WO2019208008A1 - Power conversion device - Google Patents

Power conversion device Download PDF

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Publication number
WO2019208008A1
WO2019208008A1 PCT/JP2019/010462 JP2019010462W WO2019208008A1 WO 2019208008 A1 WO2019208008 A1 WO 2019208008A1 JP 2019010462 W JP2019010462 W JP 2019010462W WO 2019208008 A1 WO2019208008 A1 WO 2019208008A1
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WO
WIPO (PCT)
Prior art keywords
switching circuit
circuit
output
input
power
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PCT/JP2019/010462
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French (fr)
Japanese (ja)
Inventor
信太朗 田中
大内　貴之
裕二 曽部
琢磨 小野
高橋　直也
Original Assignee
日立オートモティブシステムズ株式会社
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Publication of WO2019208008A1 publication Critical patent/WO2019208008A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac

Definitions

  • the present invention relates to a power conversion device.
  • An automobile that travels using such electric energy is provided with a high-voltage battery that supplies electric power to a motor for driving wheels.
  • a power conversion device that steps down the output power from the high-voltage battery and supplies the necessary power to low-voltage electric devices mounted on the automobile, such as air conditioners and audio, various ECUs (Electronic Control Units), etc., is provided.
  • Such a power converter converts input DC power into DC power of a different voltage, and is also called a DC-DC converter.
  • a DC-DC converter has a switching circuit capable of switching operation, and performs voltage conversion of DC power by controlling on / off of the switching circuit. Specifically, the input DC power is temporarily converted into AC power using a switching circuit, and the AC power is transformed (stepped up or stepped down) using a transformer. Then, the transformed AC power is converted into DC power again using an output circuit such as a rectifier circuit. As a result, a DC output having a voltage different from the input voltage can be obtained.
  • the switching circuit is configured by using a semiconductor switch element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor).
  • MOSFET Metal-Oxide-Semiconductor Field-Effect Transistor
  • IGBT Insulated Gate Bipolar Transistor
  • the loss generated in the DC-DC converter includes a switching loss generated by a switching operation, a resistance loss (copper loss) generated in a transformer and a semiconductor switch element, and the like.
  • the following patent document 1 is known regarding high efficiency of a power converter.
  • the switching timing of the two synchronous rectification switches of the rectifying / smoothing circuit is controlled based on the output current, and stored in the rectifying / smoothing circuit so as to act equivalent to the increase in the output current at light load.
  • a power supply device that performs zero volt switching by returning the energy returned to the full bridge circuit and increasing the current flowing through the full bridge circuit is disclosed.
  • Patent Document 1 requires a current detector that detects an output current, and thus has a problem of increasing the size and cost as compared with a conventional power converter.
  • the power conversion device includes an input switching circuit that converts first DC power input from an input power source into AC power, a transformer that performs voltage conversion of the AC power, and the AC that is voltage-converted by the transformer.
  • An output switching circuit that converts electric power into second DC power and outputs the output; a control circuit that controls the input switching circuit and the output switching circuit; a reactor component provided between the input switching circuit and the transformer;
  • the input switching circuit includes a pair of input switch elements connected in series between the positive and negative electrodes of the input power source and controlled to be switched by the control circuit, and the output switching circuit is controlled by the control circuit.
  • An output switch element that is switching-controlled, and in parallel with the output switch element A snubber circuit provided, and the control circuit supplies a current to the snubber circuit in a circulation period in which a circulation current circulating through the input switching circuit, the reactor component, and the transformer flows without passing through the input power supply.
  • the input switching circuit is controlled so that the circulating current increases due to the current flowing, and the input switching circuit is shifted to a dead time period in which both of the pair of input switch elements are off after the circulating period. Control the circuit.
  • FIG. 3 is a timing chart showing how the voltage and current of each part change with time during the operation of the DC-DC converter according to the first embodiment of the present invention. It is a figure which shows the switching state and direction of an electric current of each switch element in period # 1 of the DC-DC converter which concerns on the 1st Embodiment of this invention. It is a figure which shows the switching state of each switch element, and direction of an electric current in period # 2 of the DC-DC converter which concerns on the 1st Embodiment of this invention.
  • FIG. 1 is a diagram showing a configuration of a vehicle power source according to an embodiment of the present invention.
  • the vehicle power source according to the present embodiment is mounted on a vehicle 1000 and uses a DC-DC converter 100 to perform power conversion between the high voltage battery V1 and the low voltage battery V2. It is a system.
  • the low-voltage side of the DC-DC converter 100 that is, the side connected to the low-voltage battery V2 is referred to as “L side”, and is connected to the high-voltage side of the DC-DC converter 100, ie, the high-voltage battery V1.
  • the side that is on is called the “H side”.
  • One end of the low voltage battery V2 is connected to one end on the L side of the DC-DC converter 100, and the other end of the low voltage battery V2 is connected to the other end on the L side of the DC-DC converter 100.
  • One end of the auxiliary equipment 400 such as an air conditioner is connected to one end on the L side of the DC-DC converter 100 and one end of the low-voltage battery V2, and the other end of the auxiliary equipment 400 is connected to the other side on the L side of the DC-DC converter 100.
  • One end and the other end of the low-voltage battery V2 are connected.
  • One end of the HV system device 300 is connected to one end on the H side of the DC-DC converter 100 and one end of the high voltage battery V1, and the other end of the HV system device 300 is connected to the other end on the H side of the DC-DC converter 100 and the high voltage.
  • the other end of the battery V1 is connected.
  • One end of the high voltage battery V1 is connected to one end on the H side of the DC-DC converter 100, and the other end of the high voltage battery V1 is connected to the other end on the H side of the DC-DC converter 100.
  • the DC-DC converter 100, the HV system device 300, and the auxiliary device 400 are connected to the vehicle power supply control unit 200.
  • the vehicle power supply control unit 200 controls the operation of these devices, the power transmission direction of the power exchanged between these devices and the high voltage battery V1 and the low voltage battery V2, the amount of power, and the like.
  • FIG. 2 is a diagram showing a basic circuit configuration of the DC-DC converter 100 according to the first embodiment of the present invention.
  • the DC-DC converter 100 of this embodiment includes an input switching circuit 10, a transformer 20, an output switching circuit 30, a voltage detector 41, a control circuit 50, and gate drivers 60 and 61. .
  • the input switching circuit 10 is connected via a positive input terminal 1 and a negative input terminal 2 to a high voltage battery V1 that acts as an input power source for the DC-DC converter 100.
  • the input switching circuit 10 includes switch elements 11a to 14a connected in a bridge. By switching the switch elements 11a to 14a, the DC power input from the high voltage battery V1 is changed to high frequency AC power. Converted and output to the primary side of the transformer 20.
  • the transformer 20 insulates the primary side from the secondary side, performs voltage conversion of AC power between the primary side and the secondary side, and steps down (or boosts) the AC power generated by the input switching circuit 10. The AC power thus output is output to the output switching circuit 30.
  • the output switching circuit 30 is connected to the low voltage battery V ⁇ b> 2 through the positive output terminal 3 and the negative output terminal 4.
  • the output switching circuit 30 includes switch elements 31a and 32a and snubber circuits 33 and 34 that are provided in parallel to the switch elements 31a and 32a and protect the switch elements 31a and 32a.
  • the output switching circuit 30 rectifies the AC power voltage-converted by the transformer 20 using the switch elements 31a and 32a, converts it into DC power, and outputs the DC power to the low-voltage battery V2.
  • the voltage detector 41 detects the output voltage of the output switching circuit 30 by detecting the voltage between the positive electrode output terminal 3 and the negative electrode output terminal 4. The output voltage detected by the voltage detector 41 is input to the control circuit 50.
  • the control circuit 50 is provided, for example, in the vehicle power supply control unit 200 of FIG. 1, and controls the switching operations of the switch elements 11a to 14a in the input switching circuit 10 based on the output voltage detected by the voltage detector 41, respectively. Output signals 51 to 54 are generated and output. Further, based on the output voltage detected by the voltage detector 41, output signals 55 to 56 for controlling the switching operations of the switch elements 31a and 32a in the output switching circuit 30 are generated and output.
  • the gate driver 60 converts the output signals 51 to 54 output from the control circuit 50 into drive signals 71 to 74 for driving the switch elements 11a to 14a, respectively, and outputs them to the input switching circuit 10.
  • the gate driver 60 insulates between the input switching circuit 10 and the control circuit 50.
  • the gate driver 61 converts the output signals 55 to 56 output from the control circuit 50 into drive signals 75 and 76 for driving the switch elements 31a and 32a, respectively, and outputs them to the output switching circuit 30.
  • the gate driver 61 insulates between the output switching circuit 30 and the control circuit 50.
  • the input switching circuit 10 converts DC power input from the high-voltage battery V ⁇ b> 1 through the positive input terminal 1 and the negative input terminal 2 into high-frequency AC power according to the control of the control circuit 50, and the primary winding of the transformer 20. It has a role to supply to the line N1.
  • a smoothing capacitor C1 is connected between the positive input terminal 1 and the negative input terminal 2 in parallel with the high voltage battery V1.
  • the input switching circuit 10 has a configuration in which four switch elements 11a to 14a are connected in a full bridge. That is, between the positive input terminal 1 and the negative input terminal 2, a series circuit of two switch elements 11a and 12a (hereinafter referred to as “first leg”), two switch elements 13a and 14a. A series circuit (hereinafter referred to as “second leg”) is connected to each other. A connection point A between the switch element 11a and the switch element 12a in the first leg is connected to one end side of the primary winding N1 of the transformer 20, and a connection between the switch element 13a and the switch element 14a in the second leg. Point B is connected to the other end of primary winding N1 of transformer 20.
  • the switch elements 11a to 14a can be configured by using any element capable of switching operation, and for example, an FET (field effect transistor) or the like is preferable.
  • the switch elements 11a to 14a are connected in parallel with flywheel diodes 11b to 14b and capacitors 11c to 14c, respectively. These diodes 11b to 14b and capacitors 11c to 14c may be configured as separate elements from the switch elements 11a to 14a, or may be parasitic components of the switch elements 11a to 14a. These may be used in combination.
  • a phase shift control method that is a drive method capable of reducing switching loss is used as a control method of the input switching circuit 10.
  • the switch element 11a on the upper side of the first leg and the switch element 14a on the lower side of the second leg Is controlled in accordance with the output voltage of the DC-DC converter 100.
  • the on / off phase difference between the switch element 12a below the first leg and the switch element 13a above the second leg is also controlled according to the output voltage of the DC-DC converter 100.
  • the period during which the switch element 11a and the switch element 14a are simultaneously turned on and the period during which the switch element 12a and the switch element 13a are simultaneously turned on are adjusted according to the output voltage.
  • the power transmitted from the input switching circuit 10 (primary side of the transformer 20) to the output switching circuit 30 (secondary side of the transformer 20) is a period during which the switch element 11a and the switch element 14a are simultaneously turned on
  • the switching element 12a and the switching element 13a are determined by a period during which the switching element 12a is turned on at the same time. Therefore, by controlling the phase difference as described above, the output voltage of the DC-DC converter 100 can be stabilized at a desired value.
  • the period in which the switch element 11a and the switch element 14a are simultaneously turned on and the period in which the switch element 12a and the switch element 13a are simultaneously turned on have the same length. Further, the ratio of the lengths of these periods in one cycle may be referred to as a duty ratio.
  • the transformer 20 has a role of performing voltage conversion on the AC power generated by the input switching circuit 10 and outputting the AC power after voltage conversion to the output switching circuit 30.
  • the transformer 20 includes a primary winding N1 connected to the input switching circuit 10 and a secondary winding N2 connected to the output switching circuit 30.
  • the transformer 20 has a center tap configuration in order to realize a full-wave rectifier circuit in combination with the output switching circuit 30, and the secondary winding N2 is divided into two secondary windings N2a and N2b in the middle. Has been.
  • the turn ratio (N1 / N2a or N1 / N2b) between the primary winding N1 and the secondary windings N2a and N2b is a voltage range of the input voltage Vin applied between the positive input terminal 1 and the negative input terminal 2, and It is set according to the voltage range of the output voltage Vout to be supplied between the positive electrode output terminal 3 and the negative electrode output terminal 4.
  • the transformer 20 has a predetermined leakage inductance in series with the primary winding N1, and this leakage inductance acts as a reactor component L1 for resonance.
  • the value of the leakage inductance in the transformer 20 is small, the value of the reactor component L1 may be increased by connecting an inductor by another reactor element in series with the primary winding N1. That is, the reactor component L1 provided between the input switching circuit 10 and the transformer 20 has at least one of the leakage inductance of the transformer 20 and the reactor element connected between the input switching circuit 10 and the transformer 20. Constructed using.
  • connection point A which is the midpoint of the first leg in the input switching circuit 10, via a reactor component L1.
  • the other end of the primary winding N ⁇ b> 1 is connected to a connection point B that is a midpoint of the second leg in the input switching circuit 10.
  • a neutral point T which is a connection point between the secondary winding N2a and the secondary winding N2b, is connected to the output switching circuit 30 together with both ends of the secondary winding N2.
  • the output switching circuit 30 converts the AC power appearing in the secondary windings N2a and N2b into DC power by smoothing and rectifying the AC power that flows in the primary winding N1 of the transformer 20 to the positive output terminal 3 and the negative electrode It has a role of outputting to the low voltage battery V2 via the output terminal 4.
  • a voltage detector 41 is connected between the positive electrode output terminal 3 and the negative electrode output terminal 4 in parallel with the low voltage battery V2. The voltage detector 41 detects the voltage of the DC power output from the output switching circuit 30 and outputs the detected value to the control circuit 50 as the output voltage Vout of the DC-DC converter 100.
  • the output switching circuit 30 has a configuration in which two switch elements 31a and 32a are connected between the transformer 20 and the rectifying connection point S.
  • the switch element 31a is connected between one end of the secondary winding N2b of the transformer 20 and the rectification connection point S.
