Are controlled in current mode so that the switching elements Q3 and Q4 are matched in three phases.

Next, control of the switching element Q1, the switching element Q2, the switching element Q3, and the switching element Q4 at the time of light load by the control unit 13 will be described with reference to FIG.
FIG. 7 is a time chart showing an example of control at the time of light load of the DC / DC converter 10 according to the present embodiment.
In this figure, each waveform of the waveforms W21 to W24 shows voltage waveforms of the drive signals G1 to G4 at light load in order from the top. In this figure, the horizontal axis indicates time, and the vertical axis indicates the logical level.

  At time T21, the control unit 13 first sets the drive signal G1 for the switching element Q1 to the H state. In this case, the control unit 13 maintains the driving signal G2 of the switching element Q2, the driving signal G3 of the switching element Q3, and the driving signal G4 of the switching element Q4 in the L state. Thereby, the switching element Q1 is turned on, and the switching element Q2, the switching element Q3, and the switching element Q4 are turned off. In this case, the full bridge circuit 20 operates like a half bridge circuit, for example, due to the parasitic capacitances of the switching element Q3 and the switching element Q4. As a result, power is generated from the primary side coil TL11 to the secondary side coil TL12, and the secondary side coil TL12 rectifies this power via the rectifier circuit 30 and smoothes it via the choke coil L2 and the smoothing capacitor Co. The converted DC voltage is output to the power supply line VO.

The control unit 13 sets the voltage value of the sawtooth wave signal S1 to the voltage value of the control voltage Vc1 generated by the control signal generation unit 131 so that the output signal Vo of the voltage detection unit 12 matches the reference voltage Vref. Until it reaches, the ON state of the switching element Q1 is maintained. That is, the control unit 13 controls the ON state (period DT5) of the switching element Q1 by PWM control based on the feedback voltage Vo.
Next, when the voltage value of the sawtooth signal S1 reaches the control voltage Vc1 at time T22, the comparator 132 sets the drive signal G1 to the L state via the driver 41. As a result, the switching element Q1 is controlled to the OFF state.

  At time T23, the control unit 13 sets the drive signal G2 for the switching element Q2 to the H state. In this case, the control unit 13 maintains the driving signal G1 of the switching element Q1, the driving signal G3 of the switching element Q3, and the driving signal G4 of the switching element Q4 in the L state. As a result, the switching element Q2 is turned on, and the switching element Q1, the switching element Q3, and the switching element Q4 are turned off. In this case, the full bridge circuit 20 operates like a half bridge circuit, for example, due to the parasitic capacitances of the switching element Q3 and the switching element Q4. As a result, power is generated from the primary side coil TL11 to the secondary side coil TL12, and the secondary side coil TL12 rectifies this power via the rectifier circuit 30 and smoothes it via the choke coil L2 and the smoothing capacitor Co. The converted DC voltage is output to the power supply line VO.

In this case as well, the control unit 13 sets the sawtooth wave signal (to the voltage value of the control voltage Vc1 generated by the control signal generation unit 131 so that the output signal Vo of the voltage detection unit 12 matches the reference voltage Vref. For example, the switching element Q2 is kept on until the voltage value of the signal S2) having a phase different from that of the signal S1 is reached. That is, the control unit 13 controls the ON state (period DT7) of the switching element Q2 by PWM control based on the feedback voltage Vo.
Next, when the voltage value of the sawtooth signal S2 reaches the control voltage Vc1 at time T24, the comparator 132 sets the drive signal G2 to the L state via the driver 41. As a result, the switching element Q2 is controlled to the OFF state.

  The subsequent processing from time T25 to time T28 is the same as the processing from time T21 to time T24 described above, and therefore description thereof is omitted here. Here, a period from time T21 to time T23 is defined as a period DT6 (first period), and a period from time T23 to time T25 is defined as a period DT8 (second period). As described above, the control unit 13 alternately repeats the process of the first period (period DT6) and the process of the second period (period DT8), thereby switching the switching elements Q1 and Q2 included in the full bridge circuit 20. The ON state and OFF state of the switching element Q3 and the switching element Q4 are controlled.

