Power modules and power converters

Abstract

To provide a power module capable of suppressing enlargement.SOLUTION: A power module comprises: a main terminal part having a first conductor with one end having a P-terminal, and a second conductor with one end having an N-terminal, connected to a capacitor together with the first conductor, and installed in parallel with the first conductor via a gap; a circuit board having a power semiconductor element that converts a DC voltage from the main terminal part to an AC voltage; an output terminal part for outputting the AC voltage from the power semiconductor element; a pair of fastening parts each connecting the P-terminal and a positive electrode side terminal of the capacitor, and, the N-terminal and a negative electrode side terminal of the capacitor to each other; a base plate to which the circuit board is fixed; a case fixed to a surface of the base plate, and having an accommodation space that accommodates the P-terminal, the N-terminal, and the pair of fastening parts; and a first insulation part arranged in the accommodation space, and covering a first main surface of the P-terminal, a second main surface of the N-terminal, and the pair of fastening parts from a side opposite to the base plate in an embedded state of the gap.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a power module and a power conversion device.

Background Art

[0002] For example, Patent Document 1 discloses a power semiconductor module (power module) in which a groove portion is formed between terminal blocks on which main circuit terminals are arranged. The groove portion secures the creepage distance between the main circuit terminals, and as a result, the module is made compact while securing an insulation distance conforming to international standards. The insulation distance consists of two elements: the creepage distance and the air distance. <00.valueOf(1000000000 * Math.random())>

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the field of power modules, even if the creepage distance between terminals is secured by a groove portion, it is necessary to secure an air distance corresponding to the magnitude of the voltage applied to the terminals between the terminals. Therefore, in order to secure the insulation distance, it may be necessary to increase the air distance depending on the voltage applied to the terminals, and as a result, the power module may become large-sized.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a power module and a power conversion device capable of suppressing an increase in size.

Means for Solving the Problems

[0006] To solve the above problems, the power module according to this disclosure includes a main terminal section having a first conductor having a P terminal at one end having a first main surface and a first back surface facing the opposite side of the first main surface, and a second conductor having an N terminal at one end having a second main surface facing the same direction as the first main surface and a second back surface facing the opposite side of the second main surface, connected to a capacitor together with the first conductor, and arranged in parallel with the first conductor with a gap between them; a circuit board having a power semiconductor element that converts a DC voltage from the main terminal section to an AC voltage; and an output terminal section that outputs an AC voltage from the power semiconductor element. The circuit board comprises: a pair of fastening parts connecting the P terminal and the positive terminal of the capacitor, and the N terminal and the negative terminal of the capacitor to each other; a base plate to which the circuit board is fixed and which has surfaces facing the first back surface and the second back surface; a case fixed to the surface of the base plate and having a housing space for housing the P terminal, the N terminal, and the pair of fastening parts; and a first insulating part disposed within the housing space and covering the first main surface, the second main surface, and the pair of fastening parts from the side opposite to the base plate, while filling the gap.

[0007] The power conversion device according to this disclosure comprises the power module described above, the capacitor, and a second insulating portion that is integrally formed with the positive terminal and the negative terminal so as to extend from the first insulating portion and covers the positive terminal and the negative terminal from the outside. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a power module and a power conversion device that can suppress the increase in size. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing a schematic configuration of a power conversion device according to an embodiment of the present disclosure. [Figure 2] This is a plan view of the power module according to the first embodiment of this disclosure. [Figure 3]This is a cross-sectional view taken along the line III-III shown in Figure 2. [Figure 4] This is a cross-sectional view of a power module according to the second embodiment of this disclosure, and corresponds to the portion shown in Figure 3. [Figure 5] This is a cross-sectional view of a power module according to the third embodiment of this disclosure, corresponding to the portion shown in Figure 4. It is also a cross-sectional view in the direction of the VV line shown in Figure 6. [Figure 6] This is a plan view of the power module according to the third embodiment of this disclosure. [Modes for carrying out the invention]

[0010] The following describes the configuration for implementing the power conversion device according to this disclosure, with reference to the attached drawings.

[0011] <First Embodiment> (Power converter) A power converter is a device that converts direct current power into three-phase alternating current power, etc. Examples of power converters in this embodiment include inverters used in power grids such as those in power plants, and inverters used to drive electric motors in electric vehicles, etc.

[0012] As shown in Figure 1, the power converter 100 comprises a casing 1, an external input conductor 2, a capacitor 3, a power conversion unit 4, an external output conductor 5, and a cooling device 6.