  • the switch element 32a is connected between one end of the secondary winding N2a of the transformer 20 and the rectification connection point S. It is connected to the.
  • Snubber circuits 33 and 34 are connected in parallel to the switch elements 31a and 32a, respectively.
  • the switch elements 31a and 32a can be configured by using any element capable of switching operation like the switch elements 11a to 14a in the input switching circuit 10, for example, an FET (field effect transistor) is preferable. It is.
  • the flywheel diodes 31b and 32b and capacitors 31c and 32c are connected in parallel to the switch elements 31a and 32a, respectively. These diodes 31b and 32b and capacitors 31c and 32c may be configured as separate elements from the switch elements 31a and 32a, or may be parasitic components of the switch elements 31a and 32a. These may be used in combination.
  • a smoothing coil L2 and a smoothing capacitor C2 are connected to the output side of the output switching circuit 30.
  • the smoothing coil L2 is connected between the neutral point T and the positive electrode output terminal 3, and the smoothing capacitor C2 is connected between the positive electrode output terminal 3 and the negative electrode output terminal 4.
  • the switch elements 31a and 32a constitute a rectifier circuit that rectifies and converts the AC power output from the secondary windings N2b and N2a of the transformer 20 into DC power, respectively.
  • the smoothing coil L2 and the smoothing capacitor C2 constitute a smoothing circuit that smoothes the rectified output generated at the neutral point T.
  • the control circuit 50 is a circuit that controls the operation of the switch elements 11a to 14a of the input switching circuit 10 so that the output voltage Vout of the DC-DC converter 100 becomes a predetermined voltage target value.
  • the control circuit 50 generates output signals 51 to 54 for controlling the switch elements 11a to 14a of the input switching circuit 10 based on the output voltage Vout.
  • Output signals 51 to 54 generated by the control circuit 50 are output from the control circuit 50 to the gate driver 60 and converted into drive signals 71 to 74 by the gate driver 60, respectively.
  • the drive signals 71 to 74 are input to the respective gate terminals of the switch elements 11a to 14a in the input switching circuit 10 to drive the switch elements 11a to 14a, respectively. Thereby, the operation of the input switching circuit 10 is controlled by the control circuit 50.
  • control circuit 50 generates output signals 55 and 56 for controlling the switch elements 31a and 32a of the output switching circuit 30 based on the output voltage Vout.
  • Output signals 55 and 56 generated by the control circuit 50 are output from the control circuit 50 to the gate driver 61 and converted into drive signals 75 and 76 by the gate driver 61, respectively.
  • the drive signals 75 and 76 are input to the respective gate terminals of the switch elements 31a and 32a in the output switching circuit 30, and drive the switch elements 31a and 32a, respectively. Thereby, the operation of the output switching circuit 30 is controlled by the control circuit 50.
  • FIG. 3 is a timing chart showing how the voltage and current of each part change with time during the operation of the DC-DC converter 100 according to the first embodiment of the present invention.
  • FIGS. 4 to 9 show the switching state of each switch element at the time of operation
  • 4 to 9 correspond to periods # 1 to # 6 of the timing chart shown in FIG. 3, respectively. That is, FIGS. 4 to 9 show the on / off states of the switch elements 11a to 14a, 31a and 32a in the DC-DC converter 100 in the periods # 1 to # 6 of FIG.
  • the input switching circuit 10 the transformer 20 and the output.
  • the direction of the current flowing through the switching circuit 30 is shown.
  • the control circuit 50 controls the switching elements 11a to 14a of the input switching circuit 10 and the switching elements 31a and 32a of the output switching circuit 30 to switch the period # The transition from 1 to # 6 can be controlled.
  • voltage waveforms Vg_11a to Vg_14a represent temporal changes in the gate voltage of the switch elements 11a to 14a in the input switching circuit 10, respectively, and voltage waveform Vg_31a represents a temporal change in the gate voltage of the switch element 31a in the output switching circuit 30.
  • the current waveform I_L1 represents the time change of the current flowing through the reactor component L1 and the primary winding N1
  • the current waveforms I_N2a and I_N2b represent the time change of the current flowing through the secondary windings N2a and N2b of the transformer 20, respectively.
  • the direction of the current from the connection point A to the connection point B in FIG. 2 is positive.
  • FIG. 3 shows how each voltage and each current changes with time when the current waveform I_L1 of the reactor component L1 is negative.
  • the operation state of the DC-DC converter 100 in the periods # 1 to # 6 will be described with reference to FIGS. 4 to 9, respectively.
  • the direction of the current flowing through the secondary winding N2b is positive as shown by the arrow in FIG. It is preferable that the current polarity of the secondary winding N2b is reversed when the current flowing through the winding N2a exceeds a certain value. This point will be described in detail later in the description of the period # 2.
  • the switch elements 31a and 32a of the output switching circuit 30 are maintained in the ON state. Therefore, as indicated by an arrow in FIG. 5, a current flows in order from the transformer 20 to the smoothing coil L2, a load (not shown) connected in parallel with the smoothing capacitor C2, and the switching element 32a of the output switching circuit 30. Energy is stored in L2.
  • the direction of the current flowing through the secondary winding N2b via the switch element 31a changes according to the magnitude of the current flowing through the load. Specifically, when the negative overcurrent is large, the direction of the current flowing through the secondary winding N2b is the positive direction, that is, the direction opposite to the direction indicated by the arrow in FIG.
  • the current polarity is reversed, and the direction of the current flowing through the secondary winding N2b is the negative direction, that is, the direction indicated by the arrow in FIG.
  • the direction of the current flowing through the secondary winding N2b is reversed in the middle of the period # 1, and this state is continued even in the period # 2.
  • a resonance voltage is generated so that a current flows through the snubber circuit 33 as will be described later, and the circulating current in the input switching circuit 10 can be increased.
  • the current waveform I_N2a of the secondary winding N2a decreases, and the current waveform I_N2b of the secondary winding N2b increases in the negative direction.
  • Period # 3 Circulation period
  • the switch elements 11a and 13a are in the on state, and the switch elements 12a and 14a are in the off state.
  • the switch element 32a is maintained in the on state, and the switch element 31a is changed from the on state to the off state.
  • the switch element 31a transitions to the off state, the current flowing through the switch element 31a is cut off, and the current flows through the snubber circuit 33 connected in parallel with the switch element 31a.
  • a resonance voltage is generated by the secondary winding N2b of the transformer 20 and the snubber circuit 33.
  • the switch elements 11a and 13a are in the on state and the switch elements 12a and 14a are in the off state.
  • a circulating current that circulates through the input switching circuit 10, the reactor component L1, and the transformer 20 flows without passing through the high-voltage battery V1.
  • the resonance voltage generated by the secondary winding N2b of the transformer 20 and the snubber circuit 33 is applied from the output switching circuit 30 to the input switching circuit 10 via the transformer 20. This voltage increases the circulating current in the input switching circuit 10.
  • Period # 4 Dead time period
  • the switch element 13a is maintained in the on state, and the switch elements 12a and 14a are maintained in the off state, while the switch element 11a is in the on state. Transition from state to off state. Thereby, in a 1st leg, both a pair of switch element 11a and switch element 12a will be in an OFF state. Therefore, this period is called a dead time period.
  • the reactor component L1 keeps flowing current, so that the capacitor 11c connected in parallel to the switch element 11a is charged and the switch element 12a is charged as shown by the arrow in FIG.
  • the capacitor 12c connected in parallel is discharged.
  • the switch element 32a of the output switching circuit 30 is maintained in the on state, and the switch element 31a is maintained in the off state.
  • the polarity of the current flowing through the secondary winding N2b of the transformer 20 and the snubber circuit 33 is reversed at a predetermined timing according to the above-described resonance voltage. Note that the polarity of the current may be reversed not in the period # 4 but in a period # 5 or a period # 6 described later.
  • the operation of the DC-DC converter 100 after the period # 6 is an operation obtained by inverting the operation during the above-described periods # 1 to # 6. That is, the operation of each switching element in the input switching circuit 10 and the output switching circuit 30 and the direction of the current flowing through the input switching circuit 10 and the output switching circuit 30 in accordance with this operation are the periods # 1 to # 6 described above. The opposite is true for each. Specifically, in the input switching circuit 10, when the switch elements 11a and 14a are in the off state and the switch element 13a is in the on state, the switch element 12a is changed from the on state to the off state, and the period # 2, A circulation period similar to # 3 can be provided.
  • the switch elements 14a are connected in parallel as in the period # 4. It is possible to increase the amount of decrease in the voltage across the capacitor 14c. As a result, zero volt switching is also possible for the switch element 14a.
  • a DC-DC converter 100 that is a power converter includes an input switching circuit 10 that converts DC power input from a high-voltage battery V1 that is an input power source into AC power, and a transformer 20 that performs voltage conversion of AC power. , An output switching circuit 30 that converts the AC power voltage-converted by the transformer 20 into DC power and outputs it, a control circuit 50 that controls the input switching circuit 10 and the output switching circuit 30, and the input switching circuit 10 and the transformer 20. And a reactor component L1 provided therebetween.
  • the input switching circuit 10 includes a pair of switch elements 11a and 12a, and 13a and 14a that are connected in series between the positive and negative electrodes of the high-voltage battery V1 and controlled to be switched by the control circuit 50, respectively.
  • the output switching circuit 30 includes switch elements 31a and 32a that are controlled by the control circuit 50, and snubber circuits 33 and 34 provided in parallel with the switch elements 31a and 32a.
  • the control circuit 50 increases the circulating current by flowing the current to the snubber circuit 33 in the circulation period # 3 in which the circulating current that circulates through the input switching circuit 10, the reactor component L1, and the transformer 20 without passing through the high-voltage battery V1.
  • the output switching circuit 30 is controlled.
  • the control circuit 50 controls the input switching circuit 10 so as to shift to the dead time period # 4 in which both the pair of switch elements 11a and 12a are off after the circulation period # 3.
  • the DC-DC converter 100 can realize zero-volt switching of the input switching circuit 10 without reducing the output loss without detecting the output current. Therefore, it is possible to increase the efficiency of the DC-DC converter 100 that is a power conversion device while suppressing an increase in size and cost.
  • the reactor component L1 is configured using at least one of the leakage inductance of the transformer 20 and the reactor element connected between the input switching circuit 10 and the transformer 20. Since it did in this way, the reactor component L1 which has an optimal inductance according to the circuit characteristic of the input switching circuit 10 or the transformer 20 can be provided.
  • FIG. 10 is a diagram showing a basic circuit configuration of a DC-DC converter 100a according to the second embodiment of the present invention.
  • the DC-DC converter 100a of the present embodiment has a delay circuit between the control circuit 50 and the gate driver 60, as compared with the DC-DC converter 100 of FIG. 2 described in the first embodiment. The difference is that 90 is further provided.
  • FIG. 11 is a diagram illustrating an example of the delay circuit 90.
  • a delay circuit 90 shown in FIG. 11 is an example of an RC delay circuit configured using a resistor and a capacitor. Note that the delay circuit 90 is not limited to that shown in FIG. 11, and can have any circuit configuration. It goes without saying that the same effect can be obtained with any delay circuit 90 as long as the output signals 51 to 54 can be delayed by a desired timing.
  • the control circuit 50 outputs the output signals 51 to 54 to the input switching circuit 10 and the output signals 55 to 56 to the output switching circuit 30 in synchronization with each other.
  • the output signals 51 to 54 are delayed by the delay circuit 90, so that the switch element 11a of the input switching circuit 10 is turned off with respect to the switch element 31a of the output switching circuit 30 as described in the first embodiment.
  • the timing can be delayed.
  • a resonance voltage can be generated by the secondary winding N2b of the transformer 20 and the snubber circuit 33, and the circulating current in the input switching circuit 10 can be increased.
  • the off timing of the switch element 13a of the input switching circuit 10 can be delayed with respect to the switch element 32a of the output switching circuit 30, the resonance voltage is generated by the secondary winding N2a of the transformer 20 and the snubber circuit 34. And the circulating current in the input switching circuit 10 can be increased.
  • the DC-DC converter 100 a that is a power converter includes a delay circuit 90 provided between the control circuit 50 and the input switching circuit 10.
  • the control circuit 50 outputs output signals 51 to 54 for controlling the input switching circuit 10 and output signals 55 to 56 for controlling the output switching circuit 30 in synchronization with each other.
  • the delay circuit 90 delays the output signals 51 to 54 and outputs them to the input switching circuit 10 via the gate driver 60. Since it did in this way, it becomes possible to increase the circulating current in the input switching circuit 10 easily, without requiring special control in the control circuit 50.
  • the input switching circuit 10 that is a voltage-type full bridge circuit constituted by four switch elements 11a to 14a and the transformer 20 that is a current-type center tap circuit are combined.
  • the present invention has been described using the example of the control circuit 50 that controls the configured DC-DC converters 100 and 100a by the phase shift control method, the present invention is not limited to this.
  • An input switching circuit that converts input first DC power into AC power, a transformer that performs voltage conversion of AC power, and an output that converts AC power voltage-converted by the transformer into second DC power and outputs it If it is a power converter device which has a switching circuit, this invention can be applied and there can exist an effect similar to having demonstrated in each embodiment.
  • each embodiment described above may be applied individually or in any combination.
  • DC-DC converter 200 ... Vehicle power supply control unit, 300 ... HV system equipment, 400 ... Auxiliary equipment, 1000 ... vehicle, N1 ... primary winding, N2a, N2b ... secondary winding, S ... rectifying connection point, T ... neutral point, V1 ... high voltage battery , V2 ... low-voltage battery

Abstract

The present invention achieves high efficiency of a power conversion device while suppressing the increase of size and cost. In a DC-DC converter 100, a control circuit 50 controls an output switching circuit 30 so that current flows through a snubber circuit 33 in a circulation period during which circulating current flows that circulates through an input switching circuit 10, a reactor component L1, and a transformer 20 without passing through a high voltage battery V1 and thereby the circulating current increases. The control circuit 50 also controls the input switching circuit 10 to shift, after the circulation period, to a dead time period during which a pair of switching elements 11a, 12a are both turned off.

