Power source device

Abstract

To provide a power source device capable of outputting a larger current.SOLUTION: A power source device includes: a positive electrode-side wiring having a positive electrode-side trunk wiring and a first positive electrode-side branch line and a second positive electrode-side branch line branched from the positive electrode-side trunk wiring; a negative electrode-side wiring having a negative electrode-side trunk wiring and a first negative electrode-side branch line and a second negative electrode-side branch line branched from the negative electrode-side trunk wiring; a first capacitor connected to the first positive electrode-side branch line and the first negative electrode-side branch line; a first inverter circuit that is connected to the first positive electrode-side branch line and the first negative electrode-side branch line and outputs first AC current; a second capacitor connected to the second positive electrode-side branch line and the second negative electrode-side branch line; a second inverter circuit that is connected to the second positive electrode-side branch line and the second negative electrode-side branch line and outputs second AC current; and a current combining unit that combines the first AC current and the second AC current.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a power supply device. [Background technology]

[0002] An induction heating device requires a power supply device that supplies high-frequency power with a large current. In order for the power supply device to output a larger current, it is effective to connect multiple inverter circuits in parallel. However, even if multiple inverter circuits are connected in parallel, the current output from each inverter circuit may not be uniform. In this case, it becomes difficult to output the current as designed from the power supply device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4445216 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of an embodiment of the present invention is to provide a power supply device capable of outputting a large current. [Means for solving the problem]

[0005] A power supply device according to an embodiment of the present invention includes: a positive side wiring having a positive side trunk wiring and a first positive side branch wire and a second positive side branch wire branched from the positive side trunk wiring; a negative side wiring having a negative side trunk wiring and a first negative side branch wire and a second negative side branch wire branched from the negative side trunk wiring; a first capacitor connected to the first positive side branch wire and the first negative side branch wire; a first inverter circuit connected to the first positive side branch wire and the first negative side branch wire and outputting a first AC current; a second capacitor connected to the second positive side branch wire and the second negative side branch wire; a second inverter circuit connected to the second positive side branch wire and the second negative side branch wire and outputting a second AC current; and a current combiner that combines the first AC current and the second AC current. Effect of the Invention

[0006] According to the embodiment of the present invention, a power supply device capable of outputting a large current can be realized. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing a power supply device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an inverter unit and a current combiner unit of the power supply device according to the embodiment. [Diagram 3] FIG. 3 is a circuit diagram showing one inverter circuit of the power supply device according to the embodiment. [Figure 4] 4(a) to 4(c) are diagrams showing an impedance adjusting section of a power supply device according to an embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an inverter unit and a current combiner unit of a power supply device according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Embodiment> Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a power supply device according to the present embodiment. FIG. 2 is a diagram showing an inverter section and a current combiner section of the power supply device according to this embodiment. FIG. 3 is a circuit diagram showing one inverter circuit of the power supply device according to this embodiment. 4(a) to (c) are diagrams showing an impedance adjusting section of the power supply device according to this embodiment. The power supply device 1 according to this embodiment is, for example, a power supply for an induction heating device.

[0009] As shown in Fig. 1, the power supply device 1 according to this embodiment is provided with a converter section 10, an inverter section 20, and a current combiner section 30. The converter section 10 is connected to an external power source 100, for example, a commercial AC power source. The current combiner section 30 is connected to an external load 200. When the power supply device 1 is used as a power source for an induction heating device, the external load 200 is a matching section and an induction heating coil of the induction heating device. In this specification, "connection" means electrical connection.

[0010] The converter unit 10 converts AC current supplied from an external power source 100 into DC current and outputs the DC current to the inverter unit 20. The converter unit 10 includes, for example, a thyristor or a diode that rectifies the AC current, and a capacitor that smoothes the rectified current.

