Inverter device and inverter unit

Abstract

To provide an inverter device capable of reducing parasitic inductance.SOLUTION: A laminated bus bar 48 includes: a first bus bar 106 for electrically connecting a first diode 26 and a first switching element 28; a second bus bar 152 for electrically connecting a second switching element 30 and a second diode 32; a third bus bar 108 for electrically connecting a third diode 34 and a third switching element 36 and laminated on the second bus bar 152 via an intermediate insulation film 90; and a fourth bus bar 154 for electrically connecting a fourth switching element 38 and a fourth diode 40 and laminated on the first bus bar 106 via the intermediate insulation film 90. In a plan view of the laminated bus bar 48, a direction of a current flowing through the first bus bar 106 is opposite to that of a current flowing through the fourth bus bar 154, and a direction of a current flowing through the third bus bar 108 is opposite to that of a current flowing through the second bus bar 152.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an inverter device and an inverter unit including the same. Background Art

[0002] An inverter device is known as a power supply device for supplying AC power to an electric load (see, for example, Patent Document 1). The inverter device includes a rectifier circuit that converts three-phase AC power into DC power, an inverter circuit that converts DC power output from the rectifier circuit into AC power, and an output circuit that supplies the AC power output from the inverter circuit to the electric load. The inverter circuit is a full-bridge type inverter circuit in which a plurality of switching elements are connected in a bridge configuration. Prior Art Literature Patent Documents

[0003] Patent Document 1 Japanese Patent No. 6389945 Summary of the Invention Problem to be Solved by the Invention

[0004] In the above-described inverter device, parasitic inductance in the inverter circuit may cause ringing (current oscillation) when each switching element performs a switching operation.

[0005] The present invention aims to solve the above-described problem, and an object of the present invention is to provide an inverter device and an inverter unit that can reduce parasitic inductance. Means for Solving the Problem

[0006] An inverter device according to a first aspect of the present invention comprises: a first series circuit in which a first diode, a first switching element, a second switching element, and a second diode are connected in series in that order; a second series circuit in which a third diode, a third switching element, a fourth switching element, and a fourth diode are connected in series in that order, and the second series circuit is connected in parallel with the first series circuit; an output section electrically connected between the connection point of the first switching element and the second switching element and the connection point of the third switching element and the fourth switching element; and a stacked busbar, wherein the stacked busbar connects the first diode and the first switch The busbar comprises a first busbar that electrically connects a switching element, a second busbar that electrically connects the second switching element and the second diode, a third busbar that electrically connects the third diode and the third switching element and is laminated on the second busbar via a first insulating material, and a fourth busbar that electrically connects the fourth switching element and the fourth diode and is laminated on the first busbar via a second insulating material, wherein when the laminated busbar is viewed from above, the current flowing through the first busbar is in the opposite direction to the current flowing through the fourth busbar, and the current flowing through the third busbar is in the opposite direction to the current flowing through the second busbar.

[0007] In this embodiment, the third busbar is laminated on the second busbar via the first insulating material, and when the laminated busbar is viewed from above, the current flowing through the third busbar is in the opposite direction to the current flowing through the second busbar. As a result, the magnetic field caused by the current flowing through the third busbar and the magnetic field caused by the current flowing through the second busbar cancel each other out. Similarly, the fourth busbar is laminated on the first busbar via the second insulating material, and when the laminated busbar is viewed from above, the current flowing through the first busbar is in the opposite direction to the current flowing through the fourth busbar. As a result, the magnetic field caused by the current flowing through the first busbar and the magnetic field caused by the current flowing through the fourth busbar cancel each other out. As a result, parasitic inductance in the inverter device can be reduced, and ringing during the switching operations of the first, second, third, and fourth switching elements can be reduced.

[0008] Furthermore, in the inverter device according to the second aspect of the present invention, the laminated busbar may be configured to be a laminated busbar in the first aspect.

[0009] According to this embodiment, the inverter device can be miniaturized.

[0010] Furthermore, in an inverter device according to a third aspect of the present invention, in the first or second aspect, the first series circuit is configured such that the first diode, a plurality of first switching elements connected in parallel, a plurality of second switching elements connected in parallel, and the second diode are connected in series in this order, and the second series circuit is configured such that the third diode, a plurality of third switching elements connected in parallel, a plurality of fourth switching elements connected in parallel, and the fourth diode are connected in series in this order, and the first busbar has a first slit arranged to cross between the first diode and the plurality of first switching elements, the second busbar has a second slit arranged to cross between the second diode and the plurality of second switching elements, the third busbar has a third slit arranged to cross between the third diode and the plurality of third switching elements, and the fourth busbar has a fourth slit arranged to cross between the fourth diode and the plurality of fourth switching elements.

[0011] In this embodiment, since the first busbar has a first slit, the current from the first diode can be supplied to each of the multiple first switching elements in a balanced manner. Furthermore, since the fourth busbar has a fourth slit, the current supplied from each of the multiple fourth switching elements to the fourth diode can be directed in the opposite direction to the current flowing through the first busbar. Furthermore, since the third busbar has a third slit, the current from the third diode can be supplied to each of the multiple third switching elements in a balanced manner. Furthermore, since the second busbar has a second slit, the current supplied from each of the multiple second switching elements to the second diode can be directed in the opposite direction to the current flowing through the third busbar.

[0012] Furthermore, in the inverter device according to the fourth aspect of the present invention, in any one aspect of the first to third aspects, a flow path for cooling fluid may be formed inside at least one of the first busbar, the second busbar, the third busbar, and the fourth busbar.

[0013] According to this embodiment, heat-generating components in the inverter device can be efficiently dissipated.

[0014] Furthermore, in the inverter device according to the fifth aspect of the present invention, in any one aspect of the first to fourth aspects, the inverter device may be further configured to include a temperature sensor for detecting the temperature of the stacked busbar.

[0015] According to this embodiment, by monitoring the detection signal from the temperature sensor, it is possible to detect, for example, that a steep rise in current has occurred in the inverter device when the temperature of the stacked busbar rises rapidly.

[0016] Furthermore, the inverter unit according to the sixth aspect of the present invention comprises a DC-side busbar, an AC-side busbar, and one or more inverter devices according to any one of the first to fifth aspects, which are electrically connected between the DC-side busbar and the AC-side busbar.

