Power conversion device

Abstract

Disclosed is a power conversion device which comprises a first capacitor, a second capacitor, a plurality of switching circuits, a plurality of transformers, a first inductor, a switch, a second inductor, and a control circuit. The plurality of switching circuits include a first switching circuit and a second switching circuit. The first inductor is disposed between a series circuit and a low-potential-side terminal of the first capacitor. The switch is electrically connected to the low-potential-side terminal of the first capacitor via the series circuit. The second inductor is disposed between the switch and the low-potential-side terminal of the first capacitor. The control circuit controls the first switching circuit, the second switching circuit, and the switch. The inductance of the second inductor is lower than the inductance of the first inductor.

Description

Power Conversion Device

[0001] The present disclosure relates generally to power converters, and more particularly to power converters including multiple transformers.

[0002] Patent Document 1 discloses a transformer-inductor voltage regulator circuit (power conversion device), also known as a TLVR (Trans-Inductor Voltage Regulator) circuit. The TLVR circuit disclosed in Patent Document 1 includes multiple transformers, multiple regulator blocks, an output capacitor, and a nonlinear compensation inductor. Each transformer includes a primary winding and a secondary winding. Each regulator block has two switches. The multiple secondary windings are connected in series. Each regulator block is connected to the output capacitor via each primary winding of the multiple transformers. The nonlinear compensation inductor is connected in series to the multiple secondary windings.

[0003] The nonlinear compensation inductor has a first inductance when the current flowing through the load is in a steady state and a second inductance when the current flowing through the load is in a transient state, the first inductance being greater than the second inductance.

[0004] U.S. Pat. No. 1,145,145

[0005] The TLVR circuit described in Patent Document 1 utilizes the DC superposition characteristics of the nonlinear compensation inductor to reduce the inductance of the nonlinear compensation inductor when the current flowing through the load is in a transient state, thereby improving responsiveness to the load (load responsiveness). However, in the TLVR circuit described in Patent Document 1, the inductance of the nonlinear compensation inductor is reduced when the current flowing through the load is in a transient state, so the load responsiveness is inferior to a TLVR circuit including a nonlinear compensation inductor with a small inductance when the current flowing through the load is in a steady state. Furthermore, in the TLVR circuit described in Patent Document 1, the current ripple is larger and losses are greater than in a TLVR circuit including a nonlinear compensation inductor with a large inductance when the current flowing through the load is in a steady state.

[0006] A power conversion device according to one aspect of the present disclosure includes a first capacitor, a second capacitor, multiple switching circuits, multiple transformers, a first inductor, a switch, a second inductor, and a control circuit. The first capacitor is electrically connected across a DC power supply. The second capacitor is electrically connected across a load. The multiple switching circuits include at least a first switching circuit in which a first switching element and a second switching element are connected in series to each other at a first connection point, and a second switching circuit in which a third switching element and a fourth switching element are connected in series to each other at a second connection point, and the first switching circuit and the second switching circuit are connected in parallel to the first capacitor. The multiple transformers include at least a first transformer and a second transformer. A primary winding of the first transformer is arranged between the first connection point of the first switching element and the second switching element and a high-potential side terminal of the second capacitor. A primary winding of the second transformer is arranged between the second connection point of the third switching element and the fourth switching element and the high-potential side terminal of the second capacitor. The first inductor is arranged between a series circuit in which the secondary winding of the first transformer and the secondary winding of the second transformer are connected in series and the low-potential terminal of the first capacitor. The switch is electrically connected to the low-potential terminal of the first capacitor via the series circuit. The second inductor is arranged between the switch and the low-potential terminal of the first capacitor. The control circuit controls the first switching circuit, the second switching circuit, and the switch. The low-potential terminal of the second capacitor is electrically connected to the second switching element and the fourth switching element. The inductance of the second inductor is smaller than the inductance of the first inductor.

[0007] A power conversion device according to one aspect of the present disclosure includes a first capacitor, a second capacitor, multiple switching circuits, multiple transformers, a switch, an inductor, and a control circuit. The first capacitor is electrically connected across a DC power supply. The second capacitor is electrically connected across a load. The multiple switching circuits include at least a first switching circuit in which a first switching element and a second switching element are connected in series to each other at a first connection point, and a second switching circuit in which a third switching element and a fourth switching element are connected in series to each other at a second connection point, and the first switching circuit and the second switching circuit are connected in parallel to the first capacitor. The multiple transformers include at least a first transformer and a second transformer. A primary winding of the first transformer is arranged between the first connection point of the first switching element and the second switching element and a high-potential side terminal of the second capacitor. A primary winding of the second transformer is arranged between the second connection point of the third switching element and the fourth switching element and the high-potential side terminal of the second capacitor. The switch is electrically connected to the low-potential terminal of the first capacitor via a series circuit in which the secondary winding of the first transformer and the secondary winding of the second transformer are connected in series with each other. The inductor is disposed between the switch and the low-potential terminal of the first capacitor. The control circuit controls the first switching circuit, the second switching circuit, and the switch. The low-potential terminal of the second capacitor is electrically connected to the second switching element and the fourth switching element. The series circuit is electrically connected to the low-potential terminal of the first capacitor.

[0008] According to a power conversion device according to an aspect of the present disclosure, it is possible to improve load responsiveness and reduce loss.

[0009] FIG. 1 is a circuit diagram of a power conversion device according to a first embodiment. FIG. 2 is a diagram showing changes in output current for the power conversion device according to the first embodiment. FIG. 3 is a diagram showing a waveform of a transformer current for the power conversion device according to the first embodiment. FIG. 4 is a circuit diagram of a power conversion device of a comparative example. FIG. 5 is a circuit diagram of a power conversion device according to a second embodiment. FIG. 6 is a diagram showing changes in output current for the power conversion device according to the first embodiment. FIG. 7 is a circuit diagram of a power conversion device according to a third embodiment. FIG. 8 is a diagram showing changes in output current for the power conversion device according to the first embodiment. FIG. 9 is a circuit diagram of a power conversion device according to a fourth embodiment. FIG. 10 is a diagram showing changes in output current for the power conversion device according to the first embodiment. FIG. 11 is a circuit diagram of a power conversion device according to a fifth embodiment. FIG. 12 is a circuit diagram of a power conversion device according to a sixth embodiment. FIG. 13 is a diagram showing changes in output current for the power conversion device according to the first embodiment. FIG. 14 is a circuit diagram of a power conversion device according to a seventh embodiment. FIG. 15 is a diagram showing changes in output current for the power conversion device according to the first embodiment. FIG. 16 is another diagram showing changes in output current for the power conversion device according to the first embodiment. Fig. 17 is a circuit diagram of a power conversion device according to embodiment 8. Fig. 18 is a diagram showing a change in output current of the power conversion device according to embodiment 8.

[0010] Hereinafter, power conversion devices according to embodiments 1 to 8 will be described with reference to the drawings. The configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0011] First Embodiment A power conversion device according to a first embodiment will be described below with reference to FIGS. 1 to 3. FIG.

[0012] (1) Power Conversion Device As shown in Fig. 1, the power conversion device A1 according to the first embodiment includes a pair of input terminals 1a, 1b, a first capacitor C1, a plurality of switching circuits 10, a plurality of transformers 6, and a second capacitor C2. The power conversion device A1 also includes a first inductor L1, a second inductor L2, a switch SW1, a control circuit 20, a detector 30, and a pair of output terminals 2a, 2b. The power conversion device A1 is a DC-DC converter (for example, a step-down DC-DC converter).

[0013] (2) Components of the Power Conversion Device (2.1) Pair of Input Terminals The pair of input terminals 1a, 1b are electrically and mechanically connected to a DC power supply V1 via, for example, a pair of electrical paths (e.g., copper wires of a circuit board). That is, in the power conversion device A1, the DC power supply V1 is electrically connected between the pair of input terminals 1a, 1b. The DC power supply V1 is, for example, a power supply circuit that outputs a DC voltage. The voltage between the pair of input terminals 1a, 1b is a voltage (input voltage) Vi from the DC power supply V1. The input voltage Vi is, for example, 12 V. Note that the DC power supply V1 is not limited to a power supply circuit and may be, for example, a stabilized DC power supply. Furthermore, the pair of input terminals 1a, 1b is not limited to a pair of electrical paths and may be, for example, a pair of connecting wires (e.g., coated copper wires).

[0014] (2.2) Pair of Output Terminals The pair of output terminals 2a, 2b are electrically and mechanically connected to the load 40 via, for example, a pair of electrical paths. That is, in the power conversion device A1, the load 40 is electrically connected between the pair of output terminals 2a, 2b. The load 40 is, for example, a microprocessor such as a CPU or a GPU. The voltage between the pair of output terminals 2a, 2b is the voltage (output voltage) Vo across the second capacitor C2. The output voltage Vo is, for example, 1 V. Note that the load 40 is not limited to a microprocessor, and may be, for example, a control IC, another DC-DC converter, or the like. Furthermore, the pair of output terminals 2a, 2b is not limited to a pair of electrical paths, and may be, for example, a pair of connecting wires, or the like.

[0015] (2.3) First Capacitor The first capacitor C1 is electrically connected between a pair of input terminals 1a and 1b. The high-potential side terminal of the first capacitor C1 is electrically connected to the input terminal 1a. The low-potential side terminal of the first capacitor C1 is electrically connected to the input terminal 1b. In other words, the first capacitor C1 is electrically connected across the DC power supply V1. The low-potential side terminal of the first capacitor C1 is electrically connected to, for example, the ground of the power conversion device A1 (for example, the ground of a circuit board including the power conversion device A1).

[0016] (2.4) Switching Circuits The multiple switching circuits 10 include a first switching circuit 11, a second switching circuit 12, and a third switching circuit 13. In the first switching circuit 11, a first switching element Q1 and a second switching element Q2 are connected in series. In the second switching circuit 12, a third switching element Q3 and a fourth switching element Q4 are connected in series. In the third switching circuit 13, a fifth switching element Q5 and a sixth switching element Q6 are connected in series. Each of the switching elements Q1 to Q6 is, for example, a metal-oxide-semiconductor field effect transistor (MOSFET). Each of the switching elements Q1 to Q6 has a first main terminal, a second main terminal, and a control terminal. Note that, hereinafter, to facilitate understanding of the description of the embodiments, the first main terminal will be referred to as a drain terminal, the second main terminal will be referred to as a source terminal, and the control terminal will be referred to as a gate terminal.

[0017] The first switching circuit 11 is connected in parallel to the first capacitor C1. The drain terminal of the first switching element Q1 is electrically connected to the high-potential side terminal of the first capacitor C1. The gate terminal of the first switching element Q1 is electrically connected to the control circuit 20. The source terminal of the first switching element Q1 is electrically connected to a primary winding L3 of a first transformer T1 (described later). The source terminal of the first switching element Q1 is electrically connected to the drain terminal of the second switching element Q2. The gate terminal of the second switching element Q2 is electrically connected to the control circuit 20. The source terminal of the second switching element Q2 is electrically connected to the low-potential side terminal of the first capacitor C1.

