Semiconductor module and power converter

Abstract

The present application relates to a semiconductor module which reduces a surge voltage caused by a wiring inductance by effectively suppressing the wiring inductance of a bus bar. The semiconductor module according to the present application has a switching circuit composed of a first semiconductor element (103a) and a second semiconductor element (103b) connected in series, is provided with a first bus bar (201) connected to a positive electrode side of the first semiconductor element (103a), a second bus bar (202) connected to a negative electrode side of the second semiconductor element (103b), and a third bus bar (203) connected to a negative electrode side of the first semiconductor element (103a) and a positive electrode side of the second semiconductor element (103b), and the second bus bar (202) is arranged so as to sandwich the third bus bar (203) and the first bus bar (201) while the first bus bar (201), the second bus bar (202), and the third bus bar (203) extend in the same direction.

Description

Technical Field

[0001] This application relates to a semiconductor module and a power converter having the semiconductor module. Background Technology

[0002] In power converters, those requiring high power density and low power loss are increasingly relying on IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs to provide power. The increasing current, high voltage, and high speed switching of switching elements such as metal-oxide-semiconductor field-effect transistors (MOSFETs) leads to a rise in surge voltage during switching. This, in turn, increases switching losses and heat generation. While heat dissipation components are considered to suppress heat generation, increased costs or larger device sizes are unavoidable.

[0003] The magnitude of the surge voltage caused by the switching of a switching element depends on the inductance of the wiring, such as the busbars electrically connected to the switching element. A larger wiring inductance results in a larger surge voltage. Effective methods to reduce wiring inductance include shortening the busbars or directing current flow in opposite directions to counteract the magnetic flux generated by a pair of busbars.

[0004] Conventionally, in a semiconductor module where switching elements of the upper and lower arms are connected in series, the busbar includes a positive input busbar connecting the positive side of the switching element in the upper arm, a negative input busbar connecting the negative side of the switching element in the lower arm, and an output busbar connecting the negative side of the switching element in the upper arm and the positive side of the switching element in the lower arm. The positive and negative input buses are arranged parallel to each other at the same height, and the output busbar is arranged orthogonally to the positive and negative input buses. By connecting the switching elements of the upper and lower arms using the output busbar, the module is compactly constructed without using wiring perpendicular to the positive and negative input buses, thereby suppressing the increase in wiring inductance. Furthermore, since the parallel positive and negative input buses flow current in opposite directions, the generated magnetic flux is canceled out, and the inductance is reduced (see Patent Document 1). Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent No. 3793407 Summary of the Invention The technical problem that the invention aims to solve

[0006] In the power converter of Patent Document 1, the busbar wiring is made as compact as possible by arranging a pair of positive and negative input buses parallel to each other to reduce inductance. However, since a fastening part for the module housing is provided on the output busbar portion, which is orthogonally arranged between the pair of positive and negative input buses, the output busbar becomes longer, requiring an increase in the distance between the positive and negative input buses. Therefore, the inductance cannot be sufficiently reduced solely by eliminating the magnetic flux between the pair of buses. Furthermore, in the output busbar, the current flows in a direction orthogonal to the positive and negative input buses, so the magnetic flux generated between the output busbar and the positive input busbar, and between the output busbar and the negative input busbar, does not cancel each other out. Therefore, the wiring inductance in the output busbar cannot be reduced, and inductance reduction cannot be achieved in the overall semiconductor module.

[0007] This application discloses a technology for solving the above-mentioned problems, with the aim of providing a semiconductor module and a power converter that can effectively suppress the wiring inductance of the busbar. Technical means for solving technical problems

[0008] The semiconductor module disclosed in this application has a switching circuit composed of a first semiconductor element and a second semiconductor element connected in series. The device is provided with a first busbar, a second busbar, and a third busbar, with the first busbar connected to the positive electrode side of the first semiconductor element. The second busbar is connected to the negative electrode side of the second semiconductor element. The third busbar is connected to the negative electrode side of the first semiconductor element and the positive electrode side of the second semiconductor element. While the first busbar, the second busbar, and the third busbar extend in the same direction, The busbar of either the first busbar or the second busbar is configured to clamp the third busbar and the other busbar of either the first busbar or the second busbar.

