Power converter

Abstract

To provide a power conversion device that can be miniaturized while suppressing the decrease in inductance at the application terminal. [Solution] The power converter 10 includes two or more sets of two switching circuits 30 connected in series with each other. The switching circuits 30 include two semiconductor elements 33 connected in parallel with each other. The semiconductor element 33 includes a plurality of application terminals 35 and an element body 34 to which the plurality of application terminals 35 are connected. The plurality of application terminals 35 are connected to a control board 11. At least one of the plurality of application terminals 35 includes a first portion 51 that is closer to the element body 34 in the direction in which the applied current flows through the application terminal 35, and a second portion 52 that is further away from the element body 34 than the first portion 51. The applied current flowing through the second portion 52 is opposite to the applied current flowing through the first portion 51. The application terminal 35 having the first portion 51 and the second portion 52 has a magnetic member 60 interposed between the first portion 51 and the second portion 52.

Description

Technical Field

[0001] The present invention relates to a power conversion device.

Background Art

[0002] Conventionally, in a power conversion device including a plurality of semiconductor elements such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), there are cases where a plurality of semiconductor elements connected in parallel are provided for the purpose of reducing heat generation in each semiconductor element. In a power conversion device including semiconductor elements connected in parallel, oscillation may occur between the inductance of the wiring and the parasitic capacitance of the semiconductor element in a circuit including the semiconductor element. The inductance is generated by different lengths of the wiring connecting the power supply and each semiconductor element in a circuit including semiconductor elements connected in parallel. Oscillation occurring between the inductance of the wiring and the parasitic capacitance of the semiconductor element leads to ringing in the semiconductor element. For example, in Patent Document 1, a power conversion device is disclosed that includes two main circuits as switching circuits on a substrate and a sub-circuit including a switching element and a capacitor. The power conversion device suppresses oscillation on the substrate by connecting the sub-circuit in parallel to at least one of the two main circuits.

[0003] As a means for suppressing the above oscillation, it is also conceivable to make the length of the wiring connecting one semiconductor element and the power supply equal to the length of the wiring connecting the other semiconductor element and the power supply in two semiconductor elements connected in parallel. Specifically, by extending the lead wire, which is the application terminal of the semiconductor element with a short wiring length from the power supply, while folding it back, the length is made equal to the lead wire of the semiconductor element with a long wiring length from the power supply. Specifically, the lengths of the two wirings are made equal to the length of the lead wire of the semiconductor element with a long wiring length from the power supply by extending the lead wire, which is the application terminal of the semiconductor element with a short wiring length from the power supply, while folding it back. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2012-186915 [Overview of the project] [Problems that the invention aims to solve]

[0005] In a power converter, when the application terminal is extended by folding the lead wire, the folding of the lead wire may cause the direction of the current flowing through a portion of the application terminal to be opposite to the direction of the current flowing through another portion located nearby. In this case, the magnetic field of a portion of the application terminal may couple with the magnetic field of another portion, potentially causing the inductance generated at that application terminal to become smaller than the inductance required to suppress the oscillation described above.

[0006] Furthermore, if space is secured between a portion of the application terminal and other portions in order to suppress the coupling of magnetic fields between those portions, the power conversion device may become larger due to this space. For these reasons, it is desirable for power conversion devices to be miniaturized while suppressing the decrease in inductance at the application terminals. [Means for solving the problem]

[0007] A power conversion device for solving the above problems comprises two or more sets of two switching circuits connected in series with each other, each switching circuit comprises two semiconductor elements connected in parallel with each other, each semiconductor element comprises a plurality of application terminals through which an applied current flows, a plurality of application terminals connected to a control board, and an element body to which the plurality of application terminals are connected, at least one of the plurality of application terminals comprises a first portion closer to the element body in the direction in which the applied current flows through the application terminal, and a second portion further from the element body than the first portion, the applied current flowing through the second portion is opposite to the applied current flowing through the first portion, and the gist of the power conversion device for converting DC power to AC power is that a magnetic member is interposed between the first portion and the second portion of the application terminal.

[0008] According to this, at the application terminal, the applied current flowing through the first part flows in a direction opposite to the applied current flowing through the second part. The magnetic fields generated by the applied currents flowing through the first and second parts pass through the magnetic member. As a result, the magnetic member suppresses the decrease in inductance at the application terminal caused by the coupling of the magnetic fields of the first and second parts. In power converters without a magnetic member, the decrease in inductance due to the coupling of the magnetic fields of the first and second parts can sometimes be suppressed by securing a space between the first and second parts. Compared to this case, the power converter can suppress the decrease in inductance due to the coupling of the magnetic fields of the first and second parts without securing a space between them. In other words, by interposing a magnetic member between the first and second parts, the power converter can be made smaller and the coupling of the magnetic fields described above can be suppressed compared to the case where a space is secured between the first and second parts.