[0013] (Casing) The casing 1 forms the outer shell of the power converter 100. In this embodiment, the casing 1 is made of a metal such as aluminum or a synthetic resin, and has a rectangular parallelepiped shape. The casing 1 has two sides that are arranged back to back. Hereinafter, one of these two sides will be referred to as the "input side side 1a" and the other side as the "output side side 1b". An external input conductor 2 for inputting DC power is drawn out from the input side side 1a.

[0014] (External input conductor) The external input conductor 2 is a pair of electrical conductors (bus bars) that supply DC power supplied from an external power system or the like of the power conversion device 100 to the capacitor. The external input conductor 2 in the present embodiment is formed of a metal containing copper or the like. One end of the external input conductor 2 is connected to the capacitor, and the other end of the external input conductor 2 extends in a direction intersecting the input side surface 1a of the casing 1.

[0015] (Capacitor) The capacitor 3 is a smoothing capacitor that stores the electric charge input from the external input conductor 2 and suppresses voltage fluctuations accompanying power conversion. The DC voltage input from the external input conductor 2 is supplied to the power conversion unit 4 via the capacitor 3. The capacitor 3 has a main body portion 3a and a connection conductor 3b. The main body portion 3a is a portion that mainly exhibits the function of the above-described smoothing capacitor.

[0016] <00,00086>The connection conductor 3b is an electrical conductor (bus bar) for transmitting power from the main body portion 3a to the power conversion unit 4. The connection conductor 3b is formed of a metal such as copper. The connection conductor 3b has a positive electrode side terminal 3p and a negative electrode side terminal 3n.

[0017] ​​​​​​​​​As shown in FIGS. 2 and 3, fastening holes h1 are formed in the positive electrode side terminal 3p and the negative electrode side terminal 3n.

[0020] Hereinafter, the interval generated between the positive electrode side terminal 3p and the negative electrode side terminal 3n when they are arranged side by side is referred to as a gap G1. In other words, the negative electrode side terminal 3n is arranged side by side with the positive electrode side terminal 3p via the gap G1. A space distance (insulation distance) is ensured in the gap G1 so that discharge does not occur between the positive electrode side terminal 3p and the negative electrode side terminal 3n due to the potential difference generated therebetween. The space distance in the present embodiment is preferably, for example, 1 mm or more and 10 mm or less.

[0021] (Power conversion unit) As shown in FIG. 1, the power conversion unit 4 converts the voltage input from the capacitor 3. The power conversion unit 4 in the present embodiment has three power modules 400 each responsible for the outputs for the U-phase, V-phase, and W-phase in order to output three-phase AC power. Therefore, the power conversion device 100 in the present embodiment is a three-phase inverter including three power modules 400. The configuration of the power module 400 will be described in detail later.

[0022] (External output conductor) The external output conductor 5 is an electric conductor (bus bar) that supplies the AC power converted by the power conversion unit 4 to a device provided outside the power conversion device 100. The power conversion device 100 in the present embodiment includes three external output conductors 5 for the U-phase, V-phase, and W-phase, and these external output conductors 5 are provided one by one in each power module 400.

[0023] In this embodiment, the external output conductor 5 is made of a metal including copper. One end of each external output conductor 5 is connected to the power module 400, and the other end of the external output conductor 5 extends in a direction intersecting the output side surface 1b of the casing 1. As shown in Figures 2 and 3, a fastening hole h2 is formed on one end (power module 400 side) of the external output conductor 5. Wiring or terminals for current output (not shown) are connected to the other end of the external output conductor 5. This makes it possible to output AC power to the outside of the power converter 100.

[0024] (cooling device) As shown in Figure 1, the cooling device 6 is primarily a device for cooling the power module 400 of the power conversion unit 4. The cooling device 6 is installed stacked on the casing 1 and is fixed and integrated with the casing 1. A liquid coolant, such as water, is introduced into the cooling device 6 from an external source. This liquid coolant exchanges heat with the power module 400 and is heated, thereby cooling the power module 400.

[0025] The configuration of the power module 400 in the power conversion unit 4 of this embodiment will be described below.

[0026] (Power module) The power module 400 is a device that converts and outputs the input power. In this embodiment, the power module 400 constitutes a part of the power conversion unit 4. As shown in Figures 2 and 3, the power module 400 includes a base plate 10, a circuit board 20, a main terminal section 30, a main terminal side fastening section 40 (a pair of fastening sections), an output terminal section 50, an output side fastening section 60, a case 70, a first insulating section 80, and a bonding wire Wb.

[0027] (Base plate) The base plate 10 is a flat plate-shaped component. The base plate 10 has a surface 10a and a back surface 10b located on the back side of the surface 10a. That is, the surface 10a and the back surface 10b of the base plate 10 are parallel to each other and are back to back.