[0009] The power converter disclosed in this application has a filter capacitor for filtering the DC voltage applied to the semiconductor module. The first busbar has a first terminal portion for wiring connection with the positive side of the filter capacitor. The second busbar has a second terminal portion for wiring connection with the negative side of the filter capacitor. The first terminal portion and the second terminal portion protrude in the same direction. Invention Effects

[0010] The semiconductor module and power converter disclosed in this application can effectively suppress the wiring inductance of the busbar. Attached Figure Description

[0011] Figure 1 This is a circuit diagram illustrating the power conversion device with a semiconductor module according to Embodiment 1. Figure 2 This is a circuit diagram showing the switching action of the U-phase arm in a three-phase inverter circuit. Figure 3 This is a top cross-sectional view of the semiconductor module involved in Embodiment 1. Figure 4 yes Figure 3 Sectional view along line A-A in the diagram. Figure 5 This is a top cross-sectional view of the semiconductor module involved in Embodiment 1. Figure 6 yes Figure 5 BB line section view. Figure 7 It means in Figure 3 The diagram shows a top sectional view of the semiconductor module with the filter capacitor connected to it. Figure 8 yes Figure 7 The CC line section view. Figure 9 This is a top cross-sectional view of the semiconductor module involved in Embodiment 1. Figure 10 This is a simplified top view showing the shape of the busbars in a semiconductor module. Figure 11 It is a graph representing the result obtained by analyzing and calculating the relationship between the ratio of self-inductance and combined inductance. Figure 12 This is a top cross-sectional view of the semiconductor module involved in Embodiment 2. Figure 13 This is a top cross-sectional view of the semiconductor module involved in Embodiment 2. Figure 14 This is the equivalent circuit diagram of the semiconductor module involved in Implementation Method 2. Detailed Implementation

[0012] Implementation method 1. This embodiment relates to a semiconductor module having a busbar and a power converter having the semiconductor module. Figure 1This is a circuit diagram showing the power conversion device with a semiconductor module according to Embodiment 1, and a structural diagram showing the three-phase inverter circuit that drives a three-phase AC motor. The power conversion device according to this embodiment includes a DC power supply 101 and a three-phase AC motor 106. The DC power supply 101 is then connected to a filter capacitor 102 for filtering the DC voltage applied to the semiconductor module. After the filter capacitor 102, a three-phase inverter circuit is connected, consisting of a U-phase arm 103 with switching elements 103a and 103b connected in series, a V-phase arm 104 with switching elements 104a and 104b connected in series, and a W-phase arm 105 with switching elements 105a and 105b connected in series. The three-phase AC motor 106 is connected after the three-phase inverter circuit. Then, the switching elements 103a to 105b that control each phase arm 103 to 105 are turned on and off in a predetermined sequence to generate three-phase AC current and drive the three-phase AC motor 106.

[0013] Switching elements 103a to 105b are, for example, composed of MOSFETs (Metal-Oxide-Semiconductor-Filler-Effect Transistors). Switching elements 103a to 105b can use self-arc-suppressing semiconductor switching elements such as IGBTs (Insulated-Gate Bipolar Transistors) with diodes connected in anti-parallel, or wide-bandgap semiconductors such as SiC (Silicon Carbide) or GaN (Gallium Nitride). In this embodiment, the case where MOSFETs are used as switching elements 103a to 105b will be described.

[0014] Furthermore, the U-phase arm 103, V-phase arm 104, and W-phase arm 105 may be constructed, for example, as a 2-in-1 semiconductor module that integrates the switching elements and busbars of the upper and lower arms through resin molding. Alternatively, they may be constructed as a 6-in-1 semiconductor module that integrates all the switching elements of the upper and lower arms of the three phases through resin molding. In this embodiment, the case using a 2-in-1 semiconductor module will be described.

[0015] Next, the relationship between wiring inductance and surge voltage will be explained. Figure 2 For the purpose of simplification Figure 1 The circuit diagram shows the switching action of the U-phase arm 103 in a three-phase inverter circuit, representing the circuit obtained by replacing the three-phase AC motor 106 with an inductive load 113. The principle of surge voltage generation is related to... Figure 1 The three-phase inverter circuit is the same and will use... Figure 2Explanation will be provided. In Figure 2 In the diagram, the wiring inductance on the positive side of the filter capacitor 102 is represented by 107, and the wiring inductance on the negative side is represented by 108.

