Inverter Structure

Abstract

To make inductance of bus bars and the like uniform.SOLUTION: In an inverter that has a smoothing capacitor 19 and a plurality of power modules 20, the smoothing capacitor 19 comprises: a plurality of columnar unit capacitors 45 each having electrodes at both ends; a one-end-side bus plate 19c connected with the electrode at one end of each unit capacitor 45; and an other-end-side bus plate 19d connected with the electrode at the other end of each unit capacitor 45. The plurality of unit capacitors 45 are arranged so as to be aligned in a direction perpendicular to an axial direction while their axial directions are in parallel with each other. The unit capacitors 45 are arranged at positions at distances equal to each other from the center. Distances of the respective power modules from each closest unit capacitor 45 are the same as each other.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to the structure of an inverter device mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle. [Background technology]

[0002] 2. Description of the Related Art Inverters that convert direct current into alternating current are known, and include power modules that include switching elements.

[0003] This type of inverter handles large amounts of power, so high voltages are applied and large currents flow through it. Consequently, it generates a lot of heat during operation, requiring cooling. It also generates large surge voltages. This means that the individual electronic components that make up the inverter tend to be large and heavy. Therefore, conventional inverters are a barrier to improving fuel economy and power efficiency.

[0004] In addition, inverters are usually placed near the drive motor to shorten the transmission distance. However, in the case of automobiles, there are many devices to be installed, so the space available for placing the inverter is limited. The balance of the vehicle body also needs to be taken into consideration. For this reason, it is difficult to properly place a large and heavy inverter in an automobile.

[0005] For example, as an inverter structure for an inverter-integrated AC motor, a configuration is known in which a donut-shaped inverter case has a + bus bar and a - bus bar integrally molded with resin and connected to a switching element (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-274992 Summary of the Invention [Problem to be solved by the invention]

[0007] The inverter is equipped with a power module including a switching element, a smoothing capacitor, etc. As mentioned above, in the case of an inverter compatible with a high-voltage power supply, these electronic components are generally large and heavy.

[0008] The metal fittings (bus bars), which are electronic components that connect these components, are also large and heavy because they carry large currents. The longer the bus bar wiring, the higher the electrical resistance becomes, resulting in copper loss when current is passed through them. Bus bars also generate a lot of heat. Furthermore, inverters use switching control to turn large currents on and off at high speeds, which causes large magnetic changes in the bus bars.

[0009] As a result, when the inverter is operating, magnetic changes cause noise, vibration, electromagnetic interference, etc. in the busbars. These result in energy loss and have various adverse effects on the performance of the vehicle. Therefore, measures to address these issues are necessary. The more complex the busbar shape, the more pronounced the effects become.

[0010] When connecting switching elements and smoothing capacitors via + bus bars and - bus bars that are integrally molded with resin into the inverter case as in Patent Document 1, it is not easy to reduce and further uniform the inductance of the bus bars due to restrictions on wiring length and wiring width.

[0011] The present invention has been made in view of the above points, and has as its object to easily make uniform the inductance of wiring connected to a smoothing capacitor while reducing it. [Means for solving the problem]

[0012] To achieve the above objectives, The first invention is An inverter structure of an inverter having a smoothing capacitor and a plurality of power modules, the smoothing capacitor comprises a plurality of columnar unit capacitors each having an electrode on both ends, a plate-like one-end bus plate connected to the electrode at one end of each unit capacitor, and a plate-like other-end bus plate connected to the electrode at the other end, the plurality of unit capacitors being arranged so that their axial directions are parallel to each other and so that they are aligned in a direction along a plane perpendicular to the axial direction, The plurality of unit capacitors are arranged at positions equidistant from a predetermined center, and The distance between each power module and at least the unit capacitor closest to each power module is set equal to each other.

[0013] Since the multiple unit capacitors are arranged so that their axial directions are parallel to each other and aligned in a direction perpendicular to the axial direction, the inverter can be made smaller in size in the axial direction. Furthermore, by providing a flat-shaped one-end bus plate connected to one end electrode of each unit capacitor and a flat-shaped other-end bus plate connected to the other end electrode, it becomes easy to arrange the power modules so that the distance to the smoothing capacitors is short. This means that the degree of freedom in the layout of the power modules can be increased.

