JP6137947B2 - Bi-directional isolated DC-DC converter - Google Patents

Description

  The present invention relates to a bidirectional insulated DC-DC converter.

  Increasing the capacity of battery packs used in electric motorcycles, electric vehicles, etc. will increase the cruising range, but as the capacity increases, the battery pack becomes heavier. For this reason, it becomes difficult to attach the battery pack to the vehicle or to remove it for charging. In addition, the price of the battery pack itself increases.

  Therefore, it is considered to increase the capacity of the entire battery pack by connecting a plurality of standard battery packs in parallel. For example, when connecting a plurality of battery packs in parallel, they are connected by a chargeable / dischargeable bidirectional DC-DC converter. This bidirectional DC-DC converter is desired to be highly efficient in order to use the battery effectively. Moreover, since it attaches to each standard battery pack to connect several or more, it is desirable that it is small and cheap.

  In particular, in an insulated power supply apparatus using a transformer, the transformer cannot be reduced in size because the transformer is large. In addition, there is a problem that the loss due to the core of the transformer is large and the efficiency cannot be increased.

  For this reason, an insulated power supply device using a capacitor instead of a transformer has been proposed. However, although a unidirectional power supply device has been proposed, a bidirectional power supply device has not been proposed. In addition, a method for controlling a bidirectional insulated power supply using a capacitor has not been proposed.

JP 2004-282828 A JP-A-2-123967 JP 2001-78459 A JP 2011-239492 A

  Accordingly, an object of the present invention is to provide a small bidirectional insulated DC-DC converter.

  A bidirectional insulation type DC-DC converter according to the present invention includes (A) a first resonance circuit in which a first capacitor for insulation and a first inductor are connected in series, and (B) a first resonance circuit. A second resonance circuit in which a second capacitor and a second inductor are connected in series; and (C) a first high-side switch and a first low-side switch. A first drive circuit connected to one end of the first resonance circuit with the low-side switch, and (D) a second high-side switch and a second low-side switch. A second drive circuit connected to one end of the second resonance circuit between the first low-side switch and the second low-side switch; and (E) a third high-side switch and a third low-side switch, High side switch and third A third drive circuit connected to the other end of the first resonance circuit between the first side circuit and the second side switch; and (F) a fourth high side switch and a fourth low side switch. A fourth drive circuit connected to the other end of the second resonance circuit between the switch and the fourth low-side switch; and (G) a control circuit for controlling switching of the first to fourth drive circuits. Have. The first and second drive circuits are connected, and the third and fourth drive circuits are connected.

  Further, the control circuit described above sets (g1) the period during which the first to fourth high-side switches are on based on the control target, and (g2) the first and second drive circuit side In the two drive circuits related to the higher one of the first voltage and the second voltage on the third and fourth drive circuit sides, the low-side switch is turned on according to the period during which the high-side switch is turned off. A period is set, (g3) between the two drive circuits related to the higher one of the first voltage and the second voltage, the period during which the high-side switch is on is shifted by a half cycle of the switching period, (G4) In the two drive circuits according to the lower one of the first voltage and the second voltage, the period during which the high-side switch is on and the period during which the low-side switch is on are the same length and Switching lap It controls so shifted by a half cycle only.

  In this way, a full-bridge drive circuit is arranged at both ends of the two LC resonance circuits, and switching is controlled by the control circuit as described above, so that a small isolated DC that can convert power bidirectionally. -A DC converter is obtained. The control target may be based on the first voltage and the second voltage, or may be a fixed duty ratio or constant current control.

  In the control circuit described above, when the absolute value of the difference between the first voltage and the second voltage is not more than a predetermined value, (g5) the first to fourth high-side switches are turned on. A certain period is set based on half of the period corresponding to the resonance frequency of resonance by the first and second resonance circuits, and (g6) a period during which the high-side switch in the first to fourth drive circuits is on. Control may be performed so that the period during which the low-side switch is on is shifted by a half cycle of the switching cycle. If the first voltage and the second voltage are approximately the same, by performing such control, an efficient operation can be performed with a simple operation.

