Power converter

Abstract

Power converter (1) comprising: a semiconductor module (52) containing a power conversion circuit unit (4); a capacitor (51) which smoothes a DC power and supplies the DC power to the power conversion circuit unit (4); a control circuit board (45a) arranged remotely from the capacitor (51) and containing a control circuit (172) that controls the power conversion circuit unit (4); a connecting conductor (10) connecting the semiconductor module (52) and the capacitor (51); a base (33) electrically connected to a ground of the control circuit board (45a), wherein the control circuit board (45a) is arranged on the base (33); and an electrical conductor (35) electrically connected to the base (33) and extending in a stacking direction in which the base (33) and the control circuit board (45a) are stacked, wherein the connecting conductor (10) runs around the electrical conductor (35) and is connected to the semiconductor module (52).

Description

Technical area

[0001] The present invention relates to a power converter. Technical background

[0002] Vehicles such as hybrid vehicles, plug-in hybrid vehicles, and electric vehicles are equipped with various power converters, such as an inverter for driving a motor, a charger for charging a high-voltage battery with power from a commercial power supply, and a DC-DC converter for supplying power to an auxiliary battery. A power converter such as an inverter for driving a motor has a structure in which a capacitor for smoothing DC power, a semiconductor module containing a power conversion circuit unit for converting DC power into AC power, and a bus bar for connecting the capacitor and a power module to a DC power supply are housed in a metal case.

[0003] As an example of such a power converter, a structure is known in which a control circuit board is arranged above the power module, the capacitor is arranged on one side of the power module, and the capacitor and the power module are connected by a positive-side bus bar and a negative-side bus bar connected to the DC power supply. The positive-side and negative-side bus bars are integrally formed with resin and are connected to a positive-side terminal and a negative-side terminal of the power module, respectively. A connection portion in which the positive-side and negative-side bus bars are connected to the positive-side and negative-side terminals of the power module is arranged near the control circuit board and directly facing the control circuit board (see, for example, Fig. 2 of PTL 1). Furthermore, PTL 2 discloses an electrical power converter comprising a semiconductor module with switching elements and a cooler. Two types of bypass capacitors are used to suppress noise currents over a wide frequency range: A proximal bypass capacitor, formed by the module's heat dissipation plate, an insulating layer, and the grounded cooler, acts close to the switching element to counteract high-frequency noise. In addition, distal bypass capacitors with larger capacitance connect the DC busbars to ground and filter low-frequency noise. PTL 3 describes a power converter, particularly for vehicles, that aims to improve noise immunity while simultaneously reducing weight through the use of resin materials.The core of the teaching is a housing structure comprising a resin housing for the power semiconductor module (whose metallic module housing extends into an integrated coolant channel) and a metal housing for the control board, with a metallic base separating these two areas. Finally, PTL 4 describes a structure for reducing the propagation of electromagnetic noise in power conversion devices. To prevent noise from active circuit sections (e.g., converters) from reaching a filter circuit through gaps between a first partition in the chassis and a base plate, it is proposed that the base plate itself have a second partition, with this second partition being positioned along the first partition. Citation listPatent literature PTL 1: JP 2018-27000 A, PTL 2: US 2015 / 0 195 957 A1, PTL 3: DE 11 2015 003 244 T5, PTL 4: DE 11 2015 005 695 T5 Summary of the inventionTechnical problem

[0004] As disclosed in PTL 1, a power converter having a structure in which a capacitor circuit unit, which is a high-voltage circuit unit, and a control circuit, which is a low-voltage circuit unit, are arranged close to each other has a protection mechanism against a malfunction of the control circuit due to an increase in an electromagnetic compatibility (EMC) noise current flowing via a control circuit board, but the protection mechanism is required to be further improved. Solution to the problem

[0005] The invention relates to a power converter comprising the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims. Advantageous effects of the invention

[0006] According to the present invention, it is possible to reduce a stray capacitance between the positive-side and negative-side bus bars and the control circuit board to reduce an electromagnetic compatibility (EMC) noise current flowing across a control circuit board. Brief description of the drawings [ Fig. 1] Fig. 1 is a diagram showing an example of a circuit diagram of a power converter according to the present invention. [ Fig. 2] Fig. 2 is an external perspective view of the power converter according to an embodiment of the present invention. [ Fig. 3] Fig. 3 is an exploded perspective view of the power converter used in Fig. 2 is shown. [ Fig. 4] Fig. 4 is a perspective view of a connection structure of the power converter used in Fig. 2, wherein a capacitor and a connecting conductor are connected. [ Fig. 5] Fig. Fig. 5 is a cross-sectional view taken along a line VV of the power converter used in Fig. 2 is shown. [ Fig. 6] Fig. 6 is a schematic diagram showing a flow of EMC noise current in the power converter used in Fig. 5 is shown. [ Fig. 7] Fig. 7 is a diagram showing a flow of EMC noise current in a power converter according to a comparative example. [ Fig. 8] Fig. Figure 8 is a diagram showing the flow of EMC noise current in the power converter used in Fig. 5 is shown. Description of the embodiments

[0007] Hereinafter, a power converter according to an embodiment of the present invention will be described with reference to the drawings.