[0017] According to this embodiment, the rated output of the inverter unit can be easily changed by changing the number of inverter devices. [Effects of the Invention]

[0018] According to one aspect of the present invention, an inverter device can reduce parasitic inductance. [Brief explanation of the drawing]

[0019] [Figure 1] This diagram shows the circuit configuration of an induction heating device according to an embodiment. [Figure 2]1 is a perspective view of an inverter device according to an embodiment. [Figure 3] It is an exploded perspective view of the inverter device according to the embodiment. [Figure 4] It is a plan view showing a circuit unit of the inverter device according to the embodiment. [Figure 5] It is an exploded perspective view showing a laminated busbar of the inverter device according to the embodiment. [Figure 6] It is a plan view showing an upstream busbar layer of the laminated busbar in FIG. 5. [Figure 7] It is a plan view showing a downstream busbar layer of the laminated busbar in FIG. 5. [Figure 8] It is a side view showing an output busbar of the inverter device according to the embodiment. [Figure 9] It is a bottom view showing an output busbar of the inverter device according to the embodiment. [Figure 10] It is a side view showing an inverter unit according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments will be specifically described with reference to the drawings.

[0021] All of the embodiments described below are illustrative of generic or specific examples. Numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the scope of the claims. Further, among the constituent elements in the following embodiments, constituent elements that are not recited in the independent claim representing the most generic inventive concept are described as optional constituent elements.

[0022] Furthermore, the respective drawings are not necessarily strictly illustrated. In each drawing, substantially identical configurations are denoted by the same reference numerals, and duplicate descriptions are omitted or simplified.

[0023] Embodiment [1. Circuit configuration of induction heating device] First, the circuit configuration of the induction heating device 2 according to the embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing the circuit configuration of the induction heating device 2 according to the embodiment.

[0024] As shown in Figure 1, the induction heating device 2 is a device for induction heating (so-called high-frequency induction hardening) of the object to be heated 4 at a high frequency of, for example, several kHz to several hundred kHz. High-frequency induction hardening is a heat treatment that hardens the surface of the object to be heated 4 by inducing high-frequency electromagnetic induction. The object to be heated 4 is, for example, a tubular metal part used in a vehicle or machine tool.

[0025] The induction heating device 2 has a circuit configuration comprising a rectifier circuit 6, choke coils 8 and 10, an inverter device 12, a matching circuit 14, and an induction coil 16.

[0026] The rectifier circuit 6 is a full-wave rectifier circuit using, for example, six thyristors 18, and converts AC power from the power supply 20 into DC power. The power supply 20 is a three-phase AC power supply such as a commercial power supply, and supplies three-phase 60Hz (or 50Hz) AC power.

[0027] The choke coils 8 and 10 are electrically connected to the positive and negative sides of the output side (DC side) of the rectifier circuit 6, respectively, and smooth the DC power from the rectifier circuit 6.

[0028] The inverter device 12 is an oscillator for outputting a high-frequency current of a predetermined frequency, and is, for example, a single-phase full-bridge type inverter circuit. The inverter device 12 is electrically connected to the output side of the rectifier circuit 6 via choke coils 8 and 10, and converts the smoothed DC power into single-phase high-frequency power. As a result, the inverter device 12 generates a high-frequency current of a predetermined frequency.

[0029] The inverter device 12 has a first series circuit 22 and a second series circuit 24. The first series circuit 22 and the second series circuit 24 are electrically connected in parallel.

[0030] The first series circuit 22 is configured by electrically connecting a first diode 26, a plurality (four in this embodiment) of first switching elements 28, a plurality (four in this embodiment) of second switching elements 30, and a second diode 32 in this order in series.

[0031] The anode side of the first diode 26 is electrically connected to the choke coil 8, and the cathode side of the first diode 26 is electrically connected to each of the multiple first switching elements 28.

[0032] Multiple first switching elements 28 are electrically connected in parallel. Each of the multiple first switching elements 28 is, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and has a drain terminal 28d, a source terminal 28s, and a gate terminal 28g. In each of the multiple first switching elements 28, the conduction between the drain terminal 28d and the source terminal 28s is controlled according to the voltage input to the gate terminal 28g. Each drain terminal 28d of the multiple first switching elements 28 is electrically connected to the cathode side of the first diode 26, and each source terminal 28s of the multiple first switching elements 28 is electrically connected to each of the multiple second switching elements 30.

[0033] Multiple second switching elements 30 are electrically connected in parallel. Each of the multiple second switching elements 30 is, for example, a MOSFET and has a drain terminal 30d, a source terminal 30s, and a gate terminal 30g. In each of the multiple second switching elements 30, the conduction between the drain terminal 30d and the source terminal 30s is controlled according to the voltage input to the gate terminal 30g. Each drain terminal 30d of the multiple second switching elements 30 is electrically connected to each source terminal 28s of the multiple first switching elements 28, and each source terminal 30s of the multiple second switching elements 30 is electrically connected to the second diode 32.

[0034] The anode side of the second diode 32 is electrically connected to each source terminal 30s of the plurality of second switching elements 30, and the cathode side of the second diode 32 is electrically connected to the choke coil 10.

[0035] The second series circuit 24 is configured by electrically connecting the third diode 34, a plurality (four in this embodiment) of third switching elements 36, a plurality (four in this embodiment) of fourth switching elements 38, and the fourth diode 40 in this order in series.

[0036] The anode side of the third diode 34 is electrically connected to the choke coil 8, and the cathode side of the third diode 34 is electrically connected to each of the multiple third switching elements 36.

[0037] Multiple third switching elements 36 are electrically connected in parallel. Each of the multiple third switching elements 36 is, for example, a MOSFET and has a drain terminal 36d, a source terminal 36s, and a gate terminal 36g. In each of the multiple third switching elements 36, the conduction between the drain terminal 36d and the source terminal 36s is controlled according to the voltage input to the gate terminal 36g. Each drain terminal 36d of the multiple third switching elements 36 is electrically connected to the cathode side of the third diode 34, and each source terminal 36s of the multiple third switching elements 36 is electrically connected to each of the multiple fourth switching elements 38.

[0038] Multiple fourth switching elements 38 are electrically connected in parallel. Each of the multiple fourth switching elements 38 is, for example, a MOSFET and has a drain terminal 38d, a source terminal 38s, and a gate terminal 38g. In each of the multiple fourth switching elements 38, conduction between the drain terminal 38d and the source terminal 38s is controlled according to the voltage input to the gate terminal 38g. Each drain terminal 38d of the multiple fourth switching elements 38 is electrically connected to each source terminal 36s of the multiple third switching elements 36, and each source terminal 38s of the multiple fourth switching elements 38 is electrically connected to the fourth diode 40.

[0039] The anode side of the fourth diode 40 is electrically connected to each source terminal 38s of the plurality of fourth switching elements 38, and the cathode side of the fourth diode 40 is electrically connected to the choke coil 10.

[0040] In this embodiment, each of the multiple first switching elements 28, multiple second switching elements 30, multiple third switching elements 36, and multiple fourth switching elements 38 is configured as a MOSFET, but the embodiment is not limited to this, and may be configured as, for example, an IGBT (Insulated Gate Bipolar Transistor) or a bipolar transistor. An IGBT has a collector terminal, an emitter terminal, and a gate terminal, and the conduction between the collector terminal and the emitter terminal is controlled according to the current input to the gate terminal. A bipolar transistor has a collector terminal, an emitter terminal, and a base terminal, and the conduction between the collector terminal and the emitter terminal is controlled according to the current input to the base terminal.

