Integrated power supply device and control method of integrated power supply device

Abstract

Provided is an integrated power supply device in which AC sides of three or more DC / AC circuits are coupled by a transformer having three or more windings, said integrated power supply device being capable of accurately outputting power in all of the assumed operation modes (power directions) without adding a discharge device, and being capable of reducing loss. In an integrated power supply device in which AC sides of three or more DC / AC circuits are coupled by a transformer having three or more windings, the three or more DC / AC circuits include: a first DC / AC circuit having a first switching circuit and a capacitor connected in parallel with the first switching circuit; and a second DC / AC circuit that has a second switching circuit connected to a power storage unit, and when power is supplied from the second DC / AC circuit to a load connected to a DC / AC circuit other than the first DC / AC circuit, if the first switching circuit has no load or the connected load is equal to or less than a predetermined power consumption value, the first DC / AC circuit is switched on or off by the second switching circuit, and the second DC / AC circuit is switched on or off by the second switching circuit when power is supplied from the second DC / AC circuit to the load connected to the DC / AC circuit other than the first DC / AC circuit. The first switching circuit is switched so that a period during which power is supplied from the capacitor to the first switching circuit is set.

Description

Technical Field

[0001] The present invention relates to the structure of a power supply device and a control method thereof, and particularly to an effective technology applicable to an integrated power supply device coupling the AC sides of three or more DC / AC circuits using a transformer with three or more windings. Background Art

[0002] Isolated DC / DC converters, which isolate and output a stable voltage across a wide input voltage range, are widely used as power conversion circuits for vehicles, information and communication equipment such as base stations and routers, and servers.

[0003] In recent years, efforts have been made to further couple other circuits to the transformer of this isolated DC / DC converter to achieve miniaturization, weight reduction, and multifunctionality of the circuit.

[0004] For example, in the automotive field, to miniaturize onboard power supplies, integrated power supply devices are being developed that use multi-winding transformers to integrate an onboard battery charger (OBC), a DC / AC converter for a vehicle-to-live (V2L) outlet, and an auxiliary battery circuit.

[0005] As background technology in this technical field, there is a technology such as Patent Document 1. Patent Document 1 discloses a "power conversion device that supplies power to a plurality of loads via a multi-winding transformer."

[0006] Patent Document 1 discloses coupling, via a composite winding transformer 10, an AC power source 1 such as a commercial AC power source or a home generator, a first DC voltage source 2 such as a high-voltage battery for vehicle operation, a second DC voltage source 3 such as a lead battery as a power source (LV) for vehicle electrical components, and an inverter 4 applicable to a system (V2L) as a 100V AC power source that can be used in the vehicle. (Patent Document 1) Figure 1 and paragraph

[0011] , etc.) Prior art literature Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-146681 Summary of the Invention Problems to be solved by the invention

[0008] The integrated circuit described in Patent Document 1 can connect a bridge circuit to each winding of a multi-winding transformer, thereby reducing circuit elements and is therefore effective in reducing the size and weight of the circuit.

[0009] However, in the case of an integrated on-board charger (OBC), when the OBC is not in use, such as when the vehicle is driving, the switching circuit related only to the OBC is not used (i.e., it becomes unloaded). However, since it is coupled to the transformer, even if the unloaded switching circuit is disconnected, the output capacitance of the switch, the leakage inductance of the transformer, and the diode perform the step-up circuit operation, so the unloaded DC section becomes overcharged.

[0010] In Patent Document 1, only the LV circuit or the V2L circuit is used, and when the OBC is not in use, the bridge circuit on the OBC side is disconnected. In this case, the DC portion of the disconnected circuit may be overcharged due to the influence of the LV or V2L power supply, necessitating a separate discharge device such as a discharge resistor.

[0011] Therefore, an object of the present invention is to provide an integrated power supply device and a control method thereof, in which, in an integrated power supply device in which the AC sides of three or more DC / AC circuits are coupled using a transformer with three or more windings, power is accurately output in all assumed operating modes (power directions) without adding a discharge device, and low losses are achieved. Technical means to solve the problem

[0012] To address the above-mentioned problems, the present invention provides an integrated power supply device comprising three or more DC / AC circuits coupled to their respective AC sides using a transformer having three or more windings. The three or more DC / AC circuits include: a first DC / AC circuit having a first switching circuit and a capacitor connected in parallel with the first switching circuit; and a second DC / AC circuit having a second switching circuit connected to a power storage unit. When the second DC / AC circuit supplies power to a load connected to a DC / AC circuit other than the first DC / AC circuit, if the first switching circuit is unloaded or the connected load has a power consumption value or less, the first switching circuit is switched in conjunction with the switching of the second switching circuit to provide a period during which power is supplied from the capacitor to the first switching circuit.