[0008] Fig. 1 is a diagram showing an example of a circuit diagram of the power converter according to the present invention.

[0009] A power converter 1 includes an inverter main circuit 3 that converts DC power into AC power, a noise filter circuit unit 20 that reduces electromagnetic noise caused when the inverter main circuit 3 performs the power conversion, and a control unit 170. The power converter 1, which is in Fig. 1 has a structure surrounded by a box and including the inverter main circuit 3, the noise filter circuit unit 20, and the control unit 170.

[0010] The inverter main circuit 3 includes a power conversion circuit unit 4 that converts DC power into AC power and a capacitor circuit unit 5 that smoothes the DC power.

[0011] The power conversion circuit unit 4 includes three series circuits 4a, 4b, 4c of an upper and a lower arm. Each of the series circuits 4a, 4b, 4c of an upper and a lower arm includes a switching element 328 such as an insulated gate bipolar transistor (IGBT) and a diode 156 serving as an upper arm, and a switching element 330 such as an IGBT and a diode 166 serving as a lower arm. The upper arm switching element 328 and the lower arm switching element 330 convert DC power into AC power. The diodes 156, 166 can also convert AC power into DC power during regeneration.

[0012] The series connection of an upper and a lower branch 4a is connected to a u-phase of a motor generator MG via an AC connection 270a. The series connection of an upper and a lower branch 4b is connected to a v-phase of the motor generator MG via the AC connection 270a. The series connection of an upper and a lower branch 4c is connected to a w-phase of the motor generator MG via the AC connection 270a.

[0013] The motor generator MG outputs driving power for an HEV or an EV based on the AC power supplied from the inverter main circuit 3 via the AC terminal 270a. The motor generator MG also functions as a generator that regenerates AC power when the motor is rotated by an external force and feeds the AC power back to a high-voltage battery 2. The high-voltage battery 2 is a DC power supply for an HEV or an EV.

[0014] The capacitor circuit unit 5 includes a capacitor 51 and is connected between the high-voltage battery 2 and the power conversion circuit unit 4 to smooth a DC power and supply the thereby smoothed DC power to the power conversion circuit unit 4.

[0015] The noise filter circuit unit 20 is provided between a DC power supply terminal 6 and the capacitor circuit unit 5 and reduces electromagnetic noise caused when the power conversion circuit unit 4 performs power conversion.

[0016] The noise filter circuit unit 20 includes a connecting conductor 10, an X capacitor 31, positive-side and negative-side Y capacitors 32p, 32n, and a core element 21. The connecting conductor 10 is a power transmission path connecting the high-voltage battery 2 and the capacitor circuit unit 5. The connecting conductor 10 includes a positive-side connecting conductor 10p and a negative-side connecting conductor 10n. The positive-side and negative-side connecting conductors 10p, 10n are connected to a positive-side and a negative-side terminal of the high-voltage battery 2 via a positive-side DC power supply terminal 6p and a negative-side DC power supply terminal 6n, respectively.

[0017] The X-capacitor 31 is provided between the positive-side connecting conductor 10p and the negative-side connecting conductor 10n, and smoothes power with a higher frequency than the power to be smoothed by the capacitor circuit unit 5. The positive-side and negative-side Y-capacitors 32p, 32n are provided between the positive-side connecting conductor 10p and a ground terminal 134, and between the negative-side connecting conductor 10n and the ground terminal 134, respectively, and smooth power.

[0018] The core element 21 reduces electromagnetic noise by absorbing fluctuations of a current flowing through the connecting conductor 10.

[0019] A positive-side terminal of the capacitor switching unit 5 is connected to a collector of the switching element 328 and a cathode of the diode 156 of each upper branch via the positive-side connecting conductor 10p. Furthermore, a negative-side terminal of the capacitor 51 is connected to an emitter of the switching element 330 and an anode of the diode 166 of each lower branch via the negative-side connecting conductor 10n.

[0020] The control unit 170 includes two circuits: a driver circuit 174 that drives and controls the power conversion circuit unit 4, and a control circuit 172 that supplies a control signal to the driver circuit 174 via a signal line (a bus line) 176. Gate terminals and emitter detection terminals of the IGBTs 328, 330 of each of the upper and lower arm series circuits 4a, 4b, 4c are connected to the control unit 170. The upper and lower arm series circuits 4a, 4b, 4c operate in response to a drive signal output from the control unit 170 to convert DC power supplied from the high-voltage battery 2 into three-phase AC power. The power obtained as a result of the conversion is supplied to an armature winding of the motor generator MG.

[0021] The control circuit 172 includes a microcomputer that calculates switching timings of the IGBTs 328, 330. The microcomputer receives as input information a target torque value required for the motor generator MG, a current value to be supplied from the series circuits 4a, 4b, 4c of an upper and a lower arm of the armature winding of the motor generator MG, and a magnetic pole position of a rotor of the motor generator MG. The target torque value uses a command signal output from a host control device (not shown) as a basis. The current value is detected based on a detection signal output from a current sensor (not shown). The magnetic pole position is detected based on a detection signal output from a rotating magnetic pole sensor (not shown) provided in the motor generator MG.