[0016] Furthermore, the wiring inductance on the drain side of the switching element (first semiconductor element) 103a is represented by 109, the wiring inductance on the source side of the switching element 103a (drain side of the switching element 103b) is represented by 110, the wiring inductance on the source side of the switching element 103b (second semiconductor element) is represented by 111, and the wiring inductance between the connection point X of the switching elements 103a and 103b and the load inductance 113 is represented by 112. Specifically, the wiring inductances 109 to 112 are the wiring inductances caused by the busbars within the semiconductor module.

[0017] The turn-off surge voltage ΔVs when the switching element 103a changes from the on state to the off state is explained. Figure 2 In the diagram, when switching element 103a is turned on, a current path is formed as shown by the solid arrow; when switching element 103a is turned off, a current path is formed as shown by the dashed arrow. As switching element 103a changes from on to off, the current path switches, therefore, the current flowing through the wiring changes with a slope of di / dt. Then, let the wiring inductance 107 be L. 107 The wiring inductance 108 has a value of L. 108 The wiring inductance 109 has a value of L. 109 The wiring inductance 110 has a value of L. 110 The wiring inductance 111 has a value of L. 111 Then the surge voltage ΔVs can be expressed by the following formula (1). ΔVs=(L 107 +L 108 +L 109 +L 110 +L 111 )×di / dt···· (1)

[0018] As shown in equation (1), the turn-off surge voltage ΔVs and the wiring inductance L 107 L 108 L 109 L 110 L 111 The sum is proportional. Therefore, if these wiring inductance components can be reduced, surge voltage can be reduced.

[0019] Figure 3 This is a top cross-sectional view of the semiconductor module involved in Embodiment 1. Figure 4 yes Figure 3 A sectional view along line AA. In Figure 3 , Figure 4 In this diagram, the height direction of the semiconductor module is defined as the Z-direction, and the directions perpendicular to the Z-direction are defined as the X-direction and Y-direction. That is, the XY-direction represents the planar directions within the semiconductor module. Figure 3 This is a top view in the XY direction. Figure 4 This is a cross-sectional view along the XZ direction. In the figure, switching elements 103a and 103b, P busbar 201, N busbar 202a and N busbar 202b, AC busbar 203, and load busbar 204 are molded with resin to form a semiconductor module (first semiconductor module) 200. The molding resin 208 is made of insulating resin materials such as epoxy resin. After the resin-molded components are arranged in the molding mold, resin is injected into the molding mold, and the module is formed by sealing.

[0020] exist Figure 3 , Figure 4 In the above, the busbar on the positive side of the switching element 103a connected to the upper arm is called the P busbar (first busbar) 201, the busbar on the negative side of the switching element 103b connected to the lower arm is called the N busbar (second busbar) 202a, 202b, and the busbar connecting the negative side of the switching element 103a on the upper arm and the positive side of the switching element 103b on the lower arm is called the AC busbar (third busbar) 203. Inside the molding resin 208, the P busbar 201 and the heat sink 205 are connected via a connecting member 213a; the heat sink 205 and the drain terminal of the switching element 103a are connected via a connecting member 213b; the source terminal of the switching element 103a and the AC busbar 203 are connected via a connecting member 213c; the AC busbar 203 and the heat sink 206 are connected via a connecting member 213d; the heat sink 206 and the drain terminal of the switching element 103b are connected via a connecting member 213e; the source terminal of the switching element 103b and the N busbar 202 are connected via a connecting member 213f; and the heat sink 206 and the load busbar 204 are connected via a connecting member 213g. The heat sinks 205 and 206 are made of metal conductors such as copper. The heat sink 205 has the same potential as the drain terminal of the switching element 103a, and the heat sink 206 has the same potential as the drain terminal of the switching element 103b. The connecting components 213a to 213g are made of solder or the like. The heat sinks 205 and 206 are connected to the metal plate 212 made of copper or the like via the insulating sheet 207 and are insulated from the outside of the module.