[0011] The inverter unit 20 converts the DC current supplied from the converter unit 10 into an AC current of an arbitrary frequency and outputs the AC current to the current combiner unit 30. As described later, the inverter unit 20 is provided with a plurality of inverter circuits which are connected in parallel to each other. The current combiner unit 30 combines the AC currents output from the plurality of inverter circuits of the inverter unit 20.

[0012] 2, the inverter section 20 is provided with a positive electrode side wiring 21, a negative electrode side wiring 22, three capacitors 23 to 25, and three inverter circuits 27 to 29. In the present embodiment, an example in which three capacitors and three inverter circuits are provided is shown, but the present invention is not limited to this, and two capacitors and two inverter circuits may be provided, or four or more capacitors and two inverter circuits may be provided.

[0013] The positive wiring 21 includes a positive main wiring 21a and three positive branch lines 21c, 21d, and 21e branched from the positive main wiring 21a via a positive connection point 21b. The negative wiring 22 includes a negative main wiring 22a and three negative branch lines 22c, 22d, and 22e branched from the negative main wiring 22a via a negative connection point 22b. The positive main wiring 21a and the negative main wiring 22a are connected to the converter unit 10.

[0014] The capacitor 23 is connected to the positive branch line 21c and the negative branch line 22c, and stores electric charge between the positive branch line 21c and the negative branch line 22c. The capacitor 24 is connected to the positive branch line 21d and the negative branch line 22d, and stores electric charge between the positive branch line 21d and the negative branch line 22d. The capacitor 25 is connected to the positive branch line 21e and the negative branch line 22e, and stores electric charge between the positive branch line 21e and the negative branch line 22e. The capacitances of the capacitors 23 to 25 are equal to each other.

[0015] The inverter circuit 27 is connected to the positive branch line 21c and the negative branch line 22c, and receives a direct current from the converter unit 10 via the positive branch line 21c and the negative branch line 22c. A direct current is also input to and output from the inverter circuit 27 from the capacitor 23. The inverter circuit 27 outputs a first AC current I1 via a U-terminal 27U and a V-terminal 27V.

[0016] The inverter circuit 28 is connected to the positive branch line 21d and the negative branch line 22d, and receives a direct current from the converter unit 10 via the positive branch line 21d and the negative branch line 22d. A direct current is also input to and output from the inverter circuit 28 from the capacitor 24. The inverter circuit 28 outputs a second AC current I2 via a U-terminal 28U and a V-terminal 28V.

[0017] The inverter circuit 29 is connected to the positive branch line 21e and the negative branch line 22e, and receives a direct current from the converter unit 10 via the positive branch line 21e and the negative branch line 22e. A direct current is also input to and output from the inverter circuit 29 from the capacitor 25. The inverter circuit 29 outputs a third AC current I3 via a U-terminal 29U and a V-terminal 29V.

[0018] The inverter circuits 27 to 29 have the same configuration. The configuration of the inverter circuit 27 will be described below as an example.

[0019] As shown in Fig. 3, the inverter circuit 27 is provided with four power semiconductor elements Q1 to Q4. The power semiconductor elements Q1 to Q4 are switching elements that receive two levels of potential and can switch the output potential based on a control signal input from the outside, and are, for example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The power semiconductor elements Q1 to Q4 may be IGBTs (Insulated Gate Bipolar Transistors). A free wheel diode D is connected in parallel to each of the power semiconductor elements Q1 to Q4. The power semiconductor elements Q1 to Q4 have the same configuration.

[0020] In the inverter circuit 27, the power semiconductor elements Q1 to Q4 form a full bridge circuit. That is, the inverter circuit 27 is provided with a positive branch line 21c and a negative branch line 22c to which a direct current is input from the converter unit 10, and a U-terminal 27U and a V-terminal 27V to which an alternating current is output to the current combiner 30. The power semiconductor elements Q1 and Q2 are connected in series between the positive branch line 21c and the negative branch line 22c, and the power semiconductor elements Q3 and Q4 are also connected in series between the positive branch line 21c and the negative branch line 22c.