[0014] Furthermore, by making the distance between each power module and at least the unit capacitor closest thereto equal, it is possible to equalize the inductance and improve the controllability of the motor.

[0015] The second invention is: An inverter structure according to a first aspect of the present invention, The one end bus plate and the other end bus plate are characterized in that they have circular outer shapes.

[0016] This allows connection by taking out terminals from anywhere in the circumferential direction of the smoothing capacitor, for example, and makes it easy to increase the degree of freedom in the layout of the power module.

[0017] The third invention is An inverter structure according to any one of the first and second inventions, The power module further comprises an input bus bar that connects the outer edges of the one end bus plate and the other end bus plate to the power module.

[0018] The fourth invention is: An inverter structure according to any one of the first and second inventions, The outer edge of at least one of the one end bus plate and the other end bus plate is connected to the power module.

[0019] As a result, it is possible to reduce and level the inductance while facilitating the connection between the smoothing capacitor and the power module.

[0020] The fifth invention is An inverter structure according to any one of the first to fourth inventions, The outer surface of at least one of the one end bus plate and the other end bus plate is arranged to be flush with the outer surface of the power module.

[0021] This makes it possible to more easily reduce the size of the inverter in the axial direction. [Effects of the Invention]

[0022] According to the present disclosure, the inductance of the wiring connected to the smoothing capacitor can be easily made uniform. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of a vehicle system including a drive unit according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of a drive unit including a motor and an inverter. [Figure 3]FIG. 3 is a cross-sectional view of the motor as seen from the inverter side. [Figure 4] FIG. 4 is a circuit diagram of the inverter. [Figure 5] Figure 5 shows a comparison between SiC-MOSFET and IGBT. [Figure 6] FIG. 6 shows a detailed structure of the power module in a perspective view and a circuit diagram. [Figure 7] FIG. 7 is a cross-sectional view of the inverter as seen from the opposite side to the motor. [Figure 8] FIG. 8 is a vertical cross-sectional view of the inverter. [Figure 9] FIG. 9 is a perspective view of the bus bar. [Figure 10] FIG. 10 is a graph showing the relationship between the size of the busbar and the inductance sensitivity. [Figure 11] FIG. 11 is a cross-sectional view of the cooling passage of the inverter as seen from the motor side. [Figure 12] FIG. 12 is a view corresponding to FIG. 11 according to a first modified example of the first embodiment, and is a cross-sectional view of the cooling passage of the inverter as seen from the motor side. [Figure 13] FIG. 13 is a cross-sectional view of the inverter as seen from the opposite side to the motor, corresponding to FIG. 7, according to a second modification of the first embodiment. [Figure 14] FIG. 14 is a view corresponding to FIG. 7 according to the second embodiment, and is a cross-sectional view of the inverter as seen from the opposite side to the motor. [Figure 15] FIG. 15 is a vertical cross-sectional view of an inverter according to the second embodiment, corresponding to FIG. 8. In FIG. [Figure 16] FIG. 16 is a cross-sectional view of the inverter according to the third embodiment, corresponding to FIG. 7, seen from the opposite side to the motor. [Figure 17] FIG. 17 is a diagram corresponding to FIG. 8 according to the third embodiment, and is a vertical cross-sectional view of an inverter. [Figure 18] FIG. 18 is a schematic diagram showing an example of the arrangement of a power module and unit capacitors according to yet another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiment is essentially merely an example and is not intended to limit the present invention, its applications, or its uses. In the following embodiments and modifications, components having the same functions as those in other embodiments will be designated by the same reference numerals and will not be described again.

[0025] First Embodiment (Vehicle configuration) 1 shows a vehicle 1 equipped with a drive unit A according to the first embodiment, as seen from below. The vehicle 1 transmits power from at least one of an engine 2 and a drive motor 3, both located at the front of the vehicle, to rear wheels 4, both located at the rear of the vehicle. In other words, the vehicle 1 is a front-engine, rear-wheel-drive (FR) hybrid vehicle.