Description

電力変換装置Power converter
　本発明は、電力変換装置に関する。 The present invention relates to a power conversion device.
　近年、化石燃料の枯渇や地球環境問題を背景として、ハイブリッド自動車や電気自動車のような、電気エネルギーを利用して走行する自動車への関心が高まっており、実用化されている。このような電気エネルギーを利用して走行する自動車には、車輪を駆動するためのモータに電力を供給する高圧バッテリが備えられている。さらに、高圧バッテリからの出力電力を降圧して、自動車に搭載された低圧の電気機器、例えばエアコンやオーディオ、各種ＥＣＵ（Electronic Control Unit）等へ必要な電力を供給する電力変換装置が備えられることもある。こうした電力変換装置は、入力された直流電力を異なる電圧の直流電力に変換するものであり、ＤＣ－ＤＣコンバータとも呼ばれる。 In recent years, with the background of fossil fuel depletion and global environmental problems, interest in automobiles that use electric energy, such as hybrid cars and electric cars, has increased and is being put to practical use. An automobile that travels using such electric energy is provided with a high-voltage battery that supplies electric power to a motor for driving wheels. Furthermore, a power conversion device that steps down the output power from the high-voltage battery and supplies the necessary power to low-voltage electric devices mounted on the automobile, such as air conditioners and audio, various ECUs (Electronic Control Units), etc., is provided. There is also. Such a power converter converts input DC power into DC power of a different voltage, and is also called a DC-DC converter.
　一般にＤＣ－ＤＣコンバータは、スイッチング動作可能なスイッチング回路を有しており、このスイッチング回路のオン／オフを制御することで、直流電力の電圧変換を行う。具体的には、入力された直流電力をスイッチング回路を用いて交流電力に一旦変換し、その交流電力をトランスを用いて変圧（昇圧または降圧）する。そして、整流回路などの出力回路を用いて、変圧後の交流電力を再び直流電力に変換する。これにより、入力電圧とは異なる電圧を持った直流出力を得ることができる。スイッチング回路は、例えばＭＯＳＦＥＴ（Metal-Oxide-Semiconductor Field-Effect Transistor）やＩＧＢＴ（InsulatedGate Bipolar Transistor）などの半導体スイッチ素子を用いて構成される。 Generally, a DC-DC converter has a switching circuit capable of switching operation, and performs voltage conversion of DC power by controlling on / off of the switching circuit. Specifically, the input DC power is temporarily converted into AC power using a switching circuit, and the AC power is transformed (stepped up or stepped down) using a transformer. Then, the transformed AC power is converted into DC power again using an output circuit such as a rectifier circuit. As a result, a DC output having a voltage different from the input voltage can be obtained. The switching circuit is configured by using a semiconductor switch element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor).
　車載用の電力変換装置では、自然エネルギーの有効活用や二酸化炭素の削減を目的として、一般に高効率が求められる。そのため、電力変換時の損失をできるだけ低減することが重要となる。ここで、ＤＣ－ＤＣコンバータにおいて発生する損失には、スイッチング動作により発生するスイッチング損失や、トランスや半導体スイッチ素子で発生する抵抗損失（銅損）等がある。電力変換装置の高効率化に関して、下記の特許文献１が知られている。特許文献１には、出力電流に基づいて整流平滑回路の２つの同期整流スイッチの切換えタイミングを制御して、軽負荷時には出力電流が増加したのと同等に作用するように整流平滑回路に蓄えられたエネルギーをフルブリッジ回路に戻し、フルブリッジ回路に流れる電流の増加を図ることによってゼロボルトスイッチングを行う電源装置が開示されている。 In-vehicle power converters generally require high efficiency in order to effectively use natural energy and reduce carbon dioxide. Therefore, it is important to reduce the loss during power conversion as much as possible. Here, the loss generated in the DC-DC converter includes a switching loss generated by a switching operation, a resistance loss (copper loss) generated in a transformer and a semiconductor switch element, and the like. The following patent document 1 is known regarding high efficiency of a power converter. In Patent Document 1, the switching timing of the two synchronous rectification switches of the rectifying / smoothing circuit is controlled based on the output current, and stored in the rectifying / smoothing circuit so as to act equivalent to the increase in the output current at light load. A power supply device that performs zero volt switching by returning the energy returned to the full bridge circuit and increasing the current flowing through the full bridge circuit is disclosed.
特開２０１１－１６６９４９号公報JP 2011-166949 A
　特許文献１に記載の技術では、出力電流を検出する電流検出器が必要であるため、従来の電力変換装置と比べてサイズやコストの増大を招くという問題がある。 The technique described in Patent Document 1 requires a current detector that detects an output current, and thus has a problem of increasing the size and cost as compared with a conventional power converter.
　本発明による電力変換装置は、入力電源から入力された第１の直流電力を交流電力に変換する入力スイッチング回路と、前記交流電力の電圧変換を行うトランスと、前記トランスにより電圧変換された前記交流電力を第２の直流電力に変換して出力する出力スイッチング回路と、前記入力スイッチング回路および前記出力スイッチング回路を制御する制御回路と、前記入力スイッチング回路と前記トランスの間に設けられたリアクトル成分と、を備え、前記入力スイッチング回路は、前記入力電源の正負極間に直列接続されて前記制御回路によりそれぞれスイッチング制御される一対の入力スイッチ素子を有し、前記出力スイッチング回路は、前記制御回路によりスイッチング制御される出力スイッチ素子と、前記出力スイッチ素子と並列に設けられたスナバ回路と、を有し、前記制御回路は、前記入力電源を介さずに前記入力スイッチング回路、前記リアクトル成分および前記トランスを循環する循環電流が流れる循環期間において、前記スナバ回路に電流が流れることで前記循環電流が増大するように、前記出力スイッチング回路を制御し、前記循環期間の後に前記一対の入力スイッチ素子が両方ともオフであるデッドタイム期間に移行するように、前記入力スイッチング回路を制御する。 The power conversion device according to the present invention includes an input switching circuit that converts first DC power input from an input power source into AC power, a transformer that performs voltage conversion of the AC power, and the AC that is voltage-converted by the transformer. An output switching circuit that converts electric power into second DC power and outputs the output; a control circuit that controls the input switching circuit and the output switching circuit; a reactor component provided between the input switching circuit and the transformer; The input switching circuit includes a pair of input switch elements connected in series between the positive and negative electrodes of the input power source and controlled to be switched by the control circuit, and the output switching circuit is controlled by the control circuit. An output switch element that is switching-controlled, and in parallel with the output switch element A snubber circuit provided, and the control circuit supplies a current to the snubber circuit in a circulation period in which a circulation current circulating through the input switching circuit, the reactor component, and the transformer flows without passing through the input power supply. The input switching circuit is controlled so that the circulating current increases due to the current flowing, and the input switching circuit is shifted to a dead time period in which both of the pair of input switch elements are off after the circulating period. Control the circuit.
　本発明によれば、サイズやコストの増大を抑えつつ、電力変換装置の高効率化を図ることができる。 According to the present invention, it is possible to increase the efficiency of the power conversion device while suppressing an increase in size and cost.
本発明の一実施形態に係る車両電源の構成を示す図である。It is a figure which shows the structure of the vehicle power supply which concerns on one Embodiment of this invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの基本回路構成を示す図である。It is a figure which shows the basic circuit structure of the DC-DC converter which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの動作時における各部分の電圧および電流の時間変化の様子を表したタイミングチャートを示す図である。FIG. 3 is a timing chart showing how the voltage and current of each part change with time during the operation of the DC-DC converter according to the first embodiment of the present invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの期間＃１における各スイッチ素子の切替状態および電流の向きを示す図である。It is a figure which shows the switching state and direction of an electric current of each switch element in period # 1 of the DC-DC converter which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの期間＃２における各スイッチ素子の切替状態および電流の向きを示す図である。It is a figure which shows the switching state of each switch element, and direction of an electric current in period # 2 of the DC-DC converter which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの期間＃３における各スイッチ素子の切替状態および電流の向きを示す図である。It is a figure which shows the switching state and direction of an electric current of each switch element in period # 3 of the DC-DC converter which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの期間＃４における各スイッチ素子の切替状態および電流の向きを示す図である。It is a figure which shows the switching state of each switch element, and direction of an electric current in period # 4 of the DC-DC converter which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの期間＃５における各スイッチ素子の切替状態および電流の向きを示す図である。It is a figure which shows the switching state and direction of an electric current of each switch element in period # 5 of the DC-DC converter which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係るＤＣ－ＤＣコンバータの期間＃６における各スイッチ素子の切替状態および電流の向きを示す図である。It is a figure which shows the switching state and direction of an electric current of each switch element in period # 6 of the DC-DC converter which concerns on the 1st Embodiment of this invention. 本発明の第２の実施形態に係るＤＣ－ＤＣコンバータの基本回路構成を示す図である。It is a figure which shows the basic circuit structure of the DC-DC converter which concerns on the 2nd Embodiment of this invention. 遅延回路の一例を示す図である。It is a figure which shows an example of a delay circuit.
　以下、図面を参照して、本発明に係る電力変換装置の実施の形態について説明する。なお、各図において同一要素については同一の符号を記し、重複する説明は省略する。ただし、本発明は以下の実施形態に限定されることなく、本発明の技術的な概念の中で種々の変形例や応用例をもその範囲に含むものである。 Hereinafter, embodiments of a power conversion device according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is described about the same element and the overlapping description is abbreviate | omitted. However, the present invention is not limited to the following embodiments, and includes various modifications and application examples within the scope of the technical concept of the present invention.
－第１の実施形態－
（車両電源構成）
　図１は、本発明の一実施形態に係る車両電源の構成を示す図である。図１に示すように、本実施形態に係る車両電源は、車両１０００に搭載されており、ＤＣ－ＤＣコンバータ１００を使用して高圧バッテリＶ１と低圧バッテリＶ２の間で相互に電力変換を行う電源系統である。なお、以下の説明では、ＤＣ－ＤＣコンバータ１００の低圧側、すなわち低圧バッテリＶ２に接続されている側を「Ｌ側」と称し、ＤＣ－ＤＣコンバータ１００の高圧側、すなわち高圧バッテリＶ１に接続されている側を「Ｈ側」と称する。 -First embodiment-
(Vehicle power supply configuration)
FIG. 1 is a diagram showing a configuration of a vehicle power source according to an embodiment of the present invention. As shown in FIG. 1, the vehicle power source according to the present embodiment is mounted on a vehicle 1000 and uses a DC-DC converter 100 to perform power conversion between the high voltage battery V1 and the low voltage battery V2. It is a system. In the following description, the low-voltage side of the DC-DC converter 100, that is, the side connected to the low-voltage battery V2 is referred to as “L side”, and is connected to the high-voltage side of the DC-DC converter 100, ie, the high-voltage battery V1. The side that is on is called the “H side”.
　低圧バッテリＶ２の一端は、ＤＣ－ＤＣコンバータ１００のＬ側の一端に接続され、低圧バッテリＶ２の他端は、ＤＣ－ＤＣコンバータ１００のＬ側の他端に接続されている。エアコンなどの補機機器４００の一端は、ＤＣ－ＤＣコンバータ１００のＬ側の一端および低圧バッテリＶ２の一端に接続され、補機機器４００の他端は、ＤＣ－ＤＣコンバータ１００のＬ側の他端および低圧バッテリＶ２の他端に接続されている。ＨＶ系機器３００の一端は、ＤＣ－ＤＣコンバータ１００のＨ側の一端および高圧バッテリＶ１の一端に接続され、ＨＶ系機器３００の他端は、ＤＣ－ＤＣコンバータ１００のＨ側の他端および高圧バッテリＶ１の他端に接続されている。高圧バッテリＶ１の一端は、ＤＣ－ＤＣコンバータ１００のＨ側の一端に接続され、高圧バッテリＶ１の他端は、ＤＣ－ＤＣコンバータ１００のＨ側の他端に接続されている。 One end of the low voltage battery V2 is connected to one end on the L side of the DC-DC converter 100, and the other end of the low voltage battery V2 is connected to the other end on the L side of the DC-DC converter 100. One end of the auxiliary equipment 400 such as an air conditioner is connected to one end on the L side of the DC-DC converter 100 and one end of the low-voltage battery V2, and the other end of the auxiliary equipment 400 is connected to the other side on the L side of the DC-DC converter 100. One end and the other end of the low-voltage battery V2 are connected. One end of the HV system device 300 is connected to one end on the H side of the DC-DC converter 100 and one end of the high voltage battery V1, and the other end of the HV system device 300 is connected to the other end on the H side of the DC-DC converter 100 and the high voltage. The other end of the battery V1 is connected. One end of the high voltage battery V1 is connected to one end on the H side of the DC-DC converter 100, and the other end of the high voltage battery V1 is connected to the other end on the H side of the DC-DC converter 100.
　ＤＣ－ＤＣコンバータ１００、ＨＶ系機器３００および補機機器４００は、車両電源制御部２００と接続されている。車両電源制御部２００は、これらの各機器の動作や、これらの各機器と高圧バッテリＶ１および低圧バッテリＶ２との間でやり取りされる電力の送電方向、電力量等を制御する。 The DC-DC converter 100, the HV system device 300, and the auxiliary device 400 are connected to the vehicle power supply control unit 200. The vehicle power supply control unit 200 controls the operation of these devices, the power transmission direction of the power exchanged between these devices and the high voltage battery V1 and the low voltage battery V2, the amount of power, and the like.
（ＤＣ－ＤＣコンバータ１００の基本構成）
　図２は、本発明の第１の実施形態に係るＤＣ－ＤＣコンバータ１００の基本回路構成を示す図である。図２に示すように、本実施形態のＤＣ－ＤＣコンバータ１００は、入力スイッチング回路１０、トランス２０、出力スイッチング回路３０、電圧検出器４１、制御回路５０、ゲートドライバ６０、６１を有している。 (Basic configuration of DC-DC converter 100)
FIG. 2 is a diagram showing a basic circuit configuration of the DC-DC converter 100 according to the first embodiment of the present invention. As shown in FIG. 2, the DC-DC converter 100 of this embodiment includes an input switching circuit 10, a transformer 20, an output switching circuit 30, a voltage detector 41, a control circuit 50, and gate drivers 60 and 61. .