[0021] A connection point N1 between power semiconductor elements Q1 and Q2 is connected to U-terminal 27U, and a connection point N2 between power semiconductor elements Q3 and Q4 is connected to V-terminal 27V. An external control signal is input to the gates of power semiconductor elements Q1 to Q4. As a result, a state in which power semiconductor elements Q1 and Q4 are on and power semiconductor elements Q2 and Q3 are off and a state in which power semiconductor elements Q2 and Q3 are on and power semiconductor elements Q1 and Q4 are off are alternately repeated, whereby a first AC current I1 is output from U-terminal 27U and V-terminal 27V.

[0022] Similarly, a second AC current I2 is output from the U-terminal 28U and the V-terminal 28V of the inverter circuit 28, and a third AC current I3 is output from the U-terminal 29U and the V-terminal 29V of the inverter circuit 29.

[0023] As shown in FIG. 2, the current combiner 30 includes a pair of bus bars 31U and 31V, and three pairs of conductive members 32U and 32V, 33U and 33V, and 34U and 34V. The bus bars 31U and 31V are made of a metal material with high conductivity such as copper, and are strip-shaped. The bus bars 31U and 31V have a thickness of, for example, about 3 mm, a width of, for example, about 200 mm, and extend in one direction. For example, an insulating sheet (not shown) is inserted between the bus bars 31U and 31V. The distance between the bus bars 31U and 31V is, for example, about 3 mm, and the thickness of the insulating sheet is, for example, about 2 mm. One end of the bus bars 31U and 31V is connected to an external load 200. The conductive members 32U, 32V, 33U, 33V, 34U, and 34V are also made of a metal material having high conductivity such as copper, and are shaped like a strip.

[0024] Conductive member 32U is connected to U-terminal 27U of inverter circuit 27, and conductive member 32V is connected to V-terminal 27V of inverter circuit 27. Conductive member 33U is connected to U-terminal 28U of inverter circuit 28, and conductive member 33V is connected to V-terminal 28V of inverter circuit 28. Conductive member 34U is connected to U-terminal 29U of inverter circuit 29, and conductive member 34V is connected to V-terminal 29V of inverter circuit 29. In this way, current combiner 30 combines first AC current I1, second AC current I2, and third AC current I3.

[0025] The distance between the connection point 42U of the bus bar 31U and the conductive member 32U and the external load 200 is set to L1. The distance between the connection point 42V of the bus bar 31V and the conductive member 32V and the external load 200 is also approximately L1. The distance between the connection point 43U of the bus bar 31U and the conductive member 33U and the external load 200 is set to L2. The distance between the connection point 43V of the bus bar 31V and the conductive member 33V and the external load 200 is also approximately L2. The distance between the connection point 44U of the bus bar 31U and the conductive member 34U and the external load 200 is set to L3. The distance between the connection point 44V of the bus bar 31V and the conductive member 34V and the external load 200 is also approximately L3. The distance L1 is shorter than the distance L2, and the distance L2 is shorter than the distance L3. That is, L1 <L2<L3である。

[0026] As shown in FIGS. 4(a) to 4(c), conductive member 32U and conductive member 32V are spaced apart from each other, for example, via insulating sheet 52, and constitute impedance adjustment section 37. Conductive member 33U and conductive member 33V are spaced apart from each other, for example, via insulating sheet 53, and constitute impedance adjustment section 38. Conductive member 34U and conductive member 34V are spaced apart from each other, for example, via insulating sheet 54, and constitute impedance adjustment section 39. Distance d1 between conductive member 32U and conductive member 32V is longer than distance d2 between conductive member 33U and conductive member 33V. Distance d2 is longer than distance d3 between conductive member 34U and conductive member 34V. That is, d1>d2>d3.

[0027] Next, the operation of the power supply device according to this embodiment will be described. As shown in FIG. 1, when AC current is input to the power supply device 1 from an external power source 100, the converter unit 10 converts this AC current into DC current and outputs it to the inverter unit 20 via the positive pole side main wiring 21a and the negative pole side main wiring 22a.