  That is, the control unit 13 applies PWM (pulse) to the switching element Q1 connected between the first end of the primary coil TL11 of the transformer TL1 and the power supply line VI in the first period (period DT6) at light load. The switching element Q3 and the switching element Q4 connected to the second end of the primary coil TL11 are controlled to be in the OFF state, while being controlled to be in the ON state by width modulation. In addition, in the second period (period DT8) at light load, the control unit 13 applies PWM (pulse) to the switching element Q2 connected between the first end of the primary coil TL11 of the transformer TL1 and the power supply line GND1. The switching element Q3 and the switching element Q4 connected to the second end of the primary coil TL11 are controlled to be in the OFF state, while being controlled to be in the ON state by width modulation).

  In the above-described example of the present embodiment, an example in which each of the three-phase DC / DC converters 10 includes the control unit 13 has been described. However, in the present embodiment, a part of the control unit 13 is shared, It is possible to control the phases collectively. Here, with reference to FIG. 8, an example in the case of collectively controlling the three phases according to the present embodiment will be described.

FIG. 8 is a block diagram illustrating an example of three-phase collective control according to the present embodiment.
The control unit 13a shown in this figure includes a control signal generation unit 131a, comparators (133-1, 133-2, 133-3), OR circuits (134-1, 134-2, 134-3), RS Flip-flops (135-1, 135-2, 135-3).
In the example shown in this figure, the drive signal G4 for driving the switching element Q4 of each DC / DC converter 10 is described, and the other portions are not shown.

The control signal generation unit 131a shares processing with the three-phase DC / DC converter 10 and supplies the generated signal RST, signal CLK1, and signal Vc2 to the three-phase DC / DC converter 10. The signals Vi (U), Vi (V), and Vi (W) are signals Vi detected by the three-phase DC / DC converters 10.
The comparators (133-1, 133-2, 133-3) are configured to control the voltage Vc2 generated by the control signal generator 131a at once, the signal Vi (U) and the signal Vi detected by each DC / DC converter 10, respectively. (V) and Vi (W) are respectively compared. Each configuration of the comparators (133-1, 133-2, 133-3) is the same as the comparator 133 described above.

The configurations of the OR circuits (134-1, 134-2, 134-3) are the same as those of the OR circuit 134 described above, and the RS flip-flops (135-1, 135-2, 135-3) are the same. Each configuration is the same as the RS flip-flop 135 described above.
The RS flip-flop 135-1 outputs a U-phase drive signal G4 (U) via the driver 44-1, and the RS flip-flop 135-2 receives a V-phase drive signal via the driver 44-2. G4 (V) is output. The RS flip-flop 135-3 outputs a W-phase drive signal G4 (W) via the driver 44-3.
In addition, each structure of a driver (44-1, 44-2, 44-3) is the same as the driver 44 mentioned above.

  Thus, in this embodiment, the control signal can be simplified by sharing the control signals in the plurality of DC / DC converters 10 like the control signal generator 131a described above.

  As described above, the power supply device 1 according to the present embodiment includes the full-bridge DC / DC converter 10. The DC / DC converter 10 includes a full bridge circuit 20, a transformer TL1, and a control unit 13. The full bridge circuit 20 includes a switching element Q1 (first switching element), a switching element Q2 (second switching element), a switching element Q3 (third switching element), and a switching element Q4 (fourth switching element). Have In the transformer TL1, the full bridge circuit 20 is connected to the primary coil TL11, and the rectifier circuit 30 that rectifies the output from the secondary coil TL12 is connected to the secondary coil TL12. The control unit 13 controls the switching element Q1 and the switching element Q2 connected to the first end of the primary side coil TL11 of the transformer TL1 with a predetermined fixed duty, and is connected to the second end of the primary side coil TL11. The switching element Q3 and the switching element Q4 are controlled in a current mode.