　入力スイッチング回路１０は、正極入力端子１および負極入力端子２を介して、ＤＣ－ＤＣコンバータ１００の入力電源として作用する高圧バッテリＶ１と接続されている。入力スイッチング回路１０は、ブリッジ接続されたスイッチ素子１１ａ～１４ａを有しており、これらのスイッチ素子１１ａ～１４ａをスイッチング動作させることで、高圧バッテリＶ１から入力された直流電力を高周波の交流電力に変換し、トランス２０の一次側に出力する。 The input switching circuit 10 is connected via a positive input terminal 1 and a negative input terminal 2 to a high voltage battery V1 that acts as an input power source for the DC-DC converter 100. The input switching circuit 10 includes switch elements 11a to 14a connected in a bridge. By switching the switch elements 11a to 14a, the DC power input from the high voltage battery V1 is changed to high frequency AC power. Converted and output to the primary side of the transformer 20.
　トランス２０は、一次側と二次側の間を絶縁すると共に、一次側と二次側の間で交流電力の電圧変換を行い、入力スイッチング回路１０で生成された交流電力から降圧（または昇圧）された交流電力を出力スイッチング回路３０に出力する。 The transformer 20 insulates the primary side from the secondary side, performs voltage conversion of AC power between the primary side and the secondary side, and steps down (or boosts) the AC power generated by the input switching circuit 10. The AC power thus output is output to the output switching circuit 30.
　出力スイッチング回路３０は、正極出力端子３および負極出力端子４を介して低圧バッテリＶ２と接続されている。出力スイッチング回路３０は、スイッチ素子３１ａ、３２ａと、スイッチ素子３１ａ、３２ａに対してそれぞれ並列に設けられてスイッチ素子３１ａ、３２ａを保護するスナバ回路３３、３４とを有している。出力スイッチング回路３０は、スイッチ素子３１ａ、３２ａを用いて、トランス２０により電圧変換された交流電力を整流して直流電力に変換し、低圧バッテリＶ２に出力する。 The output switching circuit 30 is connected to the low voltage battery V <b> 2 through the positive output terminal 3 and the negative output terminal 4. The output switching circuit 30 includes switch elements 31a and 32a and snubber circuits 33 and 34 that are provided in parallel to the switch elements 31a and 32a and protect the switch elements 31a and 32a. The output switching circuit 30 rectifies the AC power voltage-converted by the transformer 20 using the switch elements 31a and 32a, converts it into DC power, and outputs the DC power to the low-voltage battery V2.
　電圧検出器４１は、正極出力端子３と負極出力端子４の間の電圧を検出することで、出力スイッチング回路３０の出力電圧を検出する。電圧検出器４１が検出した出力電圧は、制御回路５０に入力される。 The voltage detector 41 detects the output voltage of the output switching circuit 30 by detecting the voltage between the positive electrode output terminal 3 and the negative electrode output terminal 4. The output voltage detected by the voltage detector 41 is input to the control circuit 50.
　制御回路５０は、例えば図１の車両電源制御部２００内に設けられており、電圧検出器４１が検出した出力電圧に基づいて、入力スイッチング回路１０におけるスイッチ素子１１ａ～１４ａのスイッチング動作をそれぞれ制御するための出力信号５１～５４を生成して出力する。また、電圧検出器４１が検出した出力電圧に基づいて、出力スイッチング回路３０におけるスイッチ素子３１ａ、３２ａのスイッチング動作をそれぞれ制御するための出力信号５５～５６を生成して出力する。 The control circuit 50 is provided, for example, in the vehicle power supply control unit 200 of FIG. 1, and controls the switching operations of the switch elements 11a to 14a in the input switching circuit 10 based on the output voltage detected by the voltage detector 41, respectively. Output signals 51 to 54 are generated and output. Further, based on the output voltage detected by the voltage detector 41, output signals 55 to 56 for controlling the switching operations of the switch elements 31a and 32a in the output switching circuit 30 are generated and output.
　ゲートドライバ６０は、制御回路５０から出力された出力信号５１～５４を、スイッチ素子１１ａ～１４ａを駆動するための駆動信号７１～７４にそれぞれ変換し、入力スイッチング回路１０に出力する。ゲートドライバ６０は、入力スイッチング回路１０と制御回路５０の間を絶縁する。 The gate driver 60 converts the output signals 51 to 54 output from the control circuit 50 into drive signals 71 to 74 for driving the switch elements 11a to 14a, respectively, and outputs them to the input switching circuit 10. The gate driver 60 insulates between the input switching circuit 10 and the control circuit 50.
　ゲートドライバ６１は、制御回路５０から出力された出力信号５５～５６を、スイッチ素子３１ａ、３２ａを駆動するための駆動信号７５、７６にそれぞれ変換し、出力スイッチング回路３０に出力する。ゲートドライバ６１は、出力スイッチング回路３０と制御回路５０の間を絶縁する。 The gate driver 61 converts the output signals 55 to 56 output from the control circuit 50 into drive signals 75 and 76 for driving the switch elements 31a and 32a, respectively, and outputs them to the output switching circuit 30. The gate driver 61 insulates between the output switching circuit 30 and the control circuit 50.
　以下では、ＤＣ－ＤＣコンバータ１００が有する入力スイッチング回路１０、トランス２０および出力スイッチング回路３０の各構成および制御回路５０の詳細について説明する。 Hereinafter, each configuration of the input switching circuit 10, the transformer 20, and the output switching circuit 30 included in the DC-DC converter 100 and details of the control circuit 50 will be described.
（入力スイッチング回路１０）
　入力スイッチング回路１０は、高圧バッテリＶ１から正極入力端子１および負極入力端子２を介して入力される直流電力を、制御回路５０の制御に応じて高周波の交流電力に変換し、トランス２０の一次巻線Ｎ１に供給する役割を有する。正極入力端子１と負極入力端子２の間には、高圧バッテリＶ１と並列に平滑コンデンサＣ１が接続されている。 (Input switching circuit 10)
The input switching circuit 10 converts DC power input from the high-voltage battery V <b> 1 through the positive input terminal 1 and the negative input terminal 2 into high-frequency AC power according to the control of the control circuit 50, and the primary winding of the transformer 20. It has a role to supply to the line N1. A smoothing capacitor C1 is connected between the positive input terminal 1 and the negative input terminal 2 in parallel with the high voltage battery V1.
　入力スイッチング回路１０は、４つのスイッチ素子１１ａ～１４ａがフルブリッジ接続された構成を有する。すなわち、正極入力端子１と負極入力端子２の間に、２つのスイッチ素子１１ａおよびスイッチ素子１２ａの直列回路（以下、「第１レッグ」と称する）と、２つのスイッチ素子１３ａおよびスイッチ素子１４ａの直列回路（以下、「第２レッグ」と称する）とが、それぞれ接続されている。第１レッグにおけるスイッチ素子１１ａとスイッチ素子１２ａの間の接続点Ａは、トランス２０の一次巻線Ｎ１の一端側に接続されており、第２レッグにおけるスイッチ素子１３ａとスイッチ素子１４ａの間の接続点Ｂは、トランス２０の一次巻線Ｎ１の他端側に接続されている。なお、スイッチ素子１１ａ～１４ａは、スイッチング動作が可能な任意の素子を用いて構成することができ、例えばＦＥＴ（電界効果トランジスタ）等が好適である。 The input switching circuit 10 has a configuration in which four switch elements 11a to 14a are connected in a full bridge. That is, between the positive input terminal 1 and the negative input terminal 2, a series circuit of two switch elements 11a and 12a (hereinafter referred to as “first leg”), two switch elements 13a and 14a. A series circuit (hereinafter referred to as “second leg”) is connected to each other. A connection point A between the switch element 11a and the switch element 12a in the first leg is connected to one end side of the primary winding N1 of the transformer 20, and a connection between the switch element 13a and the switch element 14a in the second leg. Point B is connected to the other end of primary winding N1 of transformer 20. The switch elements 11a to 14a can be configured by using any element capable of switching operation, and for example, an FET (field effect transistor) or the like is preferable.
　スイッチ素子１１ａ～１４ａには、フライホイール用のダイオード１１ｂ～１４ｂおよびコンデンサ１１ｃ～１４ｃがそれぞれ並列接続されている。これらのダイオード１１ｂ～１４ｂおよびコンデンサ１１ｃ～１４ｃは、スイッチ素子１１ａ～１４ａとは別素子で構成しても良いし、あるいはスイッチ素子１１ａ～１４ａの寄生成分であっても良い。また、これらを併用しても良い。 The switch elements 11a to 14a are connected in parallel with flywheel diodes 11b to 14b and capacitors 11c to 14c, respectively. These diodes 11b to 14b and capacitors 11c to 14c may be configured as separate elements from the switch elements 11a to 14a, or may be parasitic components of the switch elements 11a to 14a. These may be used in combination.
　本実施形態のＤＣ－ＤＣコンバータ１００では、入力スイッチング回路１０の制御方式として、スイッチング損失を低減可能な駆動方式である位相シフト制御方式が用いられる。位相シフト制御方式においては、フルブリッジ型の入力スイッチング回路１０を構成する４つのスイッチ素子１１ａ～１４ａのうち、第１レッグの上側にあるスイッチ素子１１ａと第２レッグの下側にあるスイッチ素子１４ａとのオン／オフの位相差が、ＤＣ－ＤＣコンバータ１００の出力電圧に応じて制御される。同様に、第１レッグの下側にあるスイッチ素子１２ａと第２レッグの上側にあるスイッチ素子１３ａとのオン／オフの位相差も、ＤＣ－ＤＣコンバータ１００の出力電圧に応じて制御される。これにより、スイッチ素子１１ａとスイッチ素子１４ａが同時にオン状態となる期間、並びに、スイッチ素子１２ａとスイッチ素子１３ａが同時にオン状態となる期間が、出力電圧に応じて調整される。ここで、入力スイッチング回路１０（トランス２０の一次側）から出力スイッチング回路３０（トランス２０の二次側）に伝送される電力は、スイッチ素子１１ａとスイッチ素子１４ａが同時にオン状態となる期間、並びに、スイッチ素子１２ａとスイッチ素子１３ａが同時にオン状態となる期間によって決まる。したがって、上記のように位相差を制御することで、ＤＣ－ＤＣコンバータ１００の出力電圧を所望の値に安定させることが可能となる。なお、以下の説明では、スイッチ素子１１ａとスイッチ素子１４ａが同時にオン状態となる期間と、スイッチ素子１２ａとスイッチ素子１３ａが同時にオン状態となる期間とが、同じ長さであるものとする。また、一周期におけるこれらの期間の長さの比率を、デューティ比と呼ぶこともある。 In the DC-DC converter 100 of the present embodiment, a phase shift control method that is a drive method capable of reducing switching loss is used as a control method of the input switching circuit 10. In the phase shift control method, among the four switch elements 11a to 14a constituting the full bridge type input switching circuit 10, the switch element 11a on the upper side of the first leg and the switch element 14a on the lower side of the second leg. Is controlled in accordance with the output voltage of the DC-DC converter 100. Similarly, the on / off phase difference between the switch element 12a below the first leg and the switch element 13a above the second leg is also controlled according to the output voltage of the DC-DC converter 100. Thereby, the period during which the switch element 11a and the switch element 14a are simultaneously turned on and the period during which the switch element 12a and the switch element 13a are simultaneously turned on are adjusted according to the output voltage. Here, the power transmitted from the input switching circuit 10 (primary side of the transformer 20) to the output switching circuit 30 (secondary side of the transformer 20) is a period during which the switch element 11a and the switch element 14a are simultaneously turned on, The switching element 12a and the switching element 13a are determined by a period during which the switching element 12a is turned on at the same time. Therefore, by controlling the phase difference as described above, the output voltage of the DC-DC converter 100 can be stabilized at a desired value. In the following description, it is assumed that the period in which the switch element 11a and the switch element 14a are simultaneously turned on and the period in which the switch element 12a and the switch element 13a are simultaneously turned on have the same length. Further, the ratio of the lengths of these periods in one cycle may be referred to as a duty ratio.
（トランス２０） 
　トランス２０は、入力スイッチング回路１０により生成された交流電力に対して電圧変換を行い、電圧変換後の交流電力を出力スイッチング回路３０に出力する役割を有する。トランス２０は、入力スイッチング回路１０に接続されている一次巻線Ｎ１と、出力スイッチング回路３０に接続されている二次巻線Ｎ２とを備える。なお、トランス２０は、出力スイッチング回路３０と組み合わせて全波整流回路を実現するためにセンタータップ構成を有しており、二次巻線Ｎ２が中間で２つの二次巻線Ｎ２ａ、Ｎ２ｂに分割されている。一次巻線Ｎ１と二次巻線Ｎ２ａ、Ｎ２ｂとの巻数比（Ｎ１／Ｎ２ａまたはＮ１／Ｎ２ｂ）は、正極入力端子１と負極入力端子２の間に印加される入力電圧Ｖｉｎの電圧範囲、および正極出力端子３と負極出力端子４の間に供給すべき出力電圧Ｖｏｕｔの電圧範囲に応じて設定される。 (Transformer 20)
The transformer 20 has a role of performing voltage conversion on the AC power generated by the input switching circuit 10 and outputting the AC power after voltage conversion to the output switching circuit 30. The transformer 20 includes a primary winding N1 connected to the input switching circuit 10 and a secondary winding N2 connected to the output switching circuit 30. The transformer 20 has a center tap configuration in order to realize a full-wave rectifier circuit in combination with the output switching circuit 30, and the secondary winding N2 is divided into two secondary windings N2a and N2b in the middle. Has been. The turn ratio (N1 / N2a or N1 / N2b) between the primary winding N1 and the secondary windings N2a and N2b is a voltage range of the input voltage Vin applied between the positive input terminal 1 and the negative input terminal 2, and It is set according to the voltage range of the output voltage Vout to be supplied between the positive electrode output terminal 3 and the negative electrode output terminal 4.