[0026] As shown in FIG. 1, the vehicle 1 includes an engine 2, a transmission 5 connected to the engine 2, a drive motor 3 arranged between the engine 2 and the transmission 5, a propeller shaft 6 connected to the transmission 5 and transmitting power from the engine 2 and the drive motor 3 to the rear wheels, and a differential 7 connected to the propeller shaft 6 and transmitting power from the engine 2 and the drive motor 3 to the left and right rear wheels 4.

[0027] The propeller shaft 6 extends in the front-to-rear direction of the vehicle below the floor panel 8. A tunnel portion 9 is provided on the center side of the floor panel 8 in the vehicle width direction. The propeller shaft 6 is disposed inside the tunnel portion 9.

[0028] The vehicle 1 is equipped with an exhaust pipe 10 that extends in the longitudinal direction of the vehicle from the engine 2. A catalytic converter 11 is disposed upstream of the exhaust pipe 10. Although not shown, a silencer is disposed downstream of the exhaust pipe 10.

[0029] The vehicle 1 includes a fuel tank (not shown) that stores fuel to be supplied to the engine 2, and a battery 12 that stores power to be supplied to the motor 3. The drive motor 3 transmits power to the rear wheels 4, and is rotated by a propeller shaft 6 when the vehicle decelerates to generate regenerative power, which is then supplied to the battery 12. The battery 12 is composed of a first battery unit 12a and a second battery unit 12b, which are arranged on both sides in the vehicle width direction. The second battery unit 12b is longer in the vehicle front-to-rear direction than the first battery unit 12a. Each of the battery units 12a, 12b is composed of a plurality of battery cells. The battery cells are, for example, lithium-ion batteries.

[0030] An in-wheel motor 14 is connected to each of the left and right front wheels 13. The in-wheel motor 14 functions as an assist motor that generates power and transmits it to the front wheels 13 when the vehicle 1 starts moving. The in-wheel motor 14 also functions as a regenerative brake that generates power when the vehicle decelerates. Like the drive motor 3, the in-wheel motor 14 is supplied with power from the battery 12.

[0031] As shown in FIG. 1 , an inverter 15 is interposed between the drive motor 3 and the transmission 5. The drive motor 3 and the inverter 15 are arranged adjacent to each other in the axial direction of the drive motor 3 (vehicle front-rear direction). An inverter 16 is arranged inside the in-wheel motor 14 in the vehicle width direction. The in-wheel motor 14 and the inverter 16 are arranged adjacent to each other in the axial direction of the in-wheel motor 14 (vehicle width direction). The drive motor 3 and the inverter 15 constitute a drive unit A. Similarly, the in-wheel motor 14 and the inverter 16 constitute a drive unit A.

[0032] Inverters 15, 16 convert DC power stored in battery 12 into AC power and supply it to motors 3, 14, and also convert AC power generated by motors 3, 14 during vehicle deceleration into DC power to charge the battery.

[0033] (Drive unit) The drive unit A of the vehicle 1 will be described using the drive motor 3 and the inverter 15 as examples. FIG. 2 is a perspective view of the drive unit A. As described above, the drive unit A is composed of the motor 3 and the inverter 15. The motor 3 and the inverter 15 are arranged coaxially and adjacent to each other in the axial direction of the motor 3. Specifically, the central axis O of the motor 3 and the central axis O of the inverter 15 coincide with each other. The motor 3 (specifically, the casing of the motor 3) is formed in a cylindrical shape. The inverter 15 (specifically, the casing of the inverter 15) is formed in a cylindrical shape corresponding to the motor 3. The rotating shaft 3a of the motor 3 passes through the inverter 15 in the axial direction. The thickness Wiv of the inverter 15 is thin, for example, 50 mm or less (preferably 30 mm or less). A cooling passage 61, which will be described later, is provided inside the inverter 15. An inlet pipe 62 and an outlet pipe 63 for cooling, which communicate with the cooling passage 61, are connected to the upper part of the inverter.