[0018] The second switching circuit 12 is connected in parallel to the first capacitor C1. In other words, the second switching circuit 12 is connected in parallel to the first switching circuit 11. The drain terminal of the third switching element Q3 is electrically connected to the drain terminal of the first switching element Q1. The gate terminal of the third switching element Q3 is electrically connected to the control circuit 20. The source terminal of the third switching element Q3 is electrically connected to a primary winding L5 of a second transformer T2 (described later). The source terminal of the third switching element Q3 is electrically connected to the drain terminal of the fourth switching element Q4. The gate terminal of the fourth switching element Q4 is electrically connected to the control circuit 20. The source terminal of the fourth switching element Q4 is electrically connected to the source terminal of the second switching element Q2.

[0019] The third switching circuit 13 is connected in parallel with the first capacitor C1. In other words, the third switching circuit 13 is connected in parallel with the second switching circuit 12. The drain terminal of the fifth switching element Q5 is electrically connected to the drain terminal of the third switching element Q3. The gate terminal of the fifth switching element Q5 is electrically connected to the control circuit 20. The source terminal of the fifth switching element Q5 is electrically connected to a primary winding L7 of a third transformer T3 (described later). The source terminal of the fifth switching element Q5 is electrically connected to the drain terminal of a sixth switching element Q6. The gate terminal of the sixth switching element Q6 is electrically connected to the control circuit 20. The source terminal of the sixth switching element Q6 is electrically connected to the source terminal of the fourth switching element Q4.

[0020] (2.5) Transformers The multiple transformers 6 include a first transformer T1, a second transformer T2, and a third transformer T3. The first transformer T1 has a primary winding L3 and a secondary winding L4. The second transformer T2 has a primary winding L5 and a secondary winding L6. The third transformer T3 has a primary winding L7 and a secondary winding L8.

[0021] The first switching element Q1 and the second switching element Q2 in the first switching circuit 11 are connected in series to each other at a connection point 3. A first end of a primary winding L3 of the first transformer T1 is electrically connected to the connection point 3 of the first switching element Q1 and the second switching element Q2 in the first switching circuit 11. A second end of the primary winding L3 of the first transformer T1 is electrically connected to a primary winding L5 of the second transformer T2. A first end of a secondary winding L4 of the first transformer T1 is electrically connected to the first inductor L1 and the switch SW1. A second end of the secondary winding L4 of the first transformer T1 is electrically connected to a secondary winding L6 of the second transformer T2.

[0022] The third switching element Q3 and the fourth switching element Q4 in the second switching circuit 12 are connected in series to each other at a connection point 4. A first end of a primary winding L5 of the second transformer T2 is electrically connected to the connection point 4 of the third switching element Q3 and the fourth switching element Q4 in the second switching circuit 12. A second end of the primary winding L5 of the second transformer T2 is electrically connected to a primary winding L7 of the third transformer T3. A first end of a secondary winding L6 of the second transformer T2 is electrically connected to a second end of the secondary winding L4 of the first transformer T1. A second end of the secondary winding L6 of the second transformer T2 is electrically connected to a secondary winding L8 of the third transformer T3.

[0023] The fifth switching element Q5 and the sixth switching element Q6 in the third switching circuit 13 are connected in series to each other at a connection point 5. A first end of a primary winding L7 of the third transformer T3 is electrically connected to the connection point 5 of the fifth switching element Q5 and the sixth switching element Q6 in the third switching circuit 13. A second end of the primary winding L7 of the third transformer T3 is electrically connected to the high-potential terminal of the second capacitor C2. A first end of a secondary winding L8 of the third transformer T3 is electrically connected to the second end of the secondary winding L6 of the second transformer T2. A second end of the secondary winding L8 of the third transformer T3 is electrically connected to the low-potential terminal of the first capacitor C1.

[0024] (2.6) Second Capacitor The second capacitor C2 is electrically connected between the pair of output terminals 2a and 2b. The high-potential side terminal of the second capacitor C2 is electrically connected to the output terminal 2a. The low-potential side terminal of the second capacitor C2 is electrically connected to the output terminal 2b. In other words, the second capacitor C2 is electrically connected across the load 40. The high-potential side terminal of the second capacitor C2 is electrically connected to the second end of the primary winding L7 of the third transformer T3. The low-potential side terminal of the second capacitor C2 is electrically connected to the source terminal of the sixth switching element Q6. In other words, the low-potential side terminal of the second capacitor C2 is electrically connected to the second switching element Q2, the fourth switching element Q4, and the sixth switching element Q6.

[0025] (2.7) First Inductor and Second Inductor The first end of the first inductor L1 is electrically connected to the first end of the secondary winding L4 of the first transformer T1. In other words, the first end of the first inductor L1 is electrically connected to a series circuit 8 (first end of the series circuit 8) in which the secondary winding L4 of the first transformer T1, the secondary winding L6 of the second transformer T2, and the secondary winding L8 of the third transformer T3 are connected in series with each other. The second end of the first inductor L1 is electrically connected to the low-potential terminal of the first capacitor C1. The first end of the second inductor L2 is electrically connected to the first end of the secondary winding L4 of the first transformer T1 via the switch SW1. In other words, the first end of the second inductor L2 is electrically connected to the series circuit 8 (first end of the series circuit 8) via the switch SW1. The second end of the second inductor L2 is electrically connected to the low-potential terminal of the first capacitor C1. The series circuit 8 (the second end of the series circuit 8) is electrically connected to the low potential side terminal of the first capacitor C1.

[0026] The first inductor L1 is an inductor connected in series to a composite inductor on the secondary side of multiple transformers 6 (hereinafter simply referred to as the "secondary-side composite inductor"). In other words, the first inductor L1 is an inductor (first adjusting inductor) for adjusting the inductance of the secondary-side composite inductor. The secondary-side composite inductor is a composite inductor of the secondary winding L4 of the first transformer T1, the secondary winding L6 of the second transformer T2, and the secondary winding L8 of the third transformer T3.

[0027] The second inductor L2 is an inductor connected in parallel to the first inductor L1 when the switch SW1 is in the on state. In other words, the second inductor L2 is an inductor (second adjustment inductor) for adjusting the inductance of the secondary-side combined inductor. In short, the power conversion device A1 includes an adjustment inductor 7 (first adjustment inductor and second adjustment inductor) for adjusting the inductance of the secondary-side combined inductor. The inductance of the second inductor L2 is smaller than the inductance of the first inductor L1.

[0028] (2.8) Switch The switch SW1 is a switching element such as a MOSFET. The switch SW1 has a first main terminal, a second main terminal, and a control terminal. In the following, to facilitate understanding of the embodiments, the first main terminal will be referred to as the drain terminal, the second main terminal will be referred to as the source terminal, and the control terminal will be referred to as the gate terminal.

[0029] The drain terminal of the switch SW1 is electrically connected to a first end of the secondary winding L4 of the first transformer T1. The gate terminal of the switch SW1 is electrically connected to the control circuit 20. The source terminal of the switch SW1 is electrically connected to a first end of the second inductor L2.

[0030] (2.9) Control Circuit The control circuit 20 is realized, for example, by a computer system having one or more processors and one or more memories. In other words, the functions of the control circuit 20 are realized by the one or more processors executing a program recorded in the memory. The program may be pre-recorded in the memory, or may be provided via a telecommunications line such as the Internet, or may be recorded on a non-transitory recording medium such as a memory card and provided.

[0031] The control circuit 20 controls the first switching circuit 11. More specifically, the control circuit 20 controls the first switching element Q1 and the second switching element Q2. The control circuit 20 switches the first switching element Q1 between an ON state and an OFF state. The control circuit 20 also switches the second switching element Q2 between an ON state and an OFF state. The control circuit 20 also controls the first switching element Q1 and the second switching element Q2 so that a trade-off relationship exists between the first switching element Q1 and the second switching element Q2. For example, when the control circuit 20 turns the first switching element Q1 on, the control circuit 20 turns the second switching element Q2 off. On the other hand, when the control circuit 20 turns the first switching element Q1 off, the control circuit 20 turns the second switching element Q2 on. The control circuit 20 may also turn the first switching element Q1 off and the second switching element Q2 off.

[0032] The control circuit 20 also controls the second switching circuit 12. More specifically, the control circuit 20 controls the third switching element Q3 and the fourth switching element Q4. The control circuit 20 also controls the third switching circuit 13. More specifically, the control circuit 20 controls the fifth switching element Q5 and the sixth switching element Q6. Note that the operation of the control circuit 20 to control the third switching element Q3 and the fourth switching element Q4 is similar to the operation of the control circuit 20 to control the first switching element Q1 and the second switching element Q2, except for the switching elements that are controlled, and therefore a description thereof will be omitted. Note that the operation of the control circuit 20 to control the fifth switching element Q5 and the sixth switching element Q6 is similar to the operation of the control circuit 20 to control the first switching element Q1 and the second switching element Q2, except for the switching elements that are controlled, and therefore a description thereof will be omitted.

[0033] The control circuit 20 also controls the first switching element Q1, the third switching element Q3, and the fifth switching element Q5 to be in the ON state when the operation of the load 40 is stable (when the load 40 is in a steady state). In this case, the timing when the first switching element Q1 is in the ON state, the timing when the third switching element Q3 is in the ON state, and the timing when the fifth switching element Q5 is in the ON state are time-shifted. In other words, the control circuit 20 performs an interleaving operation (phase shift) on the first switching element Q1, the third switching element Q3, and the fifth switching element Q5. The control circuit 20 also controls the amount of phase shift to be different when the operation of the load 40 is stable and when the operation of the load 40 changes.

[0034] The control circuit 20 also controls the switch SW1. More specifically, the control circuit 20 switches the switch SW1 between an on state and an off state. The control of the switch SW1 by the control circuit 20 will be described in detail later.

[0035] (2.10) Detector The detector 30 detects, for example, the transformer current IL. The transformer current IL is, for example, a current flowing through a composite inductor (a composite inductor on the primary sides of the multiple transformers 6) made up of the primary winding L3 of the first transformer T1, the primary winding L5 of the second transformer T2, and the primary winding L7 of the third transformer T3. For ease of explanation, hereinafter, the "composite inductor on the primary sides of the multiple transformers 6" will be simply referred to as the "composite inductor on the primary sides."

[0036] The detector 30 includes, for example, a detection circuit in which a resistor and a capacitor are connected in series at a connection point, and the detection circuit is connected in parallel to a primary-side composite inductor to detect a voltage (a voltage across both ends) between the connection point of the resistor and the capacitor and one end of the primary-side composite inductor. In other words, the detector 30 indirectly detects the transformer current IL by detecting the voltage across both ends. The detector 30 also outputs the voltage across both ends to the control circuit 20.