[0022] Fig. 2 is an external perspective view of the power converter according to one embodiment of the present invention.

[0023] The power converter 1 includes a housing formed from a case 7 and a cover (not shown).

[0024] Fig. 2 shows a state in which the cover is removed from the housing 7. Side walls of the housing 7 defining a housing portion are not shown, and only a bottom surface 7a of the housing portion is shown.

[0025] In the following description, the x-direction, y-direction and z-direction are as shown in the drawings.

[0026] The housing 7 is made of metal such as an aluminum alloy.

[0027] A capacitor housing portion 53 is provided approximately at a center of the housing 7 in a width direction (the y-direction), and a base 33 is arranged on one side of the housing 7 (the right side in the drawing) in a length direction (the x-direction) and adjacent to the capacitor housing portion 53. Although details will be described later, a plurality of capacitor elements 51a (see Fig. 4) forming the capacitor 51 are housed in the capacitor housing section 53. A control circuit board 45a is arranged on the base 33 and is fixed to the base 33 with a fixing member 61 such as a screw.

[0028] Fig. 3 is an exploded perspective view of the power converter used in Fig. 2 is shown, and Fig. 4 is a perspective view of a connection structure of the power converter used in Fig. 2, wherein the capacitor and the connecting conductor are connected. Fig. Fig. 5 is a cross-sectional view taken along a line VV of the power converter used in Fig. 2 is shown.

[0029] The base 33 is made of a conductive metal such as an aluminum alloy, iron, or copper. The base 33 includes a support 34 having an approximately planar shape, an electrical conductor 35 extending in a direction (the z-direction) approximately perpendicular to an xy-plane of the support 34, and a plurality of mounting legs 38 extending from the support 34 to the bottom surface 7a of the housing 7.

[0030] The control circuit board 45a is arranged on the support 34 of the base 33, and a control circuit board 45b is arranged below the support 34 of the base 33. That is, the support 34 of the base 33 is clamped between the control circuit board 45a and the control circuit board 45b when viewed from above. The control circuit board 45a and the control circuit board 45b contain the control circuit 172, which is Fig. 1 is shown.

[0031] As in Fig. 5, the electrical conductor 35 extends in a stacking direction (the z-direction) in which the carrier 34 of the base 33 and the control circuit boards 45a, 45b are stacked. As shown in Fig. 3, the electrical conductor 35 includes a wide portion 35a extending in the y-direction along one side of the support 34, and a pair of sides 35b, 35c provided at both ends of the wide portion 35a and extending in the -x direction (toward the capacitor 51), that is, approximately at a right angle to the wide portion 35a. The electrical conductor 35 includes a first electrical conductor 36 extending upward (+z direction) from the support 34 and a second electrical conductor 37 extending downward (-z direction) from the support 34. The pair of sides 35b, 35c are provided on both the first electrical conductor 36 and the second electrical conductor 37.

[0032] Each mounting leg 38 (see Fig. 3) has a mounting hole 38a provided at a distal end of the mounting leg 38. A fastener (not shown) such as a screw or a bolt is inserted into the mounting hole 38a of the mounting leg 38 to fix the base 33 to a projection 7b provided on the housing 7, as shown in Fig. 2 is shown.

[0033] A semiconductor module 52 is arranged under the support 34 of the base 33 and is fixed to a fixing portion 7c provided on the bottom 7a of the housing 7. The semiconductor module 52 includes the series circuits 4a, 4b, 4c of an upper and a lower branch, which are arranged in Fig. 1. As shown in Fig. As shown in Figure 3, the semiconductor module 52 includes a positive DC terminal 52p, a negative DC terminal 52n, and an AC terminal 52t of each of the series circuits 4a, 4b, 4c of an upper and a lower branch. A drive circuit board 46 is arranged between the carrier 34 of the base 33 and the semiconductor module 52. The drive circuit board 46 includes the driver circuit 174, which is shown in Fig. 1 is shown.

[0034] As in Fig. 3 and Fig. 5, a positive-side bus bar 41 and a negative-side bus bar 42 connect the capacitor 51 and the semiconductor module 52 (see Fig. 3). The positive-side busbar 41 and the negative-side busbar 42 correspond to the positive-side connecting conductor 10p and the negative-side connecting conductor 10n, respectively, which are Fig. 1. The capacitor 51 and the base 33 form an EMC noise reduction structure, which is described below.

[0035] The positive side busbar 41 is connected to the positive side DC power supply terminal 6p (see Fig. 1) of the DC power supply terminal 6, by means of a connecting section 71 (see Fig. 5) is connected to a positive terminal (not shown) of the capacitor 51 and by means of a connecting end 41c (see Fig. 4), located at the other end of the positive-side busbar 41, with each positive DC terminal 52p (see Fig. 3) of the semiconductor module 52. The negative-side busbar 42 is connected to the negative-side DC power supply terminal 6n (see Fig. 1) of the DC power supply terminal 6, by means of a connecting section 72 (see Fig. 5) is connected to a negative terminal (not shown) of the capacitor 51 by means of the connecting portion 72 (see Fig. 5) is connected to the negative terminal (not shown) of the capacitor 51 and by means of a connecting end 42c (see Fig. 4), located at the other end of the negative-side busbar 42, to each negative DC terminal 52n (see Fig. 3) of the semiconductor module 52. AC power obtained by the series circuits 4a, 4b, 4c of an upper and a lower arm is output from the AC terminal 52t of the semiconductor module 52.