[0028] The back surface 10b of the base plate 10 is fixed to, for example, the cooling device 6 (see Figure 1) via a bonding material or the like (not shown). In this embodiment, copper is used for the base plate 10. However, a metal such as aluminum may also be used for the base plate 10.

[0029] (Circuit board) The circuit board 20 includes an insulating plate 21, a surface pattern 22, a power semiconductor element 23, and a back surface pattern 24.

[0030] The insulating plate 21 is flat. The insulating plate 21 has a first surface 21a and a second surface 21b located on the back side of the first surface 21a. That is, the first surface 21a and the second surface 21b of the insulating plate 21 are parallel to each other and are back to back. A back surface pattern 24, which is a pattern of copper foil or the like, is formed on one surface of the second surface 21b of the insulating plate 21. This back surface pattern 24 is fixed to the center of the surface 10a of the base plate 10 via a bonding material S.

[0031] In this embodiment, the insulating plate 21 is formed of an insulating material such as ceramic. In addition to ceramic, other materials such as paper phenol, paper epoxy, glass composite, glass epoxy, glass polyimide, and fluororesin can be used as the insulating material for forming the insulating plate 21.

[0032] The surface pattern 22 is a planar pattern of copper foil or the like that is formed on the first surface 21a of the insulating plate 21. The surface pattern 22 is formed, for example, by fixing it to the first surface 21a of the insulating plate 21 by bonding or the like, and then etching or the like.

[0033] Multiple surface patterns 22 are arranged on the first surface 21a of the insulating plate 21. These multiple surface patterns 22 are arranged adjacent to each other with gaps in between in the direction in which the insulating plate 21 expands. In this embodiment, the case in which three surface patterns 22 are arranged on the first surface 21a will be described as an example. Hereinafter, as shown in Figure 2, for the sake of explanation, these three surface patterns 22 will be referred to as the first surface pattern 221, the second surface pattern 222, and the third surface pattern 223.

[0034] The first surface pattern 221 and the second surface pattern 222 are patterns for exchanging DC current input and output with the capacitor 3, and correspond to the inlet or outlet portion of the loop between PN formed on the surface pattern 22. An external output conductor 5 is connected to the third surface pattern 223 for outputting the AC current converted by the power semiconductor element 23 to a load (not shown) provided outside the power converter 100.

[0035] The power semiconductor element 23 is a circuit element that converts power by switching voltage and current on and off. The power semiconductor element 23 is, for example, a switching element such as an IGBT or a MOSFET. When using an IGBT, it is necessary to arrange a diode in parallel that allows current to flow in the opposite direction to the IGBT. In this embodiment, as an example, a case in which a MOSFET is applied as the power semiconductor is shown, and four power semiconductor elements 23 are connected to the surface pattern 22 of the circuit board 20.

[0036] In this embodiment, the four power semiconductor elements 23 are composed of two first power semiconductor elements 231 and two second power semiconductor elements 232. The first power semiconductor elements 231 are connected to the first surface pattern 221. The second power semiconductor elements 232 are connected to the third surface pattern 223.

[0037] When the power semiconductor element 23 is a MOSFET, the power semiconductor element 23 has an input surface on which an input terminal corresponding to the drain (not shown) is formed, an output surface on which an output terminal corresponding to the source (not shown) is formed, and a gate corresponding to a control signal input terminal for controlling the switching of the power semiconductor element 23.

[0038] The input surface of the power semiconductor element 23 is electrically connected to the surface pattern 22 via a bonding material. One end of a bonding wire Wb, which acts as a conductor, is electrically connected to the output surface of the power semiconductor element 23. The bonding wire Wb is made of a metal such as aluminum. That is, the surface patterns 22 formed on the first surface 21a are electrically connected to each other by wire bonding.

[0039] The input surface of the first power semiconductor element 231 is connected to the first surface pattern 221. The other end of a bonding wire Wb, one end of which is connected to the output surface of the first power semiconductor element 231, is connected to the third surface pattern 223. The input surface of the second power semiconductor element 232 is connected to the third surface pattern 223. The other end of a bonding wire Wb, one end of which is connected to the output surface of the second power semiconductor element 232, is connected to the second surface pattern 222.

[0040] DC power is input to the first power semiconductor element 231 via the first surface pattern 221, and DC power is input to the second power semiconductor element 232 via the second surface pattern 222 and the bonding wire Wb connecting the second surface pattern 222 and the second power semiconductor element 232. By switching between the first power semiconductor element 231 and the second power semiconductor element 232, the above DC power is converted to AC power and output to the third surface pattern 223.