  Further, a plurality of devices including the above-described bidirectional insulated DC-DC converter and a storage battery connected to the first and second drive circuit sides in the bidirectional insulated DC-DC converter are connected in series or in parallel. A connected power supply may be used. If it does in this way, a small-sized power supply device can be constituted using a standard storage battery.

  The embodiment described below is only an example, and various modifications can be made in accordance with the gist of the present invention.

  A small bidirectional insulated DC-DC converter can be obtained.

FIG. 1 is a diagram illustrating an example of a bidirectional insulated DC-DC converter according to an embodiment. 2A to 2D are diagrams showing FET drive signals when V1> V2. FIGS. 3A to 3D are diagrams showing FET drive signals when V1 <V2. 4A to 4D are diagrams showing FET drive signals when V1 and V2 are substantially the same. FIG. 5 is a diagram showing details of the drive signal of the FET when V1> V2. FIG. 6 is a diagram showing details of the drive signal of the FET at approximately V1 = V2. FIG. 7 is a diagram illustrating the relationship between the duty ratio and Vout / Vin. FIG. 8 is a diagram for specifying a voltage and a current. FIGS. 9A to 9N are diagrams showing various waveforms when V1> V2. FIGS. 10A to 10N are diagrams showing various waveforms at approximately V1 = V2. FIG. 11 is a diagram illustrating an example of a power supply device to which a bidirectional insulated DC-DC converter is applied. FIG. 12 is a diagram illustrating an example of a power supply device to which a bidirectional insulated DC-DC converter is applied. FIG. 13 is a diagram illustrating an example of a power supply device to which a bidirectional insulated DC-DC converter is applied.

[Embodiment]
FIG. 1 shows a basic circuit example of a bidirectional insulation type DC-DC converter according to the present embodiment. In the bidirectional insulation type DC-DC converter according to the present embodiment, a first resonance circuit in which an inductor Lr1 and an insulation capacitor Cr1 are connected in series, an inductor Lr2 and an insulation capacitor Cr2 in series. A second resonant circuit connected; a first full-bridge driving circuit in which one end of the inductor Lr1 is connected to the midpoint; a second full-bridge driving circuit in which one end of the inductor Lr2 is connected to the midpoint; A third full-bridge driving circuit in which one end of the capacitor Cr1 is connected to the middle point, a fourth full-bridge driving circuit in which one end of the capacitor Cr2 is connected to the middle point, and first and second full-bridge driving circuits A capacitor C1 connected in parallel with each other, a capacitor C2 connected in parallel with the third and fourth full-bridge drive circuits, and first to fourth full-bridge drive circuits. And a control circuit 100 for controlling.

  In one example, a storage battery is connected to the first and second full bridge drive circuit sides, and a charger and a load are connected to the third and fourth full bridge drive circuit sides.

  The first full-bridge drive circuit includes an FET (Q1AH) that is a high-side switch and an FET (Q1AL) that is a low-side switch. The drain of the FET (Q1AH) is connected to the high side switch and one end of the capacitor C1 in the second full bridge drive circuit. The source of the FET (Q1AH) is connected to the drain of the FET (Q1AL), and the source of the FET (Q1AL) is grounded.

  The second full bridge drive circuit includes an FET (Q1BH) that is a high-side switch and an FET (Q1BL) that is a low-side switch. The drain of the FET (Q1BH) is connected to the high side switch and one end of the capacitor C1 in the first full bridge drive circuit. The source of the FET (Q1BH) is connected to the drain of the FET (Q1BL), and the source of the FET (Q1BL) is grounded. The other end of the capacitor C1 is also grounded.