[0013] The present invention also provides a control method for an integrated power supply device in which the AC sides of three or more DC / AC circuits, including a first DC / AC circuit on the primary side and a second DC / AC circuit on the secondary side, are coupled using a transformer with three or more windings. The method is characterized in that, when power is supplied from the second DC / AC circuit to a load connected to a DC / AC circuit other than the first DC / AC circuit, if a first switching circuit of the first DC / AC circuit is unloaded or the connected load has a power consumption value or less, the first switching circuit is switched in conjunction with the switching of the second switching circuit of the second DC / AC circuit so as to provide a period during which power is supplied from a capacitor connected in parallel with the first switching circuit to the first switching circuit. Effects of the Invention

[0014] According to the present invention, in an integrated power supply device formed by coupling the AC sides of three or more DC / AC circuits using a transformer with three or more windings, without adding a discharge device, it is possible to realize an integrated power supply device that can accurately output power in all envisioned operating modes (power directions) and can reduce losses, and a control method thereof.

[0015] This can contribute to miniaturization, weight reduction, and higher efficiency of the integrated power supply device.

[0016] Other problems, structures, and effects than those described above will become clear from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a diagram showing a schematic configuration of a bidirectional charging device according to a first embodiment of the present invention. Figure 2 Yes Figure 1 The timing diagram of the operation of the switch circuit 1 and the switch circuit 2. Figure 3A It is schematically represented Figure 1 FIG. 1 is a diagram illustrating the operation of the switching circuit 1. Figure 3B It is schematically represented Figure 1 FIG. 1 is a diagram illustrating the operation of the switching circuit 1. Figure 3C It is schematically represented Figure 1 FIG. 1 is a diagram illustrating the operation of the switching circuit 1. Figure 4A Yes Figure 1 FIG. 1 is a diagram illustrating a method for controlling the switching element Q1 (Q2). Figure 4B Yes Figure 1 FIG. 1 is a diagram illustrating a method for controlling the switching element Q1 (Q2). Figure 5This is a timing chart showing the operations of the switch circuit 1 and the switch circuit 2 according to the second embodiment of the present invention. Figure 6 This is a diagram schematically showing the operation of the switching circuit 1 according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present invention will be described using the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals, and detailed descriptions of the duplicated components are omitted. Example 1

[0019] Reference Figures 1 to 4B An integrated power supply device and a control method thereof according to a first embodiment of the present invention will be described.

[0020] Figure 1 1 is a diagram showing a schematic configuration of a bidirectional charging device 7 according to this embodiment.

[0021] like Figure 1 As shown, the bidirectional charging device 7 of this embodiment includes a switching circuit 1, a switching circuit 2, an AC / DC circuit 3, an AC / DC converter 4, and a transformer 10 as its main components. The switching circuit 1 is coupled to the primary side of the transformer 10 via a winding N1. The switching circuit 2 and the AC / DC circuit 3 are connected to the secondary side of the transformer 10 via windings N2 and N3, respectively. Furthermore, the DC / DC converter 6 is comprised of the switching circuit 1, the switching circuit 2, and the transformer 10.

[0022] The AC / DC converter 4 is connected to the switching circuit 1 , receives AC power from the AC power source 5 , converts the received AC power into DC power, and supplies a DC voltage to the capacitor C1 .

[0023] The DC / DC converter 6 converts the DC voltage applied to the capacitor C1 into a DC voltage applied to the capacitor C2 and the battery V2.

[0024] The bidirectional charging device 7 of this embodiment is an integrated charger consisting of a winding N3 (a winding with N3 turns) added to a transformer 10 having an excitation inductance Lm, which is a component of a DC / DC converter 6, namely, a winding N1 (a winding with N1 turns) and a winding N2 (a winding with N2 turns), and an AC / DC circuit 3 connected thereto.

[0025] The switching circuit 1 comprises two switching arms in which switching elements Q1 and Q2 and switching elements Q3 and Q4 are connected in series. A series circuit of a capacitor Cr1 and a reactor Lr1 is connected between the output (input) and the primary side of the transformer 10 .

[0026] The switching circuit 2 is composed of two switching arms in which switching elements Q5 and Q6 and switching elements Q7 and Q8 are connected in series. A series circuit of a capacitor Cr2 and a reactor Lr2 is connected between its input (output) and the secondary side of the transformer 10 .