[0021] Here, the wiring inductance caused by busbar 201 is equivalent to Figure 2 The wiring inductance 109 in the circuit is equivalent to the wiring inductance caused by busbar N 202. Figure 2 The wiring inductance 111 in the diagram is equivalent to the wiring inductance caused by the AC busbar 203. Figure 2 The wiring inductance 110 in the circuit is equivalent to the wiring inductance caused by the load busbar 204. Figure 2 The wiring inductance is 112. Additionally, the connection terminal between the P busbar 201 and the positive side wiring of the filter capacitor 102 is 209; the connection terminals between the N busbars 202a and 202b and the negative side wiring of the filter capacitor 102 are 210a and 210b; and the connection terminal between the load busbar 204 and the load wiring is 211. The control circuit wiring, such as the gate wiring of the switching elements 103a and 103b, is omitted from the diagram.

[0022] exist Figure 3 In the semiconductor module 200, N buses 202a and 202b are configured to sandwich P bus 201 and AC bus 203. Specifically, in the semiconductor module 200, in the direction (X direction) protruding from the positive terminal 209 of P bus 201 and the negative terminal 210a and b of N buses 202a and 202b, a P bus 201 and an AC bus 203 are arranged between two branches (U-shaped planar cross-section) of N buses 202a and 202b. In the XY plane, which is perpendicular to the X direction and the Y direction, at least a portion of the surfaces of P bus 201, N bus 202a, 202b, and AC bus 203 are arranged to be substantially the same plane and parallel. That is, as shown... Figure 4 As shown, even if a portion of the AC busbar 203 has stepped portions 203A and 203B, the other portions of the surfaces of the P busbar 201, N busbars 202a and 202b, and the AC busbar 203 are approximately the same plane and parallel.

[0023] Next, explain the process. Figure 3 The structure of the semiconductor module 200 shown reduces the wiring inductances 109, 110, and 111 caused by the P bus 201, N bus 202a, 202b, and AC bus 203. Figure 3The dashed arrows in the diagram indicate the current path when surge voltage is generated. In the P bus 201 and AC bus 203, which are configured to be sandwiched by N bus bars 202a and 202b, the current flows in the opposite direction to that of the N bus bars 202a and 202b. That is, by arranging N bus bars 202a and 202b, which carry reverse current, adjacent to each other on both sides of the P bus bar 201 and AC bus bar 203, the magnetic flux generated in the P bus bar 201 and AC bus bar 203 and the N bus bars 202a and 202b, respectively, can be effectively eliminated. Therefore, the wiring inductances 109, 110, and 111 caused by the P bus bar 201, N bus bar 202a and 202b, and AC bus bar 203 can be reduced. By arranging P busbar 201, N busbars 202a, 202b, and AC busbar 203 on the same plane (XY plane), compared with arranging them on different planes, the distances between N busbars 202a, 202b and P busbar 201, as well as the distances between N busbars 202a, 202b and AC busbar 203, can be shortened, resulting in a higher flux elimination effect.

[0024] Figure 5 This is a top cross-sectional view showing other semiconductor modules involved in Embodiment 1. Figure 6 yes Figure 5 A sectional view along the BB line. Figure 3 , Figure 4 The text describes the configuration of N busbars 202a and 202b in a way that clamps P busbar 201 and AC busbar 203, but it can also be configured as follows: Figure 5 As shown, the P busbars 301a and 301b are configured to clamp the N busbar 302 and the AC busbar 303. In the figure, switching elements 103a, 103b and P busbars 301a, 301b, N busbar 302, and AC busbar 303 are molded with resin. The molding resin 308 is made of an insulating resin material such as epoxy resin. After the resin-molded components are arranged in the molding mold, resin is injected into the molding mold, and the mold is formed by sealing.

[0025] Inside the molding resin 308, the P busbar 301a and the heat sink 306 are connected via a connecting member 313a, the P busbar 301b and the heat sink 306 are connected via a connecting member 313b, the heat sink 306 and the drain terminal of the switching element 103a are connected via a connecting member 313c, the source terminal of the switching element 103a and the AC busbar 303 are connected via a connecting member 313d, the AC busbar 303 and the heat sink 305 are connected via a connecting member 313e, the heat sink 305 and the drain terminal of the switching element 103b are connected via a connecting member 313f, the source terminal of the switching element 103b and the N busbar 302 are connected via a connecting member 313g, and the source terminal of the switching element 103a and the load busbar 304 are connected via a connecting member 313d. Heat sinks 305 and 306 are made of copper or other metal conductors. Heat sink 306 has the same potential as the drain terminal of switching element 103a, and heat sink 305 has the same potential as the drain terminal of switching element 103b. Heat sinks 305 and 306 are connected to a metal plate 312 made of copper or other metals via an insulating sheet 307, and are insulated from the outside of the module.