[0041] The matching circuit 14 is for supplying the active power generated by the inverter device 12 to the induction coil 16 with high efficiency. The input side of the matching circuit 14 is electrically connected to the AC side of the inverter device 12, that is, between the connection point between the source terminals 28s of the plurality of first switching elements 28 and the drain terminals 30d of the plurality of second switching elements 30 and the connection point between the source terminals 36s of the plurality of third switching elements 36 and the drain terminals 38d of the plurality of fourth switching elements 38. The matching circuit 14 is a parallel resonant circuit composed of a capacitor 42 and a matching transformer 44.

[0042] The induction coil 16 is electrically connected to the output side of the matching circuit 14. The induction coil 16 is for inductively heating the object to be heated 4 and is positioned to surround the outer surface of the object to be heated 4. The object to be heated 4 is inductively heated when a high-frequency current from the inverter device 12 is supplied to the induction coil 16 via the matching circuit 14.

[0043] The inverter device 12 described above is controlled by a controller (not shown) to switch between a first state and a second state at a high frequency. In the first state, each of the multiple first switching elements 28 and the multiple fourth switching elements 38 is turned on, and each of the multiple second switching elements 30 and the multiple third switching elements 36 is turned off. As a result, as shown by the black arrow P in Figure 1, current flows in the following order: first diode 26 → multiple first switching elements 28 → matching circuit 14 → induction coil 16 → matching circuit 14 → multiple fourth switching elements 38 → fourth diode 40.

[0044] On the other hand, in the second state, each of the multiple second switching elements 30 and the multiple third switching elements 36 is made conductive, while each of the multiple first switching elements 28 and the multiple fourth switching elements 38 is made non-conductive. As a result, as shown by the white arrow Q in Figure 1, current flows in the following order: third diode 34 → multiple third switching elements 36 → matching circuit 14 → induction coil 16 → matching circuit 14 → multiple second switching elements 30 → second diode 32.

[0045] [2. Modular structure of the inverter device] Next, the modular structure of the inverter device 12 will be described with reference to Figures 2 to 9. Figure 2 is a perspective view of the inverter device 12 according to the embodiment. Figure 3 is an exploded perspective view of the inverter device 12 according to the embodiment. Figure 4 is a plan view showing the circuit unit 46 of the inverter device 12 according to the embodiment. Figure 5 is an exploded perspective view showing the stacked busbar 48 of the inverter device 12 according to the embodiment. Figure 6 is a plan view showing the upstream busbar layer 88 of the stacked busbar 48 in Figure 5. Figure 7 is a plan view showing the downstream busbar layer 92 of the stacked busbar 48 in Figure 5. Figure 8 is a side view showing the output busbar 50 of the inverter device 12 according to the embodiment. Figure 9 is a bottom view showing the output busbar 50 of the inverter device 12 according to the embodiment.

[0046] In Figures 2 to 9, the left-right direction of the inverter device 12 is defined as the X-axis, the front-to-back direction of the inverter device 12 is defined as the Y-axis, and the height direction of the inverter device 12 is defined as the Z-axis. In the following explanation, the positive side of the Z-axis is defined as "up," and the negative side of the Z-axis is defined as "down."

[0047] As shown in Figures 2 and 3, the inverter device 12 has a modular structure comprising a circuit unit 46, a stacked busbar 48, and an output busbar 50 (an example of an output section). In other words, the inverter device 12 is modularized by combining the circuit unit 46, the stacked busbar 48, and the output busbar 50.

[0048] As shown in Figure 4, the circuit unit 46 includes a heat sink 52, a first diode 26, a plurality of first switching elements 28, a plurality of second switching elements 30, a second diode 32, a third diode 34, a plurality of third switching elements 36, a plurality of fourth switching elements 38, and a fourth diode 40.

[0049] The heat sink 52 is formed in a rectangular plate shape when viewed from above, and is made of a metal with high heat dissipation properties, such as aluminum. A channel (not shown) for cooling water is formed inside the heat sink 52. On the upper surface of the heat sink 52, a first diode 26, a plurality of first switching elements 28, a plurality of second switching elements 30, a second diode 32, a third diode 34, a plurality of third switching elements 36, a plurality of fourth switching elements 38, and a fourth diode 40 are supported in a manner that allows heat transfer, and are arranged in the first, second, third, and fourth rows. The first to fourth rows are arranged in this order, spaced apart, from one end (the positive Y-axis end) to the other end (the negative Y-axis end) of the heat sink 52.

[0050] As shown in Figure 4, the first column has the first diode 26 and the fourth diode 40 arranged side by side in the left-right direction (X-axis direction). The first diode 26 and the fourth diode 40 are located in the center of the heat sink 52 in the left-right direction. The second column has the first switching element 28 and the fourth switching element 38 arranged alternately in the left-right direction. The third column has the second switching element 30 and the third switching element 36 arranged alternately in the left-right direction. The fourth column has the second diode 32 and the third diode 34 arranged side by side in the left-right direction. The second diode 32 and the third diode 34 are located in the center of the heat sink 52 in the left-right direction.

[0051] The heat generated in each of the first diode 26, the multiple first switching elements 28, the multiple second switching elements 30, the second diode 32, the third diode 34, the multiple third switching elements 36, the multiple fourth switching elements 38, and the fourth diode 40 is dissipated by being transferred to the cooling water flowing through the internal channels of the heat sink 52 via the heat sink 52.

[0052] In this embodiment, the heat dissipation method by the heat sink 52 is water-cooled, but it is not limited to this, and air cooling may also be used. In this case, multiple heat dissipation fins (not shown) may be formed on the lower surface of the heat sink 52.

[0053] The first diode 26 has a package 54, a pair of anode terminals 56, and a pair of cathode terminals 58. The package 54 is made of an insulating material such as resin. The pair of anode terminals 56 are located at one end of the top surface of the package 54 (the end furthest from the second row). The pair of cathode terminals 58 are located at the other end of the top surface of the package 54 (the end closer to the second row).

[0054] The fourth diode 40 has a package 60, a pair of anode terminals 62, and a pair of cathode terminals 64. The package 60 is made of an insulating material such as resin. The pair of anode terminals 62 are located at one end of the top surface of the package 60 (the end closer to the second row). The pair of cathode terminals 64 are located at the other end of the top surface of the package 60 (the end further from the second row).