[0009] In the power conversion device, the first and second portions may extend parallel to the control board. According to this, the power converter can reduce the space occupied by the application terminals comprising the first and second parts in the direction in which each of the first and second parts extends, compared to a case where the direction in which each of the first and second parts extends includes a direction perpendicular to the control board. By reducing the space occupied by the application terminals, the power converter can be made smaller.

[0010] In the power conversion device, the magnetic member is preferably held between the first portion and the second portion. According to this, the magnetic member can be interposed between the first and second parts without being attached to a member other than the application terminals on which the first and second parts are provided. For example, compared to a case where a part of the magnetic member is attached to a member surrounding the semiconductor element and extends to interpose between the first and second parts, the member surrounding the semiconductor element does not need to have a portion for attaching the magnetic member. Also, compared to a case where the magnetic member is attached to a member surrounding the semiconductor element, the magnetic member does not need to be enlarged in order to reach the member surrounding the semiconductor element. Therefore, the power converter can interpose the magnetic member between the first and second parts without increasing the size of the member surrounding the semiconductor element or the magnetic member. As a result, the power converter can be miniaturized.

[0011] In a power conversion device, the magnetic member is preferably a thin plate-like body whose thickness direction is the direction in which the first portion and the second portion are aligned. According to this, for example, compared to the case where the magnetic member is in block shape, the power conversion device can be miniaturized in the direction in which the first and second parts are aligned.

[0012] In a power conversion device, the magnetic member should not overlap with the element body when viewed in a plan view from the thickness direction of the magnetic member. According to this, the power conversion device can suppress interference between the magnetic field caused by the applied current flowing through the application terminal, which is equipped with a magnetic element, and the main body of the element. [Effects of the Invention]

[0013] According to the present invention, it is possible to reduce the size of the device while suppressing the decrease in inductance at the application terminal. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a partial perspective view showing a switching circuit. [Figure 2] Figure 2 is a circuit diagram showing a power converter. [Figure 3] Figure 3 is a circuit diagram showing a switching circuit. [Figure 4] Figure 4 is an enlarged cross-sectional view showing a semiconductor device. [Figure 5] Figure 5 is a top view showing a switching circuit. [Modes for carrying out the invention]

[0015] The following describes one embodiment of the power conversion device. The power conversion device of this embodiment is mounted on a vehicle. Hereafter, the power conversion device will be described as an inverter device connected to an electric motor on board the vehicle.

[0016] <Electric motor> As shown in Figure 2, the electric motor 100 is equipped with a coil 101. The electric motor 100 is mounted on a vehicle (not shown). The electric motor 100 is, for example, a motor for driving the vehicle. The power converter 10 may also be used to drive a motor mounted on an on-board electric compressor. The electric motor 100 is connected to the power converter 10. The electric motor 100 is driven by power supplied from an on-board DC power supply E. More specifically, the electric motor 100 is driven by power supplied from the DC power supply E and converted by the power converter 10, which is then energized by the coil 101.

[0017] Coil 101 has a U-phase coil 101u, a V-phase coil 101v, and a W-phase coil 101w. That is, the electric motor 100 is a three-phase motor. The U-phase coil 101u, the V-phase coil 101v, and the W-phase coil 101w are Y-connected. Note that the connection mode of the U-phase coil 101u, the V-phase coil 101v, and the W-phase coil 101w is not limited to Y-connection and is arbitrary. For example, it may be delta connection.

[0018] <Overall image of the power conversion device> As shown in FIGS. 1 and 2, the power conversion device 10 includes a control board 11, a heat sink 20, a plurality of switching circuits 30, and a control unit 40. In FIG. 1, only one of the plurality of switching circuits 30 is shown. Also, the control board 11 and the heat sink 20 shown in FIG. 1 are each a part of the control board 11 and the heat sink 20 provided in the power conversion device 10. In FIG. 1, the control board 11 is shown by a two-dot chain line.

[0019] As shown in FIG. 1, the control board 11 is a plate-like body. The control board 11 separates both end faces in the thickness direction from the heat sink 20. The control board 11 is arranged separated from the heat sink 20 by being provided on, for example, a frame (not shown).

[0020] A wiring part 12 is mounted on the control board 11. In FIG. 1, the wiring part 12 is shown by a two-dot chain line on the control board 11. The wiring part 12 is electrically connected to the DC power supply E. Thereby, DC power is supplied from the DC power supply E to the control board 11.