  The third full bridge drive circuit includes an FET (Q2AH) that is a high-side switch and an FET (Q2AL) that is a low-side switch. The drain of the FET (Q2AH) is connected to the high side switch and one end of the capacitor C2 in the fourth full bridge drive circuit. The source of the FET (Q2AH) is connected to the drain of the FET (Q2AL), and the source of the FET (Q2AL) is grounded.

  The fourth full bridge drive circuit includes an FET (Q2BH) that is a high-side switch and an FET (Q2BL) that is a low-side switch. The drain of the FET (Q2BH) is connected to the high side switch and one end of the capacitor C2 in the third full bridge drive circuit. The source of the FET (Q2BH) is connected to the drain of the FET (Q2BL), and the source of the FET (Q2BL) is grounded. The other end of the capacitor C2 is also grounded.

  The control circuit 100 includes a first FET driver circuit 120 that performs switching of the first and second full-bridge drive circuits, a V1 detection circuit 110 that detects a voltage V1 on the first and second full-bridge drive circuits, A first drive signal generation circuit 130 which is connected to the 1FET driver circuit 120 and the V1 detection circuit 110 and outputs a signal for controlling the switching of the first FET driver circuit 120; and third and fourth full-bridge drive circuits A second FET driver circuit 140 that performs switching, a V2 detection circuit 150 that detects a voltage V2 on the third and fourth full-bridge drive circuit sides, a second FET driver circuit 140, and a V2 detection circuit 150; Second drive signal generation circuit for outputting a signal for controlling the switching of the second FET driver circuit 140 Has a 160, the isolator 170 to be connected to the first drive signal generation circuit 130 while insulating the second drive signal generation circuit 160.

  The first drive signal generation circuit 130 and the second drive signal generation circuit 160 communicate via the isolator 170. More specifically, the synchronization signal, V1 and V2, and a signal such as a duty ratio corresponding to a period in which the gate of the FET driven by the first FET driver circuit 120 is turned on are exchanged. In some cases, the value of the current flowing at the midpoint (the connection point between the FET and the FET) in the first to fourth full-bridge driving circuits, and other current values (for example, flowing through the first and second full-bridge driving circuits). (Current) may be exchanged.

  The isolator 170 is an insulating element such as a photocoupler, a digital isolator, or an analog isolator.

  Next, control modes of the first to fourth full-bridge drive circuits by the control circuit 100 will be described with reference to FIGS.

  In the control circuit 100 of the bidirectional insulated DC-DC converter according to the present embodiment, the voltage V1 on the first and second full bridge drive circuit side is higher than the voltage V2 on the third and fourth full bridge drive circuit side. If higher, control is performed so that power is transmitted from the first and second full bridge drive circuit sides to the third and fourth full bridge drive circuit sides.

  That is, as shown in FIG. 2 (a), the drive signal for the gate of the FET (Q1AL) in accordance with the period during which the drive signal (VG_1A_H) for the gate of the FET (Q1AH) is turned on in the first full bridge drive circuit. The drive signal (VG_1A_L) is turned on in accordance with a period in which (VG_1A_L) is turned off and the drive signal (VG_1A_H) is turned off. Such control is called asymmetric control. The period during which the drive signal (VG_1A_H) is on is determined based on, for example, V1 and V2, but may be set according to other control targets. Note that a dead time for preventing a through current is provided when switching between ON and OFF, but is omitted in FIG.

  Similarly, as shown in FIG. 2B, the driving of the gate of the FET (Q1BL) according to the period during which the driving signal (VG_1B_H) for the gate of the FET (Q1BH) is turned on in the second full bridge driving circuit. The drive signal (VG_1B_L) is turned off in accordance with a period in which the signal (VG_1B_L) is turned off and the drive signal (VG_1B_H) is turned off. Thus, asymmetric control is performed. Note that the period during which the drive signal (VG_1B_H) is on is the same as the period during which the drive signal (VG_1A_H) is on, and is shifted from this period by a half cycle of the switching period.