[0055] Each of the multiple first switching elements 28 has a package 66, a drain terminal 28d, a source terminal 28s, and a gate terminal 28g. The package 66 is formed of an insulating material such as resin. The drain terminal 28d is located at one end of the upper surface of the package 66 (the end closer to the first row). The source terminal 28s is located at the other end of the upper surface of the package 66 (the end further from the first row).

[0056] Each of the multiple fourth switching elements 38 has a package 68, a drain terminal 38d, a source terminal 38s, and a gate terminal 38g. The package 68 is formed of an insulating material such as resin. The drain terminal 38d is located at one end of the upper surface of the package 68 (the end furthest from the first row). The source terminal 38s is located at the other end of the upper surface of the package 68 (the end closer to the first row).

[0057] Each of the multiple second switching elements 30 has a package 70, a drain terminal 30d, a source terminal 30s, and a gate terminal 30g. The package 70 is made of an insulating material such as resin. The drain terminal 30d is located at one end of the top surface of the package 70 (the end furthest from the fourth row). The source terminal 30s is located at the other end of the top surface of the package 70 (the end closer to the fourth row).

[0058] Each of the multiple third switching elements 36 has a package 72, a drain terminal 36d, a source terminal 36s, and a gate terminal 36g. The package 72 is made of an insulating material such as resin. The drain terminal 36d is located at one end of the top surface of the package 72 (the end closer to the fourth row). The source terminal 36s is located at the other end of the top surface of the package 72 (the end further from the fourth row).

[0059] The second diode 32 has a package 74, a pair of anode terminals 76, and a pair of cathode terminals 78. The package 74 is made of an insulating material such as resin. The pair of anode terminals 76 are located at one end of the top surface of the package 74 (the end closer to the third row). The pair of cathode terminals 78 are located at the other end of the top surface of the package 74 (the end further from the third row).

[0060] The third diode 34 has a package 80, a pair of anode terminals 82, and a pair of cathode terminals 84. The package 80 is made of an insulating material such as resin. The pair of anode terminals 82 are located at one end of the top surface of the package 80 (the end furthest from the third row). The pair of cathode terminals 84 are located at the other end of the top surface of the package 80 (the end closer to the third row).

[0061] As shown in Figures 2 and 3, the laminated busbar 48 is formed in a roughly U-shape in an XY plan view and is positioned opposite the upper surface of the heat sink 52 of the circuit unit 46. The laminated busbar 48 is made of, for example, a laminated busbar. Specifically, as shown in Figure 5, the laminated busbar 48 has a structure in which an outer insulating film 86, an upstream busbar layer 88, an intermediate insulating film 90, a downstream busbar layer 92, and an outer insulating film 94 are laminated in this order.

[0062] In this specification, "upstream side" means the upstream side of the current flow in the inverter device 12, and "downstream side" means the downstream side of the current flow in the inverter device 12.

[0063] As shown in Figure 5, the outer insulating film 86 is an insulating film for electrically insulating the lower surface of the upstream busbar layer 88. The outer insulating film 86 is formed in a roughly U-shape in an XY plan view and is positioned to cover the lower surface of the upstream busbar layer 88. That is, the lower surface of the upstream busbar layer 88 is laminated by the outer insulating film 86. The outer insulating film 86 has a plurality of rectangular openings 96, 98, 100, 102 formed therein for exposing the first diode 26, the second diode 32, the third diode 34, and the fourth diode 40, respectively.

[0064] As shown in Figures 5 and 6, the upstream busbar layer 88 includes a positive busbar 104, a first busbar 106, and a third busbar 108. The positive busbar 104, the first busbar 106, and the third busbar 108 are arranged on the same plane and are electrically insulated from each other.

[0065] The positive busbar 104 is made of a metal such as copper and has a thickness of approximately 2-3 mm. The positive busbar 104 has a first connecting portion 104a, a second connecting portion 104b, and a third connecting portion 104c.

[0066] The first connection portion 104a extends upward from one end in the longitudinal direction of the second connection portion 104b and the third connection portion 104c, and is electrically connected to the choke coil 8 (see Figure 1).

[0067] The second connection portion 104b is formed in a substantially L-shape in an XY plan view. One end of the second connection portion 104b in the longitudinal direction is electrically connected to the choke coil 8 via the first connection portion 104a. The other end of the second connection portion 104b in the longitudinal direction has a pair of circular through holes 110 formed therein to expose the pair of anode terminals 56 of the first diode 26. By screwing a screw 112 (see Figure 2) through the through holes 110 into the anode terminals 56, the other end of the second connection portion 104b in the longitudinal direction is electrically connected to the pair of anode terminals 56 of the first diode 26. As a result, the pair of anode terminals 56 of the first diode 26 are electrically connected to the choke coil 8 via the first connection portion 104a and the second connection portion 104b.

[0068] The third connector 104c is formed in a substantially L-shape in an XY plan view. One end of the third connector 104c in the longitudinal direction is electrically connected to the choke coil 8 via the first connector 104a. The other end of the third connector 104c in the longitudinal direction has a pair of circular through holes 114 formed therein to expose the pair of anode terminals 82 of the third diode 34. By screwing a screw 116 (see Figure 2) through the through holes 114 into the anode terminals 82, the other end of the third connector 104c in the longitudinal direction is electrically connected to the pair of anode terminals 82 of the third diode 34. As a result, the pair of anode terminals 82 of the third diode 34 are electrically connected to the choke coil 8 via the first connector 104a and the third connector 104c.

[0069] The first busbar 106 is made of a metal such as copper and has a thickness of approximately 2-3 mm. In an XY plan view, the first busbar 106 extends in the left-right direction between the first and second rows of the circuit unit 46 (see Figure 4). A pair of circular through holes 118 are formed at one end of the first busbar 106 in the short direction (Y-axis direction) to expose the pair of cathode terminals 58 of the first diode 26. By screwing a screw 120 (see Figure 2) through the through holes 118 into the cathode terminals 58, the one end of the first busbar 106 in the short direction is electrically connected to the pair of cathode terminals 58 of the first diode 26.

[0070] Furthermore, a plurality of protrusions 122 are formed on the other end of the first busbar 106 in the short direction. The plurality of protrusions 122 are spaced along the longitudinal direction (X-axis direction) of the first busbar 106, corresponding to the spacing of the drain terminals 28d of the plurality of first switching elements 28. Each of the plurality of protrusions 122 has a circular through hole 124 formed therein to expose the drain terminal 28d of the first switching element 28. By screwing a screw 126 (see Figure 3) through the through hole 124 into the drain terminal 28d, the other end of the first busbar 106 in the short direction is electrically connected to the drain terminal 28d of the plurality of first switching elements 28.

[0071] As a result, the first busbar 106 electrically connects each of the pair of cathode terminals 58 of the first diode 26 to each drain terminal 28d of the plurality of first switching elements 28. The first busbar 106 also has a first slit 128 formed therein that penetrates the first busbar 106 in its thickness direction (Z-axis direction). In an XY plan view, the first slit 128 extends in the left-right direction so as to cross between the first diode 26 and the plurality of first switching elements 28.