[0021] As shown in FIG. 2, the wiring part 12 is electrically connected to each of the U-phase coil 101u, the V-phase coil 101v, and the W-phase coil 101w. The DC power supplied to the control board 11 is supplied to various components electrically connected to the wiring part 12 via the wiring part 12.

[0022] The power converter 10 converts the DC power supplied from the DC power source E into AC power, and then outputs AC power to the U-phase coil 101u, the V-phase coil 101v, and the W-phase coil 101w, respectively. The electric motor 100 is driven by energizing the U-phase coil 101u, the V-phase coil 101v, and the W-phase coil 101w in a predetermined pattern.

[0023] As shown in Figure 1, the heat sink 20 is a plate-shaped body. The heat sink 20 is made of a metal material. Semiconductor elements 33, which will be described later and are included in each switching circuit 30, are mounted on the heat sink 20. Heat generated in the semiconductor elements 33 is transferred to the heat sink 20.

[0024] <Switching Circuit> As shown in Figure 2, the power converter 10 is equipped with two or more sets of two switching circuits 30. The power converter 10 is equipped with a number of switching circuits 30 corresponding to the number of phases of the coil 101 of the electric motor 100. Specifically, the power converter 10 is equipped with one set of two switching circuits 30 for each phase of the coil 101. In this embodiment, the power converter 10 is equipped with three sets of two switching circuits 30. In other words, the power converter 10 is equipped with six switching circuits 30. Each of the six switching circuits 30 is mounted on the control board 11 so as to be electrically connected to the wiring section 12.

[0025] In the power converter 10, each of the U-phase coil 101u, V-phase coil 101v, and W-phase coil 101w is connected to two switching circuits 30 by a wiring section 12. Hereafter, the two switching circuits 30 connected to the U-phase coil 101u will be referred to as U-phase switching circuits 31u and 32u. The two switching circuits 30 connected to the V-phase coil 101v will be referred to as V-phase switching circuits 31v and 32v. The two switching circuits 30 connected to the W-phase coil 101w will be referred to as W-phase switching circuits 31w and 32w.

[0026] When describing a configuration common to all of the U-phase switching circuits 31u, 32u, V-phase switching circuits 31v, 32v, and W-phase switching circuits 31w, 32w, it will simply be referred to as the switching circuit 30.

[0027] The two switching circuits 30 are connected in series with each other. In other words, the two switching circuits 30 corresponding to each phase of the coil 101 are connected in series with each other. Specifically, the U-phase switching circuits 31u and 32u are connected in series with each other between the positive and negative terminals of the DC power supply E. Of the U-phase switching circuits 31u and 32u, the U-phase switching circuit 31u is on the positive terminal side and the U-phase switching circuit 32u is on the negative terminal side in terms of the direction of current flow.

[0028] The V-phase switching circuits 31V and 32V are connected in series with each other between the positive and negative terminals of the DC power supply E. Of the V-phase switching circuits 31V and 32V, in terms of the direction of current flow, the V-phase switching circuit 31V is on the positive terminal side and the V-phase switching circuit 32V is on the negative terminal side.

[0029] The W-phase switching circuits 31w and 32w are connected in series with each other between the positive and negative terminals of the DC power supply E. Of the W-phase switching circuits 31w and 32w, the W-phase switching circuit 31w is on the positive terminal side and the W-phase switching circuit 32w is on the negative terminal side in terms of the direction of current flow.

[0030] One end of the U-phase coil 101u is connected to the connection point of the U-phase switching circuits 31u and 32u. One end of the V-phase coil 101v is connected to the connection point of the V-phase switching circuits 31v and 32v. One end of the W-phase coil 101w is connected to the connection point of the W-phase switching circuits 31w and 32w.

[0031] The U-phase switching circuit 31u, the V-phase switching circuit 31v, the W-phase switching circuit 31w, and the DC power supply E are connected in parallel. The U-phase switching circuit 31u, the V-phase switching circuit 31v, and the W-phase switching circuit 31w are located on the upper arm in Figure 2. The U-phase switching circuit 32u, the V-phase switching circuit 32v, the W-phase switching circuit 32w, and the DC power supply E are connected in parallel. The U-phase switching circuit 32u, the V-phase switching circuit 32v, and the W-phase switching circuit 32w are located on the lower arm in Figure 2.

[0032] <Semiconductor devices and control units> As shown in Figure 3, the switching circuit 30 comprises two semiconductor elements 33. Specifically, the U-phase switching circuits 31u, 32u, the V-phase switching circuits 31v, 32v, and the W-phase switching circuits 31w, 32w each comprise two semiconductor elements 33. In this embodiment, the semiconductor element 33 is a MOSFET. The semiconductor element 33 includes a freewheeling diode P1. The freewheeling diode P1 is realized by the body diode of the semiconductor element 33.