　トランス２０は、一次巻線Ｎ１と直列に所定の漏れインダクタンスを有しており、この漏れインダクタンスが共振用のリアクトル成分Ｌ１として作用する。このリアクトル成分Ｌ１と、入力スイッチング回路１０においてスイッチ素子１１ａ～１４ａにそれぞれ並列接続されているコンデンサ１１ｃ～１４ｃの容量成分とにより、入力スイッチング回路１０において発生するスイッチング損失を低減するための共振回路が形成される。なお、トランス２０における漏れインダクタンスの値が小さい場合、一次巻線Ｎ１と直列に別のリアクトル素子によるインダクタを接続することで、リアクトル成分Ｌ１の値を大きくしても良い。すなわち、入力スイッチング回路１０とトランス２０の間に設けられたリアクトル成分Ｌ１は、トランス２０の漏れインダクタンスと、入力スイッチング回路１０とトランス２０の間に接続されたリアクトル素子と、のいずれか少なくとも一方を用いて構成される。 The transformer 20 has a predetermined leakage inductance in series with the primary winding N1, and this leakage inductance acts as a reactor component L1 for resonance. A resonance circuit for reducing the switching loss generated in the input switching circuit 10 by the reactor component L1 and the capacitance components of the capacitors 11c to 14c connected in parallel to the switching elements 11a to 14a in the input switching circuit 10, respectively. It is formed. When the value of the leakage inductance in the transformer 20 is small, the value of the reactor component L1 may be increased by connecting an inductor by another reactor element in series with the primary winding N1. That is, the reactor component L1 provided between the input switching circuit 10 and the transformer 20 has at least one of the leakage inductance of the transformer 20 and the reactor element connected between the input switching circuit 10 and the transformer 20. Constructed using.
　一次巻線Ｎ１の一端は、入力スイッチング回路１０における第１レッグの中点である接続点Ａにリアクトル成分Ｌ１を介して接続されている。また、一次巻線Ｎ１の他端は、入力スイッチング回路１０における第２レッグの中点である接続点Ｂに接続されている。二次巻線Ｎ２ａと二次巻線Ｎ２ｂとの接続点である中性点Ｔは、二次巻線Ｎ２の両端と共に出力スイッチング回路３０に接続されている。 One end of the primary winding N1 is connected to a connection point A, which is the midpoint of the first leg in the input switching circuit 10, via a reactor component L1. The other end of the primary winding N <b> 1 is connected to a connection point B that is a midpoint of the second leg in the input switching circuit 10. A neutral point T, which is a connection point between the secondary winding N2a and the secondary winding N2b, is connected to the output switching circuit 30 together with both ends of the secondary winding N2.
（出力スイッチング回路３０）
　出力スイッチング回路３０は、トランス２０の一次巻線Ｎ１に流れる交流電力に応じて二次巻線Ｎ２ａおよびＮ２ｂに現れる交流電力を平滑および整流することで直流電力に変換し、正極出力端子３および負極出力端子４を介して低圧バッテリＶ２に出力する役割を有する。正極出力端子３と負極出力端子４の間には、低圧バッテリＶ２と並列に電圧検出器４１が接続されている。電圧検出器４１は、出力スイッチング回路３０から出力される直流電力の電圧を検出し、その検出値をＤＣ－ＤＣコンバータ１００の出力電圧Ｖｏｕｔとして制御回路５０に出力する。 (Output switching circuit 30)
The output switching circuit 30 converts the AC power appearing in the secondary windings N2a and N2b into DC power by smoothing and rectifying the AC power that flows in the primary winding N1 of the transformer 20 to the positive output terminal 3 and the negative electrode It has a role of outputting to the low voltage battery V2 via the output terminal 4. A voltage detector 41 is connected between the positive electrode output terminal 3 and the negative electrode output terminal 4 in parallel with the low voltage battery V2. The voltage detector 41 detects the voltage of the DC power output from the output switching circuit 30 and outputs the detected value to the control circuit 50 as the output voltage Vout of the DC-DC converter 100.
　出力スイッチング回路３０は、トランス２０と整流接続点Ｓの間に２つのスイッチ素子３１ａ、３２ａが接続された構成を有する。スイッチ素子３１ａは、トランス２０の二次巻線Ｎ２ｂの一端と整流接続点Ｓの間に接続されており、スイッチ素子３２ａは、トランス２０の二次巻線Ｎ２ａの一端と整流接続点Ｓの間に接続されている。スイッチ素子３１ａ、３２ａには、スナバ回路３３、３４がそれぞれ並列接続されている。なお、スイッチ素子３１ａ、３２ａは、入力スイッチング回路１０におけるスイッチ素子１１ａ～１４ａと同様に、スイッチング動作が可能な任意の素子を用いて構成することができ、例えばＦＥＴ（電界効果トランジスタ）等が好適である。 The output switching circuit 30 has a configuration in which two switch elements 31a and 32a are connected between the transformer 20 and the rectifying connection point S. The switch element 31a is connected between one end of the secondary winding N2b of the transformer 20 and the rectification connection point S. The switch element 32a is connected between one end of the secondary winding N2a of the transformer 20 and the rectification connection point S. It is connected to the. Snubber circuits 33 and 34 are connected in parallel to the switch elements 31a and 32a, respectively. The switch elements 31a and 32a can be configured by using any element capable of switching operation like the switch elements 11a to 14a in the input switching circuit 10, for example, an FET (field effect transistor) is preferable. It is.
　スイッチ素子３１ａ、３２ａには、フライホイール用のダイオード３１ｂ、３２ｂおよびコンデンサ３１ｃ、３２ｃがそれぞれ並列接続されている。これらのダイオード３１ｂ、３２ｂおよびコンデンサ３１ｃ、３２ｃは、スイッチ素子３１ａ、３２ａとは別素子で構成しても良いし、あるいはスイッチ素子３１ａ、３２ａの寄生成分であっても良い。また、これらを併用しても良い。 The flywheel diodes 31b and 32b and capacitors 31c and 32c are connected in parallel to the switch elements 31a and 32a, respectively. These diodes 31b and 32b and capacitors 31c and 32c may be configured as separate elements from the switch elements 31a and 32a, or may be parasitic components of the switch elements 31a and 32a. These may be used in combination.
　出力スイッチング回路３０の出力側には、平滑コイルＬ２および平滑コンデンサＣ２が接続されている。平滑コイルＬ２は、中性点Ｔと正極出力端子３の間に接続されており、平滑コンデンサＣ２は、正極出力端子３と負極出力端子４の間に接続されている。 A smoothing coil L2 and a smoothing capacitor C2 are connected to the output side of the output switching circuit 30. The smoothing coil L2 is connected between the neutral point T and the positive electrode output terminal 3, and the smoothing capacitor C2 is connected between the positive electrode output terminal 3 and the negative electrode output terminal 4.
　上記のような回路構成の出力スイッチング回路３０において、スイッチ素子３１ａ、３２ａは、トランス２０の二次巻線Ｎ２ｂ、Ｎ２ａから出力される交流電力をそれぞれ整流して直流電力に変換する整流回路を構成する。また、平滑コイルＬ２と平滑コンデンサＣ２は、中性点Ｔに発生する整流出力を平滑する平滑回路を構成する。 In the output switching circuit 30 having the circuit configuration as described above, the switch elements 31a and 32a constitute a rectifier circuit that rectifies and converts the AC power output from the secondary windings N2b and N2a of the transformer 20 into DC power, respectively. To do. The smoothing coil L2 and the smoothing capacitor C2 constitute a smoothing circuit that smoothes the rectified output generated at the neutral point T.
（制御回路５０）
　制御回路５０は、ＤＣ－ＤＣコンバータ１００の出力電圧Ｖｏｕｔが予め定められた電圧目標値となるように、入力スイッチング回路１０のスイッチ素子１１ａ～１４ａの動作を制御する回路である。制御回路５０は、出力電圧Ｖｏｕｔに基づいて、入力スイッチング回路１０のスイッチ素子１１ａ～１４ａをそれぞれ制御するための出力信号５１～５４を生成する。制御回路５０が生成した出力信号５１～５４は、制御回路５０からゲートドライバ６０に出力され、ゲートドライバ６０において駆動信号７１～７４にそれぞれ変換される。駆動信号７１～７４は、入力スイッチング回路１０においてスイッチ素子１１ａ～１４ａがそれぞれ有する各ゲート端子に入力され、スイッチ素子１１ａ～１４ａをそれぞれ駆動させる。これにより、入力スイッチング回路１０の動作が制御回路５０によって制御される。 (Control circuit 50)
The control circuit 50 is a circuit that controls the operation of the switch elements 11a to 14a of the input switching circuit 10 so that the output voltage Vout of the DC-DC converter 100 becomes a predetermined voltage target value. The control circuit 50 generates output signals 51 to 54 for controlling the switch elements 11a to 14a of the input switching circuit 10 based on the output voltage Vout. Output signals 51 to 54 generated by the control circuit 50 are output from the control circuit 50 to the gate driver 60 and converted into drive signals 71 to 74 by the gate driver 60, respectively. The drive signals 71 to 74 are input to the respective gate terminals of the switch elements 11a to 14a in the input switching circuit 10 to drive the switch elements 11a to 14a, respectively. Thereby, the operation of the input switching circuit 10 is controlled by the control circuit 50.
　また、制御回路５０は、出力電圧Ｖｏｕｔに基づいて、出力スイッチング回路３０のスイッチ素子３１ａ、３２ａをそれぞれ制御するための出力信号５５、５６を生成する。制御回路５０が生成した出力信号５５、５６は、制御回路５０からゲートドライバ６１に出力され、ゲートドライバ６１において駆動信号７５、７６にそれぞれ変換される。駆動信号７５、７６は、出力スイッチング回路３０においてスイッチ素子３１ａ、３２ａがそれぞれ有する各ゲート端子に入力され、スイッチ素子３１ａ、３２ａをそれぞれ駆動させる。これにより、出力スイッチング回路３０の動作が制御回路５０によって制御される。 Further, the control circuit 50 generates output signals 55 and 56 for controlling the switch elements 31a and 32a of the output switching circuit 30 based on the output voltage Vout. Output signals 55 and 56 generated by the control circuit 50 are output from the control circuit 50 to the gate driver 61 and converted into drive signals 75 and 76 by the gate driver 61, respectively. The drive signals 75 and 76 are input to the respective gate terminals of the switch elements 31a and 32a in the output switching circuit 30, and drive the switch elements 31a and 32a, respectively. Thereby, the operation of the output switching circuit 30 is controlled by the control circuit 50.
（動作状態）
　ＤＣ－ＤＣコンバータ１００の動作状態について、図３～図９を用いて以下に説明する。図３は、本発明の第１の実施形態に係るＤＣ－ＤＣコンバータ１００の動作時における各部分の電圧および電流の時間変化の様子を表したタイミングチャートを示す図であり、図４～図９は、本発明の第１の実施形態に係るＤＣ－ＤＣコンバータ１００の動作時における各スイッチ素子の切替状態および電流の向きを示す図である。なお、図４～図９は、図３に示したタイミングチャートの期間＃１～＃６にそれぞれ対応している。すなわち、図４～図９は、図３の期間＃１～＃６でのＤＣ－ＤＣコンバータ１００における各スイッチ素子１１ａ～１４ａ、３１ａ、３２ａのオンオフ状態と、入力スイッチング回路１０、トランス２０および出力スイッチング回路３０を流れる電流の向きとをそれぞれ示している。本実施形態のＤＣ－ＤＣコンバータ１００では、制御回路５０の制御により、入力スイッチング回路１０のスイッチ素子１１ａ～１４ａおよび出力スイッチング回路３０のスイッチ素子３１ａ、３２ａのオンオフ状態をそれぞれ切り替えることで、期間＃１～＃６の遷移を制御可能である。 (Operating state)
The operation state of the DC-DC converter 100 will be described below with reference to FIGS. FIG. 3 is a timing chart showing how the voltage and current of each part change with time during the operation of the DC-DC converter 100 according to the first embodiment of the present invention. These are figures which show the switching state of each switch element at the time of operation | movement of the DC-DC converter 100 which concerns on the 1st Embodiment of this invention, and direction of an electric current. 4 to 9 correspond to periods # 1 to # 6 of the timing chart shown in FIG. 3, respectively. That is, FIGS. 4 to 9 show the on / off states of the switch elements 11a to 14a, 31a and 32a in the DC-DC converter 100 in the periods # 1 to # 6 of FIG. 3, the input switching circuit 10, the transformer 20 and the output. The direction of the current flowing through the switching circuit 30 is shown. In the DC-DC converter 100 of the present embodiment, the control circuit 50 controls the switching elements 11a to 14a of the input switching circuit 10 and the switching elements 31a and 32a of the output switching circuit 30 to switch the period # The transition from 1 to # 6 can be controlled.
　図３において、電圧波形Vg_11a～Vg_14aは、入力スイッチング回路１０におけるスイッチ素子１１ａ～１４ａのゲート電圧の時間変化をそれぞれ表し、電圧波形Vg_31aは、出力スイッチング回路３０におけるスイッチ素子３１ａのゲート電圧の時間変化を表している。また、電流波形I_L1は、リアクトル成分Ｌ１および一次巻線Ｎ１に流れる電流の時間変化を表し、電流波形I_N2a、I_N2bは、トランス２０の二次巻線Ｎ２ａ、Ｎ２ｂにそれぞれ流れる電流の時間変化を表している。なお、電流波形I_L1では、図２の接続点Ａから接続点Ｂに向かう電流の向きを正としている。また、電流波形I_N2a、I_N2bでは、図２の整流接続点Ｓからスイッチ素子３２ａ、３１ａおよび二次巻線Ｎ２ａ、Ｎ２ｂを介して中性点Ｔに向かう電流の向きをそれぞれ正としている。 In FIG. 3, voltage waveforms Vg_11a to Vg_14a represent temporal changes in the gate voltage of the switch elements 11a to 14a in the input switching circuit 10, respectively, and voltage waveform Vg_31a represents a temporal change in the gate voltage of the switch element 31a in the output switching circuit 30. Represents. Further, the current waveform I_L1 represents the time change of the current flowing through the reactor component L1 and the primary winding N1, and the current waveforms I_N2a and I_N2b represent the time change of the current flowing through the secondary windings N2a and N2b of the transformer 20, respectively. ing. In the current waveform I_L1, the direction of the current from the connection point A to the connection point B in FIG. 2 is positive. Further, in the current waveforms I_N2a and I_N2b, the direction of the current from the rectifying connection point S in FIG. 2 toward the neutral point T via the switch elements 32a and 31a and the secondary windings N2a and N2b is positive.