[0026] Here, the wiring inductance caused by busbars 301a and 301b is equivalent to Figure 2 The wiring inductance 109 in the circuit is equivalent to the wiring inductance caused by bus N 302. Figure 2 The wiring inductance 111 in the diagram is equivalent to the wiring inductance caused by the AC busbar 303. Figure 2 The wiring inductance 110 in the circuit is equivalent to the wiring inductance caused by the load busbar 304. Figure 2 The wiring inductance is 112. Additionally, the connection terminals between P busbars 301a and 301b and the positive side wiring of filter capacitor 102 are designated as 309a and 309b, the connection terminal between N busbar 302 and the negative side wiring of filter capacitor 102 is designated as 310, and the connection terminal between load busbar 304 and load wiring is designated as 311. The control circuit wiring, including the gate wiring of switching elements 103a and 103b, is omitted from the diagram.

[0027] exist Figure 5 , Figure 6In this configuration, P buses 301a and 301b are arranged to sandwich N bus 302 and AC bus 303. Specifically, in the semiconductor module (second semiconductor module) 300, N bus 302 and AC bus 303 are arranged between the two P buses 301a and 301b in the direction (X direction) in which the terminals 309a and 309b of the P buses 301a and 301b and the terminal 310 of the N bus 302 protrude. In the XY plane, which is the X direction and the direction orthogonal to it (Y direction), at least a portion of the surfaces of the P buses 301a and 301b, the N bus 302, and the AC bus 303 are arranged to be substantially coplanar and parallel.

[0028] Next, the explanation is as follows: Figure 5 , Figure 6 The structure of the semiconductor module 300 shown reduces the wiring inductance caused by the P busbars 301a, 301b, N busbar 302, and AC busbar 303. (Using...) Figure 5 The dashed arrows indicate the current path when surge voltage is generated. In the N bus 302 and AC bus 303, which are configured to be sandwiched between two P busbars 301a and 301b, the current flows in the opposite direction to that of the P busbars 301a and 301b. That is, by arranging two P busbars 301a and 301b flowing with reverse current adjacent to each other on both sides of the N busbar 302 and the AC busbar 303, the magnetic flux generated between the P busbars 301a and 301b and the AC busbar 303 and N busbar 302, respectively, can be effectively eliminated. Therefore, the wiring inductances 109, 110, and 111 caused by the P busbars 301a and 301b, the N busbar 302, and the AC busbar 303 can be reduced. By arranging P busbars 301a, 301b, N busbar 302, and AC busbar 303 in the same plane (XY plane), the distance between P busbars 301a, 301b and N busbars 302 and AC busbar 303 can be reduced compared to arranging them in different planes, thus achieving a higher flux elimination effect.

[0029] In addition, such as Figures 3-6 As shown, if the upper and lower arm switching elements are 2-in-1 semiconductor modules, the length of the busbar connecting the upper and lower arms can be made smaller compared to when the upper and lower arms are composed of other modules, thereby further reducing the wiring inductance caused by the busbar. That is, in Figures 3-6 In this design, the first semiconductor element and the second semiconductor element are packaged in the same module.

[0030] In addition, such as Figures 3-6As shown, by arranging the connection terminals (first terminal portions) 209 and 309 of the positive side wiring of the filter capacitor 102 to the P busbar of the semiconductor modules 200 and 300 and the connection terminals (second terminal portions) 210 and 310 of the negative side wiring of the filter capacitor 102 to the N busbar of the semiconductor modules 200 and 300 in the same direction, the wiring inductance of the filter capacitor 102 can be reduced. Figure 7 It means in Figure 3 The diagram shows a top cross-sectional view of the semiconductor module 200 with the filter capacitor 102 connected to it. Figure 8 yes Figure 7 The cross-sectional view is shown along the CC line. The positive-side busbar 214 of the filter capacitor 102 is connected to the P busbar 201 of the semiconductor module 200 at the positive-side connection terminal 209. Additionally, the negative-side busesbars 215a and 215b of the filter capacitor 102 are connected to the N busbars 202a and 202b of the semiconductor module 200 at the negative-side connection terminals 210a and 210b. The connections between the buses are made using TIG (Tungsten Inert Gas) welding or other arc welding methods. Here, the wiring inductance caused by the positive-side busbar 214 of the filter capacitor 102 is equivalent to... Figure 2 The wiring inductance 107 in the circuit is equivalent to the wiring inductance caused by the negative side busbars 215a and 215b of the filter capacitor 102. Figure 2 The wiring inductance is 108.