[0033] The two semiconductor elements 33 are connected in parallel. In other words, the power supplied to the control board 11 from the DC power supply E is supplied to each switching circuit 30 and then distributed to the two semiconductor elements 33.

[0034] As shown in Figure 1, the semiconductor element 33 comprises an element body 34, a plurality of application terminals 35, and a control terminal 36. In this embodiment, the semiconductor element 33 comprises two application terminals 35 and one control terminal 36. The element body 34 is a long plate-shaped body. The element body 34 has a thickness direction perpendicular to the control substrate 11. In other words, the thickness direction of the element body 34 coincides with the thickness direction of the control substrate 11. Hereafter, the longitudinal direction of the element body 34 will be described as the first direction D1, and the thickness direction of the element body 34 will be described as the second direction D2. Furthermore, the direction perpendicular to each of the first direction D1 and the second direction D2 will be described as the third direction D3. The first direction D1 and the third direction D3 are directions parallel to the control substrate 11 and the heat sink 20. The second direction D2 is a direction perpendicular to the control substrate 11 and the heat sink 20. The element body 34 has a connecting end face 341 on one of its end faces in the first direction D1. The connecting end face 341 is perpendicular to the control board 11.

[0035] The element body 34 is interposed between the control board 11 and the heat sink 20. The element body 34 is in contact with the heat sink 20 while moving away from the control board 11 in the second direction D2.

[0036] The two application terminals 35 and the one control terminal 36 are provided on the element body 34. In other words, the two application terminals 35 are connected to the element body 34. The two application terminals 35 and the one control terminal 36 are provided on the connection end face 341. That is, the element body 34 has the application terminals 35 and the control terminal 36 on the end face in a direction perpendicular to the thickness direction. The two application terminals 35 and the one control terminal 36 are aligned in the third direction D3 on the connection end face 341.

[0037] The two application terminals 35 are connected to the control board 11. In other words, the semiconductor element 33 is connected to the control board 11 by the two application terminals 35. More specifically, the semiconductor element 33 is electrically connected to the control board 11 by connecting the two application terminals 35 to the wiring section 12. Note that in Figure 4, only the wiring section 12 connected to one of the two application terminals 35 is shown. The two application terminals 35 connected by the wiring section 12 shown in Figure 4 are connected in parallel to each other by the wiring section 12.

[0038] Each of the two application terminals 35 and the one control terminal 36 has a base end closer to the connection end face 341 and a tip end closer to the control board 11. Each of the two application terminals 35 and the one control terminal 36 has a bent portion 37 to connect the connection end face 341 and the control board 11. Each of the two application terminals 35 and the one control terminal 36 extends from the base end closer to the connection end face 341 and connects its tip end to the control board 11 while bending at the bent portion 37.

[0039] In this embodiment, the two application terminals 35 are the drain terminal 351 and the source terminal 352. Note that in Figure 4, only the wiring section 12 connected to the drain terminal 351 is shown, while the wiring section 12 connected to the source terminal 352 is not shown.

[0040] The drain terminal 351 is connected to the positive side of the DC power supply E. The source terminal 352 is connected to the negative side of the DC power supply E. Therefore, the applied current Id flows through the semiconductor element 33 from the drain terminal 351 to the source terminal 352. In other words, the semiconductor element 33 has multiple application terminals 35 through which the applied current Id flows.

[0041] The control terminal 36 is a gate terminal. The control terminal 36 is electrically connected to the control unit 40 via a driver circuit (not shown). The control unit 40 is implemented, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program. Some or all of these components may be implemented by hardware such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or GPU (Graphics Processing Unit), or by the cooperation of software and hardware. The program may be stored in advance in a storage device (not shown) equipped with a non-transient storage medium such as an HDD (Hard Disk Drive) or flash memory.

[0042] The storage device may be implemented using any of the above methods, or by EEPROM (Electrically Erasable Programmable Read Only Memory), ROM (Read Only Memory), RAM (Random Access Memory), etc.

[0043] The control unit 40 is connected to the control terminal 36 of each semiconductor element 33 and is configured to periodically control each semiconductor element 33 on and off. The on / off control of the semiconductor elements 33 by the control unit 40 is performed for each switching circuit 30. The control unit 40 controls the on / off of two semiconductor elements 33 included in the multiple switching circuits 30 so that AC power is output to the coil 101 of each phase.

[0044] Specifically, the semiconductor element 33 is configured to be switchable by the control unit 40 between an ON state in which an applied current Id flows and an OFF state in which the applied current Id does not flow. The two semiconductor elements 33 included in each switching circuit 30 can switch between the ON state and the OFF state based on the same signal from the control unit 40.