[0072] The third busbar 108 is made of a metal such as copper and has a thickness of approximately 2-3 mm. In an XY plan view, the third busbar 108 extends in the left-right direction between the third and fourth rows of the circuit unit 46. A pair of circular through holes 130 are formed at one end of the third busbar 108 in the short direction (Y-axis direction) to expose the pair of cathode terminals 84 of the third diode 34. The short end of the third busbar 108 is electrically connected to the pair of cathode terminals 84 of the third diode 34 by screwing a screw 132 (see Figure 2) through the through holes 130 into the cathode terminals 84.

[0073] Furthermore, a plurality of protrusions 134 are formed on the other end of the third busbar 108 in the short direction. The plurality of protrusions 134 are spaced along the longitudinal direction (X-axis direction) of the third busbar 108, corresponding to the spacing of the drain terminals 36d of the plurality of third switching elements 36. Each of the plurality of protrusions 134 has a circular through hole 136 formed therein to expose the drain terminal 36d of the third switching element 36. By screwing a screw 138 (see Figure 3) through the through hole 136 into the drain terminal 36d, the other end of the third busbar 108 in the short direction is electrically connected to the drain terminal 36d of the plurality of third switching elements 36.

[0074] As a result, the third busbar 108 electrically connects each of the pair of cathode terminals 84 of the third diode 34 to each drain terminal 36d of the plurality of third switching elements 36. The third busbar 108 also has a third slit 140 that penetrates the third busbar 108 in its thickness direction (Z-axis direction). In an XY plan view, the third slit 140 extends in the left-right direction so as to cross between the third diode 34 and the plurality of third switching elements 36.

[0075] As shown in Figure 5, the intermediate insulating film 90 is an insulating film for electrically insulating the upper surface of the upstream busbar layer 88 and the lower surface of the downstream busbar layer 92. The intermediate insulating film 90 is formed in a roughly U-shape in an XY plan view and is arranged to cover the upper surface of the upstream busbar layer 88 and the lower surface of the downstream busbar layer 92, respectively. That is, the upper surface of the upstream busbar layer 88 and the lower surface of the downstream busbar layer 92 are laminated by the intermediate insulating film 90. The intermediate insulating film 90 has a plurality of rectangular openings 142, 144 formed therein for exposing the second diode 32 and the fourth diode 40, respectively. The intermediate insulating film 90 also has a plurality of circular through holes 146 formed therein for exposing the pair of anode terminals 56 and the pair of cathode terminals 58 of the first diode 26, respectively. Furthermore, the intermediate insulating film 90 has a plurality of circular through holes 148 formed therein to expose the pair of anode terminals 82 and the pair of cathode terminals 84 of the third diode 34, respectively.

[0076] As shown in Figures 5 and 7, the downstream busbar layer 92 includes a negative busbar 150, a second busbar 152, and a fourth busbar 154. The negative busbar 150, the second busbar 152, and the fourth busbar 154 are arranged on the same plane and are electrically insulated from each other.

[0077] The negative busbar 150 is made of a metal such as copper and has a thickness of approximately 2-3 mm. The negative busbar 150 has a first connecting portion 150a, a second connecting portion 150b, and a third connecting portion 150c.

[0078] The first connection portion 150a extends upward from one end of the second connection portion 150b and the third connection portion 150c in their respective longitudinal directions and is electrically connected to the choke coil 10 (see Figure 1).

[0079] The second connection portion 150b is formed in a substantially L-shape in an XY plan view. One end of the second connection portion 150b in the longitudinal direction is electrically connected to the choke coil 10 via the first connection portion 150a. The other end of the second connection portion 150b in the longitudinal direction has a pair of circular through holes 156 formed therein to expose the pair of cathode terminals 64 of the fourth diode 40. By screwing a screw 158 (see Figure 2) through the through holes 156 into the cathode terminals 64, the other end of the second connection portion 150b in the longitudinal direction is electrically connected to the pair of cathode terminals 64 of the fourth diode 40. As a result, the pair of cathode terminals 64 of the fourth diode 40 are electrically connected to the choke coil 10 via the first connection portion 150a and the second connection portion 150b.

[0080] The third connection portion 150c is formed in a substantially L-shape in an XY plan view. One end of the third connection portion 150c in the longitudinal direction is electrically connected to the choke coil 10 via the first connection portion 150a. The other end of the third connection portion 150c in the longitudinal direction has a pair of circular through holes 160 formed therein to expose the pair of cathode terminals 78 of the second diode 32. By screwing a screw 162 (see Figure 2) through the through holes 160 into the cathode terminals 78, the other end of the third connection portion 150c in the longitudinal direction is electrically connected to the pair of cathode terminals 78 of the second diode 32. As a result, the pair of cathode terminals 78 of the second diode 32 are electrically connected to the choke coil 10 via the first connection portion 150a and the third connection portion 150c.

[0081] The fourth busbar 154 is made of a metal such as copper and has a thickness of approximately 2-3 mm. In an XY plan view, the fourth busbar 154 extends in the left-right direction between the first and second rows of the circuit unit 46 so as to overlap with the first busbar 106 (see Figure 6). That is, the fourth busbar 154 is laminated on the first busbar 106 via an intermediate insulating film 90 (an example of a second insulating material).

[0082] One end of the fourth busbar 154 in the short direction (Y-axis direction) has a pair of circular through holes 164 formed therein, each exposing a pair of anode terminals 62 of the fourth diode 40. By screwing a screw 166 (see Figure 2) through the through holes 164 into the anode terminals 62, one end of the fourth busbar 154 in the short direction is electrically connected to the pair of anode terminals 62 of the fourth diode 40.

[0083] Furthermore, a plurality of protrusions 168 are formed on the other end of the fourth busbar 154 in the short direction. The plurality of protrusions 168 are spaced apart along the longitudinal direction (X-axis direction) of the fourth busbar 154, corresponding to the spacing of the source terminals 38s of the plurality of fourth switching elements 38. Each of the plurality of protrusions 168 has a circular through hole 170 formed therein to expose the source terminals 38s of the fourth switching elements 38. By screwing a screw 172 (see Figure 3) through the through hole 170 into the source terminals 38s, the other end of the fourth busbar 154 in the short direction is electrically connected to the source terminals 38s of the plurality of fourth switching elements 38.

[0084] As a result, the fourth busbar 154 electrically connects each of the pair of anode terminals 62 of the fourth diode 40 to each of the source terminals 38s of the plurality of fourth switching elements 38. The fourth busbar 154 also has a fourth slit 174 that penetrates the busbar 154 in its thickness direction (Z-axis direction). In an XY plan view, the fourth slit 174 extends in the left-right direction so as to cross between the fourth diode 40 and the plurality of fourth switching elements 38.