[0036] As in Fig. 5, the positive-side and negative-side busbars 41, 42 are arranged in the longitudinal direction (the x-direction) next to the electrical conductor 35 of the base 33. As shown in Fig. As shown in Figure 2, the length in the width direction (y-direction) of the positive-side and negative-side busbars 41, 42 is slightly smaller than the length between the pair of sides 35b, 35c of the electrical conductor 35, and the positive-side and negative-side busbars 41, 42 are respectively arranged away from both sides 35b, 35c of the electrical conductor 35. Resin 43 (see Fig. 5) is arranged to insulate the positive-side busbar 41 from the negative-side busbar 42. The positive-side busbar 41 and the negative-side busbar 42 may be formed together with the resin 43 by injection molding into a molded busbar body.

[0037] The positive-side and negative-side busbars 41, 42 each have sloping portions 41a, 42a. The sloping portions 41a, 42a extend downward along the electrical conductor 35 from one side near an upper end 36a of the first electrical conductor 36, approximately parallel to the electrical conductor 35 (-z direction). The positive-side and negative-side busbars 41, 42 are fastened to the positive and negative DC terminals 52p, 52n of the semiconductor module 52 with fastening elements (not shown) such as screws or bolts below a lower end 37a of the second electrical conductor 37.

[0038] As in Fig. As shown in Figure 4, the capacitor 51 includes the plurality of capacitor elements 51a. The plurality of capacitor elements 51a are electrically connected in parallel through positive-side and negative-side terminals 71p, 72n of the positive-side and negative-side connecting portions 71, 72 of the positive-side and negative-side bus bars 41, 42.

[0039] Note that, according to the present embodiment, a structure in which the positive-side busbar 41 is arranged above the negative-side busbar 42 in the (+z direction) was exemplified. Alternatively, a structure in which the negative-side busbar 42 is arranged above the (+z direction) of the positive-side busbar 41 may be employed.

[0040] As in Fig. 5, the upper end 36a of the first electrical conductor 36 of the electrical conductor 35 extends further upward (+z direction) than the connecting portions 71, 72, wherein the positive-side and negative-side bus bars 41, 42 are connected to the capacitor 51.

[0041] As described above, the control circuit board 45a is mounted on the support 34 of the base 33 (+z direction). The control circuit board 45b is mounted below the support 34 of the base 33 (-z direction). The control circuit board 45a is arranged below the upper end 36a of the first electrical conductor 36 of the electrical conductor 35 (-z direction), in other words, adjacent to the support 34. The control circuit board 45b is arranged above the lower end 37a of the second electrical conductor 37 of the electrical conductor 35 (-z direction), in other words, adjacent to the support 34.

[0042] The semiconductor module 52 includes a metal housing with high thermal conductivity, such as an aluminum alloy. With reference to Fig. 5, the metal casing of the semiconductor module 52 includes a pair of wide surfaces 52a, 52b having a rectangular shape, and two pairs of circumferential side surfaces 52c having a narrow width and provided between peripheries of the wide surfaces 52a, 52b. That is, the circumferential side surfaces 52c include four rectangular side surfaces. A wide surface 52a of the metal casing of the semiconductor module 52 is coupled to the fixing portion 7c provided on the bottom surface 7a of the casing 7 in a heat-conductive manner, that is, thermally coupled to the fixing portion 7c. Although not shown, a cooling channel through which a refrigerant such as coolant flows is provided in the casing 7, and the semiconductor module 52 is cooled by means of the fixing portion 7c of the casing 7. Cooling fins may be provided on the wide surface 52a of the semiconductor module 52.

[0043] As in Fig. As shown in Figure 5, the capacitor 51 is arranged on the left side (-x direction) of the electrical conductor 35, which runs in the vertical direction (z direction). The control circuit boards 45a, 45b, which are arranged on the support 34 of the base 33, are arranged on the right side (+ direction) of the electrical conductor 35. The semiconductor module 52 is arranged in a space provided between the support 34 of the base 33 and the bottom surface 7a of the housing 7. The semiconductor module 52 is arranged by means of the fixing portion 7c with the wide surface 52a in contact with the bottom surface 7a of the housing 7. The wide surface 52a of the metal housing of the semiconductor module 52 has a large area to improve heat dissipation, such that when the wide surface 52a is arranged perpendicular to the bottom surface 7a of the housing 7, the profile of the power converter 1 is higher.According to the present embodiment, the wide surface 52a of the semiconductor module 52 is arranged parallel to the bottom surface 7a of the housing 7. As described above, the structure in which the semiconductor module 52 is arranged between the support 34 of the base 33 and the bottom surface 7a of the housing 7 enables a reduction in the profile and size of the power converter 1.