[0045] Of the two semiconductor elements 33, the one with the shorter wiring distance is referred to as the first semiconductor element 33a, and the one with the longer wiring distance is referred to as the second semiconductor element 33b. Each of the U-phase switching circuits 31u, 32u, V-phase switching circuits 31v, 32v, and W-phase switching circuits 31w, 32w is equipped with the first semiconductor element 33a and the second semiconductor element 33b.

[0046] In this specification, "wiring distance" refers to the length of the wiring section 12 that the power supplied from the DC power supply E to the control board 11 passes through before reaching the tip of the drain terminal 351 of the semiconductor element 33.

[0047] <Shape of the application terminal> As shown in Figures 1 and 4, the first semiconductor element 33a has a deformable portion 50 formed on at least one of its multiple application terminals 35, and is also equipped with a magnetic member 60. Specifically, of the two semiconductor elements 33, the one with the shorter wiring distance has a deformable portion 50 and a magnetic member 60 on at least one of its multiple application terminals 35. In this embodiment, the application terminal 35 equipped with the deformable portion 50 and the magnetic member 60 is the drain terminal 351.

[0048] In this embodiment, each of the first semiconductor elements 33a in the U-phase switching circuits 31u, 32u, the V-phase switching circuits 31v, 32v, and the W-phase switching circuits 31w, 32w is equipped with a deformable portion 50 and a magnetic member 60. In other words, all first semiconductor elements 33a included in the power converter 10 are equipped with a deformable portion 50 and a magnetic member 60. The power converter 10 is equipped with six deformable portions 50 and six magnetic members 60.

[0049] The deformed portion 50 is formed on the drain terminal 351 of the first semiconductor element 33a, specifically in the part closer to the tip. The deformed portion 50 is formed on the drain terminal 351 between the bent portion 37 and the tip. Therefore, the deformed portion 50 is formed on the drain terminal 351 in the part extending in the second direction D2.

[0050] The drain terminal 351 on which the deformed portion 50 is formed is extended by the amount of the deformed portion 50. Specifically, the drain terminal 351 of the first semiconductor element 33a is longer than the drain terminal 351 of the second semiconductor element 33b. The difference in the drain terminals 351 between the first semiconductor element 33a and the second semiconductor element 33b corresponds to the difference in wiring distance between the first semiconductor element 33a and the second semiconductor element 33b. In other words, the length by which the drain terminal 351 is extended by the deformed portion 50 is set so that the combined distance of the wiring distance and the drain terminal 351 is the same for both the first semiconductor element 33a and the second semiconductor element 33b.

[0051] An inductance corresponding to the length of the section where the wiring section 12 and the drain terminal 351 are combined is generated. In other words, the length to which the drain terminal 351 is extended by the deformed section 50 is set so that the inductance related to the first semiconductor element 33a matches the inductance related to the second semiconductor element 33b.

[0052] As shown in Figure 4, the deformed portion 50 comprises a first portion 51, a second portion 52, and a connecting portion 53. That is, at least one of the two application terminals 35 comprises the first portion 51, the second portion 52, and the connecting portion 53. In this embodiment, the first portion 51, the second portion 52, and the connecting portion 53 are provided on the drain terminal 351 of the two application terminals 35. Each of the first portion 51, the second portion 52, and the connecting portion 53 is a part of the drain terminal 351. The bent portion 37, the first portion 51, the connecting portion 53, and the second portion 52 are arranged in this order along the drain terminal 351 in the direction from the base end to the tip end.

[0053] The first portion 51 is the part of the application terminal 35 that is closer to the semiconductor element 33 than the second portion 52. In other words, the first portion 51 is the part of the drain terminal 351 of the first semiconductor element 33a that is closer to the base end than the second portion 52. The first portion 51 extends in the first direction D1. The first portion 51 extends parallel to the element body 34 and the control board 11. In other words, the first portion 51 is the part of the drain terminal 351 that extends in a direction perpendicular to the connection end face 341 and parallel to the control board 11. As shown in Figure 5, the first portion 51 does not overlap with the element body 34 in a plan view from the second direction D2.

[0054] As shown in Figure 4, the second portion 52 is the part of the application terminal 35 that is closer to the control board 11 than the first portion 51. In other words, the second portion 52 is the part of the drain terminal 351 of the first semiconductor element 33a that is closer to the tip. The second portion 52 extends in the first direction D1. That is, the second portion 52 extends parallel to the element body 34 and the control board 11. The second portion 52 is the part of the drain terminal 351 that extends in a direction perpendicular to the connection end face 341 and parallel to the control board 11.