[0085] The second busbar 152 is made of a metal such as copper and has a thickness of approximately 2-3 mm. In an XY plan view, the second busbar 152 extends in the left-right direction between the third and fourth rows of the circuit unit 46 so as to overlap with the third busbar 108 (see Figure 6). That is, the second busbar 152 is laminated on the third busbar 108 via an intermediate insulating film 90 (an example of the first insulating material).

[0086] One end of the second busbar 152 in the short direction (Y-axis direction) has a pair of circular through holes 176 formed therein, each exposing a pair of anode terminals 76 of the second diode 32. By screwing a screw 178 (see Figure 2) through the through holes 176 into the anode terminals 76, one end of the second busbar 152 in the short direction is electrically connected to the pair of anode terminals 76 of the second diode 32.

[0087] Furthermore, a plurality of protrusions 180 are formed on the other end of the second busbar 152 in the short direction. The plurality of protrusions 180 are spaced apart along the longitudinal direction (X-axis direction) of the second busbar 152, corresponding to the spacing of the source terminals 30s of the plurality of second switching elements 30. Each of the plurality of protrusions 180 has a circular through hole 182 formed therein to expose the source terminals 30s of the second switching elements 30. By screwing a screw 184 (see Figure 3) through the through hole 182 into the source terminal 30s, the other end of the second busbar 152 in the short direction is electrically connected to the source terminals 30s of the plurality of second switching elements 30.

[0088] As a result, the second busbar 152 electrically connects each of the pair of anode terminals 76 of the second diode 32 to each of the source terminals 30s of the plurality of second switching elements 30. The second busbar 152 also has a second slit 186 formed therein that penetrates the busbar 152 in its thickness direction (Z-axis direction). In an XY plan view, the second slit extends in the left-right direction so as to cross between the second diode 32 and the plurality of second switching elements 30.

[0089] As shown in Figure 5, the outer insulating film 94 is an insulating film for electrically insulating the upper surface of the downstream busbar layer 92. The outer insulating film 94 is formed in a roughly U-shape in an XY plan view and is arranged to cover the upper surface of the downstream busbar layer 92. That is, the upper surface of the downstream busbar layer 92 is laminated by the outer insulating film 94. The outer insulating film 94 has a plurality of circular through holes 188 formed therein to expose a pair of anode terminals 56 and a pair of cathode terminals 58 of the first diode 26, respectively. The outer insulating film 94 also has a plurality of circular through holes 190 formed therein to expose a pair of anode terminals 76 and a pair of cathode terminals 78 of the second diode 32, respectively. The outer insulating film 94 also has a plurality of circular through holes 192 formed therein to expose a pair of anode terminals 82 and a pair of cathode terminals 84 of the third diode 34, respectively. Furthermore, the outer insulating film 94 has a plurality of circular through-holes 194 formed therein to expose the pair of anode terminals 62 and the pair of cathode terminals 64 of the fourth diode 40, respectively.

[0090] Here, we will explain the current flow in the stacked busbar 48 when the inverter device 12 is switched to the first state. As shown by the black arrow P1 in Figure 6, the current from the choke coil 8 flows through the first connection part 104a and the second connection part 104b of the positive busbar 104 and is supplied to the pair of anode terminals 56 of the first diode 26.

[0091] Next, as shown by the black arrow P2 in Figure 6, the current from the pair of cathode terminals 58 of the first diode 26 flows through the first busbar 106 and is supplied to each drain terminal 28d of the first switching element 28. At this time, the current from the pair of cathode terminals 58 of the first diode 26 is blocked by the first slit 128, causing it to flow toward both ends of the first slit 128 in the longitudinal direction (X-axis direction). Then, the current flows from both ends of the first slit 128 in the longitudinal direction toward each drain terminal 28d of the multiple first switching elements 28. This allows current to be supplied in a balanced manner to each drain terminal 28d of the multiple first switching elements 28.

[0092] Next, as shown by the black arrow P3 in Figure 7, the current from each source terminal 38s of the fourth switching element 38 flows through the fourth busbar 154 and is supplied to the pair of anode terminals 62 of the fourth diode 40. At this time, since the fourth slit 174 is formed in the fourth busbar 154, in an XY plane view, the current path in the fourth busbar 154 overlaps with the current path in the first busbar 106. That is, when the stacked busbar 48 is viewed in an XY plane, the current flowing through the first busbar 106, shown by the black arrow P2 in Figure 6, is in the opposite direction to the current flowing through the fourth busbar 154, shown by the black arrow P3 in Figure 7.

[0093] Next, as shown by the black arrow P4 in Figure 7, the current from the pair of cathode terminals 64 of the fourth diode 40 flows through the second connection part 150b and the first connection part 150a of the negative busbar 150 and is supplied to the choke coil 10. At this time, when the laminated busbar 48 is viewed in the XY plane, the current flowing through the positive busbar 104, shown by the black arrow P1 in Figure 6, is in the opposite direction to the current flowing through the negative busbar 150, shown by the black arrow P4 in Figure 7.

[0094] Next, we will describe the current flow in the stacked busbar 48 when the inverter device 12 is switched to the second state. As shown by the white arrow Q1 in Figure 6, the current from the choke coil 8 flows through the first connection part 104a and the third connection part 104c of the positive busbar 104 and is supplied to the pair of anode terminals 82 of the third diode 34.

[0095] Next, as shown by the white arrow Q2 in Figure 6, the current from the pair of cathode terminals 84 of the third diode 34 flows through the third busbar 108 and is supplied to each drain terminal 36d of the third switching element 36. At this time, the current from the pair of cathode terminals 84 of the third diode 34 is blocked by the third slit 140, causing it to flow toward both ends of the third slit 140 in the longitudinal direction (X-axis direction). Then, the current flows from both ends of the third slit 140 in the longitudinal direction toward each drain terminal 36d of the multiple third switching elements 36. This allows current to be supplied in a balanced manner to each drain terminal 36d of the multiple third switching elements 36.

[0096] Next, as shown by the white arrow Q3 in Figure 7, the current from each source terminal 30s of the second switching element 30 flows through the second busbar 152 and is supplied to the pair of anode terminals 76 of the second diode 32. At this time, since the second slit 186 is formed in the second busbar 152, in an XY plane view, the current path in the second busbar 152 overlaps with the current path in the third busbar 108. That is, when the stacked busbar 48 is viewed in an XY plane, the current flowing through the third busbar 108, shown by the white arrow Q2 in Figure 6, is in the opposite direction to the current flowing through the second busbar 152, shown by the white arrow Q3 in Figure 7.