[0027] Reactors Lr1 and Lr2 can also serve as the leakage inductance of transformer 10. DC / DC converter 6 can also be a resonant converter using capacitors Cr1 and Cr2 and reactors Lr1 and Lr2 as resonant elements, a phase-shift or dual-active bridge converter using capacitors as DC cutoff elements, or a converter without capacitors. Switching elements Q1 to Q8 are assumed to be MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors).

[0028] Figure 1 Arrows 8 in FIG. 8 represent the flow of electric power during the operation of the bidirectional charging device 7 of this embodiment, schematically indicating that electric power is supplied from the battery V2 to the load L, and that no electric power is supplied from the AC power supply 5 .

[0029] An example of the bidirectional charging device 7 of this embodiment is an onboard charger. In this case, the battery V2 corresponds to a lithium-ion battery, and the load L corresponds to an auxiliary battery or an in-vehicle outlet converter. The power supply (arrow 8) from the lithium-ion battery to the auxiliary battery or in-vehicle outlet corresponds to the operation during vehicle operation.

[0030] Figure 2 Yes Figure 1 The timing diagram of the operation of the switch circuit 1 and the switch circuit 2.

[0031] Q1~Q8 represent the on / off status of the switching elements Q1~Q8, V TR Represents the voltage applied to the transformer 10. Figure 1 As shown, the switching elements Q5 to Q8 are switching elements for supplying power to the load L from the battery V2.

[0032] exist Figure 2 In the figure, it is assumed that DC / DC converter 6 is of a resonant type, and switching elements Q5 and Q8 and switching elements Q6 and Q7 are switched simultaneously at a duty cycle of approximately 50%. However, this is not necessarily required. For example, a phase shift method may be used, in which Q5 is turned off earlier than Q8, and Q6 is turned off earlier than Q7.

[0033] The characteristic of this embodiment is that the transformer applies a voltage V TRThat is, after a positive voltage is applied to the transformer 10, the switching elements Q1 and Q4 are turned on with a slight delay, and after a negative voltage is applied to the transformer 10, the switching elements Q2 and Q3 are turned on with a slight delay.

[0034] use Figures 3A to 3C Explain this advantage. Figures 3A to 3C It is schematically represented Figure 1 FIG. 1 is a diagram illustrating the operation of the switching circuit 1.

[0035] Figure 3A 1 shows the flow of current immediately after a positive voltage is applied to the transformer 10 , charging the output capacitances of the switching elements Q2 and Q3 and discharging the switching elements Q1 and Q4 .

[0036] Figure 3B This is the state where the voltage of the switching element Q2 is higher than the sum of the voltage of the capacitor C1 and the forward voltage of the reverse diode of the switching element Q1, and the reactor Lr1 acts as a current source to charge the capacitor C1. This phenomenon is the problem that the present invention aims to solve.

[0037] Therefore, in this embodiment, Figure 3B At this moment, the switching elements Q1 and Q4 are turned on. At this moment, the switching elements Q1 and Q4 are in a zero voltage conduction state due to the diode conduction state, and the loss is small.

[0038] If the conduction state continues, Figure 3C As shown, the direction of the current can be reversed by the voltage rise of the capacitor C1, and the capacitor C1 can be discharged. The length of this period, that is, the pulse width of the switching element Q1, determines the amount of discharge.

[0039] In addition, even if the switching elements Q1 and Q4 are not turned on, the diodes can be reverse-recovered. Figure 3C Therefore, it can be said that the problem of overcharging of the capacitor C1 has resurfaced due to the short reverse recovery time of the diode and the emergence of SiC or GaN as materials for next-generation devices.

[0040] Figure 4A and Figure 4B It shows how to control the pulse width of the switching element Q1 (the pulse width of the switching element Q2 when a negative voltage is applied). Figure 4A This shows how the pulse width is controlled so that the voltage of capacitor C1 remains constant. Figure 4B This shows a method of switching only when the voltage of the capacitor C1 exceeds a threshold value.