[0055] The second part 52 extends parallel to the first part 51 and aligns with it in the second direction D2. In a plan view from the second direction D2, the first part 51 overlaps with the second part 52. Therefore, in Figure 5, only the second part 52 is shown of the two parts 51 and 52.

[0056] As shown in Figure 4, the connection portion 53 is the part of the deformed portion 50 that connects the first portion 51 and the second portion 52. The deformed portion 50 is folded back by the connection portion 53 in a plane perpendicular to the third direction D3. The connection portion 53 is the part furthest from the element body 34 in the first direction D1. Therefore, the deformed portion 50 can also be said to be the part of the drain terminal 351 that has been deformed to move away from the element body 34.

[0057] The applied current Id flowing from the control board 11 toward the element body 34 flows from the tip to the base at the drain terminal 351. The applied current Id reaches the element body 34 at the drain terminal 351, passing through the tip, second portion 52, connection portion 53, first portion 51, bent portion 37, and base. For this reason, the drain terminal 351 can be said to have a first portion 51 that is closer to the element body 34 in the direction in which the applied current Id flows toward the drain terminal 351, and a second portion 52 that is further away from the element body 34 than the first portion 51.

[0058] The applied current Id that flows through the second section 52 is reflected back in the first direction D1 at the connection section 53 and then flows through the first section 51. Therefore, the applied current Id flowing through the second section 52 is in the opposite direction to the applied current Id flowing through the first section 51. In other words, the applied current Id flowing through the second section 52 is opposite to the applied current Id flowing through the first section 51.

[0059] The magnetic member 60 is interposed between the first portion 51 and the second portion 52. The semiconductor element 33 has the magnetic member 60 interposed between the first portion 51 and the second portion 52 at at least one of the plurality of application terminals 35. In other words, an application terminal 35 having a first portion 51 and a second portion 52 has the magnetic member 60 interposed between the first portion 51 and the second portion 52. In this embodiment, the first semiconductor element 33a has the magnetic member 60 interposed between the first portion 51 and the second portion 52 at the drain terminal 351.

[0060] The magnetic member 60 is a thin plate-like body whose thickness direction is the direction in which the first portion 51 and the second portion 52 are aligned. In other words, the thickness direction of the magnetic member 60 coincides with the second direction D2. The magnetic member 60 is formed from a ferrite material into a thin plate shape. The magnetic member 60 is rectangular when viewed from the second direction D2. The thickness of the magnetic member 60 is slightly greater than the distance between the first portion 51 and the second portion 52 in the second direction D2. The width of the magnetic member 60 in the third direction D3 is greater than the dimension of the drain terminal 351 in the third direction D3. The width of the magnetic member 60 in the first direction D1 is smaller than the lengths of the first portion 51 and the second portion 52 in the first direction D1.

[0061] The magnetic member 60 is held between the first portion 51 and the second portion 52. Specifically, the magnetic member 60 is inserted between the first portion 51 and the second portion 52 and is held in place by being sandwiched between the first portion 51 and the second portion 52. Therefore, both end faces of the magnetic member 60 in the thickness direction are in contact with the first portion 51 and the second portion 52, respectively.

[0062] As shown in Figure 5, the magnetic member 60 does not overlap with the element body 34 in a plan view taken from the thickness direction. As shown in Figure 4, the magnetic member 60 is in contact only with the first portion 51 and the second portion 52 of the semiconductor element 33, and overlaps only with the first portion 51 and the second portion 52 in the second direction D2. The portion of the magnetic member 60 that does not overlap with the first portion 51 and the second portion 52 in the first direction D1 faces the control substrate 11 or the heat sink 20.

[0063] The applied current Id flowing through the deformable portion 50 generates a magnetic field around the first portion 51 at the first portion 51. The applied current Id flowing through the deformable portion 50 also generates a magnetic field around the second portion 52 at the second portion 52. The magnetic flux related to the magnetic field of the first portion 51 and the magnetic flux related to the magnetic field of the second portion 52 each pass through the interior of the magnetic member 60.

[0064] [Operation of this embodiment] The operation of this embodiment will now be explained. The power converter 10 converts DC power input from the DC power supply E into AC power by controlling the on / off state of semiconductor elements 33. The current related to the DC power supplied from the DC power supply E flows through the control board 11 and the drain terminal 351 in the power converter 10. The distance over which the current flows through the control board 11 differs for each of the two semiconductor elements 33 included in each switching circuit 30. The power converter 10 includes a first part 51, a second part 52, and a magnetic member 60 in the first semiconductor element 33a, which has a shorter distance. Because the power converter 10 includes the first part 51 and the second part 52, the distance over which the current related to the DC power flows through the control board 11 and the drain terminal 351 is the same for the two semiconductor elements 33 of the switching circuit 30.