  As a result, the power supply device 1 according to the present embodiment performs current mode control of the switching element Q3 and the switching element Q4. For example, when a plurality of phases of AC power is input, the peak current of each converter in each phase AC You can align the values. Moreover, since the power supply device 1 according to the present embodiment does not need to perform a phase shift for generating a control signal for each switching element, the response of the switching element can be improved. Therefore, the power supply device 1 according to the present embodiment can improve the conversion efficiency of the power supply and improve the response of the switching element.

In the present embodiment, the control unit 13 controls the switching element Q1 and the switching element Q2 by PWM (pulse width modulation) and controls the switching element Q3 and the switching element Q4 to be in an OFF state at a light load.
Thereby, the power supply device 1 according to the present embodiment can cause the full bridge circuit 20 to function like a half bridge circuit. The power supply device 1 according to the present embodiment can suppress an increase in output voltage at a light load by reducing the conversion efficiency equivalent to that of a half-bridge circuit, and can output an appropriate output voltage. Is possible.

In the present embodiment, the control unit 13 controls the switching element Q1 and the switching element Q2 with a predetermined fixed duty, and controls the switching element Q3 and the switching element Q4 with PWM (pulse width modulation).
Accordingly, the power supply device 1 according to the present embodiment can perform current mode control with a simple configuration.

In the present embodiment, the power supply device 1 includes a plurality of DC / DC converters 10. The plurality of DC / DC converters 10 carry out current mode control of the switching element Q3 and the switching element Q4 so that the respective current peak values of the current waveform flowing through the primary coil TL11 coincide with each other.
As a result, the power supply device 1 can easily improve the conversion efficiency of the power supply by controlling the current mode so that the current peak values match even when a plurality of phases of AC power is input. it can.

In the present embodiment, the switching element Q1 and the switching element Q3 are connected to the power supply line VI (first power supply line), and the switching element Q2 and the switching element Q4 are connected to the power supply line GND1 (second power supply line). Connected. In the first period (period DT1), the control unit 13 controls the switching element Q1 to be in an ON state with a predetermined fixed duty and sets the switching element Q4 to be in an ON state by current mode control when the load is not light. Control. In addition, when the load is not light, the control unit 13 controls the switching element Q2 to be in the ON state with the predetermined fixed duty in the second period (period DT3), and controls the switching element Q3 by current mode control. Control to ON state.
Thereby, the power supply device 1 by this embodiment can improve the conversion efficiency of a power supply by simple control by the full bridge circuit 20. FIG.

In the present embodiment, the DC / DC converter 10 includes a series reactor L1 connected in series with the primary coil TL11.
As a result, the power supply device 1 according to the present embodiment causes the switching elements Q1 to Q4 and the rectifier diodes (D7 and D8) to perform the ZVS operation by resonance between the series reactor L1, the parasitic capacitances C1 to C4, and the wiring capacitance. Can do. As a result, the power supply device 1 according to the present embodiment can reduce the switching loss, thereby further improving the conversion efficiency of the power supply.

The power control method according to the present embodiment is a power control method for the power supply device 1 including the full-bridge DC / DC converter 10. Here, the DC / DC converter 10 includes the above-described full bridge circuit 20, the transformer TL1, and the control unit 13. In the power supply control method according to the present embodiment, the control unit 13 is arranged between the first end of the primary coil TL11 of the transformer TL1 and the power supply line VI (first power supply line) in the first period (period DT1). The switching element Q1 connected is controlled to be in an ON state by a predetermined fixed duty, and the switching element Q4 connected between the second end of the primary coil TL11 and the power supply line GND1 (second power supply line) is controlled. It is controlled to ON by current mode control. Then, in the second period (period DT3), the control unit 13 controls the switching element Q2 connected between the first end of the primary coil TL11 and the power supply line GND1 to the ON state with a predetermined fixed duty. At the same time, the switching element Q3 connected between the second end of the primary coil TL11 and the power supply line VI is controlled to be turned on by current mode control.
Thereby, the power supply control method by this embodiment can improve the conversion efficiency of a power supply, and can improve the response of a switching element (switching element) similarly to the power supply device 1 mentioned above.

