JP2013251965A - Power-supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-supply circuit that allows reducing loss in a switching element or a capacitor and easy controlling of switching at a primary side and a secondary side.SOLUTION: A power-supply circuit includes: a switching circuit outputting an AC voltage; a transformer having first to third coils; a rectifier circuit rectifying an output from the second coil; a power conversion circuit having at least one first rectifier, a second switching element, a second rectifier, an inductive element, and a capacitive element; and a control circuit controlling switching timing. The control circuit progressively increases a first duty ratio of the switching of the switching circuit, and performs on and off control of the second switching element by a second duty ratio larger than the first duty ratio until an output voltage across the capacitive element reaches a predetermined output.

Description

  The present invention relates to a power supply circuit.

  In a vehicle-mounted power supply circuit or the like, a plurality of outputs may be required, and a power supply circuit that integrates a multi-stage voltage conversion circuit may be used. In such a power supply circuit, the primary side switching element and the secondary side switching element are synchronized.

  For example, in a multi-output stabilized power supply device having a primary winding and first and second secondary windings, a first switching element for turning on and off an input signal to the primary winding, and a second 2 There is an example including a second switching element that turns on and off a switching signal induced in the next winding. At this time, synchronization means is provided for synchronizing the on / off timing of the second switching element with the timing of the first switching element. In this example, the synchronization unit turns on the second switching element while the first switching element is on.

Japanese Utility Model Publication No. 3-60879

  In such a power supply circuit, for example, a soft start is performed in order to prevent a loss caused by a switching element on the primary side or a capacitor provided on the output side due to an inrush current flowing at the time of startup. There is. At the start of soft start, a pulse with a low duty ratio is applied to the switching element. By the way, when switching elements are provided on both the primary side and the secondary side as in Patent Document 1, the switching timing of the primary side and the secondary side needs to be synchronized. However, there is a problem that it is very difficult to synchronize pulses having a low duty ratio as at the start of soft start.

  In view of the above problems, the present invention provides a power supply circuit that can reduce loss in a switching element and a capacitor and can easily control switching between a primary side and a secondary side.

  A power supply circuit according to one aspect includes at least one first switching element, a switching circuit that outputs an alternating voltage by controlling a switching timing of the at least one first switching element, and the switching A first coil connected to the circuit, a transformer having a second coil and a third coil provided on the secondary side, a rectifier circuit for rectifying the output of the second coil, and the rectifier circuit A power connected to the smoothing circuit connected to the third coil and having at least one first rectifying element, a second switching element, a second rectifying element, an inductive element, and a capacitive element. A conversion circuit; and a control circuit that controls switching timing of the switching circuit and the second switching element, and the control circuit The first duty ratio of switching of the switching circuit is gradually increased, and the second switching element is made larger than the first duty ratio until the output voltage at both ends of the capacitive element reaches a predetermined output. It is characterized in that control to turn on / off at a duty ratio of 2 is performed.

  According to another aspect, a power supply circuit includes at least one first switching element, a switching circuit that outputs an alternating voltage by controlling a switching timing of the at least one first switching element, and the switching A first coil connected to the circuit, a transformer having a second coil and a third coil provided on the secondary side, a rectifier circuit for rectifying the output of the second coil, and the rectifier circuit A power connected to the smoothing circuit connected to the third coil and having at least one first rectifying element, a second switching element, a second rectifying element, an inductive element, and a capacitive element. A conversion circuit; and a control circuit that controls a switching timing of the switching circuit and the second switching element. The switching duty ratio of the switching circuit is gradually increased until the output voltage of the smoothing circuit reaches a predetermined output. When the output voltage of the smoothing circuit reaches a predetermined output, the switching timing of the second switching element is increased. Control is started, and the switching duty ratio of the second switching element is gradually increased until the outputs at both ends of the capacitive element reach a predetermined output.

  According to another aspect, a power supply circuit includes at least one first switching element, a switching circuit that outputs an alternating voltage by controlling a switching timing of the at least one first switching element, and the switching A first coil connected to the circuit; a transformer having a second coil and a third coil provided on the secondary side; and third to sixth switching elements. A bridge circuit that rectifies the output of the coil and converts the DC power into AC by controlling the timing of the third to sixth switching elements during regeneration, and outputs the output to the second coil; and the bridge circuit A smoothing circuit connected to the third coil, at least one first rectifying element connected to the third coil, and a second switch A power conversion circuit having an element, a second rectifying element, an inductive element, and a capacitive element, and a control circuit for controlling switching timing of the bridge circuit and the second switching element, and the control During regeneration, the circuit gradually increases the first duty ratio of switching of the bridge circuit, and causes the second switching element to move to the first duty until the output voltage at both ends of the capacitive element reaches a predetermined output. Control is performed to turn on / off at a second duty ratio larger than the ratio.