[0065] When an applied current Id flows through the first semiconductor element 33a, a magnetic field related to the applied current Id is generated at the drain terminal 351. In addition, a magnetic field related to the current flowing through the first part 51 is generated around the first part 51, and a magnetic field related to the current flowing through the second part 52 is generated around the second part 52. The magnetic flux related to the magnetic field of the first part 51 passes through the part of the magnetic member 60 closest to the first part 51. The magnetic flux related to the magnetic field of the second part 52 passes through the part of the magnetic member 60 closest to the second part 52.

[0066] [Effects of this embodiment] The effects of this embodiment will now be explained. (1) The power converter 10 has a first portion 51 and a second portion 52 at the drain terminal 351 of the first semiconductor element 33a, and a magnetic member 60 is provided between the first portion 51 and the second portion 52. At the drain terminal 351, the applied current Id flowing through the first portion 51 flows in the opposite direction to the applied current Id flowing through the second portion 52. The magnetic field generated by the applied current Id flowing through the first portion 51 and the second portion 52 passes through the magnetic member 60. As a result, the magnetic member 60 suppresses the decrease in inductance at the drain terminal 351 caused by the coupling of the magnetic fields of the first portion 51 and the second portion 52.

[0067] In a power converter 10 without a magnetic member 60, a space can be secured between the first part 51 and the second part 52 to suppress the decrease in inductance caused by the coupling of the magnetic fields of the first part 51 and the second part 52. Compared to this case, the power converter 10 can suppress the decrease in inductance caused by the coupling of the magnetic fields of the first part 51 and the second part 52 without securing a space between them. In other words, by interposing the magnetic member 60 between the first part 51 and the second part 52, the power converter 10 can be made smaller and the coupling of magnetic fields can be suppressed compared to the case where a space is secured between the first part 51 and the second part 52. As described above, the power converter 10 can be made smaller while suppressing the decrease in inductance at the drain terminal 351.

[0068] In this way, the power converter 10 can be miniaturized while generating inductance at the drain terminal 351 of the first semiconductor element 33a while suppressing the decrease due to magnetic field coupling. The deformed portion 50, including the first portion 51 and the second portion 52, is set so that the combined distance of the wiring distance and the drain terminal 351 is the same for the first semiconductor element 33a and the second semiconductor element 33b. In other words, the power converter 10 with the above configuration can be miniaturized while suppressing ringing caused by the difference in inductance between the first semiconductor element 33a and the second semiconductor element 33b.

[0069] (2) The first portion 51 and the second portion 52 extend parallel to the element body 34 and the control board 11. With this arrangement, the power converter 10 can reduce the space occupied by the drain terminal 351 in the second direction D2 compared to, for example, the case where the second direction D2 is included in the direction in which each of the first portion 51 and the second portion 52 extends. In other words, the power converter 10 can be miniaturized by reducing the space occupied by the drain terminal 351.

[0070] (3) The magnetic member 60 is held by the first portion 51 and the second portion 52. Therefore, the magnetic member 60 can be interposed between the first portion 51 and the second portion 52 without being attached to a member other than the drain terminal 351. For example, consider the case in which a part of the magnetic member 60 is attached to a member surrounding the semiconductor element 33 and extends to interpose between the first portion 51 and the second portion 52. An example of a member to which a part of the magnetic member 60 is attached is the control board 11. Compared to this case, the member does not need to have a portion for attaching the magnetic member 60. As a result, the power converter 10 can interpose the magnetic member 60 between the first portion 51 and the second portion 52 without increasing the size of the member surrounding the semiconductor element 33.

[0071] (4) Because the magnetic member 60 is a thin plate-like body, the power conversion device 10 can be made smaller in the direction in which the first part 51 and the second part 52 are aligned, compared to, for example, the case in which the magnetic member 60 is block-shaped.

[0072] (5) The magnetic member 60 is positioned so as not to overlap with the element body 34 in a plan view from the second direction D2. This allows the power converter 10 to suppress interference between the magnetic field related to the current flowing through the drain terminal 351 on which the magnetic member 60 is provided and the element body 34.

[0073] [Example of changes] The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0074] ○ The magnetic member 60 may overlap with the element body 34 in a plan view from the second direction D2. In this case, it is preferable to separate the first portion 51 from the element body 34 in the second direction D2 to an extent that interference between the magnetic field related to the first portion 51 and the element body 34 can be suppressed.

[0075] ○ The shape of the magnetic member 60 does not have to be a thin plate. In this case, it is preferable that the magnetic member 60 has flat surfaces on the parts facing the first part 51 and the second part 52, respectively, in order to facilitate holding by the first part 51 and the second part 52.