Further, in the power supply control method according to the present embodiment, the control unit 13 determines the first end of the primary coil TL11 and the power supply line VI (first power supply line) in the first period (period DT6) at light load. The switching element Q1 connected between the two is controlled to be turned on by PWM (pulse width modulation), and the switching element Q3 and the switching element Q4 connected to the second end of the primary coil TL11 are controlled to be turned off. Then, the control unit 13 switches the switching element Q2 connected between the first end of the primary coil TL11 and the power supply line GND1 (second power supply line) in the second period (period DT8) at the time of light load. Is controlled to be in the ON state by PWM (pulse width modulation), and the switching element Q3 and the switching element Q4 connected to the second end of the primary coil TL11 are controlled to be in the OFF state.
Thereby, the power supply control method by this embodiment can suppress that an output voltage raises at the time of light load similarly to the power supply device 1 mentioned above, and can output an appropriate output voltage. become.

The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention.
For example, as an example of the present embodiment, the configurations of the power supply device 1 illustrated in FIG. 1 and the DC / DC converter 10 illustrated in FIG. 2 have been described, but the present invention is not limited to these. For example, the power supply device 1 may have a configuration corresponding to a multi-phase AC power source including three or more DC / DC converters 10 or may not have the PFC unit 2.
Further, the DC / DC converter 10 may be configured not to include some or all of the series reactor L1, the resonant capacitor C5, and the diodes (D5, D6).

Moreover, although transformer TL1 demonstrated the example provided with the secondary side coil TL12 with a center tap, you may not have a center tap.
Further, the example in which the rectifier circuit 30 is a double-wave rectifier circuit has been described. However, the rectifier circuit 30 is not limited to this, and may be a full-wave rectifier circuit such as a diode bridge, or other rectifier circuit. There may be.

In the above embodiment, the switching element Q1 and the switching element Q2 have been described as the first switching element and the second switching element. However, the switching element Q3 and the switching element Q4 are the first switching element and the second switching element. It is good also as an element. Moreover, although switching element Q3 and switching element Q4 were demonstrated as a 3rd switching element and a 4th switching element, switching element Q1 and switching element Q2 are good also as a 3rd switching element and a 4th switching element.
Moreover, although the control signal generation part 131 demonstrated the example which produces | generates control voltage Vc2 based on PID control, you may produce | generate control voltage Vc2 by another control system.

Further, the control unit 13 is not limited to the circuit configuration illustrated in FIG. 4, and may be realized by another circuit configuration.
In the above-described embodiment, the processing of each unit of the control unit 13 (13a) may be realized by dedicated hardware such as an IC (Integrated Circuit) or may be realized by software processing.

  The power supply apparatus 1 described above has a computer system inside. The process of the control unit 13 (13a) described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

DESCRIPTION OF SYMBOLS 1 Power supply device 2, 2-1, 2-2, 2-3 PFC part 10, 10-1, 10-2, 10-3 DC / DC converter 11 Current detection part 12 Voltage detection part 13, 13a Control part 20 Full Bridge circuit 30 Rectifier circuit 40 Driver unit 41, 42, 43, 44, 44-1, 44-2, 44-3 Driver 131, 131a Control signal generation unit 132, 133, 133-1, 133-2, 133-3 Comparator 134, 134-1, 134-2, 134-3 OR circuit 135, 135-1, 135-2, 135-3 RS flip-flop C1, C2, C3, C4 Parasitic capacitance C5 Resonance capacitor Ci, Co Smoothing capacitor D1 , D2, D3, D4 Body diode D5, D6 Diode D7, D8 Rectifier diode L1 Series reactor L2 Choke Coil Q1, Q2, Q3, Q4 Switching element TL1 Transformer TL11 Primary coil TL12 Secondary coil RL Load

Claims (8)