[0041] The power semiconductor element 23 receives a control signal generated by a control unit (not shown) located outside the circuit board 20. The power semiconductor element 23 switches according to this control signal. If the power semiconductor element 23 is an IGBT, it has an input surface corresponding to the collector, an output surface corresponding to the emitter, and a gate corresponding to a terminal for inputting the control signal.

[0042] (Main terminal part) As shown in Figures 2 and 3, the main terminal section 30 is an electrical conductor (busbar) that exchanges DC power between the capacitor 3 and the circuit board 20. The main terminal section 30 is made of a metal such as copper. The main terminal section 30 has a first conductor 31 as the positive electrode and a second conductor 32 as the negative electrode.

[0043] These first conductor 31 and second conductor 32 are arranged side by side with a gap G2 between them. In other words, the second conductor 32 is arranged side by side with the first conductor 31 with a gap G2 between them.

[0044] The first conductor 31 has a P terminal 310 connected to the positive terminal 3p of the capacitor 3, and a first connection portion 311 that extends from the P terminal 310 integrally with the P terminal 310 and is connected to the first surface pattern 221. Therefore, the first conductor 31 has a P terminal 310 at one end.

[0045] The P terminal 310 is flat. The P terminal 310 has a first main surface 310a and a first back surface (omitted from the illustration for space limitations) facing the opposite side of the first main surface 310a. The P terminal 310 has fastening holes that pass through the P terminal 310 and open on both the first main surface 310a and the first back surface.

[0046] The P terminal 310 is positioned such that its fastening hole overlaps with the hole h1 formed in the positive terminal 3p. Therefore, the P terminal 310 is positioned overlapping with the positive terminal 3p. The first back surface of the P terminal 310 faces the surface 10a of the base plate 10.

[0047] The second conductor 32 has an N terminal 320 connected to the negative terminal 3n of the capacitor 3, and a second connection portion 321 that extends from the N terminal 320 integrally with the N terminal 320 and is connected to the second surface pattern 222. Therefore, the second conductor 32 has an N terminal 320 at one end.

[0048] The N terminal 320 is flat. The N terminal 320 has a second main surface 320a that faces the same direction as the first main surface 310a of the P terminal 310, and a second back surface 320b that faces the opposite side of the second main surface 320a. As shown in Figure 3, the N terminal 320 has fastening holes h3 that pass through the N terminal 320 and open on both the second main surface 320a and the second back surface 320b.

[0049] The N terminal 320 is positioned such that its fastening hole h3 overlaps with the hole h1 formed in the negative terminal 3n. The second back surface 320b of the N terminal 320 faces the surface 10a of the base plate 10.

[0050] (Main terminal side fastening part) The main terminal side fastening portion 40 is a pair of fastening members that connect the P terminal 310 of the first conductor 31 and the positive terminal 3p of the capacitor 3, and the N terminal 320 of the second conductor 32 and the negative terminal 3n of the capacitor 3 to each other. The main terminal side fastening portion 40 is made of a metal such as copper.

[0051] In this embodiment, the main terminal side fastening portion 40 is composed of a bolt 41 having a head 410 and a threaded portion 411 formed integrally with the head 410, and a nut 42. Below, as shown in Figure 3, the configuration of the main terminal side fastening portion 40 that connects the N terminal 320 and the negative terminal 3n will be described. The main terminal side fastening portion 40 that connects the P terminal 310 and the positive terminal 3p has the same configuration as the main terminal side fastening portion 40 that connects the N terminal 320 and the negative terminal 3n, so its description will be omitted.

[0052] The threaded portion 411 is inserted through the hole h1 of the negative terminal 3n and the hole h3 of the N terminal 320, with its head 410 in contact with the negative terminal 3n. The nut 42 is screwed onto the threaded portion 411 of the bolt 41 and is in contact with the N terminal 320 from the opposite side of the bolt 410. The negative terminal 3n and the N terminal 320 are fixed together by being sandwiched between the bolt 41 and the nut 42.

[0053] (Output terminal section) The output terminal section 50 is an electrical conductor (busbar) that electrically connects the external output conductor 5 and the circuit board 20. The output terminal section 50 is made of a metal such as copper. One end of the output terminal section 50 is connected to the third surface pattern 223 on the circuit board 20. A fastening hole h4 is formed on the other end of the output terminal section 50. The output terminal section 50 is positioned such that this fastening hole h4 overlaps with a hole h2 formed in the external output conductor 5. Therefore, the output terminal section 50 is positioned overlapping with the external output conductor 5.

[0054] (Output side fastening part) The output-side fastening portion 60 is a fastening member that connects the external output conductor 5 and the output terminal portion 50. The output-side fastening portion 60 is made of a metal such as copper. In this embodiment, the output-side fastening portion 60 is composed of a bolt 61 having a head 610 and a threaded portion 611 formed integrally with the head 610, and a nut 62.