[0076] ○ The magnetic member 60 may be fixed to the first portion 51 and the second portion 52 with an adhesive. ○ The magnetic member 60 does not necessarily have to be sandwiched between the first portion 51 and the second portion 52. For example, the magnetic member 60 may be a long plate-shaped body curved in the third direction D3, with both ends in the longitudinal direction fixed to the member surrounding the semiconductor element 33, and its longitudinal central portion interposed between the first portion 51 and the second portion 52. Examples of members to which the magnetic member 60 is attached include the control board 11, the heat sink 20, and the element body 34. In short, the magnetic member 60 only needs to be interposed between the first portion 51 and the second portion 52, and the method of holding the magnetic member 60 in the power converter 10 is not limited to the embodiment.

[0077] ○ The first portion 51 and the second portion 52 do not necessarily have to be parallel to the element body 34 and the control board 11. For example, the first portion 51 and the second portion 52 may each extend in the third direction D3. Also, the first portion 51 and the second portion 52 may extend in a direction intersecting the control board 11.

[0078] ○ The surface of the semiconductor element 33 that has multiple application terminals 35 is not limited to the connection end surface 341. The semiconductor element 33 may have application terminals 35 on any surface of the outer surface of the element body 34, excluding the surface that contacts the heat sink 20. In addition, the multiple application terminals 35 and the control terminal 36 may each be provided on different surfaces. The shape of the bent portion 37 is appropriately changed according to the surface on which each of the multiple application terminals 35 and the control terminal 36 is provided.

[0079] ○ The power converter 10 may have a first portion 51 and a second portion 52 formed on all application terminals 35, and may also be equipped with a magnetic member 60 on all application terminals 35. Furthermore, the application terminal 35 on which the first portion 51 and the second portion 52 are formed is not limited to the drain terminal 351, but may also be the source terminal 352.

[0080] ○ The power converter 10 does not necessarily have to provide a drain terminal 351 in which a magnetic member 60 is provided while a first portion 51 and a second portion 52 are formed on each of the six switching circuits 30. For example, one of the first semiconductor elements 33a of the U-phase switching circuits 31u, 32u, V-phase switching circuits 31v, 32v, and W-phase switching circuits 31w, 32w may have the above configuration.

[0081] ○ The semiconductor element 33 does not have to be a MOSFET. For example, the semiconductor element 33 may be an IGBT. If the semiconductor element 33 is an IGBT, the drain terminal 351 should be read as the collector terminal and the source terminal 352 as the emitter terminal.

[0082] ○ The number of application terminals 35 is not limited to the embodiment. For example, the semiconductor element 33 may have three or more application terminals 35 by having two or more source terminals 352.

[0083] ○ The magnetic member 60 does not have to be a ferrite material. The magnetic member 60 can be any magnetic material. It is preferable that the magnetic member 60 is a ferromagnetic material. ○ The motor driven by the power converter 10 is not limited to three phases. In this case, the number of sets of two switching circuits 30 provided by the power converter 10 is appropriately changed according to the number of phases to which it is connected. In short, the power converter 10 only needs to have two or more sets of two switching circuits 30.

[0084] ○ The power converter 10 does not have to be mounted on the vehicle. The power converter 10 may be used to supply power to a load that is not mounted on the vehicle. [Explanation of Symbols]

[0085] 10...Power converter, 11...Control board, 30...Switching circuit, 33...Semiconductor element, 34...Element body, 35...Application terminal, 51...First part, 52...Second part, 60...Magnetic material, Id...Applied current.

Claims

1. It comprises two or more sets of two switching circuits connected in series with each other. The switching circuit comprises two semiconductor elements connected in parallel to each other. The aforementioned semiconductor device is Multiple application terminals through which an applied current flows, and multiple application terminals connected to a control board, The element comprises a main body to which multiple application terminals are connected, At least one of the plurality of application terminals is A first portion of the element body in the direction in which the applied current flows through the application terminal, The element body comprises a second portion that is further away from the first portion, The applied current flowing through the second part is opposite to the applied current flowing through the first part. A power conversion device that converts DC power to AC power, The aforementioned application terminal is A power conversion device having a magnetic member interposed between the first part and the second part.

2. The power conversion device according to claim 1, wherein the first portion and the second portion extend parallel to the control board.

3. The power conversion device according to claim 1 or claim 2, wherein the magnetic member is sandwiched between the first portion and the second portion.

4. The power conversion device according to claim 3, wherein the magnetic member is a thin plate-like body whose thickness direction is the direction in which the first portion and the second portion are aligned.

5. The power conversion device according to claim 2, wherein the magnetic member does not overlap with the element body in a plan view taken from the thickness direction of the magnetic member.

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