  On the other hand, as shown in FIGS. 2C and 2D, a period during which the drive signal (VG_2A_H) for the gate of the FET (Q2AH) in the third full bridge drive circuit is on, and the fourth full bridge drive circuit. The period during which the drive signal (VG_2B_H) for the gate of the FET (Q2BH) is turned on is determined based on, for example, V1 and V2, but may be set according to other control targets. Further, the period in which the drive signal (VG_2A_H) is turned on and the period in which the drive signal (VG_2A_L) of the FET (Q2AL) is turned on have the same length and are shifted by a half cycle of the switching period. Similarly, the period in which the drive signal (VG_2B_H) is on and the period in which the drive signal (VG_2B_L) of the FET (Q2BL) is on have the same length and are shifted by a half cycle of the switching period. ing. Further, the phase of the drive signal (VG_2A_H) and the phase of the drive signal (VG_2B_H) are also shifted by a half cycle of the switching cycle. Such control is called symmetric control.

  As described above, power is transmitted by performing asymmetric control on the FET on the higher voltage V1 side and performing symmetrical control on the FET on the lower voltage V2 side.

  On the other hand, if the voltage V2 on the third and fourth full-bridge drive circuit side is higher than the voltage V1 on the first and second full-bridge drive circuit side, the control circuit 100 causes the third and fourth Control is performed so that power is transmitted from the full bridge drive circuit side to the first and second full bridge drive circuit sides.

  Specifically, as shown in FIG. 3C, the gate of the FET (Q2AL) is turned on according to the period during which the drive signal (VG_2A_H) for the gate of the FET (Q2AH) is turned on in the third full-bridge drive circuit. The drive signal (VG_2A_L) is turned on in accordance with a period in which the drive signal (VG_2A_L) is turned off and the drive signal (VG_2A_H) is turned off. That is, asymmetric control is performed. The period during which the drive signal (VG_2A_H) is on is determined based on, for example, V1 and V2, but may be set according to other control targets. When switching between ON and OFF, a dead time for preventing a through current is provided, but is omitted in FIG.

  Similarly, as shown in FIG. 3D, the driving of the gate of the FET (Q2BL) according to the period during which the driving signal (VG_2B_H) for the gate of the FET (Q2BH) is turned on in the fourth full-bridge driving circuit. The drive signal (VG_2B_L) is turned on in accordance with a period in which the signal (VG_2B_L) is turned off and the drive signal (VG_2B_H) is turned off. Thus, asymmetric control is performed. Note that the period in which the drive signal (VG_2B_H) is on is the same as the period in which the drive signal (VG_2A_H) is on, and is shifted from this period by a half cycle of the switching period.

  On the other hand, as shown in FIGS. 3A and 3B, a period when the drive signal (VG_1A_H) for the gate of the FET (Q1AH) in the first full bridge drive circuit is on, and the second full bridge drive circuit The period during which the drive signal (VG_1B_H) for the gate of the FET (Q1BH) is turned on is determined based on, for example, V1 and V2, but may be set according to other control targets. In addition, the period in which the drive signal (VG_1A_H) is on and the period in which the drive signal (VG_1A_L) of the FET (Q1AL) is on have the same length and are shifted by a half cycle of the switching period. Similarly, the period in which the drive signal (VG_1B_H) is on and the period in which the drive signal (VG_1B_L) of the FET (Q1BL) is on have the same length and are shifted by a half cycle of the switching period. ing. Further, the phase of the drive signal (VG_1A_H) and the phase of the drive signal (VG_1B_H) are also shifted by a half cycle of the switching cycle. In this way, symmetrical control is performed.

  Thus, power is transmitted by performing asymmetric control on the higher voltage V2 side and performing symmetric control on the lower voltage V1 side.

  On the other hand, when the voltages V1 and V2 are substantially the same (the absolute value of the difference is several volts = for example, about 1-2 body diodes), the duty ratio is maximum, that is, half of the period corresponding to the resonance frequency. The cycle is set to the ON period, and symmetry control is performed on the first to fourth full bridge drive circuits.