  A power supply circuit according to another aspect includes at least one first switching element, a switching circuit that outputs an alternating voltage by controlling a switching timing of the at least one first switching element, and A first coil connected to the switching circuit; a transformer having a second coil and a third coil provided on the secondary side; and third to sixth switching elements. A bridge circuit that rectifies the output of the coil and converts the DC power into AC by controlling the timing of the third to fifth switching elements during regeneration, and outputs the output to the second coil. A smoothing circuit connected to the circuit, at least one first rectifier element connected to the third coil, and a second switch. A power conversion circuit having a chucking element, a second rectifying element, an inductive element, and a capacitive element, and a control circuit for controlling the switching timing of the bridge circuit and the second switching element, The control circuit gradually increases the switching duty ratio of the switching circuit until the output voltage of the smoothing circuit reaches a predetermined output during regeneration, and when the output voltage of the smoothing circuit reaches the predetermined output, The switching timing of the switching element is controlled, and the switching duty ratio of the second switching element is gradually increased until the outputs at both ends of the capacitive element reach a predetermined output.

  ADVANTAGE OF THE INVENTION According to this invention, the loss in a switching element and a capacitor | condenser can be reduced, and the power supply circuit with easy control of switching with a primary side and a secondary side can be provided.

It is a figure which shows the structure of the power supply circuit by 1st Embodiment. It is a flowchart which shows the soft start operation | movement by 1st Embodiment. It is a figure explaining operation | movement of the switching circuit and transistor by 1st Embodiment, (a) shows the time change of a duty ratio, (b) shows the time change of a voltage. It is a flowchart which shows the soft start operation | movement by the modification of 1st Embodiment. It is a figure explaining operation | movement of the switching circuit and transistor by the modification of 1st Embodiment, (a) shows the time change of a duty ratio, (b) shows the time change of a voltage. It is a figure which shows the structure of the power supply circuit by 2nd Embodiment. It is a figure which shows the structure of the power supply circuit by 3rd Embodiment. It is a flowchart which shows the soft start operation | movement by 3rd Embodiment. It is a flowchart which shows the soft start operation | movement by the modification of 3rd Embodiment.

(First embodiment)
The power supply circuit according to the first embodiment will be described below with reference to the drawings. First, the configuration of the power supply circuit 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a power supply circuit according to the first embodiment. As shown in FIG. 1, the power supply circuit 1 includes a switching circuit 5, a transformer 51, a rectifier circuit 61, a choke coil 63, a capacitor 65, diodes D31 and D32, a transistor Q31, a diode D33, a choke coil 73, and a capacitor 76. It is configured.

  The power supply circuit 1 has a function of a charging circuit that performs charging by connecting a rechargeable battery between the terminals 67A and 67B and between the terminals 79A and 79B. For example, a higher voltage is output between the terminals 67A and 67B than between the terminals 79A and 79B.

  A power supply (not shown) is connected to the terminals 4A and 4B at both ends of the capacitor 3. The power source is a power source that rectifies and smoothes input power from, for example, a commercial power source and outputs it as DC power. The switching circuit 5 is connected in parallel with the capacitor 3. The switching circuit 5 is a bridge circuit including transistors Q11 to Q14. As the transistors Q11 to Q14, for example, an IGBT (Insulated Gate Bipolar Transistor) can be used.

  The transistors Q12 and Q13 are controlled to be turned on / off by being connected to the driver 7, and the transistors Q11 and Q14 are controlled to be turned on / off by being connected to the driver 9.

  The transformer 51 includes a primary side first coil 53, a secondary side second coil 55, and third coils 57 and 59. The first coil 53 is connected to the midpoint of one bridge side of the switching circuit 5 and the midpoint of the other bridge side.

  A rectifier circuit 61 is connected to the output side of the second coil 55. The rectifier circuit 61 is a bridge circuit including diodes D21 to D24. A choke coil 63 and a capacitor 65 are connected to the output side of the rectifier circuit 61 in parallel with the rectifier circuit 61. The choke coil 63 and the capacitor 65 are connected in series with each other. A voltmeter VS21 is connected to the capacitor 65.

  The third coil 57 has one end grounded and the other end connected to the anode side of the diode D31. The third coil 59 has one end grounded and the other end connected to the anode side of the diode D32. The third coil 57 and the third coil 59 are grounded at one end sides having opposite polarities.

  For example, a transistor Q31 is connected to the cathode side of the diodes D31 and D32. Transistor Q31 receives a drive signal from driver 81. Connected to the transistor Q31 are a choke coil 73 and a capacitor 76 connected in series with each other, and a diode D33 connected in parallel with them. The diode D33 is grounded on the anode side. A voltmeter VS31 is connected to the capacitor 76. The controller 85 is connected to the voltmeters VS21 and VS31, and is connected to the driver 7, the driver 9, and the driver 81.

  In the power supply circuit 1 configured as described above, a power supply (not shown) is connected to the terminals 4A and 4B at both ends of the capacitor 3 to supply DC power. In the switching circuit 5, the driver 7 and the driver 9 alternately turn on and off the transistors Q11 to Q14 connected to each other. As a result, a current Ip is generated, and the switching circuit 5 outputs an alternating current to the first coil 53 on the primary side of the transformer 51. The driver 7 and the driver 9 are connected to the controller 85, and generate drive signals for the transistors Q11 to Q14 based on signals from the controller 85.