[0037] The control circuit 20 switches the switch SW1 between an ON state and an OFF state based on, for example, the current value of the transformer current IL detected by the detector 30. The control circuit 20 has, for example, a threshold value, and turns the switch SW1 ON when the current value of the transformer current IL detected by the detector 30 crosses the threshold value. For example, the control circuit 20 turns the switch SW1 ON when the current value of the transformer current IL exceeds the threshold value. That is, the control circuit 20 turns the switch SW1 ON when the current value of the transformer current IL detected by the detector 30 changes. On the other hand, the control circuit 20 turns the switch SW1 OFF when the current value of the transformer current IL detected by the detector 30 does not change. More specifically, the control circuit 20 turns the switch SW1 OFF when the current value of the transformer current IL detected by the detector 30 does not change for a predetermined period of time. Furthermore, the control circuit 20 turns the switch SW1 ON when the current value of the transformer current IL becomes smaller than the threshold value. The threshold value is stored in advance in, for example, the memory of the control circuit 20. Note that the control circuit 20 compares the current value of the transformer current IL detected by the detector 30 with one threshold value to determine whether or not the current value of the transformer current IL changes, but it may also compare the current value with, for example, multiple threshold values ​​to determine whether or not the current value of the transformer current IL changes.

[0038] (3) Operation of the Power Conversion Device The power conversion device A1 steps down a first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10. In other words, the power conversion device A1 steps down the first voltage Vi to the second voltage Vo by the control circuit 20 performing synchronous rectification. In short, the power conversion device A1 is a DC-DC converter of the synchronous rectification type.

[0039] For example, when the current value of the transformer current IL does not change, that is, when the load current Io does not change (when the operation of the load 40 is stable), the control circuit 20 turns off the switch SW1. Here, the load current Io is the current flowing through the load 40. As a result, in the power conversion device A1, the electrical path between the second inductor L2 and the secondary winding L4 of the first transformer T1 becomes non-conductive, and the inductance of the first inductor L1 is added to the inductance of the combined inductor on the secondary side.

[0040] Furthermore, the control circuit 20 turns on the switch SW1, for example, when the current value of the transformer current IL changes, that is, when the load current Io changes (when the operation of the load 40 changes). For example, the control circuit 20 turns on the switch SW1 when the load 40's computational processing increases (when the load 40 changes from a low-load state to a high-load state) and the transformer current IL increases. The control circuit 20 turns on the switch SW1 when the load 40's computational processing decreases (when the load 40 changes from a high-load state to a low-load state) and the transformer current IL decreases. As a result, in the power conversion device A1, the electrical path between the second inductor L2 and the secondary winding L4 of the first transformer T1 becomes conductive, and the second inductor L2 is connected in parallel to the first inductor L1. Therefore, in the power conversion device A1, the inductance of the combined inductor of the first inductor L1 and the second inductor L2 is added to the inductance of the combined inductor on the secondary side.

[0041] Here, a power conversion device Z1 of a comparative example will be illustrated (see FIG. 4). As shown in FIG. 4, the power conversion device Z1 of the comparative example differs from the power conversion device A1 of the first embodiment in that it does not have the second inductor L2 and the switch SW1 of the power conversion device A1 of the first embodiment. Note that, with respect to the power conversion device Z1 of the comparative example, components similar to those of the power conversion device A1 of the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0042] In the power conversion device Z1 of the comparative example, the first inductor L1 is the only adjusting inductor 7 connected in series to the secondary-side composite inductor both when the operation of the load 40 is stable and when the operation of the load 40 changes. That is, in the power conversion device Z1 of the comparative example, whether the operation of the load 40 is stable or when the operation of the load 40 changes, the inductance of the adjusting inductor 7 added to the inductance of the secondary-side composite inductor is the inductance of the first inductor L1.

[0043] On the other hand, in the power conversion device A1 of the first embodiment, when the operation of the load 40 is stable, the adjustment inductor 7 connected in series to the secondary-side composite inductor is only the first inductor L1, as in the power conversion device Z1 of the comparative example. However, in the power conversion device A1, when the operation of the load 40 changes, the adjustment inductor 7 connected in series to the secondary-side composite inductor is the composite inductor of the first inductor L1 and the second inductor L2. In other words, in the power conversion device A1, when the operation of the load 40 changes, the inductance of the adjustment inductor 7 connected in series to the secondary-side composite inductor changes. In the power conversion device A1, for example, when the load 40 changes from a low-load state to a high-load state, that is, when the transformer current IL increases, the switch SW1 is turned on, and the inductance of the adjustment inductor 7 decreases. In addition, in the power conversion device A1, when the operation of the load 40 is stable, that is, when the transformer current IL is stable, the switch SW1 is turned off, and the inductance of the adjustment inductor 7 increases. Furthermore, in the power conversion device A1, for example, when the load 40 changes from a high load state to a low load state, that is, when the transformer current IL decreases, the switch SW1 is turned on and the inductance of the adjustment inductor 7 decreases.

[0044] Therefore, in the power conversion device A1 of embodiment 1, when the operation of the load 40 changes (when the current value of the transformer current IL changes), the inductance of the adjusting inductor 7 becomes smaller than the inductance of the adjusting inductor 7 in the power conversion device Z1 of the comparative example. Therefore, in the power conversion device A1 of embodiment 1, the change in the transformer current IL (the rise and fall of the transformer current IL) becomes faster than in the power conversion device Z1 of the comparative example, as shown in Fig. 2. In short, the power conversion device A1 of embodiment 1 can improve the load responsiveness more than the power conversion device Z1 of the comparative example.

[0045] Note that Ic in FIG. 2 represents the transformer current of the power conversion device Z1 of the comparative example. Also, IL in FIG. 2 represents the transformer current of the power conversion device A1 of embodiment 1. Also, t1 in FIG. 2 represents the point in time when the load 40 changes from a low load state to a high load state. Also, t2 in FIG. 2 represents the point in time when the operation of the load 40 stabilizes. Also, t3 in FIG. 2 represents the point in time when the load 40 changes from a high load state to a low load state. Also, the solid line in FIG. 2 represents the change in the transformer current. Also, the dashed line in FIG. 2 represents the change in the load current.

[0046] In the power conversion device A1 of the first embodiment, when the operation of the load 40 changes, the inductance of the adjustment inductor 7 is reduced to speed up the change in the transformer current IL and improve load responsiveness, but this results in large ripples in the transformer current IL (see FIG. 3 ). However, when the operation of the load 40 stabilizes, the power conversion device A1 switches the switch SW1 from the on state to the off state to increase the inductance of the adjustment inductor 7, thereby reducing the ripples in the transformer current IL (see FIG. 3 ). In other words, when the operation of the load 40 stabilizes, the power conversion device A1 can achieve lower loss than when the operation of the load 40 changes.

[0047] Therefore, the power conversion device A1 of the first embodiment can improve load responsiveness and reduce loss compared to the power conversion device Z1 of the comparative example. Note that ILa in Fig. 3 represents the transformer current when the operation of the load 40 is stable in the power conversion device A1 of the first embodiment. Also, ILb in Fig. 3 represents the transformer current when the operation of the load 40 changes in the power conversion device A1.

[0048] (4) Modification The inductance of the second inductor L2 is smaller than the inductance of the first inductor L1, but may be the same as the inductance of the first inductor L1, for example. However, in the power conversion device A1 of embodiment 1, by making the inductance of the second inductor L2 smaller than the inductance of the first inductor L1, the inductance of the adjustment inductor 7 can be made smaller than when the inductances are the same. As a result, in the power conversion device A1 of embodiment 1, the output current Io changes more quickly than when the inductances are the same, and load responsiveness can be improved.

[0049] The control circuit 20 controls the switch SW1 based on the transformer current (the current on the primary side of the transformer) IL detected by the detector 30, but may also control the switch SW1 based on the current on the secondary side of the transformer. The control circuit 20 controls the switch SW1 based on the transformer current (the input current of the second capacitor C2) IL detected by the detector 30, but may also control the switch SW1 based on, for example, the input voltage (voltage across both ends) of the second capacitor C2. That is, the detector 30 may detect, for example, the input voltage of the second capacitor C2. The detector 30 has the detection circuit connected in parallel to the primary-side composite inductor, but may also be connected in parallel to, for example, the primary winding L7 of the third transformer T3. The detector 30 has the detection circuit connected in parallel to the primary-side composite inductor, but may also be connected in parallel to, for example, the secondary-side composite inductor. The detector 30 has the detection circuit connected in parallel to, for example, the secondary winding L8 of the third transformer T3. The input current of the second capacitor C2 means the current that reaches the high potential side terminal of the second capacitor C2.

[0050] The control circuit 20 controls the switch SW1 based on the transformer current (input current to the second capacitor C2) IL detected by the detector 30, but may also control the switch SW1 based on, for example, the load current Io or the output voltage Vo. The control circuit 20 may also control the switch SW1 based on, for example, both the input voltage Vi of the first capacitor C1 and the voltage (output voltage) Vo across the second capacitor C2.

[0051] In addition, the control circuit 20 compares the current value of the transformer current IL detected by the detector 30 with a threshold value to determine whether the current value of the transformer current IL changes, but it may also compare, for example, the amount of change in the transformer current IL (the amount of change in the transformer current IL per unit time) with a threshold value to determine whether the current value of the transformer current IL changes.

[0052] Alternatively, the control circuit 20 may perform an error determination by detecting, for example, the transformer current IL, the load current Io, the voltage (output voltage) Vo across the second capacitor C2, the input voltage Vi of the first capacitor C1, etc., using the detector 30, and control the switch SW1 based on the error determination result. Alternatively, the control circuit 20 may perform both a threshold determination and an error determination, and control the switch SW1 based on both determination results.

[0053] The detector 30 is not limited to a detection circuit in which a resistor and a capacitor are connected in series with each other, but may also include, for example, a current detection circuit using a shunt resistor, an IC utilizing the Hall effect, or a CT (Current Transformer).

[0054] Furthermore, the control circuit 20 may control the switch SW1 in response to, for example, a signal (such as a notification signal) from the load 40. The notification signal is, for example, a signal that notifies in advance of the state of the load 40 (such as when the load 40 changes from a low load state to a high load state). Note that the notification signal is not limited to notifying in advance of the state of the load 40, but may also notify, for example, simultaneously with the timing when the state of the load 40 changes.

[0055] In the power conversion device A1 of the first embodiment, the switch SW1 is disposed between the series circuit 8 and the second inductor L2. However, for example, the switch SW1 may be disposed between the second inductor L2 and the low-potential terminal of the first capacitor C1. In this case, a first end of the second inductor L2 is electrically connected to the series circuit 8 (a first end of the secondary winding L4 of the first transformer T1). A drain terminal of the switch SW1 is electrically connected to a second end of the second inductor L2. A source terminal of the switch SW1 is electrically connected to the low-potential terminal of the first capacitor C1.