　図３では、リアクトル成分Ｌ１の電流波形I_L1が負であるときの各電圧および各電流の時間変化の様子を表している。以下では、このときの期間＃１～＃６でのＤＣ－ＤＣコンバータ１００の動作状態について、図４～図９をそれぞれ参照して説明する。 FIG. 3 shows how each voltage and each current changes with time when the current waveform I_L1 of the reactor component L1 is negative. Hereinafter, the operation state of the DC-DC converter 100 in the periods # 1 to # 6 will be described with reference to FIGS. 4 to 9, respectively.
（期間＃１）
　図３の期間♯１では、図４に示すように、入力スイッチング回路１０においてスイッチ素子１１ａおよび１４ａがオン状態にされ、スイッチ素子１２ａおよび１３ａがオフ状態にされる。また、このとき出力スイッチング回路３０のスイッチ素子３１ａおよび３２ａがオン状態にされる。これにより、高圧バッテリＶ１からリアクトル成分Ｌ１およびトランス２０の一次巻線Ｎ１に対して直流電圧が印加され、図４の矢印に示す方向に電流が流れる。このとき図３に示すように、リアクトル成分Ｌ１の電流波形I_L1が正方向に増加する。 (Period # 1)
In the period # 1 of FIG. 3, as shown in FIG. 4, in the input switching circuit 10, the switch elements 11a and 14a are turned on, and the switch elements 12a and 13a are turned off. At this time, the switch elements 31a and 32a of the output switching circuit 30 are turned on. As a result, a DC voltage is applied from high voltage battery V1 to reactor component L1 and primary winding N1 of transformer 20, and a current flows in the direction indicated by the arrow in FIG. At this time, as shown in FIG. 3, the current waveform I_L1 of the reactor component L1 increases in the positive direction.
　トランス２０の一次巻線Ｎ１に流れる電流に応じて、二次巻線Ｎ２ａおよびＮ２ｂにはそれぞれの巻数比に応じた電圧が誘起される。これにより、トランス２０の一次側から二次側へ電力が伝達される。このとき出力スイッチング回路３０では、スイッチ素子３１ａ、３２ａがオンである。そのため、トランス２０から平滑コイルＬ２、平滑コンデンサＣ２と並列に接続される負荷（図示せず）、出力スイッチング回路３０のスイッチング素子３１ａの順に電流が流れ、平滑コイルＬ２にエネルギーが蓄積される。 In accordance with the current flowing through the primary winding N1 of the transformer 20, voltages corresponding to the respective turns ratios are induced in the secondary windings N2a and N2b. Thereby, electric power is transmitted from the primary side of the transformer 20 to the secondary side. At this time, in the output switching circuit 30, the switch elements 31a and 32a are on. Therefore, current flows from the transformer 20 in the order of the load (not shown) connected in parallel with the smoothing coil L2 and the smoothing capacitor C2, and the switching element 31a of the output switching circuit 30, and energy is accumulated in the smoothing coil L2.
　なお、本実施形態のＤＣ－ＤＣコンバータ１００では、期間＃１の開始時点においては、二次巻線Ｎ２ｂに流れる電流の向きは図４の矢印に示すように正方向となっており、二次巻線Ｎ２ａに流れる電流が一定値以上になると、二次巻線Ｎ２ｂの電流極性が反転するようにすることが好ましい。この点は、後に期間＃２の説明で詳しく述べる。 In the DC-DC converter 100 of the present embodiment, at the start of the period # 1, the direction of the current flowing through the secondary winding N2b is positive as shown by the arrow in FIG. It is preferable that the current polarity of the secondary winding N2b is reversed when the current flowing through the winding N2a exceeds a certain value. This point will be described in detail later in the description of the period # 2.
（期間＃２：循環期間）
　図３の期間＃２の開始時点では、図５に示すように、入力スイッチング回路１０においてスイッチ素子１１ａがオン状態に維持され、スイッチ素子１２ａおよび１３ａがオフ状態に維持される一方で、スイッチ素子１４ａがオン状態からオフ状態へ遷移する。これにより、高圧バッテリＶ１からトランス２０の一次巻線Ｎ１への直流電圧の供給が停止する。しかし、リアクトル成分Ｌ１は電流を流し続けようとするため、スイッチ素子１３ａに並列接続されたダイオード１３ｂが導通し、ダイオード１３ｂを介して電流が流れる。その結果、図５の矢印に示すように、高圧バッテリＶ１を介さずに、入力スイッチング回路１０、リアクトル成分Ｌ１およびトランス２０を循環する循環電流が流れる。こうしてダイオード１３ｂが導通した後に、スイッチ素子１３ａがオフ状態からオン状態に切り替えられることで、ゼロボルトスイッチングが実現される。 (Period # 2: Circulation period)
At the start of period # 2 in FIG. 3, as shown in FIG. 5, in the input switching circuit 10, the switch element 11a is maintained in the on state, and the switch elements 12a and 13a are maintained in the off state, while the switch element 14a transitions from the on state to the off state. Thereby, the supply of the DC voltage from the high voltage battery V1 to the primary winding N1 of the transformer 20 is stopped. However, since the reactor component L1 tries to keep current flowing, the diode 13b connected in parallel to the switch element 13a conducts, and current flows through the diode 13b. As a result, as shown by the arrow in FIG. 5, a circulating current that circulates through the input switching circuit 10, the reactor component L1, and the transformer 20 flows without passing through the high-voltage battery V1. Thus, after the diode 13b is turned on, the switching element 13a is switched from the off state to the on state, thereby realizing zero volt switching.
　また、期間＃２では期間＃１と同様に、出力スイッチング回路３０のスイッチ素子３１ａおよび３２ａがオン状態に維持される。そのため、図５の矢印に示すように、トランス２０から平滑コイルＬ２、平滑コンデンサＣ２と並列に接続される負荷（図示せず）、出力スイッチング回路３０のスイッチング素子３２ａの順に電流が流れ、平滑コイルＬ２にエネルギーが蓄積される。このときスイッチ素子３１ａを介して二次巻線Ｎ２ｂに流れる電流の向きは、負荷に流れる電流の大きさに応じて変化する。具体的には、負過電流が大きい場合は、二次巻線Ｎ２ｂに流れる電流の向きは正方向、すなわち図５の矢印に示す方向とは逆方向となるが、負過電流が小さい場合は、トランス２０の一次側から二次側へ電力が伝達される際に電流極性が反転し、二次巻線Ｎ２ｂに流れる電流の向きは負方向、すなわち図５の矢印に示す方向となる。 In the period # 2, similarly to the period # 1, the switch elements 31a and 32a of the output switching circuit 30 are maintained in the ON state. Therefore, as indicated by an arrow in FIG. 5, a current flows in order from the transformer 20 to the smoothing coil L2, a load (not shown) connected in parallel with the smoothing capacitor C2, and the switching element 32a of the output switching circuit 30. Energy is stored in L2. At this time, the direction of the current flowing through the secondary winding N2b via the switch element 31a changes according to the magnitude of the current flowing through the load. Specifically, when the negative overcurrent is large, the direction of the current flowing through the secondary winding N2b is the positive direction, that is, the direction opposite to the direction indicated by the arrow in FIG. When the power is transmitted from the primary side to the secondary side of the transformer 20, the current polarity is reversed, and the direction of the current flowing through the secondary winding N2b is the negative direction, that is, the direction indicated by the arrow in FIG.
　本実施形態のＤＣ－ＤＣコンバータ１００では、前述のように期間＃１の途中で二次巻線Ｎ２ｂに流れる電流の向きが反対となり、期間＃２でもこの状態が継続されるようにすることが好ましい。すなわち、期間＃２において二次巻線Ｎ２ｂおよびスイッチ素子３１ａに流れる電流の向きは、出力スイッチング回路３０の整流動作に応じた電流の向きに対して反対となることが望ましい。このようにすることで、続く期間＃３において、後述のようにスナバ回路３３に電流が流れるようにして共振電圧を発生させ、入力スイッチング回路１０における循環電流を増大させることができる。このとき図３に示すように、二次巻線Ｎ２ａの電流波形I_N2aは減少し、二次巻線Ｎ２ｂの電流波形I_N2bは負方向に増大する。 In the DC-DC converter 100 of the present embodiment, as described above, the direction of the current flowing through the secondary winding N2b is reversed in the middle of the period # 1, and this state is continued even in the period # 2. preferable. That is, it is desirable that the direction of the current flowing through the secondary winding N2b and the switch element 31a in the period # 2 is opposite to the direction of the current according to the rectifying operation of the output switching circuit 30. In this way, in the subsequent period # 3, a resonance voltage is generated so that a current flows through the snubber circuit 33 as will be described later, and the circulating current in the input switching circuit 10 can be increased. At this time, as shown in FIG. 3, the current waveform I_N2a of the secondary winding N2a decreases, and the current waveform I_N2b of the secondary winding N2b increases in the negative direction.
（期間＃３：循環期間）
　図３の期間＃３では、図６に示すように、入力スイッチング回路１０においてスイッチ素子１１ａおよび１３ａがオン状態であり、スイッチ素子１２ａおよび１４ａがオフ状態である。また、このとき出力スイッチング回路３０において、スイッチ素子３２ａはオン状態に維持され、スイッチ素子３１ａがオンからオフ状態に遷移される。すると、スイッチ素子３１ａがオフ状態に遷移することで、スイッチ素子３１ａに流れる電流が遮断され、スイッチ素子３１ａと並列に接続されたスナバ回路３３へ電流が流れる。このとき、トランス２０の二次巻線Ｎ２ｂとスナバ回路３３により共振電圧が発生する。 (Period # 3: Circulation period)
In period # 3 in FIG. 3, as shown in FIG. 6, in the input switching circuit 10, the switch elements 11a and 13a are in the on state, and the switch elements 12a and 14a are in the off state. At this time, in the output switching circuit 30, the switch element 32a is maintained in the on state, and the switch element 31a is changed from the on state to the off state. Then, when the switch element 31a transitions to the off state, the current flowing through the switch element 31a is cut off, and the current flows through the snubber circuit 33 connected in parallel with the switch element 31a. At this time, a resonance voltage is generated by the secondary winding N2b of the transformer 20 and the snubber circuit 33.
　また、期間＃３では期間＃２と同様に、入力スイッチング回路１０においてスイッチ素子１１ａおよび１３ａがオン状態であり、スイッチ素子１２ａおよび１４ａがオフ状態であるため、図６の矢印に示すように、高圧バッテリＶ１を介さずに、入力スイッチング回路１０、リアクトル成分Ｌ１およびトランス２０を循環する循環電流が流れている。トランス２０の二次巻線Ｎ２ｂとスナバ回路３３により発生した共振電圧は、出力スイッチング回路３０からトランス２０を介して入力スイッチング回路１０に印加される。この電圧により、入力スイッチング回路１０における循環電流が増大する。 In the period # 3, as in the period # 2, in the input switching circuit 10, the switch elements 11a and 13a are in the on state and the switch elements 12a and 14a are in the off state. A circulating current that circulates through the input switching circuit 10, the reactor component L1, and the transformer 20 flows without passing through the high-voltage battery V1. The resonance voltage generated by the secondary winding N2b of the transformer 20 and the snubber circuit 33 is applied from the output switching circuit 30 to the input switching circuit 10 via the transformer 20. This voltage increases the circulating current in the input switching circuit 10.
（期間＃４：デッドタイム期間）
　図３の期間＃４では、図７に示すように、入力スイッチング回路１０においてスイッチ素子１３ａがオン状態に維持され、スイッチ素子１２ａおよび１４ａがオフ状態に維持される一方で、スイッチ素子１１ａがオン状態からオフ状態へ遷移する。これにより、第１レッグでは一対のスイッチ素子１１ａおよびスイッチ素子１２ａが両方ともオフ状態となる。そのため、本期間はデッドタイム期間と呼ばれる。スイッチ素子１１ａがオフ状態に遷移すると、リアクトル成分Ｌ１は電流を流し続けようとするため、図７の矢印に示すように、スイッチ素子１１ａに並列接続されたコンデンサ１１ｃは充電され、スイッチ素子１２ａに並列接続されたコンデンサ１２ｃは放電される。このとき、リアクトル成分Ｌ１に流れる循環電流が大きいほど、コンデンサ１２ｃの電荷が多く放電されるため、コンデンサ１２ｃの両端電圧の減少量を増大させることが可能となる。理想的には、期間＃４の間にコンデンサ１２ｃの両端電圧をなるべくゼロに近づけることが望ましい。 (Period # 4: Dead time period)
In period # 4 in FIG. 3, as shown in FIG. 7, in the input switching circuit 10, the switch element 13a is maintained in the on state, and the switch elements 12a and 14a are maintained in the off state, while the switch element 11a is in the on state. Transition from state to off state. Thereby, in a 1st leg, both a pair of switch element 11a and switch element 12a will be in an OFF state. Therefore, this period is called a dead time period. When the switch element 11a transitions to the OFF state, the reactor component L1 keeps flowing current, so that the capacitor 11c connected in parallel to the switch element 11a is charged and the switch element 12a is charged as shown by the arrow in FIG. The capacitor 12c connected in parallel is discharged. At this time, the larger the circulating current flowing through the reactor component L1, the more electric charge is discharged from the capacitor 12c. Therefore, it is possible to increase the amount of decrease in the voltage across the capacitor 12c. Ideally, it is desirable to make the voltage across the capacitor 12c as close to zero as possible during the period # 4.