  In the transformer 51, a current corresponding to the turn ratio between the primary side and the secondary side is induced in the second coil 55 and the third coils 57 and 59 on the secondary side by the first coil 53. . The rectifier circuit 61 on the output side of the second coil 55 rectifies the alternating current induced in the second coil 55 and outputs a current Is. The choke coil 63 and the capacitor 65 smooth the output of the rectifier circuit 61. The voltage across the capacitor 65 is measured by the voltmeter VS21 and acquired by the controller 85. The voltage across the capacitor 65 is hereinafter referred to as the HV voltage.

  The outputs of the third coil 57 and the third coil 59 are rectified by the diodes D31 and D32 to become a current It. The transistor Q31 is controlled to be turned on and off by inputting a drive signal from the driver 81 to the base terminal, and transmits the rectified power to the choke coil 73 side with a predetermined duty ratio. The transistor Q31 is controlled to synchronize with the switching timing of the switching circuit 5. Driver 81 outputs a drive signal to transistor Q31 based on a signal from controller 85.

  Choke coil 73 and capacitor 76 smooth the power from transistor Q31. The voltage across the capacitor 76 is measured by the voltmeter VS31 and acquired by the controller 85. The voltage across the capacitor 76 is hereinafter referred to as LV voltage.

  The controller 85 acquires the voltage across the capacitor 65 and the capacitor 76, and generates drive signals for the transistors Q11 to Q14 and the transistor Q31 to the driver 7, the driver 9, and the driver 81 while referring to the acquired voltages. Output a signal.

  Next, a soft start operation during charging of the power supply circuit 1 will be described with reference to FIGS. FIG. 2 is a flowchart showing the operation of the power supply circuit 1 according to the first embodiment. FIG. 3 is a diagram for explaining the operation of the switching circuit 5 and the transistor Q31. FIG. (B) shows the time change of the voltage.

  As shown in FIG. 2, first, the controller 85 outputs a signal to the driver 81, and the driver 81 drives the transistor Q31 with a duty ratio of 100% based on the signal from the controller 85 (S201). In FIG. 3, the horizontal axis represents time t, the vertical axis represents the duty ratio in (a), and the voltage in (b). As shown in FIG. 3A, from t = 0 to t = t0, the duty ratio of the transistor Q31 is 100%. On the other hand, in the switching circuit 5 on the primary side, on / off of the transistors Q11 to Q14 is controlled by the driver 7 and the driver 9 based on a signal from the controller 85. The switching circuit 5 starts switching from time t = 0, and the duty ratio is gradually increased from time t = 0 to time t = t0. Thereby, as shown in FIG.3 (b), HV voltage rises gradually.

  Returning to FIG. 2, the controller 85 monitors until the LV voltage reaches the target voltage Vl (S202: No). As shown in FIG. 3B, when the LV voltage reaches the target value voltage Vl at t = t0, the controller 85 acquires that the LV voltage has reached the target value voltage Vl (S202: Yes). Further, the controller 85 outputs a signal for causing the driver 81 to perform PWM (Pulse Width Modulation) control of the transistor Q31 so that the LV voltage becomes constant at the voltage Vl. As shown in FIG. 3A, after time t = t0, the control shifts to a substantially constant duty ratio DR31. At this time, the switching circuit 5 is controlled so that the duty ratio gradually increases (S203).

  The controller 85 monitors the HV voltage until it reaches the target value voltage Vh (SS204: No). When the controller 85 acquires that the HV voltage has reached the voltage Vh (S204: Yes), the controller 85 performs normal control to output a signal for PWM control to the switching circuit 5 so that the HV voltage becomes constant at the voltage Vh. Transition. As shown in FIG. 3B, when the HV voltage reaches the voltage Vh at time t = t1, the control shifts to a substantially constant duty ratio DR1. Thus, the soft start operation ends.

  As described above, in the power supply circuit 1 according to the first embodiment, the soft start for gradually increasing the switching timing of the switching circuit 5 on the primary side of the transformer 51 is performed. On the other hand, the transistor Q31 is set to a duty ratio of 100% until the LV voltage reaches the target value. When the LV voltage reaches the target value of voltage Vl, the controller 85 sets the transistor Q31 through the driver 81 to normal PWM control for outputting a constant LV voltage. When the HV voltage reaches the target value, the controller 85 causes the switching circuit 5 to perform normal PWM control for outputting a constant HV voltage via the driver 7 and the driver 9.

  As described above, according to the power supply circuit 1, the transistor Q31 is fixed to a duty ratio of 100% from the start of soft start until the LV voltage reaches a predetermined voltage. For this reason, when the switching circuit 5 is driven with a pulse with a low duty ratio, it is not necessary to match the timing of the pulse for driving the transistor Q31 with the switching timing of the switching circuit 5. Therefore, control of switching circuit 5 and transistor Q31 at the time of soft start becomes easy. Further, since it is driven at a duty ratio of 100% from the start of soft start until it reaches a predetermined voltage, the voltage across the capacitor 76 is quickly raised while preventing loss of the switching circuit 5 and the capacitor 76 by soft start. Is possible. Therefore, it can charge efficiently.