[0097] Next, as shown by the white arrow Q4 in Figure 7, the current from the pair of cathode terminals 78 of the second diode 32 flows through the third connection part 150c and the first connection part 150a of the negative busbar 150 and is supplied to the choke coil 10. At this time, when the laminated busbar 48 is viewed in the XY plane, the current flowing through the positive busbar 104, shown by the white arrow Q1 in Figure 6, is in the opposite direction to the current flowing through the negative busbar 150, shown by the white arrow Q4 in Figure 7.

[0098] As shown in Figures 2, 3, 8, and 9, the output busbar 50 extends horizontally between the second and third rows of the circuit unit 46 in an XY plan view, and is erected upward from the top surface of the circuit unit 46 in an XZ side view. The output busbar 50 comprises a first output busbar 196, a second output busbar 198, and an insulating film 200.

[0099] The first output busbar 196 is made of a metal such as copper and is formed in the shape of a horizontally elongated plate. The first output busbar 196 is electrically connected to the matching circuit 14 (see Figure 1). The lower end of the first output busbar 196 has a plurality of legs 202 that protrude to one side (the positive side of the Y-axis) and a plurality of legs 204 that protrude to the other side (the negative side of the Y-axis).

[0100] Multiple legs 202 are spaced along the longitudinal direction (X-axis direction) of the first output busbar 196, corresponding to the spacing of the source terminals 28s of the multiple first switching elements 28. Each of the multiple legs 202 has a circular through-hole 206 formed therein to expose the source terminals 28s of the first switching elements 28. The first output busbar 196 is electrically connected to each source terminal 28s of the multiple first switching elements 28 by screwing screws (not shown) through the through-holes 206 into the source terminals 28s.

[0101] Furthermore, the multiple legs 204 are spaced along the longitudinal direction of the first output busbar 196, corresponding to the spacing of the drain terminals 30d of the multiple second switching elements 30. Each of the multiple legs 204 has a circular through-hole 208 formed therein to expose the drain terminal 30d of the second switching element 30. The first output busbar 196 is electrically connected to each drain terminal 30d of the multiple second switching elements 30 by screwing a screw 209 (see Figure 2) through the through-hole 208 into the drain terminal 30d.

[0102] The second output busbar 198 is made of a metal such as copper and is formed in the shape of a horizontally elongated plate. The second output busbar 198 is laminated on the first output busbar 196 via an insulating film 200 and is electrically connected to the matching circuit 14. The lower end of the second output busbar 198 has a plurality of legs 210 protruding to one side (the positive side of the Y-axis) and a plurality of legs 212 protruding to the other side (the negative side of the Y-axis).

[0103] Multiple legs 210 are spaced along the longitudinal direction (X-axis direction) of the second output busbar 198, corresponding to the spacing of the drain terminals 38d of the multiple fourth switching elements 38. Each of the multiple legs 210 has a circular through-hole 214 formed therein to expose the drain terminal 38d of the fourth switching element 38. The second output busbar 198 is electrically connected to each drain terminal 38d of the multiple fourth switching elements 38 by screwing screws (not shown) through the through-holes 214 into the drain terminals 38d.

[0104] Furthermore, the multiple legs 212 are spaced along the longitudinal direction of the second output busbar 198, corresponding to the spacing of the source terminals 36s of the multiple third switching elements 36. Each of the multiple legs 212 has a circular through-hole 216 formed therein to expose the source terminals 36s of the third switching elements 36. The second output busbar 198 is electrically connected to each source terminal 36s of the multiple third switching elements 36 by screwing screws 217 (see Figure 2) through the through-holes 216 into the source terminals 36s.

[0105] In other words, the output busbar 50 is electrically connected between the connection points between the source terminals 28s of the multiple first switching elements 28 and the drain terminals 30d of the multiple second switching elements 30, and between the connection points between the source terminals 36s of the multiple third switching elements 36 and the drain terminals 38d of the multiple fourth switching elements 38.

[0106] Here, we will describe the current flow in the output busbar 50 when the inverter device 12 is switched to the first state. Current from each source terminal 28s of the multiple first switching elements 28 flows through the first output busbar 196 and is supplied to the matching circuit 14. Then, the current that returns from the matching circuit 14 via the induction coil 16 flows through the second output busbar 198 and is supplied to each drain terminal 38d of the multiple fourth switching elements 38. At this time, the current flowing through the first output busbar 196 is in the opposite direction to the current flowing through the second output busbar 198.

[0107] Next, the current flow in the output busbar 50 when the inverter device 12 is switched to the second state will be described. Current from each source terminal 36s of the multiple third switching elements 36 flows through the second output busbar 198 and is supplied to the matching circuit 14. Then, the current that returns from the matching circuit 14 via the induction coil 16 flows through the first output busbar 196 and is supplied to each drain terminal 30d of the multiple second switching elements 30. At this time, similar to the first state described above, the current flowing through the first output busbar 196 is in the opposite direction to the current flowing through the second output busbar 198.

[0108] [3. Structure of the Inverter Unit] Next, the structure of the inverter unit 218 according to the embodiment will be described with reference to Figure 10. Figure 10 is a side view showing the inverter unit 218 according to the embodiment.

[0109] As shown in Figure 10, the inverter unit 218 according to this embodiment comprises a pair of DC-side busbars 220 and 222, a pair of AC-side busbars 224 and 226, and a plurality of inverter devices 12 electrically connected in parallel between the pair of DC-side busbars 220 and 222 and the pair of AC-side busbars 224 and 226.

[0110] The pair of DC-side busbars 220 and 222 are electrically connected to the first connection points 104a and 150a of each inverter device 12 via coils 228 and 230, respectively. The coils 228 and 230 are for balancing the amount of current flowing between each of the pair of DC-side busbars 220 and 222 and the inverter device 12, and are made of, for example, a copper pipe wound with one turn. The pair of DC-side busbars 220 and 222 are also electrically connected to choke coils 8 and 10 (see Figure 1), respectively.

[0111] The pair of AC-side busbars 224 and 226 are electrically connected to the first output busbar 196 and the second output busbar 198 of each inverter device 12, respectively. Furthermore, the pair of AC-side busbars 224 and 226 are electrically connected to the matching circuit 14 (see Figure 1).

[0112] In the inverter unit 218 described above, the rated output of the inverter unit 218 can be easily changed by changing the number of modularized inverter devices 12. In this embodiment, the inverter unit 218 is provided with multiple inverter devices 12, but it is not limited to this, and for example, if the rated output of the inverter unit 218 is relatively low, it may be provided with only one inverter device 12.

[0113] [4. Effects] In this embodiment, as described above, when the inverter device 12 is switched to the first state, when the stacked busbars 48 are viewed in the XY plane, the current flowing through the first busbar 106 is in the opposite direction to the current flowing through the fourth busbar 154. As a result, the magnetic field caused by the current flowing through the first busbar 106 and the magnetic field caused by the current flowing through the fourth busbar 154 cancel each other out.