　また、期間＃４では期間＃３と同様に、出力スイッチング回路３０のスイッチ素子３２ａはオン状態に維持され、スイッチ素子３１ａはオフ状態に維持される。このとき、図７に示すように前述の共振電圧に応じた所定のタイミングで、トランス２０の二次巻線Ｎ２ｂとスナバ回路３３に流れる電流の極性が反転する。なお、期間＃４ではなく、後述する期間＃５や期間＃６において電流の極性が反転するようにしてもよい。 In the period # 4, similarly to the period # 3, the switch element 32a of the output switching circuit 30 is maintained in the on state, and the switch element 31a is maintained in the off state. At this time, as shown in FIG. 7, the polarity of the current flowing through the secondary winding N2b of the transformer 20 and the snubber circuit 33 is reversed at a predetermined timing according to the above-described resonance voltage. Note that the polarity of the current may be reversed not in the period # 4 but in a period # 5 or a period # 6 described later.
（期間＃５）
　図３の期間＃５では、図８に示すように、スイッチ素子１３ａがオン状態に維持され、スイッチ素子１１ａおよび１４ａがオフ状態に維持される一方で、スイッチ素子１２ａがオフ状態からオン状態へ遷移する。これにより、高圧バッテリＶ１からリアクトル成分Ｌ１に対して、電流波形I_L1の負方向、すなわち図２の接続点Ｂから接続点Ａに向かう方向に直流電圧が印加され、リアクトル成分Ｌ１において図８の矢印に示す方向に流れている電流が減少する。なお、期間＃４から期間＃５への遷移時にスイッチ素子１２ａをターンオンする際には、コンデンサ１２ｃの両端電圧に応じたスイッチング損失がスイッチ素子１２ａにおいて発生する。しかしながら、前述のように期間＃４でコンデンサ１２ｃの両端電圧を減少させているため、コンデンサ１２ｃの両端電圧を略ゼロとしてゼロボルトスイッチングが可能となる。 (Period # 5)
In the period # 5 of FIG. 3, as shown in FIG. 8, the switch element 13a is maintained in the on state and the switch elements 11a and 14a are maintained in the off state, while the switch element 12a is changed from the off state to the on state. Transition. Thereby, a DC voltage is applied from the high voltage battery V1 to the reactor component L1 in the negative direction of the current waveform I_L1, that is, in the direction from the connection point B to the connection point A in FIG. The current flowing in the direction shown in FIG. When the switching element 12a is turned on at the transition from the period # 4 to the period # 5, a switching loss corresponding to the voltage across the capacitor 12c occurs in the switching element 12a. However, as described above, since the voltage across the capacitor 12c is decreased in the period # 4, the voltage across the capacitor 12c is substantially zero, and zero-volt switching is possible.
　また、期間＃５では期間＃３、＃４と同様に、出力スイッチング回路３０のスイッチ素子３２ａはオン状態に維持され、スイッチ素子３１ａはオフ状態に維持されている。そのため、期間＃４と同様に、出力スイッチング回路３０では図８の矢印に示す方向に電流が流れる。 In the period # 5, similarly to the periods # 3 and # 4, the switch element 32a of the output switching circuit 30 is maintained in the on state, and the switch element 31a is maintained in the off state. Therefore, as in the period # 4, a current flows in the output switching circuit 30 in the direction indicated by the arrow in FIG.
（期間＃６）
　図３の期間＃６では、図９に示すように、スイッチ素子１２および１３ａがオン状態に維持され、スイッチ素子１１ａおよび１４ａがオフ状態に維持される。これにより、前述の期間＃５において説明したように、高圧バッテリＶ１からリアクトル成分Ｌ１に対して逆向きの直流電圧が印加される。その結果、リアクトル成分Ｌ１に流れる電流が図８の状態からさらに減少し続け、電流が０未満になると、図９の矢印に示すように電流極性が反転する。 (Period # 6)
In period # 6 of FIG. 3, as shown in FIG. 9, switch elements 12 and 13a are maintained in the on state, and switch elements 11a and 14a are maintained in the off state. As a result, as described in the above-described period # 5, a reverse DC voltage is applied from the high voltage battery V1 to the reactor component L1. As a result, the current flowing through the reactor component L1 continues to decrease further from the state of FIG. 8, and when the current becomes less than 0, the current polarity is reversed as shown by the arrow in FIG.
　なお、期間＃６以降でのＤＣ－ＤＣコンバータ１００の動作は、前述の期間＃１から＃６での動作を反転した動作となる。すなわち、入力スイッチング回路１０および出力スイッチング回路３０における各スイッチ素子の動作と、これに応じて入力スイッチング回路１０および出力スイッチング回路３０を流れる電流の向きとは、上記で説明した期間＃１から＃６のものに対してそれぞれ反対となる。具体的には、入力スイッチング回路１０においてスイッチ素子１１ａおよび１４ａがオフ状態であり、スイッチ素子１３ａがオン状態であるときに、スイッチ素子１２ａをオン状態からオフ状態へ遷移させて、期間＃２、＃３と同様の循環期間を設けることができる。この循環期間では、高圧バッテリＶ１を介さずに入力スイッチング回路１０、リアクトル成分Ｌ１およびトランス２０を循環する循環電流が流れる。これにより、スイッチ素子１１ａに並列接続されたダイオード１１ｂを導通させ、スイッチ素子１１ａのゼロボルトスイッチングが可能となる。 The operation of the DC-DC converter 100 after the period # 6 is an operation obtained by inverting the operation during the above-described periods # 1 to # 6. That is, the operation of each switching element in the input switching circuit 10 and the output switching circuit 30 and the direction of the current flowing through the input switching circuit 10 and the output switching circuit 30 in accordance with this operation are the periods # 1 to # 6 described above. The opposite is true for each. Specifically, in the input switching circuit 10, when the switch elements 11a and 14a are in the off state and the switch element 13a is in the on state, the switch element 12a is changed from the on state to the off state, and the period # 2, A circulation period similar to # 3 can be provided. In this circulation period, a circulation current that circulates through the input switching circuit 10, the reactor component L1, and the transformer 20 flows without passing through the high-voltage battery V1. Thereby, the diode 11b connected in parallel with the switch element 11a is made conductive, and the zero volt switching of the switch element 11a becomes possible.
　また、トランス２０の二次巻線Ｎ２ａおよびスイッチ素子３２ａと並列に接続されたスナバ回路３４では、期間＃３における二次巻線Ｎ２ｂおよびスナバ回路３３と同様に、共振電圧を発生して入力スイッチング回路１０に流れる循環電流を増大させることができる。これにより、その後に入力スイッチング回路１０の第２レッグにおける一対のスイッチ素子１３ａおよびスイッチ素子１４ａが両方ともオフ状態となるデッドタイム期間においても、期間＃４と同様に、スイッチ素子１４ａと並列に接続されたコンデンサ１４ｃの両端電圧の減少量を増大させることが可能となる。その結果、スイッチ素子１４ａについてもゼロボルトスイッチングが可能となる。 Further, in the snubber circuit 34 connected in parallel with the secondary winding N2a of the transformer 20 and the switch element 32a, as in the secondary winding N2b and the snubber circuit 33 in the period # 3, a resonance voltage is generated and input switching is performed. The circulating current flowing through the circuit 10 can be increased. As a result, in the dead time period in which both the pair of switch elements 13a and 14a in the second leg of the input switching circuit 10 are subsequently turned off, the switch elements 14a are connected in parallel as in the period # 4. It is possible to increase the amount of decrease in the voltage across the capacitor 14c. As a result, zero volt switching is also possible for the switch element 14a.
　以上説明した本発明の第１の実施形態によれば、以下の作用効果を奏する。 According to the first embodiment of the present invention described above, the following operational effects are obtained.
（１）電力変換装置であるＤＣ－ＤＣコンバータ１００は、入力電源である高圧バッテリＶ１から入力された直流電力を交流電力に変換する入力スイッチング回路１０と、交流電力の電圧変換を行うトランス２０と、トランス２０により電圧変換された交流電力を直流電力に変換して出力する出力スイッチング回路３０と、入力スイッチング回路１０および出力スイッチング回路３０を制御する制御回路５０と、入力スイッチング回路１０とトランス２０の間に設けられたリアクトル成分Ｌ１とを備える。入力スイッチング回路１０は、高圧バッテリＶ１の正負極間に直列接続されて制御回路５０によりそれぞれスイッチング制御される一対のスイッチ素子１１ａと１２ａ、および１３ａと１４ａを有する。出力スイッチング回路３０は、制御回路５０によりスイッチング制御されるスイッチ素子３１ａ、３２ａと、スイッチ素子３１ａ、３２ａと並列に設けられたスナバ回路３３、３４とを有する。制御回路５０は、高圧バッテリＶ１を介さずに入力スイッチング回路１０、リアクトル成分Ｌ１およびトランス２０を循環する循環電流が流れる循環期間＃３において、スナバ回路３３に電流が流れることで循環電流が増大するように、出力スイッチング回路３０を制御する。また、制御回路５０は、循環期間＃３の後に一対のスイッチ素子１１ａと１２ａが両方ともオフであるデッドタイム期間＃４に移行するように、入力スイッチング回路１０を制御する。このようにしたので、ＤＣ－ＤＣコンバータ１００では出力電流の検出を行うことなく、入力スイッチング回路１０のゼロボルトスイッチングを実現してスイッチング損失を低減できる。したがって、サイズやコストの増大を抑えつつ、電力変換装置であるＤＣ－ＤＣコンバータ１００の高効率化を図ることができる。 (1) A DC-DC converter 100 that is a power converter includes an input switching circuit 10 that converts DC power input from a high-voltage battery V1 that is an input power source into AC power, and a transformer 20 that performs voltage conversion of AC power. , An output switching circuit 30 that converts the AC power voltage-converted by the transformer 20 into DC power and outputs it, a control circuit 50 that controls the input switching circuit 10 and the output switching circuit 30, and the input switching circuit 10 and the transformer 20. And a reactor component L1 provided therebetween. The input switching circuit 10 includes a pair of switch elements 11a and 12a, and 13a and 14a that are connected in series between the positive and negative electrodes of the high-voltage battery V1 and controlled to be switched by the control circuit 50, respectively. The output switching circuit 30 includes switch elements 31a and 32a that are controlled by the control circuit 50, and snubber circuits 33 and 34 provided in parallel with the switch elements 31a and 32a. The control circuit 50 increases the circulating current by flowing the current to the snubber circuit 33 in the circulation period # 3 in which the circulating current that circulates through the input switching circuit 10, the reactor component L1, and the transformer 20 without passing through the high-voltage battery V1. Thus, the output switching circuit 30 is controlled. Further, the control circuit 50 controls the input switching circuit 10 so as to shift to the dead time period # 4 in which both the pair of switch elements 11a and 12a are off after the circulation period # 3. Thus, the DC-DC converter 100 can realize zero-volt switching of the input switching circuit 10 without reducing the output loss without detecting the output current. Therefore, it is possible to increase the efficiency of the DC-DC converter 100 that is a power conversion device while suppressing an increase in size and cost.
（２）リアクトル成分Ｌ１は、トランス２０の漏れインダクタンスと、入力スイッチング回路１０とトランス２０の間に接続されたリアクトル素子と、のいずれか少なくとも一方を用いて構成される。このようにしたので、入力スイッチング回路１０やトランス２０の回路特性に応じて最適なインダクタンスを有するリアクトル成分Ｌ１を設けることができる。 (2) The reactor component L1 is configured using at least one of the leakage inductance of the transformer 20 and the reactor element connected between the input switching circuit 10 and the transformer 20. Since it did in this way, the reactor component L1 which has an optimal inductance according to the circuit characteristic of the input switching circuit 10 or the transformer 20 can be provided.
（３）循環期間＃２、＃３においてスイッチ素子３１ａに流れる電流の向きは、出力スイッチング回路３０の整流動作に応じた電流の向きに対して反対であることが好ましい。このようにすれば、循環電流を適切に増大させることができる。 (3) It is preferable that the direction of the current flowing through the switch element 31a in the circulation periods # 2 and # 3 is opposite to the direction of the current according to the rectifying operation of the output switching circuit 30. If it does in this way, circulating current can be increased appropriately.
－第２の実施形態－
　前述の第１の実施形態では、図３に示した期間＃３と＃４において、制御回路５０が出力スイッチング回路３０のスイッチ素子３１ａと入力スイッチング回路１０のスイッチ素子１１ａのオフタイミングをそれぞれ制御することで、トランス２０の二次巻線Ｎ２ｂとスナバ回路３３により共振電圧を発生させる例を説明した。これに対して、以下に説明する本発明の第２の実施形態では、遅延回路を用いてオフタイミングの制御を行う例を説明する。 -Second Embodiment-
In the first embodiment described above, the control circuit 50 controls the off timing of the switch element 31a of the output switching circuit 30 and the switch element 11a of the input switching circuit 10 in the periods # 3 and # 4 shown in FIG. Thus, the example in which the resonance voltage is generated by the secondary winding N2b of the transformer 20 and the snubber circuit 33 has been described. On the other hand, in the second embodiment of the present invention described below, an example in which the off timing is controlled using a delay circuit will be described.
　図１０は、本発明の第２の実施形態に係るＤＣ－ＤＣコンバータ１００ａの基本回路構成を示す図である。図１０に示すように、本実施形態のＤＣ－ＤＣコンバータ１００ａは、第１の実施形態で説明した図２のＤＣ－ＤＣコンバータ１００と比べて、制御回路５０とゲートドライバ６０の間に遅延回路９０がさらに設けられている点が異なっている。 FIG. 10 is a diagram showing a basic circuit configuration of a DC-DC converter 100a according to the second embodiment of the present invention. As shown in FIG. 10, the DC-DC converter 100a of the present embodiment has a delay circuit between the control circuit 50 and the gate driver 60, as compared with the DC-DC converter 100 of FIG. 2 described in the first embodiment. The difference is that 90 is further provided.