(Modification of the first embodiment)
Next, a power supply circuit 1 according to a modification of the first embodiment will be described with reference to FIGS. 4 and 5. Since the power supply circuit 1 according to the modification of the first embodiment has the same configuration as the power supply circuit 1 according to the first embodiment, description of the configuration is omitted.

  FIG. 4 is a flowchart showing the operation of the power supply circuit 1 according to the modification of the first embodiment, FIG. 5 is a diagram for explaining the operation of the switching circuit 5 and the transistor Q31, and FIG. Change with time, (b) shows change with time of voltage.

  As shown in FIG. 4, the switching circuit 5 on the primary side starts driving by controlling the on / off of the transistors Q11 to Q14 by the driver 7 and the driver 9 based on the signal from the controller 85. At this time, the transistor Q31 is off (S211).

  In FIG. 5, the horizontal axis represents time t, the vertical axis represents the duty ratio in (a), and the voltage in (b). As shown in FIG. 5A, the switching circuit 5 starts switching from time t = 0, and the duty ratio of the switching circuit 5 gradually increases from time t = 0 to time t = t1. Thereby, as shown in FIG.5 (b), HV voltage rises gradually.

  Returning to FIG. 4, the controller 85 monitors until the HV voltage reaches the voltage Vh that is the target value (S212: No). As shown in FIG. 5B, when the HV voltage reaches the target value voltage Vh at t = t1, the controller 85 acquires that the HV voltage has reached the target value voltage Vh (S212: Yes). When the controller 85 acquires that the HV voltage has reached the voltage Vh, the controller 85 outputs to the driver 7 and driver 9 a drive signal for PWM control so that the HV voltage becomes constant at the voltage Vh. As a result, the driver 7 and the driver 9 shift to normal control for outputting a drive signal for PWM control of the switching circuit 5 with a substantially constant duty ratio. That is, as shown in FIG. 5B, when the HV voltage reaches the voltage Vh at time t = t1, the control shifts to a substantially constant duty ratio DR1.

  The controller 85 causes the driver 81 to output a drive signal for controlling the transistor Q31 so that the duty ratio gradually increases. Thereby, as shown in FIG.5 (b), LV voltage rises gradually (S213).

  The controller 85 monitors until the LV voltage reaches the target voltage Vl (SS214: No). When the controller 85 acquires that the LV voltage has reached the voltage Vl (S214), the controller 85 outputs a signal for causing the driver 81 to perform PWM control so that the LV voltage becomes constant at the voltage Vl. As a result, the driver 81 shifts to normal control in which the transistor Q31 is PWM-controlled at a substantially constant duty ratio. As shown in FIG. 5B, when the LV voltage reaches the voltage Vl at time t = t3, the control shifts to a substantially constant duty ratio DR31. Thus, the soft start operation ends.

  As described above, in the power supply circuit 1 according to the modification of the first embodiment, first, the controller 85 switches the switching timing of the switching circuit 5 on the primary side of the transformer 51 via the driver 7 and the driver 9. Perform a soft start that gradually raises. When the HV voltage becomes a predetermined voltage and the switching of the switching circuit 5 becomes normal control, the transistor Q31 starts switching control. The controller 85 gradually increases the duty ratio of the transistor Q31 until the LV voltage reaches the target value via the driver 81. When the LV voltage reaches the target value of voltage Vl, the controller 85 shifts to normal PWM control for causing the transistor Q31 to output a constant LV voltage via the driver 81.

  As described above, according to the power supply circuit 1, the transistor Q31 is turned off from the start of the soft start until the HV voltage reaches the predetermined voltage. For this reason, when the switching circuit 5 is driven with a pulse with a low duty ratio, it is not necessary to match the timing of the pulse for driving the transistor Q31 with the switching timing of the switching circuit 5. Further, after the HV voltage reaches a predetermined voltage, the transistor Q31 is soft-started. Therefore, it is not necessary to synchronize the timing of pulses having a low duty ratio, and the switching circuit 5 and the transistor Q31 for reducing the loss of the switching circuit 5 and the capacitor 76 at the time of soft start are easily controlled.

(Second Embodiment)
Next, a power circuit 230 according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, detailed description of the same configuration and operation as those of the first embodiment or its modification is omitted.

  FIG. 6 is a diagram illustrating a configuration of the power supply circuit 230 according to the second embodiment. Since the power supply circuit 230 has substantially the same configuration as the power supply circuit 1, only different parts will be described. The power supply circuit 230 includes relays 91, 105, 111 and a switch 97 in addition to the power supply circuit 1. Further, for example, a first load (not shown) is connected between the terminals 67A and 67B, and a second load (not shown) is connected between the terminals 79A and 79B. For example, if the power supply circuit 230 is an in-vehicle power supply, a vehicle high voltage battery is connected between the terminals 67A and 67B, and a vehicle low voltage battery is connected between the terminals 79A and 79B.