[0028] As shown in FIG. 2, a direct current input to the positive pole side main wiring 21a and the negative pole side main wiring 22a is branched into three positive pole side branch wires 21c, 21d, and 21e via the positive pole side connection point 21b, and is also branched into three negative pole side branch wires 22c, 22d, and 22e via the negative pole side connection point 22b.

[0029] The DC current input to the positive branch line 21c and the negative branch line 22c is stored in the capacitor 23 and is input to the inverter circuit 27. The DC current input to the positive branch line 21d and the negative branch line 22d is stored in the capacitor 24 and is input to the inverter circuit 28. The DC current input to the positive branch line 21e and the negative branch line 22e is stored in the capacitor 25 and is input to the inverter circuit 29.

[0030] 3, in the inverter circuit 27, a state in which the power semiconductor elements Q1 and Q4 are on and the power semiconductor elements Q2 and Q3 are off and a state in which the power semiconductor elements Q2 and Q3 are on and the power semiconductor elements Q1 and Q4 are off are alternately repeated, whereby a first AC current I1 is output from the U-terminal 27U and the V-terminal 27V. Similarly, a second AC current I2 is output from the inverter circuit 28, and a third AC current I3 is output from the inverter circuit 29.

[0031] 2, the first AC current I1 output from the U terminal 27U and the V terminal 27V of the inverter circuit 27 is output to the bus bars 31U and 31V via the conductive members 32U and 32V. The second AC current I2 output from the U terminal 28U and the V terminal 28V of the inverter circuit 28 is output to the bus bars 31U and 31V via the conductive members 33U and 33V. The third AC current I3 output from the U terminal 29U and the V terminal 29V of the inverter circuit 29 is output to the bus bars 31U and 31V via the conductive members 34U and 34V. The first AC current I1, the second AC current I2, and the third AC current I3 are combined in the bus bars 31U and 31V and output to the external load 200.

[0032] At this time, impedance inevitably varies among the three inverter circuits 27 to 29 connected in parallel due to the length of the current path to the external load 200 and individual differences due to manufacturing variations and the like of the power semiconductor elements Q1 to Q4 that constitute each inverter circuit.

[0033] Therefore, in this embodiment, capacitors of the same capacity are connected to the input side of each inverter circuit. As a result, the current flowing in from the positive electrode side wiring 21 is divided into a current flowing in the capacitor 23 and a current flowing in the inverter circuit 27. In addition, the current discharged from the positive electrode side terminal of the capacitor 23 returns to the negative electrode side terminal of the capacitor 23 via the inverter circuit 27 and the external load 200. The same applies to the inverter circuits 28 and 29.

[0034] Further, in the present embodiment, when the magnitude relationship of the distances L1 to L3 between the conductive members connected to the inverter circuits 27 to 29 and the external load 200 is L1 < L2 < L3, the magnitude relationship of the distances d1 to d3 between the pair of conductive members belonging to each impedance adjustment unit is set to d1 > d2 > d3.

[0035] The longer the current path to the external load 200 is for an inverter circuit, the greater the impedance between the inverter circuit and the external load 200 becomes. However, in the present embodiment, for an inverter circuit closer to the external load 200, the distance between the pair of conductive members connected to the inverter circuit is increased to increase the impedance, so that the impedances on the external load 200 side in the inverter circuits 27 to 29 match.

[0036] As a result, the impedance between the inverter circuit 27 and the external load 200 and the impedance between the inverter circuit 28 and the external load 200 are made close to the magnitude of the impedance between the inverter circuit 29, which is the farthest from the external load 200, and the external load 200. Also by this, the magnitudes of the first alternating current I1, the second alternating current I2, and the third alternating current I3 can be made closer to each other.