[0034] 3 is a cross-sectional view of the motor 3 as viewed from the inverter 15 side. The motor 3 has coils 17. Specifically, U-phase, V-phase, and W-phase coils 17u, 17v, and 17w are respectively wound in a concentrated manner on the stator of the motor 3. The U-phase coils 17u are arranged in two locations facing each other in the radial direction of the motor 3. Similarly, the V-phase coils 17v are arranged in two locations facing each other in the radial direction of the motor 3. Similarly, the W-phase coils 17w are arranged in two locations facing each other in the radial direction of the motor 3.

[0035] Three motor-side terminal blocks 18 are provided on the outer periphery of the motor 3. The three motor-side terminal blocks 18 correspond to the U-phase, V-phase, and W-phase coils 17u, 17v, and 17w. A lead wire (not shown) is drawn out from each of the U-phase coils 17u, which are arranged in two locations. The two lead wires are bundled together and then connected to the motor-side terminal block 18. The same applies to the V-phase coil 17v and the W-phase coil 17w. An iron core 27 and N-pole and S-pole permanent magnets 28 are fixed to the rotating shaft 3a as a rotor.

[0036] 4 is a circuit diagram of the inverter 15. The inverter 15 has a smoothing capacitor 19 and a plurality of power modules 20. The smoothing capacitor 19 smoothes the voltage applied to the power modules 20. The plurality of power modules 20 form an inverter circuit, and converts a DC voltage into an AC voltage.

[0037] The multiple power modules 20 include a U-phase power module 20u, a V-phase power module 20v, and a W-phase power module 20w. The U-phase power module 20u is connected to the U-phase coil 17u of the motor 3. The V-phase power module 20v is connected to the V-phase coil 17v of the motor 3. The W-phase power module 20w is connected to the W-phase coil 17w of the motor 3.

[0038] The power module 20 is composed of two switching elements: a lower arm element 21 and an upper arm element 22. In the power module 20 for each phase, when one of the lower arm element 21 and the upper arm element 22 opens, the other of the lower arm element 21 and the upper arm element 22 closes. This allows a three-phase AC current to be supplied to the motor 3.

[0039] Here, the power module 20 includes a SiC-MOSFET. Figure 5 shows a comparison between the SiC-MOSFET and an IGBT. The SiC-MOSFET is a MOSFET (metal-oxide-semiconductor field-effect transistor) containing silicon carbide (SiC), and constitutes a chip 24 including lower arm elements 21, upper arm elements 22, and other control elements. The lower surface of the chip 24 is fixed to a silicon substrate by soldering. A copper block 25 serving as a heat transfer block is fixed to the upper surface of the chip 24 by soldering. The same applies to an IGBT (Insulated Gate Bipolar Transistor).

[0040] 5, the surface area of ​​chip 24 made of SiC-MOSFET is smaller than the surface area of ​​chip 24' made of IGBT. Accordingly, the size of copper block 25 arranged above SiC-MOSFET (chip) 24 is smaller than the size of copper block 25' arranged above IGBT (chip) 24'. In addition, SiC-MOSFET has better heat resistance than IGBT.

[0041] FIG. 6 shows a perspective view and a circuit diagram of the detailed structure of the power module 20. Each power module 20 has a wide, flat shape. Specifically, each power module 20 is longer in the width direction W than in the thickness direction t. The power module 20 has a substantially rectangular parallelepiped shape. The width direction W includes a first width direction W1 and a second width direction W2 that are perpendicular to each other. Hereinafter, one side in the thickness direction of the power module 20 may be referred to as the lower side, and the other side in the thickness direction may be referred to as the upper side.

[0042] The power module 20 has a lower surface 31 as a first surface to be cooled on its lower side (one side, one side in the thickness direction). The power module 20 has an upper surface 32 on its upper side. The power module 20 has a first end surface 33 on one side in the first width direction W1. The power module 20 has a second end surface 34 on the other side in the first width direction W1.

[0043] A negative input terminal 35 is connected to a lower side of the first end surface 33 and one side in the second width direction W2. A positive input terminal 36 is connected to an upper side of the first end surface 33 and the other side in the second width direction W2. The negative input terminal 35 and the positive input terminal 36 are arranged with a gap between them in the up-down direction (thickness direction). An output terminal 37 is connected to the center of the second end surface 34.