[0044] The control circuit board 46 is arranged over the further wide surface 52b of the semiconductor module 52. The control circuit board 46 contains the driver circuit 174, which is Fig. 1. The control circuit board 46 is fixed to an upper end of the projection 7b (see Fig. 5) provided on the housing 7. The control circuit board 46 is connected by a connector 64 (see Fig. 5) is connected to the control circuit board 45b. The connector 64 corresponds to the bus line 176, which is Fig. 1 is shown.

[0045] The positive-side and negative-side busbars 41, 42 extend downward along the electrical conductor 35 from upper planar portions 41b, 42b approximately parallel to the electrical conductor 35 and are connected to the semiconductor module 52 slightly below the lower end 37a of the second electrical conductor 37, in other words, by extending around the electrical conductor 35.

[0046] As in Fig. 5, the support 34 of the base 33 includes a board support surface (a board installation surface) S f , on which a support element 34s carrying the control circuit board 45a is provided. The semiconductor module 52 is arranged in a space on one side of the board support surface S f arranged, which is connected to the board carrier surface S fviewed from above, and the connecting portions 71, 72 in which the capacitor 51 is connected to the positive-side and negative-side bus bars 41, 42 are on a side opposite to the one side on which the semiconductor module 52 is arranged, and above an extension line of the board support surface S f This means that the connecting sections 71, 72 have a higher position in the z-direction than the board support surface S f on.

[0047] A distance L1 from the board carrier surface S f to the upper end 36a of the first electrical conductor 36 is greater than a distance L2 from the board support surface S fto the connecting portions 71, 72 of the positive-side and negative-side busbars 41, 42. That is, the first electrical conductor 36 is provided extending further upward (+z direction) than the connecting portions 71, 72 of the positive-side and negative-side busbars 41, 42. This enlarges an end area between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35.

[0048] Fig. 6 is a schematic diagram showing a flow of EMC noise current in the power converter used in Fig. 5 is shown.

[0049] As in Fig. As shown in Fig. 6, the base 33 includes the support 34 provided with the support member 34s supporting the control circuit board 45a. The base 33 is provided with the electrical conductor 35 extending from the support 34 in the vertical direction (the z direction). The capacitor 51 is arranged on the left side (-x direction) of the electrical conductor 35, and the control circuit board 45a is arranged on the right side (+x direction) of the electrical conductor 35. The sloping portions 41a, 42a of the positive-side and negative-side bus bars 41, 42 are arranged on the left side (-x direction) of the electrical conductor 35. That is, the positive-side and negative-side bus bars 41, 42 and the control circuit board 45a are separated by the electrical conductor 35.

[0050] EMC noise is caused by magnetic / capacitive coupling between the positive-side and negative-side busbars 41, 42 and the control circuit board 45a. EMC noise is mainly caused by capacitive coupling.

[0051] According to the present embodiment, the electrical conductor 35 is provided between the positive-side and negative-side busbars 41, 42 and the control circuit board 45a, extending in a direction perpendicular to the xy plane, in other words, in the vertical direction in which the base 33 and the control circuit board 45a are stacked. Such a component arrangement causes capacitive coupling due to a stray capacitance C1 between the positive-side and negative-side busbars 41, 42 and the control circuit board 45a, and a stray capacitance C2 between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35.

[0052] As if by arrows in Fig. As shown in Figure 6, due to capacitive coupling caused by the stray capacitance C1 between the positive-side and negative-side busbars 41, 42 and the control circuit board 45a, the EMC noise current of the positive-side and negative-side busbars 41, 42 flows to the ground via the control circuit board 45a, the support 34 of the base 33, and the housing 7. Furthermore, due to capacitive coupling caused by the stray capacitance C2 between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35, the EMC noise current of the positive-side and negative-side busbars 41, 42 flows to the ground via the electrical conductor 35 and the support 34 of the base 33 and the housing 7.As described above, the electric conductor 35 extends in the vertical direction in which the capacitor 51 and the control circuit board 45a are stacked, and the sloping portions 41a, 42a of the positive-side and negative-side bus bars 41, 42 extend along the electric conductor 35 from a side near the upper end 36a of the electric conductor 35 to a side near the lower end 37a of the electric conductor 35 approximately parallel to the electric conductor 35. This makes the end area between the positive-side and negative-side bus bars 41, 42 and the electric conductor 35 larger, so that the stray capacitance C2 between the positive-side and negative-side bus bars 41, 42 and the electric conductor 35 becomes larger.

[0053] In Fig. 6, the EMC noise current is shown as a diagram flowing from a side 33a of the base 33 away from the electrical conductor 35 to the housing 7. As in Fig. However, as shown in Fig. 3, the base 33 includes the plurality of mounting legs 38, and each mounting leg 38 is fixed with a fixing member (not shown) to the protrusion 7b provided on the housing 7. That is, the base 33 is fixed to the housing 7 near the electrical conductor 35. This lowers the impedance of the path through which the EMC noise current flows, thus increasing the EMC noise current short-circuited to the electrical conductor 35, so that the EMC noise reduction effect can be further enhanced.