  That is, as shown in FIGS. 4A to 4D, the gates of the FETs are driven to turn on at the maximum duty ratio. In addition, the drive signal of the FET that is the high-side switch and the drive signal of the FET that is the low-side switch are shifted in phase by a half cycle of the switching cycle. In addition, the phases of the drive signal (VG_1A_H) and the drive signal (VG_1B_H) are also shifted by a half cycle of the switching cycle. Similarly, the phases of the drive signal (VG_2A_H) and the drive signal (VG_2B_H) are also shifted by a half cycle of the switching cycle.

  Thus, the voltage (or current) on the low voltage side is controlled by PWM (Pulse Width Modulation) control.

Next, the operation of the bidirectional insulated DC-DC converter will be described in more detail. For this reason, the following parameter values are assumed. That is, for example, C1 = C2 = 10 μF, Lr1 = Lr2 = 2.2 μH, Cr1 = Cr2 = 0.22 μF, switching frequency fsw = 200 kHz, and switching cycle Ts (sw) = 5 μs. The following relationship holds.

  DT is a dead time, fr is a resonance frequency, TonMax is a maximum value of on-time, and DutyMax represents a maximum duty ratio of a drive signal.

  From the parameter values described above, the period T (r) corresponding to the resonance frequency fr is 4.37 μs, and DutyMax = 43.7%.

  2 is shown in more detail in FIG. FIG. 5 shows a situation where V1> V2. In the asymmetric control, for example, a dead time is provided by shortening a period during which an FET that is a low-side switch is turned on. In this example, since the duty ratio is about 25%, the switching cycle Ts seems to be divided into four periods. The first period is represented as ST_1, the second period is represented as ST_2, the third period is represented as ST_3, and the fourth period is represented as ST_4. However, when the duty ratio rises, for example, if V1 = V2, for example, as shown in FIG. 6, the duty ratio becomes DutyMax, and ON / OFF is repeated in approximately a half cycle of the switching cycle Ts.

  FIG. 7 shows the relationship between the duty ratio (Duty), which is the ratio of the high-side switch ON period to the switching period, and Vout / Vin (the higher voltage is Vin). Thus, Vout / Vin can be changed by changing the duty ratio. However, since it is controlled in the step-down direction, it can be seen that it is a step-down step-down bidirectional converter. Note that Vout / Vin = 1 does not become 1 even when DutyMax is reached because the voltage drop due to the body diode of the FET or the current flowing in the power line causes a loss due to the resistance component of the power line itself and components included in the power line. Because there is.

  As shown in FIG. 8, the current flowing through the first resonance circuit is I_Lr1Cr1, and the current I_Lr2Cr2 flowing through the second resonance circuit. The voltage across the inductor Lr1 is V_Lr1, and the voltage across the capacitor Cr1 is V_Cr1. Similarly, the voltage across the inductor Lr2 is V_Lr2, and the voltage across the capacitor Cr2 is V_Cr2. Further, the current flowing through the FET (Q1AH) is I_Q1AH, the current flowing through the FET (Q1AL) is I_Q1AL, the current flowing through the FET (Q1BH) is I_Q1BH, and the current flowing through the FET (Q1BL) is I_Q1BL. A DC power supply is connected to the first and second full bridge drive circuit sides, and the power supply voltage Vsup is set to 15V. Further, the current flowing to the first and second full bridge drive circuit sides is I1.

  Similarly, the current flowing through the FET (Q2AH) is I_Q2AH, the current flowing through the FET (Q2AL) is I_Q2AL, the current flowing through the FET (Q2BH) is I_Q2BH, and the current flowing through the FET (Q2BL) is I_Q2BL. A load is connected to the third and fourth full bridge drive circuit sides, and the current flowing through the load is Io. Further, the current flowing to the third and fourth full bridge drive circuit sides is I2.