[0056] The first inductor L1, the second inductor L2, and the switch SW1 are electrically connected to the secondary winding L4 of the first transformer T1, but may also be electrically connected to, for example, the secondary winding L8 of the third transformer T3. In this case, a first end of the first inductor L1 is electrically connected to the secondary winding L8, and a second end of the first inductor L1 is electrically connected to the low-potential terminal of the first capacitor C1. A first end of the second inductor L2 is electrically connected to the secondary winding L8, and a second end of the second inductor L2 is electrically connected to the source terminal of the switch SW1. A drain terminal of the switch SW1 is electrically connected to the low-potential terminal of the first capacitor C1. Note that the positions of the second inductor L2 and the switch SW1 may be reversed.

[0057] Although the control circuit 20 controls the switching elements Q1 to Q6 and the switch SW1, for example, the power conversion device A1 may include a plurality of control circuits (for example, a first control circuit and a second control circuit), with the first control circuit controlling the switching elements Q1 to Q6 and the second control circuit controlling the switch SW1. In other words, the first control circuit may control the first switching circuit 11, the second switching circuit 12, and the third switching circuit 13, and the second control circuit may control the switch SW1.

[0058] The number of the multiple switching circuits 10 is not limited to three, and may be, for example, two switching circuits 10, or four or more switching circuits 10. In short, the multiple switching circuits 10 may include at least two switching circuits 10 (for example, a first switching circuit 11 and a second switching circuit 12).

[0059] The number of the multiple transformers 6 is not limited to three, but may be, for example, two transformers 6, or four or more transformers 6. In short, the multiple transformers 6 may include at least two transformers 6 (for example, a first transformer T1 and a second transformer T2).

[0060] Each of the switching elements Q1 to Q6 is not limited to a Si-MOSFET, and may be, for example, a SiC-MOSFET, a GaN-MOSFET, or the like. Furthermore, each of the switching elements Q1 to Q6 is not limited to a MOSFET, and may be, for example, an IGBT (Insulated Gate Bipolar Transistor). In this case, the first main terminal, the second main terminal, and the control terminal of each of the switching elements Q1 to Q6 become a collector terminal, an emitter terminal, and a gate terminal. The switch SW1 is not limited to a Si-MOSFET, and may be, for example, a SiC-MOSFET, a GaN-MOSFET, or the like. Furthermore, the switch SW1 is not limited to a MOSFET, and may be, for example, an IGBT, or the like. In this case, the first main terminal, the second main terminal, and the control terminal of the switch SW1 become a collector terminal, an emitter terminal, and a gate terminal.

[0061] The power conversion device A1 has a pair of input terminals 1a and 1b, but does not necessarily have to have the pair of input terminals 1a and 1b. Also, the power conversion device A1 has a pair of output terminals 2a and 2b, but does not necessarily have to have the pair of output terminals 2a and 2b. The detector 30 is located outside the control circuit 20, but may be located inside the control circuit 20. That is, in the power conversion device A1, the control circuit 20 may include the detector 30, or the control circuit 20 may have the function of the detector 30.

[0062] The control circuit 20 is not limited to a computer system having one or more processors and one or more memories, but may be, for example, a microcomputer. The number of second inductors L2 is one, but may be multiple. In other words, at least one second inductor L2 is sufficient. In this case, the number of switches SW1 is also not limited to one, but may be multiple. In other words, at least one switch SW1 is sufficient.

[0063] The power conversion device A1 is a step-down DC-DC converter, but may be a step-up DC-DC converter. The power conversion device A1 is a step-down DC-DC converter, but may be a bidirectional DC-DC converter. The power conversion device A1 is not limited to a synchronous rectification DC-DC converter, but may be, for example, an asynchronous rectification DC-DC converter.

[0064] The first embodiment and the modifications described above are merely a part of the various embodiments and modifications of the present disclosure.

[0065] Second Embodiment Hereinafter, a power conversion device according to a second embodiment will be described with reference to FIGS. 5 and 6. FIG.

[0066] The power conversion device A2 according to the second embodiment differs from the power conversion device A1 according to the first embodiment in that the first inductor L1 is represented by an equivalent circuit including an inductance component Lx1 and a DC resistance component R1, as shown in Fig. 5. Note that, with respect to the power conversion device A2 according to the second embodiment, the same components as those of the power conversion device A1 according to the first embodiment (see Figs. 1 to 3) are denoted by the same reference numerals and description thereof will be omitted.

[0067] (1) Power Conversion Device As shown in FIG. 5 , the first inductor L1 is represented by an equivalent circuit including an inductance component Lx1 and a DC resistance component R1. The inductance component Lx1 and the DC resistance component R1 are connected in series. The first end of the inductance component Lx1 is the first end of the first inductor L1. That is, the first end of the inductance component Lx1 is electrically connected to the secondary winding L4 of the first transformer T1. The second end of the inductance component Lx1 is electrically connected to the DC resistance component R1. The first end of the DC resistance component R1 is electrically connected to the second end of the inductance component Lx1. The second end of the DC resistance component R1 is the second end of the first inductor L1. That is, the second end of the DC resistance component R1 is electrically connected to the low-potential terminal of the first capacitor C1.

[0068] The second inductor L2 is represented by an equivalent circuit including an inductance component Lx2 and a DC resistance component R2. The inductance component Lx2 and the DC resistance component R2 are connected in series. The first end of the inductance component Lx2 is the first end of the second inductor L2. That is, the first end of the inductance component Lx2 is electrically connected to the switch SW1. The second end of the inductance component Lx2 is electrically connected to the DC resistance component R2. The first end of the DC resistance component R2 is electrically connected to the second end of the inductance component Lx2. The second end of the DC resistance component R2 is the second end of the second inductor L2. That is, the second end of the DC resistance component R2 is electrically connected to the low-potential terminal of the first capacitor C1.

[0069] The primary winding L3 of the first transformer T1 is represented by an equivalent circuit including an inductance component Lx3 and a DC resistance component R3. The inductance component Lx3 and the DC resistance component R3 are connected in series. The first end of the inductance component Lx3 is the second end of the primary winding L3 of the first transformer T1. That is, the first end of the inductance component Lx3 is electrically connected to the primary winding L5 of the second transformer T2. The second end of the inductance component Lx3 is electrically connected to the DC resistance component R3. The first end of the DC resistance component R3 is electrically connected to the second end of the inductance component Lx3. The second end of the DC resistance component R3 is the first end of the primary winding L3 of the first transformer T1. That is, the second end of the DC resistance component R3 is electrically connected to the connection point 3 of the first switching element Q1 and the second switching element Q2 in the first switching circuit 11.

[0070] The secondary winding L4 of the first transformer T1 is represented by an equivalent circuit including an inductance component Lx4 and a DC resistance component R4. The inductance component Lx4 and the DC resistance component R4 are connected in series. The first end of the inductance component Lx4 is the second end of the secondary winding L4 of the first transformer T1. In other words, the first end of the inductance component Lx4 is electrically connected to the secondary winding L6 of the second transformer T2. The second end of the inductance component Lx4 is electrically connected to the DC resistance component R4. The first end of the DC resistance component R4 is electrically connected to the second end of the inductance component Lx4. The second end of the DC resistance component R4 is the first end of the secondary winding L4 of the first transformer T1. In other words, the second end of the DC resistance component R4 is electrically connected to the first inductor L1 and the switch SW1.

[0071] The primary winding L5 of the second transformer T2 is represented by an equivalent circuit including an inductance component Lx5 and a DC resistance component R5. The inductance component Lx5 and the DC resistance component R5 are connected in series. The first end of the inductance component Lx5 is the second end of the primary winding L5 of the second transformer T2. In other words, the first end of the inductance component Lx5 is electrically connected to the primary winding L7 of the third transformer T3. The second end of the inductance component Lx5 is electrically connected to the DC resistance component R5. The first end of the DC resistance component R5 is electrically connected to the second end of the inductance component Lx5. The second end of the DC resistance component R5 is the first end of the primary winding L5 of the second transformer T2. In other words, the second end of the DC resistance component R5 is electrically connected to the connection point 4 of the third switching element Q3 and the fourth switching element Q4 in the second switching circuit 12.

[0072] The secondary winding L6 of the second transformer T2 is represented by an equivalent circuit including an inductance component Lx6 and a DC resistance component R6. The inductance component Lx6 and the DC resistance component R6 are connected in series. The first end of the inductance component Lx6 is the second end of the secondary winding L6 of the second transformer T2. In other words, the first end of the inductance component Lx6 is electrically connected to the secondary winding L8 of the third transformer T3. The second end of the inductance component Lx6 is electrically connected to the DC resistance component R6. The first end of the DC resistance component R6 is electrically connected to the second end of the inductance component Lx6. The second end of the DC resistance component R6 is the first end of the secondary winding L6 of the second transformer T2. In other words, the second end of the DC resistance component R6 is electrically connected to the secondary winding L4 of the first transformer T1.

[0073] The primary winding L7 of the third transformer T3 is represented by an equivalent circuit including a seventh inductance component Lx7 and a seventh DC resistance component R7. The seventh inductance component Lx7 and the seventh DC resistance component R7 are connected in series. The first end of the seventh inductance component Lx7 is the second end of the primary winding L7 of the third transformer T3. That is, the first end of the seventh inductance component Lx7 is electrically connected to the high-potential terminal of the second capacitor C2. The second end of the seventh inductance component Lx7 is electrically connected to the seventh DC resistance component R7. The first end of the seventh DC resistance component R7 is electrically connected to the second end of the seventh inductance component Lx7. The second end of the seventh DC resistance component R7 is the first end of the primary winding L7 of the third transformer T3. That is, the second end of the seventh DC resistance component R7 is electrically connected to the connection point 5 of the fifth switching element Q5 and the sixth switching element Q6 in the third switching circuit 13.

[0074] The secondary winding L8 of the third transformer T3 is represented by an equivalent circuit including an eighth inductance component Lx8 and an eighth DC resistance component R8. The eighth inductance component Lx8 and the eighth DC resistance component R8 are connected in series. The first end of the eighth inductance component Lx8 is the second end of the secondary winding L8 of the third transformer T3. In other words, the first end of the eighth inductance component Lx8 is electrically connected to the low-potential terminal of the first capacitor C1. The second end of the eighth inductance component Lx8 is electrically connected to the eighth DC resistance component R8. The first end of the eighth DC resistance component R8 is electrically connected to the second end of the eighth inductance component Lx8. The second end of the eighth DC resistance component R8 is the first end of the secondary winding L8 of the third transformer T3. In other words, the second end of the eighth DC resistance component R8 is electrically connected to the secondary winding L6 of the second transformer T2.