  The power supply circuit 230 configured as described above can change the power supply source according to the first load connected between the terminals 67A and 67B. That is, the power supply circuit 230 is supplied with power from the power supply connected between the terminals 4A and 4B when the first load is consuming power, and when power is generated from the first load, Electric power is supplied from one load.

  The power supply circuit 230 includes a relay 91 and a switch 97 at both ends of the capacitor 3 of the power supply circuit 1. The power supply circuit 230 includes a relay 105 between the choke coil 63 and the capacitor 65, and includes a relay 111 between the anodes of the diodes D22 and D24 and the terminal 67B. The connections of the relays 91, 105, 111 and the switch 97 are controlled by the controller 85 via a control line (not shown).

  Relay 91 selectively connects one end of capacitor 3 to terminal 93 or terminal 95. The switch 97 turns on and off the connection between the other end of the capacitor 3 and the terminal 99. Terminals 95 and 99 are connected to a power source (not shown). Terminal 93 is connected to terminal 107 of relay 105. The relay 105 selectively connects the terminal 67 </ b> A to the terminal 107 or the terminal 109. The relay 111 selectively connects the terminal 67B to the terminal 113 or the terminal 115.

  When the terminal 67A is connected to the terminal 109 by the relay 105 and the terminal 67B is connected to the terminal 113 by the relay 111, one end of the capacitor 3 is connected to the terminal 95 by the relay 91, and the other end of the capacitor 3 by the switch 97. Is connected to a terminal 99. At this time, the power supply circuit 230 is the same circuit as the power supply circuit 1 described above. At this time, the power supply circuit 230 is supplied with power from a power supply (not shown) connected between the terminals 4A and 4B.

  On the other hand, when a load that generates electric power is connected between the terminals 67A and 67B, the terminal 67A is connected to the terminal 107 by the relay 105, and the terminal 67B is connected to the terminal 115 by the relay 111. At this time, one end of the capacitor 3 is connected to the terminal 93 by the relay 91, and the switch 97 is turned off. The power supply circuit 230 is supplied with electric power from a load connected between the terminals 67A and 67B, and electric power is induced in the third coils 57 and 59 from the primary side of the transformer 51 as in the first embodiment. .

  The power supply circuit 230 performs a soft start operation in the same manner as the power supply circuit 1. That is, the operation similar to the operation of FIG. 2 according to the first embodiment and the operation of FIG. 4 according to the modification of the first embodiment is performed. At this time, instead of the process of monitoring whether or not the HV voltage has reached the target value in S204 of FIG. 2 and S212 of FIG. 4, for example, the voltage across the first coil 53 (for example, the effective value) is changed. You may make it monitor by providing the voltmeter to measure.

  As described above, in the power supply circuit 230, for example, from the start of soft start until the LV voltage reaches a predetermined voltage, the transistor Q31 is fixed at a duty ratio of 100%. According to such an operation, when the switching circuit 5 is driven with a pulse having a low duty ratio, it is not necessary to match the timing of the pulse for driving the transistor Q31 with the switching timing of the switching circuit 5. Therefore, control of switching circuit 5 and transistor Q31 at the time of soft start becomes easy. Further, since it is driven at a duty ratio of 100% from the start of soft start until it reaches a predetermined voltage, the voltage across the capacitor 76 is quickly raised while preventing loss of the switching circuit 5 and the capacitor 76 by soft start. Is possible. Therefore, it can charge efficiently.

  In the power supply circuit 230, for example, the transistor Q31 is turned off until the primary voltage reaches a predetermined voltage from the start of the soft start. According to such an operation, when the switching circuit 5 is driven with a pulse having a low duty ratio, it is not necessary to match the timing of the pulse for driving the transistor Q31 with the switching timing of the switching circuit 5. The transistor Q31 is soft-started after the primary side voltage reaches a predetermined voltage. Therefore, it is not necessary to synchronize the timing of pulses having a low duty ratio, and the switching circuit 5 and the transistor Q31 for reducing the loss of the switching circuit 5 and the capacitor 76 at the time of soft start are easily controlled. Further, according to the power supply circuit 230, bidirectional power conversion is possible.

(Third embodiment)
Next, a power circuit 250 according to a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the detailed description of the same configurations and operations as those of the first embodiment, the modified example of the first embodiment, and the second embodiment is omitted.

  FIG. 7 is a diagram showing a configuration of the power supply circuit 250 according to the third embodiment. Since the power supply circuit 250 has substantially the same configuration as that of the power supply circuit 1, only different portions will be described. The power circuit 250 includes a bridge circuit 90 instead of the rectifier circuit 61 of the power circuit 1.