[0031] like Figure 7 As shown, by arranging the filter capacitor 102 adjacent to the positive-side connection terminal 209 and the negative-side connection terminals 210a and 210b arranged in the same direction, the positive-side busbar 214 and the negative-side busbars 215a and 215b of the filter capacitor 102 can be made shorter. Therefore, the wiring inductance 107 and 108 caused by the positive-side busbar 214 and the negative-side busbars 215a and 215b can be reduced.

[0032] According to this embodiment, in a semiconductor module with switching elements, since two P buses are arranged to sandwich an N bus and an AC bus, or two N buses are arranged to sandwich a P bus and an AC bus, magnetic flux generated between buses flowing with opposite currents can be eliminated. Therefore, not only the magnetic flux generated by the P and N buses, but also by the AC bus, can be eliminated, reducing the overall wiring inductance of the semiconductor module. Furthermore, since the buses are arranged to sandwich a bus flowing in the opposite direction, magnetic flux can be eliminated between adjacent buses. Therefore, compared to the case consisting of a pair of buses, a semiconductor module with higher magnetic flux elimination effect and lower wiring inductance, as in the power converter of Patent Document 1, can be provided. Therefore, surge voltage caused by wiring inductance can be reduced, switching losses and heat generation of the switching elements can be suppressed, thereby reducing the need for auxiliary components such as heat sinks. Moreover, since the overall device can be miniaturized, device miniaturization and cost reduction can be achieved.

[0033] Figure 9 This is a top sectional view showing the semiconductor module involved in other methods. When multiple semiconductor modules are used side by side, if semiconductor module (first semiconductor module) 200 and semiconductor module (second semiconductor module) 300 are arranged adjacent to each other, the wiring inductance caused by the busbar can be further reduced. Figure 9 This represents a configuration example used to implement such a structure. Figure 9 The dashed arrows indicate the current path when surge voltage is generated. If semiconductor module 200 and semiconductor module 300 are configured adjacent to each other, current flows in opposite directions through adjacent busbars, thus effectively eliminating the magnetic flux generated by each. Therefore, the wiring inductances 109, 110, and 111 caused by P busbar 201, N busbar 202, AC busbar 203, P busbars 301a and 301b, N busbar 302, and AC busbar 303 can be reduced. Figure 9 The example illustrates the case of two semiconductor modules configured in parallel, but the same effect can be achieved by alternating the configuration of semiconductor module (first semiconductor module) 200 and semiconductor module (second semiconductor module) 300 in accordance with the number of parallel modules.

[0034] Implementation method 2. Next, use Figure 10 , Figure 11 , Figure 12 The width of the busbars, the spacing between the busbars, and the rate of reduction of inductance are explained. Figure 10This is a simplified top view showing the shapes of the busbars in semiconductor module 200 and semiconductor module 300. Busbars 402a and 402b are configured to clamp busbar 401. Let the self-inductance of busbars 401, 402a, and 402b be L respectively. 401 L 402a L 402b L 401 With L 402a The coupling coefficient is K a L 401 With L 402b The coupling coefficient is K b At that time, L 401 With L 402a Mutual induction M a L 401 and L 402b Mutual induction M b It can be represented by the following formula (2).

[0035] [Mathematical Expression 1]

[0036] From equation (2), we can see that the coupling coefficient K of each inductor is... a K b The larger the mutual inductance M, the greater the mutual inductance M. a M b The larger the current flows in the reverse direction through busbars 402a, 402b and busbar 401, the magnetic flux generated between adjacent busbars is eliminated, and the combined inductance L of busbar 401 increases. 401M It can be represented by the following formula (3).