（遅延回路９０）
　遅延回路９０は、制御回路５０から出力されて入力スイッチング回路１０におけるスイッチ素子１１ａ～１４ａのスイッチング動作をそれぞれ制御する出力信号５１～５４を遅延させて出力する。図１１は、遅延回路９０の一例を示す図である。図１１に示す遅延回路９０は、抵抗とコンデンサを用いて構成されたＲＣ遅延回路の例である。なお、遅延回路９０は図１１に示したものに限らず、任意の回路構成とすることが可能である。出力信号５１～５４を所望のタイミングだけ遅延させることができれば、どのような回路構成の遅延回路９０であっても同様の効果が得られることはいうまでもない。 (Delay circuit 90)
The delay circuit 90 delays and outputs output signals 51 to 54 that are output from the control circuit 50 and control the switching operations of the switch elements 11a to 14a in the input switching circuit 10, respectively. FIG. 11 is a diagram illustrating an example of the delay circuit 90. A delay circuit 90 shown in FIG. 11 is an example of an RC delay circuit configured using a resistor and a capacitor. Note that the delay circuit 90 is not limited to that shown in FIG. 11, and can have any circuit configuration. It goes without saying that the same effect can be obtained with any delay circuit 90 as long as the output signals 51 to 54 can be delayed by a desired timing.
　本実施形態において、制御回路５０は、入力スイッチング回路１０への出力信号５１～５４と、出力スイッチング回路３０への出力信号５５～５６とを、互いに同期させて出力する。このうち出力信号５１～５４が遅延回路９０によって遅延されることで、第１の実施形態で説明したように、出力スイッチング回路３０のスイッチ素子３１ａに対して入力スイッチング回路１０のスイッチ素子１１ａのオフタイミングを遅らせることが可能となる。その結果、第１の実施形態で説明したのと同様に、トランス２０の二次巻線Ｎ２ｂとスナバ回路３３により共振電圧を発生させ、入力スイッチング回路１０における循環電流を増大させることができる。また同様に、出力スイッチング回路３０のスイッチ素子３２ａに対して入力スイッチング回路１０のスイッチ素子１３ａのオフタイミングを遅らせることが可能となるため、トランス２０の二次巻線Ｎ２ａとスナバ回路３４により共振電圧を発生させ、入力スイッチング回路１０における循環電流を増大させることもできる。 In this embodiment, the control circuit 50 outputs the output signals 51 to 54 to the input switching circuit 10 and the output signals 55 to 56 to the output switching circuit 30 in synchronization with each other. Among these, the output signals 51 to 54 are delayed by the delay circuit 90, so that the switch element 11a of the input switching circuit 10 is turned off with respect to the switch element 31a of the output switching circuit 30 as described in the first embodiment. The timing can be delayed. As a result, as described in the first embodiment, a resonance voltage can be generated by the secondary winding N2b of the transformer 20 and the snubber circuit 33, and the circulating current in the input switching circuit 10 can be increased. Similarly, since the off timing of the switch element 13a of the input switching circuit 10 can be delayed with respect to the switch element 32a of the output switching circuit 30, the resonance voltage is generated by the secondary winding N2a of the transformer 20 and the snubber circuit 34. And the circulating current in the input switching circuit 10 can be increased.
　以上説明した本発明の第２の実施形態によれば、第１の実施形態で説明したのと同様の作用効果を奏する。さらに、電力変換装置であるＤＣ－ＤＣコンバータ１００ａは、制御回路５０と入力スイッチング回路１０の間に設けられた遅延回路９０を備える。制御回路５０は、入力スイッチング回路１０を制御するための出力信号５１～５４と、出力スイッチング回路３０を制御するための出力信号５５～５６とを互いに同期させて出力する。遅延回路９０は、出力信号５１～５４を遅延させ、ゲートドライバ６０を介して入力スイッチング回路１０へ出力する。このようにしたので、制御回路５０において特別な制御を必要とせずに、入力スイッチング回路１０における循環電流を容易に増大させることが可能となる。 According to the second embodiment of the present invention described above, the same operational effects as described in the first embodiment can be obtained. Further, the DC-DC converter 100 a that is a power converter includes a delay circuit 90 provided between the control circuit 50 and the input switching circuit 10. The control circuit 50 outputs output signals 51 to 54 for controlling the input switching circuit 10 and output signals 55 to 56 for controlling the output switching circuit 30 in synchronization with each other. The delay circuit 90 delays the output signals 51 to 54 and outputs them to the input switching circuit 10 via the gate driver 60. Since it did in this way, it becomes possible to increase the circulating current in the input switching circuit 10 easily, without requiring special control in the control circuit 50. FIG.
　なお、以上説明した本発明の各実施形態では、４つのスイッチ素子１１ａ～１４ａにより構成された電圧形フルブリッジ回路である入力スイッチング回路１０と、電流形センタータップ回路であるトランス２０とを組み合わせて構成されたＤＣ－ＤＣコンバータ１００および１００ａを、位相シフト制御方式により制御する制御回路５０の例を用いて本発明を説明したが、本発明はこれに限定されない。入力された第１の直流電力を交流電力に変換する入力スイッチング回路と、交流電力の電圧変換を行うトランスと、トランスにより電圧変換された交流電力を第２の直流電力に変換して出力する出力スイッチング回路とを有する電力変換装置であれば、本発明を適用可能であり、各実施形態で説明したのと同様の作用効果を奏することができる。また、以上説明した各実施形態は、それぞれ単独で適用してもよく、任意に組み合わせてもよい。 In each of the embodiments of the present invention described above, the input switching circuit 10 that is a voltage-type full bridge circuit constituted by four switch elements 11a to 14a and the transformer 20 that is a current-type center tap circuit are combined. Although the present invention has been described using the example of the control circuit 50 that controls the configured DC- DC converters 100 and 100a by the phase shift control method, the present invention is not limited to this. An input switching circuit that converts input first DC power into AC power, a transformer that performs voltage conversion of AC power, and an output that converts AC power voltage-converted by the transformer into second DC power and outputs it If it is a power converter device which has a switching circuit, this invention can be applied and there can exist an effect similar to having demonstrated in each embodiment. Moreover, each embodiment described above may be applied individually or in any combination.
　以上説明した各実施形態や各種変形例はあくまで一例であり、発明の特徴が損なわれない限り、本発明はこれらの内容に限定されるものではない。また、上記では種々の実施形態や変形例を説明したが、本発明はこれらの内容に限定されるものではない。本発明の技術的思想の範囲内で考えられるその他の態様も本発明の範囲内に含まれる。 Each embodiment and various modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. Moreover, although various embodiment and the modification were demonstrated above, this invention is not limited to these content. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.
１…正極入力端子、２…負極入力端子、３…正極出力端子、４…負極出力端子、１０…入力スイッチング回路、１１ａ～１４ａ…スイッチ素子、１１ｂ～１４ｂ…ダイオード、１１ｃ～１４ｃ…コンデンサ、２０…トランス、３０…出力スイッチング回路、３１ａ，３２ａ…スイッチ素子、３１ｂ，３２ｂ…ダイオード、３１ｃ，３２ｃ…コンデンサ、３３，３４…スナバ回路、４１…電圧検出器、５０…制御回路、５１～５６…出力信号、６０，６１…ゲートドライバ、７１～７６…駆動信号、９０…遅延回路、１００，１００ａ…ＤＣ－ＤＣコンバータ、２００…車両電源制御部、３００…ＨＶ系機器、４００…補機機器、１０００…車両、Ｎ１…一次巻線、Ｎ２ａ，Ｎ２ｂ…二次巻線、Ｓ…整流接続点、Ｔ…中性点、Ｖ１…高圧バッテリ、Ｖ２…低圧バッテリ DESCRIPTION OF SYMBOLS 1 ... Positive input terminal, 2 ... Negative input terminal, 3 ... Positive output terminal, 4 ... Negative output terminal, 10 ... Input switching circuit, 11a-14a ... Switch element, 11b-14b ... Diode, 11c-14c ... Capacitor, 20 ... Transformer, 30 ... Output switching circuit, 31a, 32a ... Switch element, 31b, 32b ... Diode, 31c, 32c ... Capacitor, 33,34 ... Snubber circuit, 41 ... Voltage detector, 50 ... Control circuit, 51-56 ... Output signal 60, 61 ... Gate driver, 71-76 ... Drive signal, 90 ... Delay circuit, 100, 100a ... DC-DC converter, 200 ... Vehicle power supply control unit, 300 ... HV system equipment, 400 ... Auxiliary equipment, 1000 ... vehicle, N1 ... primary winding, N2a, N2b ... secondary winding, S ... rectifying connection point, T ... neutral point, V1 ... high voltage battery , V2 ... low-voltage battery

Claims (4)

  1. 　入力電源から入力された第１の直流電力を交流電力に変換する入力スイッチング回路と、
    　前記交流電力の電圧変換を行うトランスと、
    　前記トランスにより電圧変換された前記交流電力を第２の直流電力に変換して出力する出力スイッチング回路と、
    　前記入力スイッチング回路および前記出力スイッチング回路を制御する制御回路と、
    　前記入力スイッチング回路と前記トランスの間に設けられたリアクトル成分と、を備え、
    　前記入力スイッチング回路は、前記入力電源の正負極間に直列接続されて前記制御回路によりそれぞれスイッチング制御される一対の入力スイッチ素子を有し、
    　前記出力スイッチング回路は、前記制御回路によりスイッチング制御される出力スイッチ素子と、前記出力スイッチ素子と並列に設けられたスナバ回路と、を有し、
    　前記制御回路は、
    　前記入力電源を介さずに前記入力スイッチング回路、前記リアクトル成分および前記トランスを循環する循環電流が流れる循環期間において、前記スナバ回路に電流が流れることで前記循環電流が増大するように、前記出力スイッチング回路を制御し、
    　前記循環期間の後に前記一対の入力スイッチ素子が両方ともオフであるデッドタイム期間に移行するように、前記入力スイッチング回路を制御する電力変換装置。     An input switching circuit that converts first DC power input from an input power source into AC power;
    A transformer that performs voltage conversion of the AC power;
    An output switching circuit that converts the AC power voltage-converted by the transformer into a second DC power and outputs the second DC power;
    A control circuit for controlling the input switching circuit and the output switching circuit;
    A reactor component provided between the input switching circuit and the transformer,
    The input switching circuit has a pair of input switch elements that are connected in series between the positive and negative electrodes of the input power source and controlled to be switched by the control circuit, respectively.
    The output switching circuit has an output switch element controlled by the control circuit, and a snubber circuit provided in parallel with the output switch element,
    The control circuit includes:
    The output switching is performed so that the circulating current increases when a current flows through the snubber circuit in a circulation period in which a circulating current that circulates through the input switching circuit, the reactor component, and the transformer flows without passing through the input power source. Control the circuit,
    The power converter which controls the said input switching circuit so that it may transfer to the dead time period when both of said pair of input switch elements are OFF after the said cycling period.
  2. 　請求項１に記載の電力変換装置において、
    　前記リアクトル成分は、前記トランスの漏れインダクタンスと、前記入力スイッチング回路と前記トランスの間に接続されたリアクトル素子と、のいずれか少なくとも一方を用いて構成される電力変換装置。     The power conversion device according to claim 1,
    The reactor component is a power converter configured using at least one of a leakage inductance of the transformer and a reactor element connected between the input switching circuit and the transformer.
  3. 　請求項１または請求項２に記載の電力変換装置において、
    　前記循環期間において前記出力スイッチ素子に流れる電流の向きは、前記出力スイッチング回路の整流動作に応じた電流の向きに対して反対である電力変換装置。     In the power converter device according to claim 1 or 2,
    A power conversion device in which a direction of a current flowing through the output switch element in the circulation period is opposite to a direction of a current according to a rectifying operation of the output switching circuit.
  4. 　請求項１から請求項３のいずれか一項に記載の電力変換装置において、
    　前記制御回路と前記入力スイッチング回路の間に設けられた遅延回路を備え、
    　前記制御回路は、前記入力スイッチング回路を制御するための第１の出力信号と、前記出力スイッチング回路を制御するための第２の出力信号とを互いに同期させて出力し、
    　前記遅延回路は、前記第１の出力信号を遅延させて前記入力スイッチング回路へ出力する電力変換装置。     In the power converter device according to any one of claims 1 to 3,
    A delay circuit provided between the control circuit and the input switching circuit;
    The control circuit outputs a first output signal for controlling the input switching circuit and a second output signal for controlling the output switching circuit in synchronization with each other,
    The delay circuit delays the first output signal and outputs the delayed signal to the input switching circuit.
PCT/JP2019/010462 2018-04-27 2019-03-14 Power conversion device WO2019208008A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007006653A (en) * 2005-06-24 2007-01-11 Hitachi Ltd Insulated resonance-type bidirectional dc/dc converter and its control method
US20110317452A1 (en) * 2010-06-25 2011-12-29 Gueorgui Iordanov Anguelov Bi-directional power converter with regulated output and soft switching
JP2015154506A (en) * 2014-02-10 2015-08-24 オリジン電気株式会社 DC-DC converter
JP2017175793A (en) * 2016-03-24 2017-09-28 株式会社デンソー DC-DC converter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007006653A (en) * 2005-06-24 2007-01-11 Hitachi Ltd Insulated resonance-type bidirectional dc/dc converter and its control method
US20110317452A1 (en) * 2010-06-25 2011-12-29 Gueorgui Iordanov Anguelov Bi-directional power converter with regulated output and soft switching
JP2015154506A (en) * 2014-02-10 2015-08-24 オリジン電気株式会社 DC-DC converter
JP2017175793A (en) * 2016-03-24 2017-09-28 株式会社デンソー DC-DC converter

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