[0075] For example, the DC resistance component R1, the DC resistance component R2, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 have the same resistance value. The DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7 have the same resistance value. Note that "same" does not necessarily mean that they are completely the same, but also includes a deviation of, for example, about ±10%.

[0076] The resistance values ​​of the DC resistance component R1, the DC resistance component R2, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 are smaller than the resistance values ​​of the DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7. The inductance of the inductance component Lx2 is smaller than the inductance of the inductance component Lx1. In other words, the inductance of the second inductor L2 is smaller than the inductance of the first inductor L1.

[0077] (2) Operation of the Power Conversion Device Similar to the power conversion device A1 of embodiment 1, the power conversion device A2 reduces the first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10.

[0078] The control circuit 20 turns the switch SW1 off when the operation of the load 40 is stable (when the current value of the transformer current IL does not change), similar to the control circuit 20 of the power conversion device A1 of embodiment 1. Furthermore, the control circuit 20 turns the switch SW1 on when the operation of the load 40 changes (when the current value of the transformer current IL changes), similar to the control circuit 20 of the power conversion device A1 of embodiment 1.

[0079] Therefore, in the power conversion device A2 of the second embodiment, similarly to the power conversion device A1 of the first embodiment, when the operation of the load 40 changes, the inductance of the adjusting inductor 7 becomes smaller than the inductance of the adjusting inductor 7 in the power conversion device Z1 of the comparative example (see FIG. 4). Therefore, in the power conversion device A2 of the second embodiment, the change in the transformer current IL is faster than in the power conversion device Z1 of the comparative example, as shown in FIG. 6. In other words, the power conversion device A2 of the second embodiment can improve the load responsiveness compared to the power conversion device Z1 of the comparative example.

[0080] Furthermore, in the power conversion device A2, the resistance values ​​of the DC resistance component R1, the DC resistance component R2, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 are smaller than the resistance values ​​of the DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7, so that the change in the transformer current IL is faster than in the power conversion device A1 of embodiment 1. Therefore, the power conversion device A2 of embodiment 2 can improve the load responsiveness more than the power conversion device Z1 of the comparative example. Therefore, the power conversion device A2 of embodiment 2 can improve the load responsiveness more than the power conversion device Z1 of the comparative example, and can achieve lower loss.

[0081] Note that Ic in FIG. 6 represents the transformer current of the power conversion device Z1 of the comparative example. Also, IL in FIG. 6 represents the transformer current of the power conversion device A2 of embodiment 2. Also, t1 in FIG. 6 represents the point in time when the load 40 changes from a low load state to a high load state. Also, t2 in FIG. 6 represents the point in time when the operation of the load 40 stabilizes. Also, t3 in FIG. 6 represents the point in time when the load 40 changes from a high load state to a low load state. Also, the solid line in FIG. 6 represents the change in the transformer current. Also, the dashed line in FIG. 6 represents the change in the load current.

[0082] (3) Modifications As a modification of the second embodiment, modifications similar to those of the power conversion device A1 according to the modification of the first embodiment are possible. Therefore, the power conversion device A2 according to the modification of the second embodiment also achieves the same effects as the power conversion device A2 according to the second embodiment.

[0083] The inductance of the inductance component Lx2 is smaller than the inductance of the inductance component Lx1, but may be the same as the inductance of the inductance component Lx1, for example. However, in the power conversion device A2 of embodiment 2, by making the inductance of the inductance component Lx2 smaller than the inductance of the inductance component Lx1, the inductance of the adjustment inductor 7 can be made smaller than when the inductances of the inductance components Lx1 and Lx2 are the same. As a result, in the power conversion device A2 of embodiment 2, the change in the transformer current IL is faster than when the inductances of the inductance components Lx1 and Lx2 are the same, and load responsiveness can be improved.

[0084] The second embodiment and the modified examples described above are merely a part of the various embodiments and modified examples of the present disclosure.

[0085] Third Embodiment Hereinafter, a power conversion device according to a third embodiment will be described with reference to FIGS. 7 and 8. FIG.

[0086] 7, the power conversion device A3 according to the third embodiment differs from the power conversion device A1 according to the first embodiment in that it further includes a second switch SW2. Note that, with respect to the power conversion device A3 according to the third embodiment, the same components as those of the power conversion device A1 according to the first embodiment (see FIGS. 1 to 3) are denoted by the same reference numerals and description thereof will be omitted.

[0087] (1) Power Conversion Device The power conversion device A3 further includes a second switch SW2 different from the switch (first switch) SW1. The second switch SW2 is a switching element such as a MOSFET. The second switch SW2 has a first main terminal, a second main terminal, and a control terminal. In the following description, to facilitate understanding of the embodiments, the first main terminal will be referred to as the drain terminal, the second main terminal as the source terminal, and the control terminal as the gate terminal.

[0088] The drain terminal of the second switch SW2 is electrically connected to the first end of the secondary winding L4 of the first transformer T1. The gate terminal of the second switch SW2 is electrically connected to the control circuit 20. The source terminal of the second switch SW2 is electrically connected to the first end of the first inductor L1.

[0089] The control circuit 20 controls the second switch SW2. More specifically, the control circuit 20 switches the second switch SW2 between an ON state and an OFF state based on, for example, the current value of the transformer current IL detected by the detector 30. For example, when the current value of the transformer current IL detected by the detector 30 crosses a threshold, the control circuit 20 turns the first switch SW1 ON and the second switch SW2 OFF. For example, when the current value of the transformer current IL is greater than the threshold, the control circuit 20 turns the first switch SW1 ON and the second switch SW2 OFF. That is, when the current value of the transformer current IL detected by the detector 30 changes, the control circuit 20 turns the first switch SW1 ON and the second switch SW2 OFF. On the other hand, when the current value of the transformer current IL detected by the detector 30 does not change, the control circuit 20 turns the first switch SW1 OFF and the second switch SW2 ON. More specifically, for example, when the current value of the transformer current IL detected by the detector 30 does not change for a predetermined period, the control circuit 20 turns the first switch SW1 to the OFF state and the second switch SW2 to the ON state. Furthermore, when the current value of the transformer current IL becomes smaller than a threshold value, the control circuit 20 turns the first switch SW1 to the ON state and the second switch SW2 to the OFF state.

[0090] (2) Operation of the Power Conversion Device Similar to the power conversion device A1 of embodiment 1, the power conversion device A3 reduces the first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10.

[0091] When the operation of the load 40 is stable (when the current value of the transformer current IL does not change), the control circuit 20 turns the first switch SW1 off and the second switch SW2 on. When the operation of the load 40 changes (when the current value of the transformer current IL changes), the control circuit 20 turns the first switch SW1 on and the second switch SW2 off.

[0092] Therefore, in the power conversion device A3 of embodiment 3, similar to the power conversion device A1 of embodiment 1, when the operation of the load 40 changes, the inductance of the adjusting inductor 7 becomes smaller than the inductance of the adjusting inductor 7 in the power conversion device Z1 of the comparative example (see FIG. 4 ). Therefore, as shown in FIG. 8 , the power conversion device A3 of embodiment 3 changes the transformer current IL more quickly than the power conversion device Z1 of the comparative example. That is, the power conversion device A3 of embodiment 3 can improve load responsiveness and reduce loss compared to the power conversion device Z1 of the comparative example. Note that Ic in FIG. 8 represents the transformer current of the power conversion device Z1 of the comparative example. Also, IL in FIG. 8 represents the transformer current of the power conversion device A3 of embodiment 3. Also, t1 in FIG. 8 represents the time when the load 40 changes from a low load state to a high load state. Also, t2 in FIG. 8 represents the time when the operation of the load 40 stabilizes. Also, t3 in FIG. 8 represents the time when the load 40 changes from a high load state to a low load state. 8 indicates the change in transformer current, and the dashed dotted line indicates the change in load current.

[0093] (3) Modifications As a modification of the third embodiment, modifications similar to those of the power conversion device A1 according to the modification of the first embodiment are possible. Therefore, the power conversion device A3 according to the modification of the third embodiment also achieves the same effects as the power conversion device A3 according to the third embodiment.

[0094] The second switch SW2 is not limited to a Si-MOSFET and may be, for example, a SiC-MOSFET, a GaN-MOSFET, etc. Furthermore, the second switch SW2 is not limited to a MOSFET and may be, for example, an IGBT, etc. In this case, the first main terminal, the second main terminal, and the control terminal of the switch SW1 become the collector terminal, the emitter terminal, and the gate terminal.

[0095] The third embodiment and the modifications described above are merely a part of the various embodiments and modifications of the present disclosure.

[0096] Fourth Embodiment Hereinafter, a power conversion device according to a fourth embodiment will be described with reference to FIGS. 9 and 10. FIG.

[0097] As shown in Fig. 9 , the power conversion device A4 according to the fourth embodiment differs from the power conversion device A3 according to the third embodiment in that, like the power conversion device A2 according to the second embodiment, the first inductor L1 is represented by an equivalent circuit including an inductance component Lx1 and a DC resistance component R1. That is, the power conversion device A4 according to the fourth embodiment is a power conversion device obtained by appropriately combining the power conversion device A3 according to the third embodiment with a portion of the configuration of the power conversion device A2 according to the second embodiment. Note that, with respect to the power conversion device A4 according to the fourth embodiment, the same components as those of the power conversion device A2 according to the second embodiment (see Fig. 5 ) and the power conversion device A3 according to the third embodiment (see Fig. 7 ) are denoted by the same reference numerals, and description thereof will be omitted.

[0098] (1) Power Conversion Device A first end of the inductance component Lx1 is electrically connected to the source terminal of the second switch SW2. A second end of the inductance component Lx1 is electrically connected to the DC resistance component R1. A first end of the DC resistance component R1 is electrically connected to the second end of the inductance component Lx1. A second end of the DC resistance component R1 is electrically connected to the low-potential terminal of the first capacitor C1.

[0099] (2) Operation of the Power Conversion Device As with the power conversion device A3 of embodiment 3, the power conversion device A4 reduces the first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10.

[0100] The control circuit 20, like the control circuit 20 of the power conversion device A1 of embodiment 3, turns the first switch SW1 off and the second switch SW2 on when the operation of the load 40 is stable (when the current value of the transformer current IL does not change). Also, like the control circuit 20 of the power conversion device A1 of embodiment 3, the control circuit 20 turns the first switch SW1 on and the second switch SW2 off when the operation of the load 40 changes (when the current value of the transformer current IL changes).

[0101] Therefore, in the power conversion device A4 of embodiment 4, similarly to the power conversion device A3 of embodiment 3, when the operation of the load 40 changes, the inductance of the adjusting inductor 7 becomes smaller than the inductance of the adjusting inductor 7 in the power conversion device Z1 of the comparative example (see FIG. 4). Therefore, in the power conversion device A4 of embodiment 4, the change in the transformer current IL is faster than in the power conversion device Z1 of the comparative example, as shown in FIG. 10. In other words, the power conversion device A4 of embodiment 4 can improve the load responsiveness compared to the power conversion device Z1 of the comparative example.