  If V1> V2, the voltage and current waveforms described above are as shown in FIG. FIGS. 9A to 9D are the same as FIG. FIG. 9E shows a state where V1> V2. For example, when power is supplied to the loads connected to the third and fourth full bridge drive circuit sides, the control circuit 100 performs a constant voltage control so that V2 / V1 becomes a desired value. The duty ratio is determined based on the relationship shown in FIG. 7, and a drive signal for each FET is generated and output.

  On the other hand, when the battery connected to the first and second full bridge drive circuit side is charged by the storage battery, V1 <V2, but as described above, the symmetric control and the asymmetric control are performed. The first and second full bridge drive circuits may be interchanged with the third and fourth full bridge drive circuits. For example, the duty ratio is determined so that the storage battery is charged with a constant current so that V1 becomes an appropriate value, and a drive signal for each FET is generated and output.

  According to FIGS. 9F to 9N, power is mainly transmitted to ST_1 and ST_3 from the first and second full bridge drive circuit sides to the third and fourth full bridge drive circuit sides. I understand that. At this time, due to the effect of the first resonance circuit and the second resonance circuit, power is accumulated in the capacitor Cr2 at ST_1 and ST_2 and discharged at ST_3, and power is accumulated at the capacitor Cr1 at ST_3 and ST_4 and discharged at ST_1. ing. Since the on / off operation is performed in a period shorter than 1/2 of the period 1 / fr corresponding to the resonance frequency fr, the current waveform is shaped such that the current change due to resonance (half-wave waveform) is interrupted halfway.

  When V1 and V2 are substantially the same, the voltage and current waveforms shown in FIG. 8 are as shown in FIG.

  10A to 10D are the same as those in FIG. FIG. 10E shows a state where V1 and V2 are approximately the same. In this case, the first to fourth full bridge drive circuits are all controlled symmetrically, and the duty ratio is fixed to DutyMax.

  10 (f) to (n), the waveforms are shown more emphasized than in FIG. 9, but since V 1 and V 2 are substantially in the same state, the first and second full bridge drive circuit sides and the third and third Almost no current flows between the fourth full bridge drive circuit side. Therefore, the loss due to FET switching is also reduced. The current waveform is a half-wave waveform due to resonance.

  In addition, by adopting symmetric control, power is automatically transmitted from the higher voltage to the lower voltage even when the state changes to V1> V2 or V2> V1, so the control is not frequently switched. May be. Therefore, control is simplified and bidirectional transmission of power is achieved.

  By performing the control as described above, an efficient bidirectional insulation type DC-DC converter is realized while performing insulation at C of the LC resonance circuit without using a transformer.

  In the example in which the duty ratio is set to DutyMax above, even when a duty ratio slightly lower than DutyMax is used, the same effect can be obtained with only a slight decrease in efficiency.

[Application Example 1]
Although briefly described in the embodiment, the bidirectionally insulated DC-DC converter according to the embodiment may be applied to a power supply device as shown in FIG. 11, for example.

  In the power supply device shown in FIG. 11, a storage battery and a current detector for detecting a current flowing through the storage battery are connected in series to the first and second full bridge drive circuit sides. The storage battery is, for example, a secondary battery such as a lithium ion battery, a NiH battery, a NiCd battery, or a lead battery. On the other hand, a DC power source or a charger and a load are connected to the third and fourth full bridge drive circuit sides so as to be switchable by a switch.

For example, when the voltage V1 on the first and second full bridge drive circuit side is higher than the voltage V2 on the third and fourth full bridge drive circuit side and the storage battery is discharged, the following control is performed. The
(A) Set the duty ratio to DutyMax (or a value close to DutyMax) and fix it (B) Perform constant voltage control according to the load (PWM control)

On the other hand, when the voltage V2 on the third and fourth full bridge drive circuit side is higher than the voltage V1 on the first and second full bridge drive circuit side, and the battery is charged from the DC power supply or the charger, The following control is performed.
(A) Until the voltage V1 on the first and second full bridge drive circuit sides reaches a predetermined voltage, constant current control is performed based on the current detected by the current detector, and the voltage V1 reaches the predetermined voltage. Then, constant voltage control is performed. Both perform PWM control.