[0055] The threaded portion 611 is inserted through the hole h2 in the external output conductor 5 and the hole h4 in the output terminal portion 50, with its head 610 in contact with the external output conductor 5. The nut 62 is screwed onto the threaded portion 611 of the bolt 61 and is in contact with the output terminal portion 50 from the opposite side of the bolt 610. The external output conductor 5 and the output terminal portion 50 are fixed together by being sandwiched between the bolt 61 and the nut 62.

[0056] (case) The case 70 is a component that mechanically reinforces the main terminal section 30 and the output terminal section 50 while being fixed to the surface 10a of the base plate 10. The case 70 is formed from, for example, a synthetic resin material (insulating material).

[0057] In this embodiment, the material used to form the case 70 can be, for example, PPS (polyphenylene sulfide). However, other synthetic resin materials may also be used for the case 70. The case 70 is fixed to the surface 10a of the base plate 10, for example, by an adhesive.

[0058] The case 70 surrounds the circuit board 20 from the outside, covering the first conductor 31 and the second conductor 32 of the main terminal section 30, as well as the output terminal section 50, from the outside. As shown in Figures 2 and 3, the case 70 forms a case that surrounds the circuit board 20 from all sides in a direction along the surface 10a of the base plate 10. Therefore, the case 70 together with the base plate 10 defines a space in which the circuit board 20 is housed. In this embodiment, this space in which the circuit board 20 is housed is referred to as the "potting space Rp".

[0059] Furthermore, the case 70 has a first groove 71 that defines a first housing space R1 (housing space) on the inside for housing the P terminal 310 of the first conductor 31, the N terminal 320 of the second conductor 32, and a pair of main terminal-side fastening parts 40, and a second groove 72 that defines a second housing space R2 on the inside for housing the output terminal part 50 and the output-side fastening part 60. In other words, the case 70 has a first housing space R1 and a second housing space R2.

[0060] In this embodiment, the portion of the first conductor 31 located within the first housing space R1 is the P terminal 310 described above, and the portion of the second conductor 32 located within the first housing space R1 is the N terminal 320 described above.

[0061] The potting space Rp and the first and second containment spaces R1 and R2 formed in the case 70 are open in a direction away from the surface 10a. The potting space Rp, the first containment space R1, and the second containment space R2 are separated by the partition wall of the case 70 in the direction in which the surface 10a expands, and thus form independent spaces from one another.

[0062] As shown in Figure 3, a first accommodating groove 71g is formed on the bottom surface 71b of the first groove 71, capable of accommodating the threaded portion 411 of the bolt 41 and the nut 42 of the main terminal side fastening portion 40. The first back surface of the P terminal 310 of the first conductor 31 and the second back surface 320b of the N terminal 320 of the second conductor 32 are in contact with the bottom surface 71b of the first groove 71. In addition, the threaded portion 411 of the bolt 41 and the nut 42 of the main terminal side fastening portion 40 are in contact with the inner surface of the first accommodating groove 71g.

[0063] A second accommodating groove 72g is formed on the bottom surface 72b of the second groove 72, capable of accommodating the threaded portion 411 of the bolt 41 and the nut 42 of the output-side fastening portion 60. The output terminal portion 50 is in contact with the bottom surface 72b of the second groove 72. In addition, the threaded portion 411 of the bolt 41 and the nut 42 of the output-side fastening portion 60 are in contact with the inner surface of the second accommodating groove 72g.

[0064] (First insulation section) The first insulating portion 80 is an insulating member located within the potting space Rp, the first housing space R1, and the second housing space R2. Liquid potting material is filled into the potting space Rp, the first housing space R1, and the second housing space R2 from the outside (potting), sealing the exposed members within each space (potting space Rp, first housing space R1, and second housing space R2).

[0065] The potting material filled into each space hardens over a predetermined period of time, electrically insulating the spaces between components and between each component and the space outside the power module 400. In this embodiment, for example, silicone gel or epoxy resin can be used as the potting material. Other synthetic resins besides silicone gel or epoxy resin may also be used as the potting material. Therefore, the first insulating portion 80 is formed by this potting material.

[0066] The first insulating portion 80 within the potting space Rp is positioned to cover the surfaces of the circuit board 20, the bonding wire Wb, the first connection portion 311 of the main terminal portion 30, and the output terminal portion 50. Therefore, the first insulating portion 80 within the potting space Rp is positioned to fill the gap G2 between the first connection portion 311 of the first conductor 31 and the second connection portion 321 of the second conductor 32.