[0044] A lower arm element 21 and an upper arm element 22 are housed within a package (box) of the power module 20. A negative input terminal 35 is connected to the lower arm element 21. A positive input terminal 36 is connected to the upper arm element 22. An output terminal 37 is connected between the lower arm element 21 and the upper arm element 22.

[0045] FIG. 7 is a horizontal cross-sectional view of the inverter 15 seen from the opposite side to the motor 3. FIG. 8 is a vertical cross-sectional view of the inverter 15 taken along line VIII-VIII. As shown in FIG. 7, a shaft through-hole 40 is provided in the center of the inverter 15, through which the rotating shaft 3a of the motor 3 passes. A cylindrical boss portion 41 is formed around the shaft through-hole 40. The smoothing capacitor 19 is arranged along the boss portion 41.

[0046] Each power module 20 (U-phase power module 20u, V-phase power module 20v, and W-phase power module 20w) is disposed on the outer periphery of smoothing capacitor 19. The power modules 20 are disposed side by side in the circumferential direction of motor 3, on the outer periphery of smoothing capacitor 19. That is, for example, they are disposed at positions (on an arc) equidistant from the center of rotating shaft 3a of motor 3. Furthermore, each power module 20 is disposed at positions equidistant from smoothing capacitor 19 (positions radial to smoothing capacitor 19). More specifically, for example, if the distance between negative electrode side input terminal 35 (or positive electrode side input terminal 36) of U-phase power module 20u and the outer edge of one end side bus plate 19c (or the other end side bus plate 19d) of smoothing capacitor 19 is x, then the same distance x is set equal for V-phase power module 20v and W-phase power module 20w. It is also possible to have the above-mentioned equidistant relationship for only one of the negative input terminal 35 and the positive input terminal 36 .

[0047] The input terminals 35, 36 (first end surface 33) and output terminal 37 (second end surface 34) of each power module 20 face in the circumferential direction of the motor 3 (inverter 15). The power modules 20 are arranged radially from the center O of the inverter 15 (motor 3). The power modules 20 are arranged so that their thickness direction t coincides with the axial direction of the motor 3. The smoothing capacitor 19 and each power module 20 are arranged in a space defined by an outer peripheral wall portion 42 and a boss portion 41 of the inverter 15.

[0048] 7 and 8, a heat sink 60 is provided on the motor 3 side of the inverter 15. The heat sink 60 is mainly used to cool each power module 20. The heat sink 60 is disposed between the outer peripheral wall portion 42 and the boss portion 41 of the inverter 15. The heat sink 60 has an upper wall portion 60a, an outer peripheral wall portion 60b, a lower wall portion 60c, and an inner peripheral wall portion 60d.

[0049] An upper surface 65 of the upper wall portion 60a of the heat sink 60 forms a mounting surface (hereinafter, sometimes referred to as "mounting surface 65") that is perpendicular to the axial direction of the motor 3. A lower surface (first cooled surface) 31 of each power module 20 (U-phase power module 20u, V-phase power module 20v, and W-phase power module 20w) faces the motor 3. In detail, the lower surfaces (first cooled surfaces) 31 of the power modules 20 are placed side by side on the same mounting surface 65.

[0050] 7 and 8, smoothing capacitor 19 is an assembly of multiple cylindrical unit capacitors 45, each having electrodes T at both ends (one end 19a and the other end 19b). The axial directions of these unit capacitors 45 are parallel to each other, i.e., parallel to the rotation shaft 3a of motor 3, and the assembly is aligned along a plane perpendicular to the axial direction. The assembly is connected from both axial sides by sandwiching the assembly between one-end bus plate 19c and the other-end bus plate 19d, each of which has a circular outer shape. One-end bus plate 19c on the lower side of smoothing capacitor 19 functions as a third cooled surface and faces motor 3. Specifically, one-end bus plate 19c of smoothing capacitor 19 is placed on mounting surface 65.

[0051] The shape of electrodes T at one end 19a and the other end 19b of unit capacitor 45 is not particularly limited, and various types are applicable, such as lead wire-like, strip-like, or plate-like electrodes. Furthermore, the method of connecting the electrodes to one end bus plate 19c and the other end bus plate 19d is also not particularly limited, and various methods are applicable, such as welding, soldering, or mechanical crimping.