[0037] Next, the effects of the present embodiment will be described. According to the present embodiment, by connecting capacitors to the input sides of the inverter circuits respectively, compared with the case where the capacitors are concentratedly arranged as in the comparative example described later, the positive-side current and the negative-side current flowing through each inverter circuit are more likely to match, and the magnitudes of the first alternating current I1, the second alternating current I2, and the third alternating current I3 can be made closer to each other. Thereby, a power supply device capable of stably outputting a large current can be realized.

[0038] Further, in the present embodiment, since the capacitor 23 is arranged between the positive-side connection point 21b and the negative-side connection point 22b and the inverter circuit 27, the current I output from the inverter circuit 27 toward the external load 200 1Aand the current I returning from the external load 200 to the inverter circuit 27 1B That is, the size of I 1A =I 1B It becomes.

[0039] Similarly, the capacitor 24 is disposed between the positive electrode side connection point 21b and the negative electrode side connection point 22b and the inverter circuit 28, so that the current I 2A and the current I returning from the external load 200 to the inverter circuit 28 2B That is, the size of I 2A =I 2B It becomes.

[0040] Furthermore, since the capacitor 25 is connected between the positive electrode side connection point 21b and the negative electrode side connection point 22b and the inverter circuit 29, the current I 3A and the current I returning from the external load 200 to the inverter circuit 29 3B That is, the size of I 3A =I 3B It becomes.

[0041] In this way, by making the current flowing in the forward direction and the current flowing in the reverse direction in each inverter circuit equal, it is possible to prevent current concentration in a specific inverter circuit, which in turn prevents the inverter circuit where current is concentrated from being thermally destroyed or having a shortened lifespan.

[0042] Furthermore, in this embodiment, the current flowing in the forward direction and the current flowing in the reverse direction in each inverter circuit are made equal by the action of the capacitors 23 to 25, so there is no need to provide a reactor in the impedance adjustment units 37 to 39. As a result, the power supply device 1 can be made smaller and less expensive.

[0043] In contrast, if the capacitors 23-25 ​​were not provided in the inverter section 20 in close proximity to each inverter circuit, when the impedance between the inverter circuits 27-29 and the external load 200 varies, the designed current would not flow through the inverter circuit with high impedance. As a result, the AC current output to the external load 200 would be smaller than the set value. In addition, the current would concentrate in the inverter circuit with a relatively low impedance, which could shorten the life of the inverter circuit or cause thermal destruction.

[0044] In the present embodiment, the inverter circuits 27 to 29 have the same configuration and the capacitors 23 to 25 have the same capacitance, but the present invention is not limited to this. If the rated currents of the inverter circuits 27 to 29 are different from each other, the capacitances of the capacitors 23 to 25 are also made different from each other in accordance with the rated currents of the inverter circuits 27 to 29. For example, a capacitor with a relatively large capacitance is connected to an inverter circuit with a relatively large rated current.

[0045] <Comparative Example> FIG. 5 is a diagram showing an inverter section and a current combiner section of a power supply device according to this comparative example. 5, in the inverter section 320 of the power supply device 301 according to this comparative example, unlike the power supply device 1 described above, the capacitors 23-25 ​​connected to the inverter circuits 27-29, respectively, are not provided, and a common capacitor 323 is provided. The common capacitor 323 is connected between the positive main wiring 21a and the negative main wiring 22b. The capacitance of the common capacitor 323 is, for example, approximately equal to the total capacitance of the three capacitors 23-25 ​​of the power supply device 1.

[0046] In the current combiner 330 of the power supply device 301, a reactor 352 is provided in the impedance adjuster 337, a reactor 353 is provided in the impedance adjuster 338, and a reactor 354 is provided in the impedance adjuster 339. The reactor 352 includes a substantially annular magnetic body surrounding the conductive members 33U and 33V. The same is true for the reactors 353 and 354.