A power supply device comprising a full-bridge DC / DC converter,
The DC / DC converter is
A full-bridge circuit having a first switching element, a second switching element, a third switching element, and a fourth switching element;
A transformer in which the full bridge circuit is connected to the primary side coil and a rectifier circuit for rectifying the output from the secondary side coil is connected to the secondary side coil;
The first switching element and the second switching element connected to the first end of the primary side coil of the transformer are controlled by a predetermined fixed duty and connected to the second end of the primary side coil. And a controller that controls the current mode of the third switching element and the fourth switching element. The controller is
The first switching element and the second switching element are controlled by pulse width modulation at the time of light load, and the third switching element and the fourth switching element are controlled to be in a non-conductive state. The power supply device according to claim 1. The controller is
The first switching element and the second switching element are controlled by a predetermined fixed duty, and the third switching element and the fourth switching element are controlled by pulse width modulation. The power supply device according to claim 1 or 2. A plurality of the DC / DC converters;
The plurality of DC / DC converters perform current mode control on the third switching element and the fourth switching element so that current peak values of current waveforms flowing in the primary side coils coincide with each other. The power supply device according to any one of claims 1 to 3. The first switching element and the third switching element are connected to a first power line,
The second switching element and the fourth switching element are connected to a second power line,
When the control unit is not under light load,
In the first period, the first switching element is controlled to be conductive by the predetermined fixed duty, and the fourth switching element is controlled to be conductive by current mode control.
The second switching element is controlled to be in a conducting state by the predetermined fixed duty in the second period, and the third switching element is controlled to be in a conducting state by current mode control. The power supply device according to any one of claims 1 to 4. A power supply device comprising a full-bridge DC / DC converter,
The DC / DC converter is
A full-bridge circuit having a first switching element, a second switching element, a third switching element, and a fourth switching element;
A transformer in which the full bridge circuit is connected to the primary side coil and a rectifier circuit for rectifying the output from the secondary side coil is connected to the secondary side coil;
When the load is light, the first switching element and the second switching element connected to the first end of the primary coil of the transformer are controlled by pulse width modulation, and the second end of the primary coil is A power supply apparatus comprising: a control unit configured to control the third switching element and the fourth switching element connected to a non-conductive state. A power supply control method for a power supply device including a full-bridge DC / DC converter,
The DC / DC converter is
A full-bridge circuit having a first switching element, a second switching element, a third switching element, and a fourth switching element;
A transformer in which the full bridge circuit is connected to the primary side coil and a rectifier circuit for rectifying the output from the secondary side coil is connected to the secondary side coil;
A control unit for controlling a conduction state and a non-conduction state of the first switching element, the second switching element, the third switching element, and the fourth switching element included in the full-bridge circuit,
The control unit is
In the first period, the first switching element connected between the first end of the primary coil of the transformer and the first power line is controlled to a conductive state with a predetermined fixed duty, Controlling the fourth switching element connected between the second end of the primary side coil and a second power supply line to a conductive state by current mode control;
In the second period, the second switching element connected between the first end of the primary coil and the second power supply line is controlled to be in a conductive state with a predetermined fixed duty, and the primary A power supply control method, wherein the third switching element connected between a second end of a side coil and the first power supply line is controlled to be in a conductive state by current mode control. A power supply control method for a power supply device including a full-bridge DC / DC converter,
The DC / DC converter is
A full-bridge circuit having a first switching element, a second switching element, a third switching element, and a fourth switching element;
A transformer in which the full bridge circuit is connected to the primary side coil and a rectifier circuit for rectifying the output from the secondary side coil is connected to the secondary side coil;
A control unit for controlling a conduction state and a non-conduction state of the first switching element, the second switching element, the third switching element, and the fourth switching element included in the full-bridge circuit,
The control unit is
In the first period at light load, the first switching element connected between the first end of the primary coil of the transformer and the first power supply line is controlled to be conductive by pulse width modulation. And controlling the third switching element and the fourth switching element connected to the second end of the primary coil to a non-conductive state,
In the second period at the time of the light load, the second switching element connected between the first end of the primary coil of the transformer and the second power supply line is controlled to be conductive by pulse width modulation. And controlling the third switching element and the fourth switching element connected to the second end of the primary coil to be in a non-conductive state.

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