[0067] Within the first housing space R1, the first insulating section 80 fills the gap G2 between the P terminal 310 and the N terminal 320, covering the first main surface 310a of the P terminal 310, the second main surface 320a of the N terminal 320, the positive terminal 3p and negative terminal 3n of the connecting conductor 3b, and the bolts 41 of the main terminal side fastening section 40 from the side opposite to the base plate 10. Within the second housing space R2, the first insulating section 80 covers the output terminal section 50 and the bolts 41 of the output side fastening section 60 from the side opposite to the base plate 10.

[0068] Here, the first insulating portion formed by filling and hardening the potting material in each space has upper surfaces 81, 82, and 83, which are the liquid levels at the time of filling. The upper surface 81 of the first insulating portion 80 located in the first space, and the upper surface 82 of the first insulating portion 80 located in the second space, are located further from the surface 10a of the base plate 10 than the upper surface 83 of the first insulating portion 80 located in the potting space Rp.

[0069] (Effects and Benefits) According to the above configuration, the first insulating section 80 is positioned so as to fill the gap G2 (space distance) in the main terminal section 30. Therefore, compared to the case where no insulating material is placed between the P terminal 310 and the N terminal 320, discharge between the P terminal 310 and the N terminal 320, and discharge between the N terminal 320 and the P terminal 310 can be suppressed. In other words, the presence of the first insulating section 80 between the P terminal 310 and the N terminal 320 can suppress dielectric breakdown between the P terminal 310 and the N terminal 320. Consequently, the gap G2 between the P terminal 310 and the N terminal 320 can be narrowed, and as a result, the size of the power module 400 can be suppressed.

[0070] Furthermore, the first insulating portion 80 covers the first main surface 310a, the second main surface 320a, and the pair of main terminal-side fastening portions 40 from the side opposite to the base plate 10, thereby suppressing dielectric breakdown between the first main surface 310a and the second main surface 320a.

[0071] Furthermore, when current flows through terminal P 310, terminal N 320 is affected by the magnetic flux generated from terminal P 310. At this time, an induced current (eddy current) flows through terminal N 320, corresponding to the magnitude of the magnetic flux. Similarly, when current flows through terminal N 320, terminal P 310 is affected by the magnetic flux generated from terminal N 320, and an induced current also flows through terminal P 310.

[0072] These induced currents generate magnetic flux from both the P terminal 310 and the N terminal 320 that cancels out the magnetic flux generated at the P terminal 310 and the N terminal 320. In other words, by narrowing the spatial distance between the P terminal 310 and the N terminal 320, the magnetic fluxes can be effectively canceled out. Therefore, the parasitic inductance generated in the main terminal section 30 can be reduced.

[0073] Furthermore, when a large current flows through the main terminal section 30, the first conductor 31 and the second conductor 32 generate heat, and for example, the surface 10a of the base plate 10 may expand due to thermal expansion. With the above configuration, since the first insulating section 80 is interposed between the P terminal 310 and the N terminal 320, the gap G2 narrows due to the thermal expansion of the P terminal 310 and the N terminal 320, preventing dielectric breakdown between these P terminals 310 and N terminals 320.

[0074] <Second Embodiment> Next, a second embodiment of the power converter according to this disclosure will be described with reference to Figure 4. In the second embodiment described below, components common to the first embodiment described above are denoted by the same reference numerals in the figure and their descriptions are omitted. In the second embodiment, the configuration of the case and the first insulating section in the power module differs from the configuration described in the first embodiment.

[0075] (case) The case 70a is a member that mechanically reinforces the main terminal section 30 and the output terminal section 50 while being fixed to the surface 10a of the base plate 10. The case 70a has a first groove 71a that defines a first housing space R1a (housing space) on the inside for housing the P terminal 310 of the first conductor 31, the N terminal 320 of the second conductor 32, and a pair of main terminal side fastening sections 40, and a second groove 72 that defines a second housing space R2 on the inside for housing the output terminal section 50 and the output side fastening section 60.

[0076] In this embodiment, the first housing space R1a is divided into a main surface space S1 and a back surface space S2, separated by the P terminal 310 and N terminal 320 of the main terminal section 30. These main surface space S1 and back surface space S2 are in communication through the gap G2 between the P terminal 310 and the N terminal 320, and through the space between the P terminal 310 and the N terminal 320 and the inner surface of the first groove section 71a. Therefore, when potting material is filled into the first housing space R1a, the potting material spreads to the back surface space S2 through the aforementioned connection between the main surface space S1 and the back surface space S2.