  In the power supply circuit 250, the power supply source can be changed according to the load connected between the terminals 67A and 67B. That is, in the power supply circuit 250, when the load connected between the terminals 67A and 67B consumes power, the power from the power supply connected between the terminals 4A and 4B is changed from the primary side to the secondary side of the transformer 51. The power running state supplied to In addition, when power is generated from the load connected between the terminals 67A and 67B, a regenerative state is established in which power from the load is supplied from the secondary side of the transformer 51 to the primary side.

  The bridge circuit 90 is a bridge circuit including transistors Q21 to Q24. The midpoint of one bridge side of the bridge circuit 90 and the midpoint of the other bridge side are connected to the second coil 55. For example, IGBTs can be used as the transistors Q21 to Q24.

  In the power running state, the bridge circuit 90 rectifies the output of the second coil 55 by the diodes connected in parallel to the transistors Q21 to Q24, similarly to the rectifier circuit 61 of the power supply circuit 1. During regeneration, the transistors Q22 and Q23 are controlled to be turned on / off by being connected to the driver 87, and the transistors Q21 and Q24 are controlled to be turned on / off by being connected to the driver 89. At this time, the driver 87 and the driver 89 alternately turn on and off the transistors Q21 to Q24 connected to each other. As a result, the bridge circuit 90 outputs an alternating current to the second coil 55 of the transformer 51. The drivers 87 and 89 are connected to the controller 85 and generate drive signals for the transistors Q21 to Q24 based on signals from the controller 85.

  Moreover, the both-ends voltage of the 2nd coil 55 is measured with the voltmeter VS22, and the controller 85 acquires the measured voltage value. The voltage (effective voltage value) measured by the voltmeter VS22 is referred to as HV2 voltage.

  Thus, the power supply circuit 250 operates substantially the same as the power supply circuit 1 during powering. Therefore, the operation at the time of soft start is also the same as that of the first embodiment and its modification. At the time of regeneration, in the bridge circuit 90, the driver 87 and the driver 89 alternately turn on and off the transistors Q21 to Q24 connected to each other as described above. As a result, the bridge circuit 90 outputs an alternating current to the second coil 55 of the transformer 51.

  In the third coils 57 and 59, a current corresponding to the turn ratio with the second coil 55 is induced. Outputs of the third coil 57 and the third coil 59 are rectified by diodes D31 and D32. The transistor Q31 is controlled to be turned on and off by inputting a drive signal from the driver 81 to the base terminal, and transmits the rectified power to the choke coil 73 side with a predetermined duty ratio. The transistor Q31 is controlled to synchronize with the switching timing of the switching circuit 5. Driver 81 outputs a drive signal to transistor Q31 based on a signal from controller 85. Choke coil 73 and capacitor 76 smooth the power from transistor Q31.

  Hereinafter, an example of the soft start operation during regeneration will be described with reference to FIG. FIG. 8 is a flowchart for explaining the soft start operation. As shown in FIG. 8, first, the controller 85 outputs a signal to the driver 81, and the driver 81 drives the transistor Q31 with a duty ratio of 100% (S301).

  On the other hand, in the bridge circuit 90, on / off of the transistors Q21 to Q24 is controlled by the driver 87 and the driver 89 based on a signal from the controller 85. As in the switching timing of the switching circuit 5 shown in FIG. 3, the bridge circuit 90 starts switching from time t = 0 and gradually increases the duty ratio from time t = 0 to time t = t0. As a result, the HV2 voltage gradually increases as in the change shown in FIG.

  Returning to FIG. 8, the controller 85 monitors until the LV voltage reaches the voltage Vl which is the target value (S302: No). As shown in FIG. 3B, when the LV voltage reaches the target value voltage Vl at t = t0, the controller 85 acquires that the LV voltage has reached the target value voltage Vl (S302: Yes). Further, the controller 85 outputs a signal for causing the driver 81 to perform PWM control of the transistor Q31 so that the LV voltage is constant at the voltage Vl. As shown in FIG. 3A, after time t = t1, the transistor Q31 shifts to driving with a substantially constant duty ratio DR31. At this time, the switching circuit 5 is controlled so that the duty ratio gradually increases (S303).

  The controller 85 monitors until the HV2 voltage reaches a voltage that is a target value (S304: No). When the controller 85 obtains that the HV2 voltage has reached the target value (S304: Yes), the controller 85 shifts to normal control for outputting a signal for PWM control to the switching circuit 5 so that the HV2 voltage becomes the target value. . Thus, the soft start operation ends.

  As described above, according to the power supply circuit 250, the transistor Q31 is fixed at a 100% duty ratio from the start of soft start until the LV voltage reaches a predetermined voltage. For this reason, when the bridge circuit 90 is driven with a pulse having a low duty ratio, it is not necessary to match the timing of the pulse for driving the transistor Q31 with the switching timing of the bridge circuit 90. Further, after the LV voltage reaches a predetermined voltage, the transistor Q31 is soft-started. Therefore, it is not necessary to synchronize the timing of pulses having a low duty ratio, and the bridge circuit 90 and the transistor Q31 can be easily controlled to reduce the loss of the bridge circuit 90 and the capacitor 76 at the time of soft start.