[0102] Furthermore, in the power conversion device A4, the resistance values ​​of the DC resistance component R1, the DC resistance component R2, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 are smaller than the resistance values ​​of the DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7. Therefore, the power conversion device A4 changes the output current Io more quickly than the power conversion device A3 of the third embodiment. Therefore, the power conversion device A4 of the fourth embodiment can improve the load response more than the power conversion device Z1 of the comparative example. That is, the power conversion device A4 of the fourth embodiment can improve the load response more than the power conversion device Z1 of the comparative example, and can achieve lower loss.

[0103] Note that Ic in Figure 10 represents the transformer current of the power conversion device Z1 of the comparative example. Also, IL in Figure 10 represents the transformer current of the power conversion device A4 of embodiment 4. Also, t1 in Figure 10 represents the point in time when the load 40 changes from a low load state to a high load state. Also, t2 in Figure 10 represents the point in time when the operation of the load 40 stabilizes. Also, t3 in Figure 10 represents the point in time when the load 40 changes from a high load state to a low load state. Also, the solid line in Figure 10 represents the change in transformer current. Also, the dashed line in Figure 10 represents the change in load current.

[0104] (3) Modifications As a modification of the fourth embodiment, modifications similar to those of the power conversion device A3 according to the modification of the third embodiment are possible. Therefore, the power conversion device A4 according to the modification of the fourth embodiment also achieves the same effects as the power conversion device A4 according to the fourth embodiment.

[0105] The fourth embodiment and the modifications described above are merely a part of the various embodiments and modifications of the present disclosure.

[0106] Fifth Embodiment Hereinafter, a power conversion device according to a fifth embodiment will be described with reference to FIG.

[0107] 11, the power conversion device A5 according to the fifth embodiment differs from the power conversion device A1 according to the first embodiment in that the power conversion device A5 does not include the second inductor L2, and the switch SW1 and the first inductor L1 are connected in series with each other. Note that, with respect to the power conversion device A5 according to the fifth embodiment, the same components as those of the power conversion device A1 according to the first embodiment (see FIGS. 1 to 3) are denoted by the same reference numerals, and description thereof will be omitted.

[0108] (1) Power Conversion Device A first end of the first inductor L1 is electrically connected to a first end of the secondary winding L4 of the first transformer T1 via a switch SW1. A second end of the first inductor L1 is electrically connected to a low-potential terminal of a first capacitor C1. A drain terminal of the switch SW1 is electrically connected to a first end of the secondary winding L4 of the first transformer T1. A gate terminal of the switch SW1 is electrically connected to the control circuit 20. A source terminal of the switch SW1 is electrically connected to the first end of the first inductor L1.

[0109] (2) Operation of the Power Conversion Device Similar to the power conversion device A1 of embodiment 1, the power conversion device A5 reduces the first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10.

[0110] The control circuit 20 turns the switch SW1 off when the operation of the load 40 is stable (when the current value of the transformer current IL does not change), similar to the control circuit 20 of the power conversion device A1 of embodiment 1. Furthermore, the control circuit 20 turns the switch SW1 on when the operation of the load 40 changes (when the current value of the transformer current IL changes), similar to the control circuit 20 of the power conversion device A1 of embodiment 1.

[0111] In the power conversion device A5 of the fifth embodiment, the switch SW1 is turned on when the operation of the load 40 changes, and so the power conversion device A5 has a so-called TLVR circuit configuration similar to the power conversion device Z1 of the comparative example. Therefore, when the operation of the load 40 changes, the inductance of the power conversion device A5 decreases, and therefore the load responsiveness can be improved more than, for example, a multi-phase DC-DC converter.

[0112] Furthermore, in the power conversion device A5, when the operation of the load 40 is stable, the switch SW1 is turned off, and the electrical path between the first inductor L1 and the secondary winding L4 of the first transformer T1 is non-conductive. In other words, when the operation of the load 40 is stable, the secondary side of the transformer is non-conductive in the power conversion device A5, resulting in a circuit configuration similar to that of a multi-phase DC-DC converter. Therefore, when the operation of the load 40 is stable, the power conversion device A5 has a smaller ripple in the transformer current IL than the power conversion device Z1 of the comparative example, making it possible to achieve low loss. Therefore, the power conversion device A5 of embodiment 5 can improve load responsiveness and achieve low loss.

[0113] (3) Modifications As a modification of the fifth embodiment, modifications similar to those of the power conversion device A1 according to the modification of the first embodiment are possible. Therefore, the power conversion device A5 according to the modification of the fifth embodiment also achieves the same effects as the power conversion device A5 according to the fifth embodiment.

[0114] The fifth embodiment and the modifications described above are merely a part of the various embodiments and modifications of the present disclosure.

[0115] Sixth Embodiment A power conversion device according to a sixth embodiment will be described below with reference to FIGS. 12 and 13. FIG.

[0116] As shown in Fig. 12 , the power conversion device A6 according to the sixth embodiment differs from the power conversion device A5 according to the fifth embodiment in that, like the power conversion device A2 according to the second embodiment, the first inductor L1 is represented by an equivalent circuit including an inductance component Lx1 and a DC resistance component R1. That is, the power conversion device A6 according to the sixth embodiment is a power conversion device obtained by appropriately combining the power conversion device A5 according to the fifth embodiment with a portion of the configuration of the power conversion device A2 according to the second embodiment. Note that, with respect to the power conversion device A6 according to the sixth embodiment, the same components as those of the power conversion device A2 according to the second embodiment (see Fig. 5 ) and the power conversion device A5 according to the fifth embodiment (see Fig. 11 ) are denoted by the same reference numerals, and description thereof will be omitted.

[0117] (1) Power Conversion Device A first end of the inductance component Lx1 is electrically connected to the source terminal of the switch SW1. A second end of the inductance component Lx1 is electrically connected to the DC resistance component R1. A first end of the DC resistance component R1 is electrically connected to the second end of the inductance component Lx1. A second end of the DC resistance component R1 is electrically connected to the low-potential terminal of the first capacitor C1.

[0118] For example, the DC resistance component R1, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 have the same resistance value. The DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7 have the same resistance value. Note that "same" does not necessarily mean that they are completely the same, but also includes a deviation of, for example, about ±10%.

[0119] The resistance values ​​of the DC resistance component R1, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 are smaller than the resistance values ​​of the DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7.

[0120] (2) Operation of the Power Conversion Device As with the power conversion device A5 of embodiment 5, the power conversion device A6 reduces the first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10.

[0121] The control circuit 20 turns the switch SW1 off when the operation of the load 40 is stable (when the current value of the transformer current IL does not change), similar to the control circuit 20 of the power conversion device A5 of embodiment 5. Also, the control circuit 20 turns the switch SW1 on when the operation of the load 40 changes (when the current value of the transformer current IL changes), similar to the control circuit 20 of the power conversion device A5 of embodiment 5.

[0122] The power conversion device A6 of the sixth embodiment is configured as a TLVR circuit when the operation of the load 40 changes, similar to the power conversion device A5 of the fifth embodiment. Therefore, when the operation of the load 40 changes, the power conversion device A6 can improve the load responsiveness more than, for example, a multi-phase DC-DC converter.

[0123] Furthermore, in the power conversion device A6, the resistance values ​​of the DC resistance component R1, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 are smaller than the resistance values ​​of the DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7. Therefore, as shown in Fig. 13, when the operation of the load 40 changes, the power conversion device A6 changes the transformer current IL more quickly than the power conversion device A5 of the fifth embodiment, and it is possible to further improve the load responsiveness.

[0124] Note that IL5 in Fig. 13 represents the transformer current of the power conversion device A5 of embodiment 5. Also, IL6 in Fig. 13 represents the transformer current of the power conversion device A6 of embodiment 6. In Fig. 13, t1 represents the point in time when the load 40 changes from a low load state to a high load state. Also, t2 in Fig. 13 represents the point in time when the operation of the load 40 stabilizes. Also, t3 in Fig. 13 represents the point in time when the load 40 changes from a high load state to a low load state. Also, the solid line in Fig. 13 represents the change in the transformer current. Also, the dashed line in Fig. 13 represents the change in the load current.

[0125] Furthermore, in the power conversion device A6, as in the power conversion device A5 of embodiment 5, when the operation of the load 40 is stable, the switch SW1 is turned off, so that the ripple of the transformer current IL is smaller than that in the power conversion device Z1 of the comparative example, and it is possible to achieve low loss. Therefore, in the power conversion device A6 of embodiment 6, it is possible to further improve the load responsiveness and achieve low loss.

[0126] (3) Modifications As a modification of the sixth embodiment, modifications similar to those of the power conversion device A5 according to the modification of the fifth embodiment are possible. Therefore, the power conversion device A6 according to the modification of the sixth embodiment also achieves the same effects as the power conversion device A6 according to the sixth embodiment.

[0127] The sixth embodiment and the modifications described above are merely a part of the various embodiments and modifications of the present disclosure.

[0128] Seventh Embodiment A power conversion device according to a seventh embodiment will be described below with reference to FIGS.

[0129] As shown in Fig. 14, the power conversion device A7 according to the seventh embodiment differs from the power conversion device A5 according to the fifth embodiment in that the power conversion device A7 according to the seventh embodiment does not include the first inductor L1. Note that, with respect to the power conversion device A7 according to the seventh embodiment, the same components as those of the power conversion device A5 according to the fifth embodiment (see Fig. 11) are denoted by the same reference numerals and description thereof will be omitted.

[0130] (1) Power Conversion Device A drain terminal of the switch SW1 is electrically connected to a first end of the secondary winding L4 of the first transformer T1. A gate terminal of the switch SW1 is electrically connected to the control circuit 20. A source terminal of the switch SW1 is electrically connected to the low-potential terminal of the first capacitor C1.

[0131] The power conversion device A7 uses a parasitic inductance component of an electric path 9 that electrically connects the source terminal of the switch SW1 and the low-potential side terminal of the first capacitor C1, instead of the first inductor L1 in the power conversion device A5 of embodiment 5. The parasitic inductance component of the electric path 9 is smaller than the inductance of the first inductor L1 (see FIG. 11 ), for example.

[0132] (2) Operation of the Power Conversion Device As with the power conversion device A5 of embodiment 5, the power conversion device A7 reduces the first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10.

[0133] The control circuit 20 turns the switch SW1 off when the operation of the load 40 is stable (when the current value of the transformer current IL does not change), similar to the control circuit 20 of the power conversion device A5 of embodiment 5. Also, the control circuit 20 turns the switch SW1 on when the operation of the load 40 changes (when the current value of the transformer current IL changes), similar to the control circuit 20 of the power conversion device A5 of embodiment 5.