[0047] This also makes it possible to compensate for the impedance variations between the inverter circuits and make the currents flowing through the inverter circuits closer to uniform. However, in this case, it is necessary to provide reactors 352 to 354, which increases the size and cost of power supply device 301 and complicates the adjustment of each impedance adjustment unit.

[0048] If the power supply device 301 is not provided with the reactors 352 to 354, the current flowing from each impedance adjustment unit to the external load 200 may not match the current returning from the external load 200 to each impedance adjustment unit. 1A and the current returning from the external load 200 to the inverter circuit 27 is I 1B and the current output from the inverter circuit 28 to the external load 200 is I 2A and the current returning from the external load 200 to the inverter circuit 28 is I 2B and the current output from the inverter circuit 29 to the external load 200 is I 3A and the current returning from the external load 200 to the inverter circuit 29 is I 3B Let I be the current flowing from the common capacitor 323 to the external load 200. A =I 1A +I 2A +I 3A The current returning from the external load 200 to the capacitor 323 is I B =I 1B +I 2B +I 3B In this case, I A =I B Although it holds, I 1A =I1B , I 2A =I 2B , I 3A =I 3B does not necessarily hold. This means that an excessive current flows through the inverter circuit, which has a relatively low impedance. If an excessive current flows through the inverter circuit, the inverter circuit may be thermally destroyed.

[0049] The above-described embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment. For example, the present invention also includes the above-described embodiment in which some components are added, deleted, or modified.

[0050] The present invention can be used, for example, in a power supply device that supplies a large high-frequency current, and can be used, for example, in a power supply device for an induction heating device.

[0051] The present invention includes the following aspects.

[0052] (Appendix 1) A positive electrode side wiring including a positive electrode side main wiring and a first positive electrode side branch wire and a second positive electrode side branch wire branched from the positive electrode side main wiring; A negative-electrode side wiring including a negative-electrode side main wiring and a first negative-electrode side branch wire and a second negative-electrode side branch wire branched from the negative-electrode side main wiring; a first capacitor connected to the first positive branch and the first negative branch; a first inverter circuit connected to the first positive branch line and the first negative branch line and configured to output a first AC current; a second capacitor connected to the second positive branch and the second negative branch; a second inverter circuit connected to the second positive branch line and the second negative branch line and configured to output a second AC current; a current synthesizing unit that synthesizes the first AC current and the second AC current; A power supply unit comprising:

[0053] (Appendix 2) 2. The power supply device of claim 1, wherein a capacitance of the first capacitor is equal to a capacitance of the second capacitor.

[0054] (Appendix 3) A third capacitor; a third inverter circuit that outputs a third AC current; Further equipped with The positive electrode side wiring further includes a third positive electrode side branch line branched from the positive electrode side main wiring, The negative electrode side wiring further includes a third negative electrode side branch line branched from the negative electrode side main wiring, the third capacitor is connected to the third positive branch and the third negative branch, the third inverter circuit is connected to the third positive branch and the third negative branch, 2. The power supply device according to claim 1, wherein the current synthesizing unit synthesizes the first AC current, the second AC current, and the third AC current.

[0055] (Appendix 4) 4. The power supply device according to claim 3, wherein the first capacitor, the second capacitor, and the third capacitor have the same capacitance.

[0056] (Appendix 5) The current synthesis unit is a first busbar connected to an external load; A second bus bar connected to the external load; a first conductive member connecting a first output terminal of the first inverter circuit to the first bus bar; a second conductive member connecting a second output terminal of the first inverter circuit to the second bus bar; a third conductive member connecting a third output terminal of the second inverter circuit to the first bus bar; a fourth conductive member connecting a fourth output terminal of the second inverter circuit to the second bus bar; having a distance between the external load and a connection point between the first bus bar and the first conductive member is shorter than a distance between the external load and a connection point between the first bus bar and the third conductive member, 5. The power supply device according to claim 1, wherein a distance between the first conductive member and the second conductive member is longer than a distance between the third conductive member and the fourth conductive member.