  Further, since it is driven at a duty ratio of 100% from the start of soft start until reaching a predetermined voltage, the voltage across the capacitor 76 is quickly raised while preventing loss of the bridge circuit 90 and the capacitor 76 by soft start. Is possible. Therefore, it can charge efficiently. Furthermore, the power supply circuit 250 can perform bidirectional power conversion.

(Modification of the third embodiment)
Next, a power supply circuit 250 according to a modification of the third embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing a soft start operation according to a modification of the third embodiment. Since the power supply circuit 250 according to the modification of the third embodiment has the same configuration as the power supply circuit 250 according to the third embodiment, description of the configuration is omitted. Since this modification is another example of the soft start operation during regeneration, only the soft start will be described.

  FIG. 9 is a flowchart showing the operation of the power supply circuit 250 according to a modification of the third embodiment. As shown in FIG. 9, the bridge circuit 90 starts driving by controlling on / off of the transistors Q <b> 21 to Q <b> 24 by the driver 87 and the driver 89 based on a signal from the controller 85. At this time, the transistor Q31 is off (S311).

  As shown in FIG. 5, also in this modification, in the bridge circuit 90, switching starts from time t = 0, and the duty ratio gradually increases from time t = 0 to time t = t1. As a result, the HV2 voltage gradually increases.

  Returning to FIG. 9, the controller 85 monitors until the HV2 voltage reaches the target value (S312: No). When the HV2 voltage reaches the target value, the controller 85 acquires that the HV2 voltage has reached the target value (S312: Yes). When the controller 85 acquires that the HV voltage has reached the target value, the driver 87 and the driver 89 normally output a drive signal for PWM control so that the HV2 voltage becomes constant at the target value. Transition to control. That is, when the HV2 voltage reaches the target value, the control shifts to a substantially constant duty ratio.

  The controller 85 causes the driver 81 to output a drive signal for controlling the transistor Q31 so that the duty ratio gradually increases. As a result, the LV voltage gradually increases (S313).

  The controller 85 monitors until the LV voltage reaches the target voltage Vl (SS314: No). When the controller 85 obtains that the LV voltage has reached the voltage Vl (S314: Yes), the controller 85 shifts to normal control for outputting a signal for PWM control to the transistor Q31 so that the LV voltage becomes constant at the voltage Vl. To do. When the LV voltage reaches the voltage Vl, the control shifts to a substantially constant duty ratio. Thus, the soft start operation ends.

  As described above, in the power supply circuit 250 according to the modification of the third embodiment, first, the controller 85 performs soft start to gradually increase the switching timing of the bridge circuit 90 via the driver 87 and the driver 89. I do. When the HV voltage becomes a predetermined voltage and the switching of the bridge circuit 90 becomes normal control, the transistor Q31 starts switching control. The controller 85 gradually increases the duty ratio of the transistor Q31 until the LV voltage reaches the target value via the driver 81. When the LV voltage reaches the target value of voltage Vl, the controller 85 shifts to normal PWM control for causing the transistor Q31 to output a constant LV voltage via the driver 81.

  As described above, according to the power supply circuit 250, the transistor Q31 is turned off from the start of the soft start until the HV2 voltage reaches a predetermined voltage. For this reason, when the bridge circuit 90 is driven with a pulse having a low duty ratio, it is not necessary to match the timing of the pulse for driving the transistor Q31 with the switching timing of the bridge circuit 90. Further, after the HV2 voltage reaches a predetermined voltage, the transistor Q31 is soft-started. Therefore, it is not necessary to synchronize the timing of pulses having a low duty ratio, and the bridge circuit 90 and the transistor Q31 for reducing the loss of the bridge circuit 90 and the capacitor 76 at the time of soft start are easily controlled.

  In each of the above embodiments, the choke coil 63 and the capacitor 65 are examples of a smoothing circuit, and the diodes D31 and D32 are examples of a first rectifying element. The transistors Q11 to Q14 are examples of the first to fourth switching elements, the transistor Q31 is an example of the second switching element, and the transistors Q21 to Q24 are examples of the sixth switching element to the sixth capacitor. is there. The diode D33 is an example of a second rectifying element, the choke coil 73 is an example of an inductive element, the capacitor 76 is an example of an inductive element, and the relays 91, 105, 111 and the switch 97 are switching circuits. It is an example.

  The present invention is not limited to the embodiments described above, and various configurations or embodiments can be adopted without departing from the gist of the present invention. For example, in the first to third embodiments, the duty ratio of the transistor Q31 is 100% from the time t = 0 to the time t = t0. However, the present invention is not limited to this. The transistor Q31 may be a value larger than the duty ratio DR31 after the transition to the normal PWM control, or a value larger than the duty ratio of the switching circuit 5 or the bridge circuit 90. In this case, although synchronization timing occurs, the number of timings is small, so that control becomes easy.