[0041] As described above, the integrated power supply device (bidirectional charging device 7) of this embodiment is an integrated power supply device formed by coupling the AC sides of three or more DC / AC circuits using a transformer 10 with three or more windings. The three or more DC / AC circuits are configured as follows: a first DC / AC circuit having a first switching circuit (switch circuit 1) and a capacitor C1 connected in parallel with the first switching circuit (switch circuit 1); and a second DC / AC circuit having a second switching circuit (switch circuit 2) connected to a power storage unit (battery V2). When power is supplied from the second DC / AC circuit to a load L connected to a DC / AC circuit (AC / DC circuit 3) other than the first DC / AC circuit, if the first switching circuit (switch circuit 1) is unloaded or the connected load has a power consumption value or less, the first switching circuit (switch circuit 1) is switched in accordance with the switching of the second switching circuit (switch circuit 2) so as to provide a period during which power is supplied from capacitor C1 to the first switching circuit (switch circuit 1).

[0042] More specifically, the first switching circuit (switching circuit 1) is switched so that power is supplied from the first switching circuit (switching circuit 1) to the DC / AC circuit (AC / DC circuit 3) other than the first DC / AC circuit and the second DC / AC circuit.

[0043] By switching the first switching circuit (switching circuit 1), overcharging of the capacitor C1 of the no-load DC section can be prevented without adding additional circuits such as a discharge resistor, and power can be returned to the original load L, such as the AC / DC circuit 3. Specifically, by switching the no-load circuit, an operating mode is established in which the DC section of the no-load circuit is discharged, and the net energy flowing into the no-load DC section can be reduced to zero.

[0044] In addition, the first switching circuit (switch circuit 1) is composed of a semiconductor switch having a reverse diode. When the first switching circuit (switch circuit 1) is unloaded or the connected load is below a specified power consumption value, the semiconductor switch is turned on while current flows through the reverse diode.

[0045] By turning on the diode while it is conducting, it becomes a zero voltage switch, thus achieving low loss.

[0046] When the first switching circuit (switching circuit 1) has no load or the connected load is equal to or less than a predetermined power consumption value, the semiconductor switch is turned off while current flows in the reverse direction of the reverse diode in the semiconductor switch.

[0047] When the current becomes the reverse direction of the reverse diode, the capacitor C1 of the no-load circuit is discharged. Therefore, if the switch is turned off after setting this period to a certain extent, a certain amount of energy is discharged from the capacitor C1.

[0048] In addition, the first switching circuit (switching circuit 1) is a full-bridge circuit composed of: a first bridge arm, which uses the first switching element Q1 and the second switching element Q2 as upper and lower arms, respectively; and a second bridge arm, which uses the third switching element Q3 and the fourth switching element Q4 as upper and lower arms, respectively. When the first switching circuit (switching circuit 1) is unloaded or the connected load is below the specified power consumption value, the first switching element Q1 and the fourth switching element Q4, or the second switching element Q2 and the third switching element Q3, are respectively turned on at the same time, and the switching element of either the first switching element Q1 and the fourth switching element Q4, or the second switching element Q2 and the third switching element Q3, is first turned off.

[0049] In a full-bridge circuit, by first disconnecting only one of the two connected elements, the voltage applied to the reactor can be reduced, thereby suppressing the current. This method can reduce the current value of the first switching circuit (switch circuit 1) and reduce conduction losses.

[0050] When the first switching circuit (switching circuit 1 ) is unloaded or the connected load is equal to or less than a predetermined power consumption value, the first switching circuit (switching circuit 1 ) is always switched so that the voltage of the capacitor C1 remains constant.

[0051] like Figure 4A As shown, if the pulse width of the first switch circuit (switching circuit 1) is controlled by the voltage value of the capacitor C1 of the no-load circuit, the voltage value can be controlled to be constant.

[0052] When the first switching circuit (switching circuit 1 ) is unloaded or the connected load is equal to or less than a predetermined power consumption value, the first switching circuit (switching circuit 1 ) is switched when the voltage of the capacitor C1 exceeds a predetermined threshold.

[0053] like Figure 4B As shown, if the first switch circuit (switch circuit 1) is switched only when the voltage value of the capacitor C1 of the no-load circuit exceeds the threshold value, the capacitor C1 of the no-load circuit can be prevented from overvoltage. Example 2

[0054] Reference Figure 5 and Figure 6 , an integrated power supply device and a control method thereof according to embodiment 2 of the present invention are described.

[0055] Figure 51 is a timing chart showing the operations of the switch circuit 1 and the switch circuit 2 of this embodiment.

[0056] Q1~Q8 represent the on / off status of the switching elements Q1~Q8, V TR Represents the voltage applied to the transformer 10. Figure 1 As shown, the switching elements Q5 to Q8 are switching elements for supplying power to the load L from the battery V2.

[0057] exist Figure 5 In FIG. 5 , the DC / DC converter 6 is assumed to be of a phase-shift type, but this is not essential.