[0057] (Appendix 6) 6. The power supply device according to claim 5, wherein the external load is a matching section and a coil of an induction heating device.

[0058] (Appendix 7) 7. The power supply device according to claim 1, further comprising a converter unit that receives an AC current, converts the AC current into a DC current, and outputs the DC current to the positive pole side trunk wiring and the negative pole side trunk wiring. [Explanation of symbols]

[0059] 1 Power supply 10 Converter section 20 Inverter section 21 Positive wiring 21a Positive side main wiring 21b Positive connection point 21c, 21d, 21e Positive side branch line 22 Negative wiring 22a Negative side main wiring 22b Negative connection point 22c, 22d, 22e Negative side branch line 23, 24, 25 Capacitors 27, 28, 29 Inverter circuit 27U, 28U, 29U U terminal 27V, 28V, 29V V terminal 30 Current combining section 31U, 31V busbar 32U, 32V, 33U, 33V, 34U, 34V conductive material 37, 38, 39 Impedance adjustment section 42U, 42V, 43U, 43N, 44U, 44V connection points 52, 53, 54 Insulation sheet 100 External power supply 200 External Load 301 Power supply 320 Inverter section 323 Capacitor 330 Current combiner 337, 338, 339 Impedance adjustment section 352, 353, 354 Reactors D Freewheeling diode L1, L2, L3 distance N1, N2 junction points Q1, Q2, Q3, Q4 Power semiconductor elements d1, d2, d3 distance

Claims

1. A positive-side wiring including a positive-side main wiring and a first positive-side branch wire and a second positive-side branch wire branched from the positive-side main wiring; A negative-side wiring including a negative-side main wiring and a first negative-side branch wire and a second negative-side branch wire branched from the negative-side main wiring; a first capacitor connected to the first positive branch and the first negative branch; a first inverter circuit connected to the first positive branch line and the first negative branch line and configured to output a first AC current; a second capacitor connected to the second positive branch and the second negative branch; a second inverter circuit connected to the second positive branch line and the second negative branch line and configured to output a second AC current; a current synthesizing unit that synthesizes the first AC current and the second AC current; A power supply unit comprising:

2. 2. The power supply device according to claim 1, wherein the capacitance of the first capacitor is equal to the capacitance of the second capacitor.

3. A third capacitor; a third inverter circuit that outputs a third AC current; Further equipped with The positive electrode side wiring further includes a third positive electrode side branch line branched from the positive electrode side main wiring, The negative electrode side wiring further includes a third negative electrode side branch line branched from the negative electrode side main wiring, the third capacitor is connected to the third positive branch and the third negative branch, the third inverter circuit is connected to the third positive branch and the third negative branch, The power supply device according to claim 1 , wherein the current combiner combines the first AC current, the second AC current, and the third AC current.

4. 4. The power supply device according to claim 3, wherein the first capacitor, the second capacitor, and the third capacitor have the same capacitance.

5. The current synthesis unit is a first bus bar connected to an external load; A second bus bar connected to the external load; a first conductive member connecting a first output terminal of the first inverter circuit to the first bus bar; a second conductive member connecting a second output terminal of the first inverter circuit to the second bus bar; a third conductive member connecting a third output terminal of the second inverter circuit to the first bus bar; a fourth conductive member connecting a fourth output terminal of the second inverter circuit to the second bus bar; having a distance between the external load and a connection point between the first bus bar and the first conductive member is shorter than a distance between the external load and a connection point between the first bus bar and the third conductive member, The power supply device according to claim 1 , wherein a distance between the first conductive member and the second conductive member is longer than a distance between the third conductive member and the fourth conductive member.

6. 6. The power supply device according to claim 5, wherein the external load is a matching section and a coil of an induction heating device.

7. 2. The power supply device according to claim 1, further comprising a converter unit that receives an AC current, converts the AC current into a DC current, and outputs the DC current to the positive pole side trunk wiring and the negative pole side trunk wiring.

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