[0054] Fig. 7 is a schematic diagram showing a flow of an EMC noise current in a power converter 1A according to a comparative example, and Fig. Fig. 8 is a schematic diagram showing a flow of EMC noise current in the power converter 1 shown in Fig. 5 is shown.

[0055] In the power converter 1A according to the comparative example shown in Fig. 7, the base 33 does not include an electric conductor 35. That is, in the power converter 1A according to the comparative example, the electric conductor 35 extending in the vertical direction (the z direction) is not provided between the support 34 of the base 33 and the positive-side and negative-side bus bars 41, 42, and the positive-side and negative-side bus bars 41, 42 are arranged directly facing one end 34a of the support 34 of the base 33 and the control circuit board 45a.

[0056] In this structure, as in Fig. As shown in Fig. 7, the stray capacitance C1 is connected in parallel between the positive-side and negative-side busbars 41, 42 and the control circuit board 45a, and the stray capacitance C2 is connected between the positive-side and negative-side busbars 41, 42 and the base 33. Such a structure causes the EMC noise current flowing from a noise source to be short-circuited to the stray capacitances C1, C2 connected in parallel at a ratio between the stray capacitances C1, C2.

[0057] In the structure according to the comparative example, the stray capacitance C1 and the stray capacitance C2 are approximately equal.

[0058] That means: C1 ≈ C2.

[0059] Therefore, EMC noise currents I1, I2 flowing through the stray capacitances C1, C2 satisfy: I1 ≈ I2.

[0060] On the other hand, in the EMC noise reduction structure according to the present embodiment shown in Fig. As shown in Fig. 8, the first electrical conductor 36, which extends in the vertical direction, is provided between the support 34 of the base 33 and the positive-side and negative-side busbars 41, 42. The positive-side and negative-side busbars 41, 42 extend in the vertical direction along the first electrical conductor 36. The control circuit board 45a is arranged away from the positive-side and negative-side busbars 41, 42 compared to the first electrical conductor 36.

[0061] Accordingly, a relationship between the stray capacitance C1 and the stray capacitance C2 satisfies: C2 >> C1.

[0062] Therefore, the EMC noise currents I1, I2 flowing through the stray capacitances C1, C2 satisfy: I2 >> I1.

[0063] That is, a large portion of the EMC noise current from the positive-side and negative-side busbars 41, 42, which are noise sources, is short-circuited to the electrical conductor 35 instead of the control circuit board 45a. Therefore, the EMC noise current flowing from the positive-side and negative-side busbars 41, 42 to the control circuit board 45a can be greatly reduced.

[0064] As described above, the distance L1 from the board support surface S f to the upper end 36a of the first electrical conductor 36 is greater than the distance L2 from the extension line of the board support surface S fto the connecting portions 71, 72 of the positive-side and negative-side busbars 41, 42. This makes the end area between the positive-side and negative-side busbars 41, 42 and the first electrical conductor 36 larger, such that the stray capacitance C2 between the positive-side and negative-side busbars 41, 42 and the base 33 becomes larger.

[0065] As in Fig.As shown in Figure 5, the second electrical conductor 37 is provided between the positive-side and negative-side busbars 41, 42 and the control circuit board 45b. The control circuit board 45b is arranged vertically above the lower end 37a of the second electrical conductor 37 (+z direction). This makes the stray capacitance between the positive-side and negative-side busbars 41, 42 and the control circuit board 45b smaller than the stray capacitance C2 between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35.

[0066] This makes the EMC noise current flowing from the positive-side and negative-side busbars 41, 42 to the control circuit board 45b smaller than the positive-side and negative-side busbars 41, 42 flowing from the positive-side and negative-side busbars 41, 42 to the base 33.

[0067] Furthermore, the electrical conductor 35 includes the second electrical conductor 37, which extends to the control circuit board 46, which contains a control circuit that controls the semiconductor module 52. This makes the stray capacitance C between the positive-side and negative-side busbars 41, 42 and the second electrical conductor 37 larger than the stray capacitance between the positive-side and negative-side busbars 41, 42 and the control circuit board 46, so that the EMC noise current flowing through the control circuit board 46 is reduced.

[0068] Note that in the above description, the electrical conductor 35 structured to extend in the direction perpendicular to the xy plane was exemplified. Alternatively, the electrical conductor 35 may have a structure inclined with respect to the xy plane. When the electrical conductor 35 has a structure inclined with respect to the xy plane, the positive-side and negative-side busbars 41, 42 preferably extend parallel to the electrical conductor 35 to increase the stray capacitance between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35.