[0058] The characteristic of this embodiment is that the transformer applies a voltage V TR The relationship between the on-time of the switching elements Q1 to Q4. That is, the voltage V TR During the period when the current is zero, the on-periods of the switching elements Q1 and Q3 are provided.

[0059] This operation is different from the first embodiment in that the energy of the capacitor C1 of the switching circuit 1 is consumed by the switching circuit 1 instead of the load L. Therefore, the voltage V is applied to the transformer. TR This is because if the transformer applies voltage V TR If φ is zero, there is no flow of electric power through the transformer 10 .

[0060] In this embodiment, if Figure 6 As shown, the switching elements Q1 and Q3 are turned on, the output capacitance of the switching elements Q1 and Q3 is short-circuited, and the charging energy of the capacitor C1 is consumed (voltage V Q1 、V Q3 →0).

[0061] In addition, Figure 5 In this example, switching elements Q1 and Q3 are turned on simultaneously. However, any switching element can be turned on as long as the output capacitor is charged. However, switching elements Q1 and Q2, or switching elements Q3 and Q4, cannot be turned on simultaneously. This is because the arms are short-circuited.

[0062] In this embodiment, since power is consumed when the switching element is on, power consumption control, that is, voltage control of the capacitor C1 is performed based on the number of on times per unit time.

[0063] As in Example 1, Figure 4A The voltage of capacitor C1 is constant in the way that the pulse width is controlled, or only in the Figure 4B The voltage of the capacitor C1 is controlled by switching when the voltage of the capacitor C1 exceeds a threshold value.

[0064] As described above, the integrated power supply device (bidirectional charging device 7) of this embodiment is different from the embodiment 1 ( Figure 1 ) Similarly, an integrated power supply device is provided in which the AC sides of three or more DC / AC circuits are coupled using a transformer 10 having three or more windings. The three or more DC / AC circuits are configured as follows: a first DC / AC circuit having a first switching circuit (switch circuit 1) and a capacitor C1 connected in parallel with the first switching circuit (switch circuit 1); and a second DC / AC circuit having a second switching circuit (switch circuit 2) connected to a storage unit (battery V2). When power is supplied from the second DC / AC circuit to a load L connected to a DC / AC circuit (AC / DC circuit 3) other than the first DC / AC circuit, when the first switching circuit (switch circuit 1) is unloaded or the connected load has a power consumption value or less, the first switching circuit (switch circuit 1) is switched in accordance with the switching of the second switching circuit (switch circuit 2) so as to provide a period during which power is supplied from the capacitor C1 to the first switching circuit (switch circuit 1).

[0065] More specifically, when the first switching circuit (switching circuit 1 ) is unloaded or the connected load is equal to or less than a predetermined power consumption value, the power supplied from the capacitor C1 is consumed by the first switching circuit (switching circuit 1 ).

[0066] In addition, the first switching circuit (switching circuit 1) is a bridge circuit composed of a switching element Q1 or Q3 of an upper arm and a switching element Q2 or Q4 of a lower arm. When the first switching circuit (switching circuit 1) is unloaded or the connected load is below a specified power consumption value, the switching element Q1 or Q3 of the upper arm or the switching element Q2 or Q4 of the lower arm is turned on while no voltage is applied to the transformer 10.

[0067] In addition, the first switching circuit (switching circuit 1) is a bridge circuit composed of a switching element Q1 or Q3 of an upper arm and a switching element Q2 or Q4 of a lower arm. When the first switching circuit (switching circuit 1) is unloaded or the connected load is below a specified power consumption value, the switching element Q1 or Q3 of the upper arm or the switching element Q2 or Q4 of the lower arm is disconnected while no voltage is applied to the transformer 10.

[0068] When a current flows through the transformer during application of the transformer voltage, energy is transferred through the transformer, resulting in the operation of the first embodiment or the operation of charging the no-load capacitor C1. This is different from the main purpose of this embodiment (consumption by the first switching circuit), so the switch is turned on during the period when no voltage is applied to the transformer.

[0069] Furthermore, the present invention is not limited to the above-described embodiments and encompasses various variations. For example, the above-described embodiments are detailed for the purpose of easily understanding the present invention and are not necessarily limited to embodiments having all the described configurations. Furthermore, a portion of the configuration of one embodiment may be replaced with a configuration of another embodiment, and a configuration of another embodiment may be added to a configuration of another embodiment. Furthermore, a portion of the configuration of each embodiment may be supplemented, deleted, or replaced with another configuration. Explanation of symbols

[0070] 1, 2…Switching circuit, 3…AC / DC circuit, 4…AC / DC converter, 5…AC power supply, 6…DC / DC converter, 7…Bidirectional charging device, 8…Power supply (power flow), 10…Transformer (transformer), C1, C2, Cr1, Cr2…Capacitors, L…Load, Lm…Magnetic inductance, Lr1, Lr2…Reactor, N1, N2, N3…Winding, Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8…Switching element, V2…Battery, V TR …the transformer applies the voltage.