[0037] [Mathematical Expression 2] L 401M =L 401 -M a -M b …(3)

[0038] According to equation (3), mutual inductance M a M b The larger the value, the greater the combined inductance L of busbar 401. 401M The smaller. Let the width of busbars 401, 402a, and 402b be a [mm], and the spacing between adjacent busbars be b [mm]. Current flows in the reverse direction through busbars 402a, 402b, and 401. With the width a [mm] of the busbars fixed and the spacing b [mm] between the busbars variable, the effect on the self-inductance L... 401 With composite inductor L 401M The results were obtained by analyzing and calculating the relationship between the ratios. Figure 11 To express it. Specifically, Figure 11 The horizontal axis represents the ratio of the spacing between busbars b [mm] to the width of the busbar a [mm], and the vertical axis represents the composite inductance L. 401M / Self-awareness L 401 The ratio. According to equations (2), (3) and the result, the smaller the spacing b [mm] between the busbars, the higher the coupling coefficient K of the inductance. a K b The larger the value, the greater the combined inductance L. 401M reduce.

[0039] If the ratio of the spacing b [mm] between busbars to the width a [mm] of the busbar is set to less than 1, then relative to the self-inductance L 401 It can synthesize inductance L 401M The suppression is below 30%. That is, if the width a [mm] of the busbar is set to be greater than or equal to the spacing b [mm] between the busbars, the inductance suppression effect can be fully achieved. exist Figure 3 Although the illustrations are omitted, in reality, as shown in the example... Figure 12 As shown, in order to drive the switching elements 103a and 103b, control terminals 214a and 214b are required as gate wiring and source wiring, respectively. Figure 12 In the illustrated configuration example, except for the portions where control terminals 214a and 214b are located, inductance can be suppressed by configuring bus P 201, bus N 202, and bus AC 203 such that the width a [mm] of the bus is greater than or equal to the spacing b [mm] between the busbars. As described above, when the width of any one of the first, second, and third busbars is a [mm] and the spacing between these busbars is b [mm], a and b are set such that b ≤ a in the relationship between at least a portion of the first, second, and third busbars.

[0040] Figure 13 This is a top cross-sectional view showing other semiconductor modules involved in Embodiment 2. Figure 14 This is the equivalent circuit diagram. In Figure 13 , Figure 14 In the middle, it means to Figure 3 The diagram shows the structure of semiconductor module 500 when the switching elements of semiconductor module 200 are connected in parallel. Switching elements 501a and 501b form the upper arm, and switching elements 502a and 502b form the lower arm. Figure 3The semiconductor module 200 shown is identical, with the N bus 504 configured to hold the P bus 503 and the AC bus 505. More specifically, in the semiconductor module 500, the P bus 503 and the AC bus 505 are arranged between the N bus 504, which is configured in a two-branch manner, in the direction (X direction) in which the terminals 512, 513a, and 513b of the P bus 503 and the N bus 504 protrude.

[0041] exist Figure 14 In the diagram, the wiring inductance on the drain side of switching element 501a is 506a, the wiring inductance on the drain side of switching element 501b is 506b, the wiring inductance on the source side of switching element 501a is 507a, the wiring inductance on the source side of switching element 501b is 507b, the wiring inductance on the drain side of switching element 502a is 508a, the wiring inductance on the drain side of switching element 502b is 508b, the wiring inductance on the source side of switching element 502a is 509a, and the wiring inductance on the source side of switching element 502b is 509b.

[0042] Here, when multiple switching elements are used in parallel, if there is a difference in their respective wiring inductances, the deviation in current shunting between the switching elements will increase, and the heat generated by the element carrying more current will increase. That is, it is preferable that wiring inductances 506a and 506b, wiring inductances 507a and 507b, wiring inductances 508a and 508b, and wiring inductances 509a and 509b are respectively equal. For example... Figure 13 As shown, the branch points 510 of the P busbar 503 and 511a and 511b of the AC busbar 505 are positioned at equal distances relative to the parallel-connected switching elements. Furthermore, the N busbar 504 is symmetrically arranged with respect to the module's centerline. This structure allows the wiring to be arranged symmetrically with respect to the module's centerline, ensuring that the wiring lengths are equal on both sides of the module's centerline. Therefore, the wiring inductances 506a and 506b, 507a and 507b, 508a and 508b, and 509a and 509b can be made equal.