[0077] The threaded portion 411 of the bolt 41 and the nut 42 in the main terminal side fastening portion 40 are located in the rear side space S2. In this embodiment, the first rear surface of the P terminal 310, the second rear surface 320b of the N terminal 320, the threaded portion 411 of the bolt 41, and the nut 42 do not come into contact with the inner surface of the first groove portion 71a.

[0078] (First insulation section) The first insulating portion 80a is an insulating member located within the potting space Rp, the first housing space R1a, and the second housing space R2. Within the first housing space R1a, the first insulating portion 80a fills the gap G2 between the first conductor 31 and the second conductor 32, and covers the first main surface 310a and the first back surface of the P terminal 310, the second main surface 320a and the second back surface 320b of the N terminal 320, the positive terminal 3p and the negative terminal 3n of the connecting conductor 3b, and the bolts 41 and nuts 42 of the main terminal side fastening portion 40 from the outside.

[0079] (Effects and Benefits) According to the above configuration, the first insulating portion 80a covers the first back surface of the P terminal 310, the second back surface 320b of the N terminal 320, and the pair of main terminal-side fastening portions 40 from the base plate 10 side as well, so that the P terminal 310 and the N terminal 320 are insulated from each other within the first housing space R1a. That is, the P terminal 310 and the N terminal 320 are solidly insulated by the first insulating portion 80a. Therefore, compared to the configuration described in the first embodiment, electrical conductivity between the P terminal 310 and the N terminal 320 can be further suppressed. In other words, the gap G2 between the P terminal 310 and the N terminal 320 can be narrowed further.

[0080] <Third Embodiment> Next, a third embodiment of the power converter according to this disclosure will be described with reference to Figures 5 and 6. In the third embodiment described below, components common to the first and second embodiments described above are denoted by the same reference numerals in the figures and their descriptions are omitted. In the third embodiment, the power converter further comprises a second insulating section.

[0081] (Second insulation section) The second insulating portion 7 is an insulating member integrally formed with the first insulating portion 80a and extending from the first insulating portion 80a toward the main body portion 3a of the capacitor 3, and is attached to the positive terminal 3p and the negative terminal 3n. The second insulating portion 7 covers the positive terminal 3p and the negative terminal 3n from the outside, filling the gap G1 between them. In this embodiment, the second insulating portion 7 is formed of a different synthetic resin material than the first insulating portion 80a.

[0082] (Effects and Benefits) According to the above configuration, the positive terminal 3p and the negative terminal 3n of the capacitor 3 are insulated from each other. That is, the positive terminal 3p and the negative terminal 3n are solid-insulated by the second insulating part 7. In other words, dielectric breakdown between the positive terminal 3p and the negative terminal 3n can be suppressed. Therefore, the gap G1 between the positive terminal 3p and the negative terminal 3n can be narrowed, and as a result, the size of the power converter 100 can be suppressed.

[0083] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to that of the embodiments, and additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the gist of this disclosure.

[0084] In the above embodiment, an inverter was used as an example to describe the power conversion device 100, but the power conversion device 100 is not limited to an inverter. The power conversion device 100 may be a device that performs power conversion using power semiconductor elements 23, such as a converter or a combination of an inverter and a converter. If the power conversion device 100 is a converter, an AC voltage may be input to the external output conductor 5 from an external input power source (not shown), the power semiconductor elements 23 on the circuit board 20 convert this AC voltage to a DC voltage, and the DC voltage from the power semiconductor elements 23 may be output to the outside of the power conversion device through the main terminal 30 and connecting conductor 3b.

[0085] Furthermore, the configuration of the third embodiment described with reference to Figures 5 and 6 may also be applied to the first embodiment. That is, the power converter 100 described in the first embodiment may further include the second insulating section 7 described in the third embodiment.

[0086] <Note> The power module and power conversion device described in each embodiment can be understood, for example, as follows.

[0087] (1) The power module 400 according to the first embodiment includes a main terminal section 30 having a first main surface 310a and a first back surface facing the opposite side of the first main surface 310a, with a P terminal 310 at one end; a second conductor 320 having a second main surface 320a facing the same direction as the first main surface 310a and a second back surface 320b facing the opposite side of the second main surface 320a, connected to the capacitor 3 together with the first conductor 31 and arranged in parallel with the first conductor 31 via a gap G2; a circuit board 20 having a power semiconductor element 23 that converts the DC voltage from the main terminal section 30 into an AC voltage; an output terminal section 50 that outputs the AC voltage from the power semiconductor element 23; and the P terminal 310 and the capacitor The circuit board 20 is fixed to a base plate 10 having a surface 10a facing the first back surface and the second back surface 320b, and fixed to the surface 10a of the base plate 10, and having a housing space (first housing space R1, R1a) that houses the P terminal 310, the N terminal 320, and the pair of fastening parts, and the first insulating parts 80, 80a that are arranged in the housing space and cover the first main surface 310a, the second main surface 320a, and the pair of fastening parts from the side opposite to the base plate 10, while filling the gap G2.