Claims

1. An integrated power supply device comprising a transformer having three or more windings and coupling the AC sides of three or more DC / AC circuits. The integrated power supply device is characterized in that: The three or more DC / AC circuits include: a first DC / AC circuit including a first switching circuit and a capacitor connected in parallel with the first switching circuit; and The second DC / AC circuit includes a second switching circuit connected to the power storage unit. When power is supplied from the second DC / AC circuit to a load connected to a DC / AC circuit other than the first DC / AC circuit, When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, As the second switching circuit is switched, the first switching circuit is switched so as to provide a period during which power is supplied from the capacitor to the first switching circuit.

2. The integrated power supply device according to claim 1, characterized in that: When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The first switching circuit is switched so that power is supplied from the first switching circuit to DC / AC circuits other than the first DC / AC circuit and the second DC / AC circuit.

3. The integrated power supply device according to claim 2, characterized in that: The first switching circuit is composed of a semiconductor switch having a reverse diode. When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The semiconductor switch is turned on while current flows through the reverse diode.

4. The integrated power supply device according to claim 3, characterized in that: When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The semiconductor switch is turned off while current is flowing in the semiconductor switch in the reverse direction of the reverse diode.

5. The integrated power supply device according to claim 3, characterized in that: The first switching circuit is a full-bridge circuit consisting of a first bridge arm having a first switching element and a second switching element as upper and lower arms, respectively, and a second bridge arm having a third switching element and a fourth switching element as upper and lower arms, respectively. When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The first switching element and the fourth switching element, or the second switching element and the third switching element, are turned on simultaneously. First, either the first switching element or the fourth switching element, or the second switching element or the third switching element is turned off.

6. The integrated power supply device according to claim 1, characterized in that: When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The power supplied from the capacitor is consumed by the first switching circuit.

7. The integrated power supply device according to claim 6, characterized in that: The first switching circuit is a bridge circuit composed of a switching element of an upper arm and a switching element of a lower arm. When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, While no voltage is applied to the transformer, the switching element of the upper arm or the switching element of the lower arm is turned on.

8. The integrated power supply device according to claim 6, characterized in that: The first switching circuit is a bridge circuit composed of a switching element of an upper arm and a switching element of a lower arm. When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, While no voltage is applied to the transformer, the switching element of the upper arm or the switching element of the lower arm is turned off.

9. The integrated power supply device according to claim 1, characterized in that: When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The first switching circuit is always switched so that the voltage of the capacitor remains constant.

10. The integrated power supply device according to claim 1, characterized in that: When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, When the voltage of the capacitor exceeds a predetermined threshold value, the first switching circuit is switched.

11. A method for controlling an integrated power supply device, wherein the integrated power supply device is formed by coupling the AC sides of three or more DC / AC circuits, including a first DC / AC circuit on the primary side and a second DC / AC circuit on the secondary side, using a transformer having three or more windings. The control method of the integrated power supply device is characterized in that: When power is supplied from the second DC / AC circuit to a load connected to a DC / AC circuit other than the first DC / AC circuit, When the first switching circuit of the first DC / AC circuit is unloaded or the connected load is less than a predetermined power consumption value, As the second switching circuit of the second DC / AC circuit is switched, the first switching circuit is switched so as to provide a period during which power is supplied from the capacitor connected in parallel to the first switching circuit to the first switching circuit.

12. The control method of the integrated power supply device according to claim 11, characterized in that: When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The first switching circuit is switched so that power is supplied from the first switching circuit to DC / AC circuits other than the first DC / AC circuit and the second DC / AC circuit.

13. The control method of the integrated power supply device according to claim 12, characterized in that: The first switching circuit is composed of a semiconductor switch having a reverse diode. When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The semiconductor switch is turned on while current flows through the reverse diode.

14. The control method of the integrated power supply device according to claim 13, characterized in that: When the first switching circuit is unloaded or the connected load is below a predetermined power consumption value, The semiconductor switch is turned off while the current flows in the reverse direction of the reverse diode through the semiconductor switch.

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