[0134] The power conversion device A7 of embodiment 7 uses the parasitic inductance component of the electric circuit 9 instead of the first inductor L1, and therefore, when the operation of the load 40 changes, the transformer current IL changes more quickly than in the power conversion device A5 of embodiment 5. That is, the power conversion device A7 of embodiment 7 can improve the load responsiveness more than the power conversion device Z1 of the comparative example ( FIGS. 15 and 16 ).

[0135] Note that Ic in Figures 15 and 16 represents the transformer current of the power conversion device Z1 of the comparative example. IL in Figures 15 and 16 represents the transformer current of the power conversion device A7 of embodiment 7. t1 in Figure 15 represents the point in time when the load 40 changes from a low load state to a high load state. t2 in Figure 16 represents the point in time when the operation of the load 40 stabilizes. t3 in Figure 16 represents the point in time when the load 40 changes from a high load state to a low load state. The solid lines in Figures 15 and 16 represent changes in the transformer current. The dashed lines in Figures 15 and 16 represent changes in the load current.

[0136] Furthermore, in the power conversion device A7 of embodiment 7, similar to the power conversion device A5 of embodiment 5, when the operation of the load 40 is stable, the switch SW1 is turned off, thereby causing the current path between the current path 9 and the secondary winding L4 of the first transformer T1 to be non-conductive. In other words, when the operation of the load 40 is stable, the secondary side of the transformer is non-conductive, resulting in a circuit configuration similar to that of a multi-phase DC-DC converter. Therefore, when the operation of the load 40 is stable, the power conversion device A7 produces a smaller ripple in the transformer current IL than the power conversion device Z1 of the comparative example, thereby enabling lower loss. Therefore, the power conversion device A7 of embodiment 7 can achieve improved load responsiveness and lower loss compared to the power conversion device Z1 of the comparative example. Furthermore, because the power conversion device A7 uses the parasitic inductance component of the current path 9 instead of the first inductor L1, the number of components can be reduced compared to the power conversion device A5 of embodiment 5, thereby enabling more effective use of the mounting space on a circuit board including the power conversion device A7.

[0137] (3) Modifications As a modification of the seventh embodiment, modifications similar to those of the power conversion device A5 according to the modification of the fifth embodiment are possible. Therefore, the power conversion device A7 according to the modification of the seventh embodiment also achieves the same effects as the power conversion device A7 according to the seventh embodiment.

[0138] The seventh embodiment and the modifications described above are merely a part of the various embodiments and modifications of the present disclosure.

[0139] Eighth Embodiment Hereinafter, a power conversion device according to an eighth embodiment will be described with reference to FIGS. 17 and 18. FIG.

[0140] As shown in Fig. 17 , the power conversion device A8 according to the eighth embodiment differs from the power conversion device A6 according to the sixth embodiment in that the power conversion device A8 does not include the switch SW1. In other words, the power conversion device A8 differs from the power conversion device Z1 of the comparative example in that the first inductor L1 is represented by an equivalent circuit including an inductance component Lx1 and a DC resistance component R1. Note that, with respect to the power conversion device A8 according to the eighth embodiment, the same components as those of the power conversion device A6 according to the sixth embodiment (see Fig. 12 ) are denoted by the same reference numerals and description thereof will be omitted.

[0141] (1) Power Conversion Device The power conversion device A8 does not include the switch SW1 of the power conversion device A6 of embodiment 6. That is, the control circuit 20 controls the first switching circuit 11, the second switching circuit 12, and the third switching circuit 13.

[0142] A first end of the inductance component Lx1 is electrically connected to the secondary winding L4 of the first transformer T1. A second end of the inductance component Lx1 is electrically connected to the DC resistance component R1. A first end of the DC resistance component R1 is electrically connected to the second end of the inductance component Lx1. A second end of the DC resistance component R1 is electrically connected to the low-potential terminal of the first capacitor C1.

[0143] (2) Operation of the Power Conversion Device As with the power conversion device A6 of embodiment 6, the power conversion device A8 reduces the first voltage (input voltage) Vi to a second voltage (output voltage) Vo by the control circuit 20 controlling the multiple switching circuits 10.

[0144] Furthermore, in the power conversion device A8, the resistance values ​​of the DC resistance component R1, the DC resistance component R4, the DC resistance component R6, and the eighth DC resistance component R8 are smaller than the resistance values ​​of the DC resistance component R3, the DC resistance component R5, and the seventh DC resistance component R7. Therefore, in the power conversion device A8 of the eighth embodiment, as shown in Fig. 18 , when the operation of the load 40 changes (when the current value of the transformer current IL changes), the change in the transformer current IL is faster than in the power conversion device Z1 of the comparative example, and the load responsiveness can be improved.

[0145] Note that Ic in FIG. 18 represents the transformer current of the power conversion device Z1 of the comparative example. Also, IL in FIG. 18 represents the transformer current of the power conversion device A8 of embodiment 8. Also, t1 in FIG. 18 represents the point in time when the load 40 changes from a low load state to a high load state. Also, t2 in FIG. 18 represents the point in time when the operation of the load 40 stabilizes. Also, t3 in FIG. 18 represents the point in time when the load 40 changes from a high load state to a low load state. Also, the solid line in FIG. 18 represents the change in the transformer current. Also, the dashed line in FIG. 18 represents the change in the load current.

[0146] (3) Modifications As a modification of the eighth embodiment, modifications similar to those of the power conversion device A6 according to the modification of the sixth embodiment are possible. Therefore, the power conversion device A8 according to the modification of the eighth embodiment also achieves the same effects as the power conversion device A8 according to the eighth embodiment.

[0147] The eighth embodiment and the modifications described above are merely a part of the various embodiments and modifications of the present disclosure.

[0148] The present disclosure is not limited to the above-described embodiments, and at least some of the configurations of the embodiments and modified examples can be combined as appropriate and applied.

[0149] (Aspects) The present specification discloses the following aspects.

[0150] A power conversion device (A1) according to a first aspect includes a first capacitor (C1), a second capacitor (C2), a plurality of switching circuits (10), a plurality of transformers (6), a first inductor (L1), a switch (SW1), a second inductor (L2), and a control circuit (20). The first capacitor (C1) is electrically connected across a DC power supply (V1). The second capacitor (C2) is electrically connected across a load (40). The plurality of switching circuits (10) include at least a first switching circuit (11) in which a first switching element (Q1) and a second switching element (Q2) are connected in series to each other at a first connection point (3), and a second switching circuit (12) in which a third switching element (Q3) and a fourth switching element (Q4) are connected in series to each other at a second connection point (4). The first switching circuit (11) and the second switching circuit (12) are connected in parallel to the first capacitor (C1). The multiple transformers (6) include at least a first transformer (T1) and a second transformer (T2). The primary winding (L3) of the first transformer (T1) is arranged between a first connection point (3) of the first switching element (Q1) and the second switching element (Q2) and the high-potential terminal of the second capacitor (C2). The primary winding (L5) of the second transformer (T2) is arranged between a second connection point (4) of the third switching element (Q3) and the fourth switching element (Q4) and the high-potential terminal of the second capacitor (C2). The first inductor (L1) is arranged between a series circuit (8) in which the secondary winding (L4) of the first transformer (T1) and the secondary winding (L6) of the second transformer (T2) are connected in series with each other, and the low-potential terminal of the first capacitor (C1). The switch (SW1) is electrically connected to the low-potential terminal of the first capacitor (C1) via the series circuit (8). The second inductor (L2) is arranged between the switch (SW1) and the low-potential terminal of the first capacitor (C1). The control circuit (20) controls the first switching circuit (11), the second switching circuit (12), and the switch (SW1). The low-potential terminal of the second capacitor (C2) is electrically connected to the second switching element (Q2) and the fourth switching element (Q4).The inductance of the second inductor (L2) is smaller than the inductance of the first inductor (L1).

[0151] According to this aspect, it is possible to improve load response and reduce loss.

[0152] In a power conversion device (A2) according to a second aspect, in the first aspect, the first inductor (L1) includes a first inductance component (Lx1) and a first DC resistance component (R1), and the first inductance component (Lx1) and the first DC resistance component (R1) are connected in series. The second inductor (L2) includes a second inductance component (Lx2) and a second DC resistance component (R2), and the second inductance component (Lx2) and the second DC resistance component (R2) are connected in series. The primary winding (L3) of the first transformer (T1) includes a third inductance component (Lx3) and a third DC resistance component (R3), and the third inductance component (Lx3) and the third DC resistance component (R3) are connected in series. The secondary winding (L4) of the first transformer (T1) includes a fourth inductance component (Lx4) and a fourth DC resistance component (R4), and the fourth inductance component (Lx4) and the fourth DC resistance component (R4) are connected in series with each other. The primary winding (L5) of the second transformer (T2) includes a fifth inductance component (Lx5) and a fifth DC resistance component (R5), and the fifth inductance component (Lx5) and the fifth DC resistance component (R5) are connected in series with each other. The secondary winding (L6) of the second transformer (T2) includes a sixth inductance component (Lx6) and a sixth DC resistance component (R6), and the sixth inductance component (Lx6) and the sixth DC resistance component (R6) are connected in series with each other. The first DC resistance component (R1), the second DC resistance component (R2), the fourth DC resistance component (R4), and the sixth DC resistance component (R6) have the same resistance value. The third DC resistance component (R3) and the fifth DC resistance component (R5) have the same resistance value. The resistance values ​​of the first DC resistance component (R1), the second DC resistance component (R2), the fourth DC resistance component (R4), and the sixth DC resistance component (R6) are smaller than the resistance values ​​of the third DC resistance component (R3) and the fifth DC resistance component (R5). The inductance of the second inductance component (Lx2) is smaller than the inductance of the first inductance component (Lx1).

[0153] According to this embodiment, it is possible to further improve the load response and reduce loss.

[0154] A power conversion device (A3; A4) according to a third aspect further includes a second switch (SW2) different from the first switch (SW1), which is the switch (SW1) in the first or second aspect. The control circuit (20) further controls the second switch (SW2). A first end of a first inductor (L1) is electrically connected to the series circuit (8) via the second switch (SW2), and a second end of the first inductor (L1) is electrically connected to the low-potential terminal of the first capacitor (C1).

[0155] According to this aspect, it is possible to improve the load response and reduce loss.