[0069] According to the embodiment described above, the following effects are obtained. (1) A power converter 1 includes a semiconductor module 52 including a power conversion circuit unit 4, a capacitor 51 that smooths a DC power and supplies the DC power to the power conversion circuit unit, a control circuit board 45a arranged adjacent to the capacitor 51 and including a control circuit that controls the power conversion circuit unit 4, positive-side and negative-side bus bars (connection conductors) 41, 42 that connect the semiconductor module 52 and the capacitor 51, a base 33 that is electrically connected to a ground of the control circuit board 45a, the control circuit board 45a being arranged on the base 33, and an electrical conductor 35 that is electrically connected to the base 33 and extends in a stacking direction in which the base 33 and the control circuit board 45a are stacked.The positive-side and negative-side busbars 41, 42 extend around the electrical conductor 35 and are connected to the semiconductor module. This can make the stray capacitance C1 between the positive-side and negative-side busbars 41, 42 and the control circuit board 45 smaller than the stray capacitance C2 between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35, so that the EMC noise current flowing through the control circuit board 45a can be reduced. (2) The electrical conductor 35 and the base 33 are formed into a single body. This enables efficient manufacturing of the electrical conductor 35 and the base 33 by molding or the like. (3) The electrical conductor 35 extends approximately parallel to the stacking direction in which the base 33 and the control circuit board 45a are stacked. This allows the end surface area between the electrical conductor 35 and the positive-side and negative-side busbars 41, 42 to be increased, thereby increasing the stray capacitance between the electrical conductor 35 and the positive-side and negative-side busbars 41, 42, and thus reducing the EMC noise current flowing through the control circuit board 45a. (4) The base 33 includes a carrier 34 on which the control circuit board 45a is arranged, the control circuit board 45a being arranged on one side of the carrier 34 in the stacking direction, and the semiconductor module 52 being arranged on the other side of the carrier 34 in the stacking direction. This structure prevents the side of the carrier 34 opposite the control circuit board 45a from being empty and has the semiconductor module 52 arranged on that side, so that the profile and size of the power converter 1 can be reduced. (5) The base 33 has a board support surface S f which carries the control circuit board 45a, the semiconductor module 52 is on one side of the board support surface S farranged in the stacking direction in which the base 33 and the control circuit board 45a are stacked, and the connecting portions 71, 72 in which the capacitor 51 is connected to the positive-side and negative-side bus bars 41, 42 are on the other side of the board support surface S f and over an extension line of the board carrier surface S f This makes the stray capacitance C1 between the positive-side and negative-side busbars 41, 42 and the control circuit board 45a smaller, so that the EMC noise current flowing through the control circuit board 45a is more effectively reduced. (6) The base 33 has the board support surface S f which carries the control circuit board 45a, and a distance L1 from the board support surface S f the base 33 to an upper end 36a of the base 33 is greater than a distance L2 from the extension line of the board support surface Sf to the connecting portions 71, 72 in which the positive-side and negative-side busbars 41, 42 are connected to the capacitor 51. This allows an increase in the end area between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35 to make the stray capacitance C2 between the positive-side and negative-side busbars 41, 42 and the electrical conductor 35 larger, so that the EMC noise current flowing through the control circuit board 45a is more effectively reduced. (7) The control circuit board 45a includes the control circuit board 45a arranged on one surface side of the base 33 and a control circuit board 45b arranged on a surface side opposite to the one surface side, the base 33 includes the carrier 34 supporting the control circuit board 45a and the control circuit board 45b, and the electrical conductor 35 includes a first electrical conductor 36 extending from the carrier 34 to the control circuit board 45a and a second electrical conductor 37 extending from the carrier 34 to the control circuit board 45b.This makes a stray capacitance C between the positive-side and negative-side busbars 41, 42 and each of the first electrical conductor 36 and the second electrical conductor 37 larger than a stray capacitance between the positive-side and negative-side busbars 41, 42 and the control circuit boards 45a, 45b, such that the EMC noise current flowing across the control circuit boards 45a, 45b is reduced. (8) Further, a drive circuit board 46 including a drive circuit that drives the semiconductor module 52 is provided, and the electrical conductor 35 includes the second electrical conductor 37 extending to the drive circuit board 46. This makes the stray capacitance C between the positive-side and negative-side bus bars 41, 42 and the electrical conductor 35 larger than the stray capacitance between the positive-side and negative-side bus bars 41, 42 and the drive circuit board 46, so that the EMC noise current flowing through the drive circuit board 46 is reduced. (9) Further, a housing 7 is provided which has a bottom surface (a surface) 7a which is approximately parallel to the control circuit board 45a, the semiconductor module 52 has a pair of wide surfaces 52a, 52b and a narrow peripheral side surface 52c surrounding a periphery of the wide surface 52a, and a wide surface 52a of the semiconductor module 52 and the bottom surface 7a of the housing 7 which is approximately parallel to the control circuit board 45a are thermally coupled.The wide surface 52a, which has a large area, of the semiconductor module 52 is arranged approximately parallel to the bottom surface 7a of the control circuit board 45a to be thermally coupled to the bottom surface 7a, such that it is possible to reduce the profile of the power converter 1 compared to a structure in which the semiconductor module 52 is arranged in a direction perpendicular to the control circuit board 45a, and thus to obtain the power converter 1 which has a low profile and can cool the semiconductor module 52.

[0070] Note that in the above-described embodiment, a structure in which the control circuit boards 45a, 45b are provided on the top and bottom surfaces of the base 33, respectively, was exemplified. Alternatively, the control circuit board 45a (45b) may be provided only on the top or bottom surfaces of the base 33.