[0043] In the above embodiment, the switching element was described as a MOSFET, but wide-bandgap semiconductors such as SiC or GaN, which are capable of high-frequency driving, have fast switching speeds (dv / dt, di / dt), and reduce losses, can also be used. If the switching speed (di / dt) is fast, the surge voltage also increases. That is, if a wide-bandgap semiconductor is used in this embodiment, surge voltage and heat generation of the switching element can be suppressed, further enabling miniaturization and high efficiency of the power converter.

[0044] Although this application describes various exemplary embodiments and examples, the various features, methods and functions described in one or more embodiments are not limited to the application of a particular embodiment and can be applied to the embodiment individually or in various combinations. Therefore, it can be assumed that numerous variations not illustrated are also included within the scope of the technology disclosed in this application. For example, this includes cases where at least one constituent element is modified, added to, or omitted, and cases where at least one constituent element is extracted and combined with constituent elements of other embodiments. Label Explanation

[0045] 101 DC power supply, 102 filter capacitor, 103 U phase arm, 103a switching element, 103b switching element, 104V phase arm, 104a switching element, 104b switching element, 105W phase arm, 105a switching element, 105b switching element, 106 three-phase AC motor, 200 semiconductor module, 201P busbar, 202N busbar 203AC busbar, 204 load busbar, 205 heatsink, 206 heatsink. 207 insulating sheet, 208 molding resin, 212 metal plate. 300 semiconductor module, 301a, 301b P busbars, 302N busbars 303AC busbar, 304 load busbar, 305 heatsink, 306 heatsink. 307 insulating sheet, 308 molding resin, 312 metal plate.

Claims

1. A semiconductor module, characterized in that, It has a switching circuit consisting of a first semiconductor element and a second semiconductor element connected in series. It is equipped with a first bus bar, a second bus bar, and a third bus bar. The first busbar is connected to the positive electrode side of the first semiconductor element. The second busbar is connected to the negative electrode side of the second semiconductor element. The third busbar is connected to the negative electrode side of the first semiconductor element and the positive electrode side of the second semiconductor element. While the first busbar, the second busbar, and the third busbar extend in the same direction, The busbar of either the first busbar or the second busbar is configured to clamp the third busbar and the other busbar of either the first busbar or the second busbar.

2. The semiconductor module as described in claim 1, characterized in that, The second busbar is configured to split into two branches. The first bus and the third bus are configured between the second bus, which is configured as two branches.

3. The semiconductor module as described in claim 1, characterized in that, It has two of the first busbars, The second bus and the third bus are configured between the two first bus bars.

4. The semiconductor module as described in claim 1, characterized in that, Constitutes the first semiconductor module and the second semiconductor module. In this first semiconductor module, the second bus is configured with two branches, and the first bus and the third bus are arranged between the two branches of the second bus. The second semiconductor module has two of the first busbars, and a second busbar and the third busbar are arranged between the two first busbars. The first semiconductor module and the second semiconductor module are configured alternately.

5. The semiconductor module as described in any one of claims 1 to 4, characterized in that, At least a portion of the first busbar, the second busbar, and the third busbar are arranged on the same plane.

6. The semiconductor module as described in any one of claims 1 to 4, characterized in that, The first semiconductor element and the second semiconductor element are packaged in the same module.

7. The semiconductor module as described in any one of claims 1 to 4, characterized in that, Let the width of any one of the first busbar, the second busbar, and the third busbar be a, and the interval between these busbars be b. Then a and b are set in such a way that b ≤ a in at least a part of the relationship between the first busbar, the second busbar, and the third busbar.

8. The semiconductor module as described in any one of claims 1 to 4, characterized in that, The first semiconductor element and the second semiconductor element are wide-bandgap semiconductors.

9. A power converter, characterized in that, The semiconductor module as described in any one of claims 1 to 8 was used. It has a filter capacitor for filtering the DC voltage applied to the semiconductor module. The first busbar has a first terminal portion for wiring connection with the positive side of the filter capacitor. The second busbar has a second terminal portion for wiring connection to the negative side of the filter capacitor. The first terminal portion and the second terminal portion protrude in the same direction.

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