[0156] A power conversion device (A5) according to a fourth aspect includes a first capacitor (C1), a second capacitor (C2), a plurality of switching circuits (10), a plurality of transformers (6), a switch (SW1), an inductor (L1), and a control circuit (20). The first capacitor (C1) is electrically connected across a DC power supply (V1). The second capacitor (C2) is electrically connected across a load (40). The plurality of switching circuits (10) include at least a first switching circuit (11) in which a first switching element (Q1) and a second switching element (Q2) are connected in series to each other at a first connection point (3), and a second switching circuit (12) in which a third switching element (Q3) and a fourth switching element (Q4) are connected in series to each other at a second connection point (4). The first switching circuit (11) and the second switching circuit (12) are connected in parallel to the first capacitor (C1). The multiple transformers (6) include at least a first transformer (T1) and a second transformer (T2). The primary winding (L3) of the first transformer (T1) is disposed between a first connection point (3) of the first switching element (Q1) and the second switching element (Q2) and a high-potential terminal of the second capacitor (C2). The primary winding (L5) of the second transformer (T2) is disposed between a second connection point (4) of the third switching element (Q3) and the fourth switching element (Q4) and a high-potential terminal of the second capacitor (C2). The switch (SW1) is electrically connected to the low-potential terminal of the first capacitor (C1) via a series circuit (8) in which the secondary winding (L4) of the first transformer (T1) and the secondary winding (L6) of the second transformer (T2) are connected in series with each other. The inductor (L1) is disposed between the switch (SW1) and the low-potential terminal of the first capacitor (C1). The control circuit (20) controls the first switching circuit (11), the second switching circuit (12), and the switch (SW1). The low-potential terminal of the second capacitor (C2) is electrically connected to the second switching element (Q2) and the fourth switching element (Q4). The series circuit (8) is electrically connected to the low-potential terminal of the first capacitor (C1).

[0157] According to this aspect, it is possible to improve load response and reduce loss.

[0158] A power conversion device (A6) according to a fifth aspect is the fourth aspect, wherein the inductor (L1) includes a first inductance component (Lx1) and a first DC resistance component (R1), and the first inductance component (Lx1) and the first DC resistance component (R1) are connected in series. The primary winding (L3) of the first transformer (T1) includes a second inductance component (Lx3) and a second DC resistance component (R3), and the second inductance component (Lx3) and the second DC resistance component (R3) are connected in series. The secondary winding (L4) of the first transformer (T1) includes a third inductance component (Lx4) and a third DC resistance component (R4), and the third inductance component (Lx4) and the third DC resistance component (R4) are connected in series. The primary winding (L5) of the second transformer (T2) includes a fourth inductance component (Lx5) and a fourth DC resistance component (R5), and the fourth inductance component (Lx5) and the fourth DC resistance component (R5) are connected in series with each other. The secondary winding (L6) of the second transformer (T2) includes a fifth inductance component (Lx6) and a fifth DC resistance component (R6), and the fifth inductance component (Lx6) and the fifth DC resistance component (R6) are connected in series with each other. The first DC resistance component (R1), the third DC resistance component (R4), and the fifth DC resistance component (R6) have the same resistance value. The second DC resistance component (R3) and the fourth DC resistance component (R5) have the same resistance value. The resistance values ​​of the first DC resistance component (R1), the third DC resistance component (R4), and the fifth DC resistance component (R6) are smaller than the resistance values ​​of the second DC resistance component (R3) and the fourth DC resistance component (R5).

[0159] According to this embodiment, it is possible to further improve the load response and reduce loss.

[0160] In the power conversion device (A7) of the sixth aspect, in the fourth aspect, the inductor (L1) includes a parasitic inductance component of the electrical path (9) that electrically connects the switch (SW1) and the low-potential side terminal of the first capacitor (C1).

[0161] According to this embodiment, it is possible to further improve the load response and reduce loss.

[0162] A seventh aspect of the present invention relates to a power conversion device (A1 to A7) according to any one of the first to sixth aspects, and further includes a detector (30) that detects an input current or an input voltage of the second capacitor (C2). The control circuit (20) controls the switch (SW1) based on the input current or the input voltage detected by the detector (30).

[0163] According to this aspect, it is possible to improve load response and reduce loss.

[0164] A power conversion device (A1 to A7) according to an eighth aspect is any one of the first to sixth aspects, wherein the control circuit (20) controls the switch (SW1) in response to an external signal.

[0165] According to this aspect, it is possible to improve load response and reduce loss.

[0166] The power conversion device (A1 to A7) according to the ninth aspect is any one of the first to sixth aspects, in which the control circuit (20) has a first control circuit that controls the first switching circuit (11) and the second switching circuit (12), and a second control circuit that controls the switch (SW1).

[0167] According to this aspect, it is possible to improve load response and reduce loss.

[0168] 3 First connection point 4 Second connection point 6 Transformer 8 Series circuit 9 Electrical path 10 Switching circuit 11 First switching circuit 12 Second switching circuit 20 Control circuit 30 Detector A1 to A7 Power conversion device C1 First capacitor C2 Second capacitor L1 First inductor (inductor) L2 Second inductor L3 Primary winding L4 Secondary winding L5 Primary winding L6 Secondary winding Lx1 Inductance component (first inductance component) Lx2 Inductance component (second inductance component) Lx3 Inductance component (third and second inductance components) Lx4 Inductance component (fourth and third inductance components) Lx5 Inductance component (fifth and fourth inductance components) Lx6 Inductance component (sixth and fifth inductance components) Q1 First switching element Q2 Second switching element Q3 Third switching element Q4 Fourth switching element R1 DC resistance component (first DC resistance component) R2 DC resistance component (second DC resistance component) R3 DC resistance component (third and second DC resistance components) R4 DC resistance component (fourth and third DC resistance components) R5 DC resistance component (fifth and fourth DC resistance components) R6 DC resistance component (sixth and fifth DC resistance components) SW1 First switch (switch) SW2 Second switch T1 First transformer T2 Second transformer

Claims

1. A first capacitor electrically connected across a DC power supply; a second capacitor electrically connected across a load; a plurality of switching circuits including at least a first switching circuit in which a first switching element and a second switching element are connected in series to each other at a first connection point, and a second switching circuit in which a third switching element and a fourth switching element are connected in series to each other at a second connection point, the first switching circuit and the second switching circuit being connected in parallel to the first capacitor; a plurality of transformers including at least a first transformer and a second transformer, the primary winding of the first transformer being arranged between the first connection point of the first switching element and the second switching element and the high potential side terminal of the second capacitor, and the primary winding of the second transformer being arranged between the second connection point of the third switching element and the fourth switching element and the high potential side terminal of the second capacitor; a first inductor arranged between a series circuit in which the secondary winding of the first transformer and the secondary winding of the second transformer are connected in series to each other and the low potential side terminal of the first capacitor; a first switch electrically connected to the low potential side terminal of the first capacitor via the series circuit; a second inductor arranged between the first switch and the low potential side terminal of the first capacitor; and a control circuit that controls the first switching circuit, the second switching circuit, and the switch, wherein the low potential side terminal of the second capacitor is electrically connected to the second switching element and the fourth switching element, and the inductance of the second inductor is smaller than the inductance of the first inductor.

2. The first inductor includes a first inductance component and a first DC resistance component, and the first inductance component and the first DC resistance component are connected in series with each other; the second inductor includes a second inductance component and a second DC resistance component, and the second inductance component and the second DC resistance component are connected in series with each other; the primary winding of the first transformer includes a third inductance component and a third DC resistance component, and the third inductance component and the third DC resistance component are connected in series with each other; the secondary winding of the first transformer includes a fourth inductance component and a fourth DC resistance component, and the fourth inductance component and the fourth DC resistance component are connected in series with each other; the primary winding of the second transformer includes a fifth inductance component and a fifth DC resistance component, and the fifth inductance component and the fifth DC resistance component are connected in series with each other; the secondary winding of the second transformer includes a sixth inductance component and a sixth DC resistance component, the sixth inductance component and the sixth DC resistance component being connected in series with each other; the first DC resistance component, the second DC resistance component, the fourth DC resistance component and the sixth DC resistance component having the same resistance value; the third DC resistance component and the fifth DC resistance component having the same resistance value; resistance values ​​of the first DC resistance component, the second DC resistance component, the fourth DC resistance component and the sixth DC resistance component being smaller than resistance values ​​of the third DC resistance component and the fifth DC resistance component; and an inductance of the second inductance component being smaller than an inductance of the first inductance component.

3. The power conversion device according to claim 1 or 2, further comprising a second switch different from the first switch, wherein the control circuit further controls the second switch, and wherein a first end of the first inductor is electrically connected to the series circuit via the second switch and a second end of the first inductor is electrically connected to the low potential side terminal of the first capacitor.

4. A first capacitor electrically connected across a DC power supply; a second capacitor electrically connected across a load; a plurality of switching circuits including at least a first switching circuit in which a first switching element and a second switching element are connected in series to each other at a first connection point, and a second switching circuit in which a third switching element and a fourth switching element are connected in series to each other at a second connection point, the first switching circuit and the second switching circuit being connected in parallel to the first capacitor; a plurality of transformers including at least a first transformer and a second transformer, the primary winding of the first transformer being arranged between the first connection point of the first switching element and the second switching element and the high potential side terminal of the second capacitor, and the primary winding of the second transformer being arranged between the second connection point of the third switching element and the fourth switching element and the high potential side terminal of the second capacitor; and a switch electrically connected to the low potential side terminal of the first capacitor via a series circuit in which the secondary winding of the first transformer and the secondary winding of the second transformer are connected in series to each other. a control circuit that controls the first switching circuit, the second switching circuit, and the switch; wherein the low potential side terminal of the second capacitor is electrically connected to the second switching element and the fourth switching element; and the series circuit is electrically connected to the low potential side terminal of the first capacitor.

5. The inductor includes a first inductance component and a first DC resistance component, and the first inductance component and the first DC resistance component are connected in series with each other; the primary winding of the first transformer includes a second inductance component and a second DC resistance component, and the second inductance component and the second DC resistance component are connected in series with each other; the secondary winding of the first transformer includes a third inductance component and a third DC resistance component, and the third inductance component and the third DC resistance component are connected in series with each other; the primary winding of the second transformer includes a fourth inductance component and a fourth DC resistance component, and the fourth inductance component and the fourth DC resistance component are connected in series with each other; the secondary winding of the second transformer includes a fifth inductance component and a fifth DC resistance component, and the fifth inductance component and the fifth DC resistance component are connected in series with each other; 5. The power conversion device according to claim 4, wherein the first DC resistance component, the third DC resistance component, and the fifth DC resistance component have the same resistance value; the second DC resistance component and the fourth DC resistance component have the same resistance value; and the resistance values ​​of the first DC resistance component, the third DC resistance component, and the fifth DC resistance component are smaller than the resistance values ​​of the second DC resistance component and the fourth DC resistance component.

6. The power conversion device according to claim 4, wherein the inductor includes a parasitic inductance component of an electric path electrically connecting the switch and the low potential side terminal of the first capacitor.

7. The power conversion device according to claim 1 or claim 4, further comprising a detector that detects an input current or an input voltage of the second capacitor, and the control circuit controls the switch based on the input current or the input voltage detected by the detector.

8. The power conversion device according to claim 1 or claim 4, wherein the control circuit controls the switch in response to an external signal.

9. The power conversion device according to claim 1 or 4, wherein the control circuit comprises a first control circuit that controls the first switching circuit and the second switching circuit, and a second control circuit that controls the switch.

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