[0114] Furthermore, when the inverter device 12 is switched to the second state, when the stacked busbars 48 are viewed in the XY plane, the current flowing through the third busbar 108 is in the opposite direction to the current flowing through the second busbar 152. As a result, the magnetic field caused by the current flowing through the third busbar 108 and the magnetic field caused by the current flowing through the second busbar 152 cancel each other out.

[0115] As a result, the parasitic inductance in the inverter device 12 can be reduced, and ringing can be reduced during the switching operations of the multiple first switching elements 28, multiple second switching elements 30, multiple third switching elements 36, and multiple fourth switching elements 38.

[0116] [5. Variant] The stacked busbars 48 of the inverter device 12 may be manufactured using a 3D printer. This makes it easy to form a flow channel for a cooling fluid (e.g., cooling water) inside at least one of the first busbars 106, second busbar 152, third busbar 108, and fourth busbar 154. The size of the flow channel in the thickness direction of each busbar is, for example, about 1 mm. With this configuration, the heat generated in each of the multiple first switching elements 28, multiple second switching elements 30, multiple third switching elements 36, and multiple fourth switching elements 38 can be efficiently dissipated.

[0117] Furthermore, in addition to the components described above, the inverter device 12 may also be equipped with a temperature sensor such as a thermistor for detecting the temperature of the stacked busbar 48. By monitoring the detection signal from the temperature sensor, it is possible to detect, for example, that a steep rise in current has occurred in the inverter device 12 when the temperature of the stacked busbar 48 rises rapidly.

[0118] (Other variations, etc.) Although inverter devices and inverter units according to one or more embodiments of the present invention have been described above based on the above embodiments, the present invention is not limited to the above embodiments. Without departing from the spirit of the present invention, various modifications that a person skilled in the art can conceive of may be applied to these embodiments, and forms constructed by combining components from different embodiments may also be included within the scope of one or more embodiments of the present invention.

[0119] In the above embodiment, the inverter device 12 was applied to the induction heating device 2, but the invention is not limited to this and may be applied to various devices such as industrial machinery or home appliances.

[0120] Furthermore, in the above embodiment, the inverter device 12 is provided with a plurality of first switching elements 28, a plurality of second switching elements 30, a plurality of third switching elements 36, and a plurality of fourth switching elements 38. However, it is not limited to this, and may be provided with one first switching element 28, one second switching element 30, one third switching element 36, and one fourth switching element 38. [Industrial applicability]

[0121] The inverter device according to the present invention can be applied, for example, to an induction heating device for high-frequency induction hardening of metal parts. [Explanation of Symbols]

[0122] 2 Induction heating device 4 Object to be heated 6 Rectifier circuit 8,10 Choke coil 12 Inverter device 14 Matching circuit 16 Induction coil 18 Thyristors 20 Power supply 22 First series circuit 24. Second series circuit 26 First diode 28 First switching element 28d, 30d, 36d, 38d drain terminals 28s, 30s, 36s, 38s source terminals 28g, 30g, 36g, 38g gate terminals 30 Second switching element 32 Second diode 34. Third diode 36. Third switching element 38. Fourth switching element 40. Fourth diode 42 Capacitors 44 Matching Transformers 46 Circuit Units 48 Laminated Busbars 50 Output Busbar 52 Heatsink 54, 60, 66, 68, 70, 72, 74, 80 packages 56, 62, 76, 82 Anode terminals 58, 64, 78, 84 Cathode terminals 86,94 Outer insulating film 88 Upstream Busber Formation 90 Intermediate insulating film 92 Downstream Busber Formation 96, 98, 100, 102, 142, 144 Openings 104 Plus side busbar 104a, 150a First connection part 104b, 150b Second connection section 104c, 150c Third connection point 106 The first bus bar 108 The Third Bus Bar 110, 114, 118, 124, 130, 136, 146, 148, 156, 160, 164, 170, 176, 182, 188, 190, 192, 194, 206, 208, 214, 216 through holes 112,116,120,126,132,138,158,162,166,172,178,184,209,217 screws 122,134,168,180 protrusions 128 First slit 140 Third slit 150 Negative side busbar 152 The second bus bar 154 The 4th Busbar 174 The fourth slit 186 Second slit 196 First Output Busbar 198 Second output busbar 200 insulating film 202,204,210,212 Legs 218 Inverter Unit 220,222 DC busbar 224,226 AC busbar 228,230 coils

Claims

1. A first series circuit in which a first diode, a first switching element, a second switching element, and a second diode are connected in series in this order, A second series circuit in which a third diode, a third switching element, a fourth switching element, and a fourth diode are connected in series in this order, and the second series circuit is connected in parallel with the first series circuit, An output section electrically connected between the connection point of the first switching element and the second switching element and the connection point of the third switching element and the fourth switching element, Equipped with a laminated busbar, The aforementioned stacked busbar is A first busbar electrically connects the first diode and the first switching element, A second busbar electrically connects the second switching element and the second diode, The third diode and the third switching element are electrically connected, and the third busbar is laminated on the second busbar via the first insulating material, The fourth switching element and the fourth diode are electrically connected, and the fourth busbar is laminated on the first busbar via a second insulating material, When the stacked busbars are viewed in plan view, the current flowing through the first busbar is in the opposite direction to the current flowing through the fourth busbar, and the current flowing through the third busbar is in the opposite direction to the current flowing through the second busbar. Inverter device.

2. The aforementioned laminated busbar is composed of laminated busbars. The inverter device according to claim 1.

3. In the first series circuit, the first diode, a plurality of first switching elements connected in parallel, a plurality of second switching elements connected in parallel, and the second diode are connected in series in this order. In the second series circuit, the third diode, a plurality of the third switching elements connected in parallel, a plurality of the fourth switching elements connected in parallel, and the fourth diode are connected in series in this order. The first busbar has a first slit that is positioned to cross between the first diode and the plurality of first switching elements, The second busbar has a second slit positioned to cross between the second diode and the plurality of second switching elements, The third busbar has a third slit positioned to cross between the third diode and the plurality of third switching elements, The fourth busbar has a fourth slit positioned to cross between the fourth diode and the plurality of fourth switching elements. The inverter device according to claim 1 or 2.

4. A flow path for cooling fluid is formed inside at least one of the first, second, third, and fourth busbars. The inverter device according to claim 1 or 2.

5. The inverter device further includes a temperature sensor for detecting the temperature of the stacked busbars. The inverter device according to claim 1 or 2.

6. DC busbar and AC busbar, The inverter device comprises one or more inverter devices according to claim 1, electrically connected between the DC-side busbar and the AC-side busbar. Inverter unit.

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