  In this way, a bidirectional insulated power supply device can be realized using a bidirectional insulated DC-DC converter.

[Application 2]
If a plurality of bidirectional insulated power supply devices according to the first application example are connected in series rather than individually, a power supply device as shown in FIG. 12 is obtained. Thereby, the output voltage with respect to the load can be increased. Moreover, the potential imbalance of each storage battery can be eliminated.

  Furthermore, if a plurality of bidirectional insulated power supply devices according to the first application example are connected in parallel, a power supply device as shown in FIG. 13 can be obtained. As a result, the capacity of the storage battery can be increased. Moreover, the potential imbalance of each storage battery can be eliminated.

  Although the embodiment of the present invention has been described above, various modifications can be made in accordance with the above-described purpose. In particular, the application examples described above are merely examples, and various applications are possible.

100 control circuit 110 V1 detection circuit 120 first FET driver circuit 130 first drive signal generation circuit 140 second FET driver circuit 150 V2 detection circuit 160 second drive signal generation circuit 170 isolator

Claims (4)

A first resonant circuit in which a first capacitor for insulation and a first inductor are connected in series;
A second resonance circuit in which a second capacitor for insulation and a second inductor are connected in series;
A first drive including a first high-side switch and a first low-side switch and connected to one end of the first resonant circuit between the first high-side switch and the first low-side switch; Circuit,
A second drive including a second high-side switch and a second low-side switch and connected to one end of the second resonant circuit between the second high-side switch and the second low-side switch; Circuit,
A third high-side switch and a third low-side switch, and a third high-side switch connected to the other end of the first resonance circuit between the third high-side switch and the third low-side switch. A drive circuit;
A fourth high-side switch and a fourth low-side switch, the fourth high-side switch being connected to the other end of the second resonance circuit between the fourth high-side switch and the fourth low-side switch; A drive circuit;
A control circuit for controlling switching of the first to fourth drive circuits;
Have
The first and second drive circuits are connected to each other ;
The third and fourth drive circuits are connected to each other ;
The control circuit comprises:
A period during which the first to fourth high-side switches are on is set according to a control target,
In the two drive circuits according to the higher one of the first voltage on the first and second drive circuit sides and the second voltage on the third and fourth drive circuit sides, a high-side switch includes: Set the period when the low-side switch is on according to the period when it is off,
Between the two drive circuits related to the higher one of the first voltage and the second voltage, the period during which the high-side switch is on is shifted by a half cycle of the switching period,
In the two drive circuits according to the lower one of the first voltage and the second voltage, the period during which the high-side switch is on and the period during which the low-side switch is on have the same length, and Bidirectional insulation type DC-DC converter that is controlled so as to be shifted by half the switching period. The control circuit comprises:
When the absolute value of the difference between the first voltage and the second voltage is not more than a predetermined value,
A period in which the first to fourth high-side switches are on is set based on a half of a period corresponding to a resonance frequency of resonance by the first and second resonance circuits;
2. The bidirectional insulated DC circuit according to claim 1, wherein the period in which the high-side switch is on and the period in which the low-side switch is on in the first to fourth drive circuits are controlled to be shifted by a half cycle of the switching cycle. DC converter. The control circuit comprises:
The ratio between the lower voltage and the higher voltage of the first voltage and the second voltage is controlled by a ratio of a period during which the high-side switch is on with respect to the switching period.
The bidirectional insulation type DC-DC converter according to claim 1 or 2. A bidirectional insulation type DC-DC converter according to any one of claims 1 to 3 ,
A storage battery connected to the first and second drive circuit sides in the bidirectional insulated DC-DC converter;
A power supply device in which a plurality of devices are connected in series or in parallel.

Images