  The circuit configurations of the power supply circuit 1, the power supply circuit 230, and the power supply circuit 250 are not limited to those described above, and it is understood that they are within the scope of the present invention as long as they have the same effects. For example, the transistors Q11 to Q14, the transistors Q21 to Q24, and the transistor Q31 may be configured using MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

1 power supply circuit 3 capacitor 5 switching circuit 7 driver 9 driver 51 transformer 53 first coil 55 second coil 57 third coil 59 first coil 61 rectifier circuit 63 choke coil 65 capacitor 81 driver 73 choke coil 76 capacitor 85 controller 230 power circuit 250 power circuit 90 bridge circuit D11-D14 diode Q11-14, Q31 transistor

Claims (6)

A switching circuit having at least one first switching element and outputting an alternating voltage by controlling a switching timing of the at least one first switching element;
A first coil connected to the switching circuit, a transformer having a second coil and a third coil provided on the secondary side,
A rectifier circuit for rectifying the output of the second coil;
A smoothing circuit connected to the rectifier circuit;
A power conversion circuit connected to the third coil and having at least one first rectifying element, a second switching element, a second rectifying element, an inductive element, and a capacitive element;
A control circuit for controlling the switching timing of the switching circuit and the second switching element;
Have
The control circuit gradually increases the first duty ratio of switching of the switching circuit, and causes the second switching element to move to the first duty ratio until an output voltage at both ends of the capacitive element reaches a predetermined output. A power supply circuit that performs control to turn on and off at a second duty ratio that is larger than the first duty ratio. A switching circuit having at least one first switching element and outputting an alternating voltage by controlling a switching timing of the at least one first switching element;
A first coil connected to the switching circuit, a transformer having a second coil and a third coil provided on the secondary side,
A rectifier circuit for rectifying the output of the second coil;
A smoothing circuit connected to the rectifier circuit;
A power conversion circuit connected to the third coil and having at least one first rectifying element, a second switching element, a second rectifying element, an inductive element, and a capacitive element;
A control circuit for controlling the switching timing of the switching circuit and the second switching element;
Have
The control circuit gradually increases the switching duty ratio of the switching circuit until the output voltage of the smoothing circuit reaches a predetermined output,
When the output voltage of the smoothing circuit reaches a predetermined output, control of the switching timing of the second switching element is started, and the second switching element until the outputs at both ends of the capacitive element reach a predetermined output. A power supply circuit characterized by gradually increasing the switching duty ratio. The rectifier circuit is a bridge circuit having third to sixth switching elements,
The control circuit further controls the switching timing of the bridge circuit;
The bridge circuit rectifies the output of the second coil during power running, and converts the DC power into AC by controlling the switching timing of the third to sixth switching elements during regeneration. The power supply circuit according to claim 1, wherein the power supply circuit outputs the power to the coil. A switching circuit that causes an output based on the electric power induced in the second coil to be output from the smoothing circuit at the time of power running, and an input to the smoothing circuit to be input to the switching circuit at the time of regeneration;
The power supply circuit according to claim 3, further comprising: A switching circuit having at least one first switching element and outputting an alternating voltage by controlling a switching timing of the at least one first switching element;
A first coil connected to the switching circuit, a transformer having a second coil and a third coil provided on the secondary side,
It has third to sixth switching elements, rectifies the output of the second coil during power running, and controls the timing of the third to sixth switching elements during regeneration to change the DC power to alternating current. A bridge circuit for converting and outputting to the second coil;
A smoothing circuit connected to the bridge circuit;
A power conversion circuit connected to the third coil and having at least one first rectifying element, a second switching element, a second rectifying element, an inductive element, and a capacitive element;
A control circuit for controlling the switching timing of the bridge circuit and the second switching element;
Have
The control circuit gradually increases the first duty ratio of switching of the bridge circuit during regeneration, and causes the second switching element to move to the first switching element until an output voltage at both ends of the capacitive element reaches a predetermined output. A power supply circuit that performs on / off control at a second duty ratio that is larger than the duty ratio. A switching circuit having at least one first switching element and outputting an alternating voltage by controlling a switching timing of the at least one first switching element;
A first coil connected to the switching circuit, a transformer having a second coil and a third coil provided on the secondary side,
It has third to sixth switching elements, rectifies the output of the second coil during power running, and changes the DC power to alternating current by controlling the timing of the third to fifth switching elements during regeneration. A bridge circuit for converting and outputting to the second coil;
A smoothing circuit connected to the bridge circuit;
A power conversion circuit connected to the third coil and having at least one first rectifying element, a second switching element, a second rectifying element, an inductive element, and a capacitive element;
A control circuit for controlling the switching timing of the bridge circuit and the second switching element;
Have
The control circuit, during regeneration, gradually increases the switching duty ratio of the switching circuit until the output voltage of the smoothing circuit reaches a predetermined output,
When the output voltage of the smoothing circuit reaches a predetermined output, control of the switching timing of the second switching element is started, and the second switching element until the outputs at both ends of the capacitive element reach a predetermined output. A power supply circuit characterized by gradually increasing the switching duty ratio.

Images