[0071] In the above-described embodiment, the base 33 having a structure in which the first electrical conductor 36 extends upward from the support 34 (+z direction) and the second electrical conductor 37 extends downward (-z direction) from the support 34 was taken as an example. Alternatively, when a structure in which the control circuit boards 45a, 45b are arranged only on one surface of the support 34 is adopted, the base 33 may have a structure in which the electrical conductor 35 (36) extends only to the side on which the control circuit boards 45a, 45b are arranged.

[0072] In the embodiment described above, the base 33 in which the first electrical conductor 36 and the second electrical conductor 37 are formed into a single body by molding or the like was exemplified. Alternatively, the first electrical conductor 36 and / or the second electrical conductor 37 may be formed as a member separate from the base 33 and fixed to the base 33.

[0073] Alternatively, the electrical conductor 35 may be formed integrally with the housing 7. For example, the electrical conductor may be connected to a side wall (not shown) provided in the housing 7.

[0074] In the embodiment described above, a structure in which one of the pair of wide surfaces 52a, 52b of the semiconductor module 52 is thermally coupled to the bottom surface 7a of the housing 7 and cooled was exemplified. Alternatively, a structure in which a cooling channel through which coolant flows is provided in the housing 7 to cool both of the pair of wide surfaces 52a, 52b of the semiconductor module 52 may be employed.

[0075] Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical spirit of the present invention also fall within the scope of the present invention. List of reference symbols 1 power converter 4 Power conversion circuit unit 7 housings 7a bottom 10 connecting conductors 33 Base 34 carriers 35 Electrical conductor 35a, 35b Large section 36 First electrical conductor 36a Upper End 37 Second electrical conductor 37a Lower end 41 Positive-side busbar (connecting conductor) 42 Negative-side busbar (connecting conductor) 45a, 45b Control circuit board 46 Control circuit board 51 Capacitor 52 semiconductor module 52a, 52b Wide surface 71, 72 connecting section 72 connecting section 170 control unit 172 control circuit S f Board carrier surface L1, L2 distance

Claims

[1] Power converter (1) comprising: a semiconductor module (52) containing a power conversion circuit unit (4); a capacitor (51) which smoothes a DC power and supplies the DC power to the power conversion circuit unit (4); a control circuit board (45a) arranged remotely from the capacitor (51) and containing a control circuit (172) that controls the power conversion circuit unit (4); a connecting conductor (10) connecting the semiconductor module (52) and the capacitor (51); a base (33) electrically connected to a ground of the control circuit board (45a), wherein the control circuit board (45a) is arranged on the base (33); and an electrical conductor (35) electrically connected to the base (33) and extending in a stacking direction in which the base (33) and the control circuit board (45a) are stacked, wherein the connecting conductor (10) runs around the electrical conductor (35) and is connected to the semiconductor module (52). [2] The power converter (1) according to claim 1, wherein the electrical conductor (35) and the base (33) are formed in a single body. [3] The power converter (1) according to claim 1, wherein the electrical conductor (35) is approximately parallel to the stacking direction in which the base (33) and the control circuit board (45a) are stacked. [4] The power converter (1) according to claim 1, wherein the base (33) includes a carrier (34) on which the control circuit board (45a) is arranged, the control circuit board (45a) is arranged on one side of the carrier (34) in the stacking direction, and the semiconductor module (52) is arranged on another side of the carrier (34) in the stacking direction. [5] Power converter (1) according to claim 1, wherein the base (33) has a board support surface (S f), which carries the control circuit board (45a), the semiconductor module (52) on one side of the board carrier surface (S f ) in the stacking direction in which the base (33) and the control circuit board (45a) are stacked, and a connecting portion (71), in which the capacitor (51) is connected to the connecting conductor (10), on another side of the board support surface (S f ) and over an extension line of the board carrier surface (S f ) is arranged. [6] Power converter (1) according to claim 1, wherein the base (33) has a board support surface (S f ) which carries the control circuit board (45a) and has a distance of the board support surface (S f ) of the base (33) to an upper end (36a) of the base (33) is greater than a distance from an extension line of the board support surface (S f) to a connecting section (71) in which a positive-side and a negative-side busbar (41, 42) are connected to the capacitor (51). [7] Power converter (1) according to claim 1, wherein the control circuit board (45a) includes a first control circuit board arranged on one surface side of the base (33) and a second control circuit board arranged on a surface side opposite to the one surface side, the base (33) contains a carrier (34) which carries both the first control circuit board and the second control circuit board, and the electrical conductor (35) includes a first electrical conductor (36) extending from the carrier (34) to the first control circuit board and a second electrical conductor (37) extending from the carrier (34) to the second control circuit board. [8] The power converter (1) according to claim 1, further comprising a drive circuit board (46) including a drive circuit that drives the semiconductor module (52), wherein the electrical conductor (35) includes a second electrical conductor (37) extending to the drive circuit board (46). [9] Power converter (1) according to one of claims 1 to 8, further comprising a housing (7) having a surface approximately parallel to the control circuit board (45a), wherein the semiconductor module (52) has a pair of wide surfaces (52a, 52b) and a narrow peripheral side surface surrounding the peripheries of the wide surfaces (52a, 52b), and one of the wide surfaces (52a, 52b) of the semiconductor module (52) and the surface of the housing (7) are thermally coupled.

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