[0088] This makes it possible to suppress discharge between terminal P 310 and terminal N 320 compared to the case where no insulating material is placed between terminal P 310 and terminal N 320. In other words, the interposition of the first insulating parts 80, 80a between terminal P 310 and terminal N 320 makes it possible to suppress dielectric breakdown between terminal P 310 and terminal N 320. Therefore, the gap G2 between terminal P 310 and terminal N 320 can be narrowed.

[0089] (2) The power module 400 according to the second embodiment is the power module 400 of (1), wherein the first insulating portion 80a may further cover the first back surface, the second back surface 320b, and the pair of fastening portions from the base plate 10 side.

[0090] As a result, the P terminal 310 and the N terminal 320 are insulated from each other within the housing space (first housing space R1, R1a). That is, the P terminal 310 and the N terminal 320 are solidly insulated by the first insulating part 80a. Therefore, electrical conductivity between the P terminal 310 and the N terminal 320 can be further suppressed.

[0091] (3) The power converter 100 according to the third embodiment comprises the power module 400 of (1) or (2), the capacitor 3, and the second insulating portion 7 which is formed integrally with the positive terminal 3p and the negative terminal 3n so as to extend from the first insulating portion 80a and covers the positive terminal 3p and the negative terminal 3n from the outside.

[0092] This prevents electrical conductivity between the positive terminal 3p and the negative terminal 3n. Therefore, the gap between the positive terminal 3p connected to terminal P 310 and the negative terminal 3n connected to terminal N 320 can be narrowed. [Explanation of Symbols]

[0093] 1…Casing 1a…Input side 1b…Output side 2…External input conductor 3…Capacitor 3a…Main body 3b…Connecting conductor 3n…Negative terminal 3p…Positive terminal 4…Power conversion section 5…External output conductor 6…Cooling device 7…Second insulating section 10…Base plate 10a…Front surface 10b…Back surface 20…Circuit board 21…Insulating plate 21a…First surface 21b…Second surface 22…Front pattern 23…Power semiconductor element 24…Back pattern 30…Main terminal section 31…First conductor 32…Second conductor 40…Main terminal side fastening section 41,61…Bolt 42,62…Nut 50…Output terminal section 60…Output side fastening section 70,70a…Case 71,71a…First groove section 71b,72b…Bottom surface 71g…First housing groove 72…Second groove 72g…Second housing groove 80,80a…First insulation part 81,82,83…Top surface 100…Power converter 221…First surface pattern 222…Second surface pattern 223…Third surface pattern 231…First power semiconductor element 232…Second power semiconductor element 310…P terminal 310a…First main surface 311…First connection part 320…N terminal 320a…Second main surface 320b…Second back surface 321…Second connection part 400…Power module 410,610…Head 411,611…Screw part G1,G2…Gap h1,h2,h3,h4…Hole R1,R1a…First housing space R2…Second housing space Rp…Potting space S…Bonding material S1…Main surface side space S2…Back side space Wb…Bonding wire

Claims

1. A first conductor having a P terminal at one end, which has a first main surface and a first back surface facing the opposite side of the first main surface, A second conductor has an N terminal at one end, which faces the same direction as the first main surface and a second back surface facing the opposite direction from the second main surface, and is connected to the capacitor together with the first conductor, and is arranged in parallel with the first conductor with a gap between them, A main terminal section having, A circuit board having a power semiconductor element that converts the DC voltage from the main terminal to an AC voltage, An output terminal section that outputs an AC voltage from the power semiconductor element, A pair of fastening parts that connect the P terminal and the positive terminal of the capacitor, and the N terminal and the negative terminal of the capacitor to each other, The circuit board is fixed to a base plate having a surface facing the first back surface and the second back surface, A case fixed to the surface of the base plate and having a housing space for housing the P terminal, the N terminal, and the pair of fastening parts, A first insulating portion is placed within the aforementioned housing space and, in a state that fills the gap, covers the first main surface, the second main surface, and the pair of fastening portions from the side opposite to the base plate, A power module equipped with the following features.

2. The power module according to claim 1, wherein the first insulating portion further covers the first back surface, the second back surface, and the pair of fastening portions from the base plate side.

3. A power module according to claim 1 or 2, The aforementioned capacitor, A second insulating portion is formed integrally with the positive terminal and the negative terminal so as to extend from the first insulating portion, and covers the positive terminal and the negative terminal from the outside. A power conversion device equipped with the following features.

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