[0052] The plurality of unit capacitors 45 are arranged, for example, at equidistant positions from the center of the rotating shaft 3a of the motor 3. The arrangement patterns of the power modules 20 and at least the unit capacitors 45 nearest to each power module 20 are set equal to each other. And / or, the distances between each power module 20 and at least the unit capacitor 45 nearest to each power module 20 are set equal to each other. More specifically, for example, if the distance between the negative input terminal 35 (or positive input terminal 36) of the U-phase power module 20u and the electrode T of the nearest unit capacitor 451 is y, then the distances y between the V-phase power module 20v and the W-phase power module 20w and the electrodes of the nearest unit capacitors are set equal to each other. The above-described equidistant relationship may be established for only one of the negative input terminal 35 and the positive input terminal 36.

[0053] This makes it easy to reduce the inductance of the connection wiring between the smoothing capacitor 19 and each power module 20 and / or equalize the inductance by making the lengths equal.

[0054] 7 and 8, the power modules 20 are arranged side by side in a direction along a plane perpendicular to the axial direction relative to the smoothing capacitor 19, and the smoothing capacitor 19 and the power modules 20 are connected to each other by a negative bus bar 51 and a positive bus bar 52 serving as input bus bars 50 (hereinafter sometimes simply referred to as "bus bars 50"). The negative bus bar 51 and the positive bus bar 52 are plate-shaped. Specifically, the negative bus bar 51 and the positive bus bar 52 are longer in the width direction W and the length direction L than in the thickness direction t.

[0055] As shown in FIG. 7 , the negative bus bar 51 and the positive bus bar 52 are configured to be wide so as to extend along the circumferential direction of the motor 3 (inverter 15). In other words, the negative bus bar 51 and the positive bus bar 52 are configured to be wide so as to extend along the direction in which the power modules 20 are arranged. The width direction W of the negative bus bar 51 and the positive bus bar 52 extends in the circumferential direction of the motor 3 (in an arc shape). The negative bus bar 51 and the positive bus bar 52 are fan-shaped. The length direction L of the negative bus bar 51 and the positive bus bar 52 extends in the radial direction of the motor 3.

[0056] One end 51i of the negative bus bar 51 is connected to the outer edge of the one end bus plate 19c provided on the underside of the smoothing capacitor 19. The other end 51o of the negative bus bar 51 is connected to the negative input terminal 35 of each power module 20. One end 52i of the positive bus bar 52 is connected to the outer edge of the other end bus plate 19d provided on the upper side of the smoothing capacitor 19. The other end 52o of the positive bus bar 52 is connected to the positive input terminal 36 of each power module 20. Note that the outer edge of at least one of the one end bus plate 19c and the other end bus plate 19d may be directly connected to the negative input terminal 35 or the positive input terminal 36 of the power module 20.

[0057] The negative bus bar 51 may have a lower surface 51a as a second surface to be cooled on its lower side (one side, one side in the thickness direction). The lower surface (second surface to be cooled) 51a of the negative bus bar 51 faces the motor 3. In detail, the lower surface (second surface to be cooled) 51a of the negative bus bar 51 may be placed on the placement surface 65.

[0058] As shown in Fig. 7, an output bus bar 54 is connected to the output terminal 37 of each power module 20. There are three output bus bars 54 in total, corresponding to the U phase, V phase, and W phase. The output bus bars 54 are interposed between each power module 20 and each coil 17. The output bus bars 54 are plate-shaped. In addition to the output bus bars 54, a wire harness or the like may be interposed between each power module 20 and each coil 17.

[0059] Three inverter-side terminal blocks 46 are provided on the outer periphery of the inverter 15. Each inverter-side terminal block 46 corresponds to a corresponding power module 20. The output bus bar 54 extends to the inverter-side terminal block 46. An electrically conductive member (such as a bus bar or a wire harness) is interposed between the inverter-side terminal block 46 and the motor-side terminal block 18.

[0060] (busbar inductance sensitivity) Fig. 9 is a perspective view of the bus bar 50. Fig. 10 is a graph showing the relationship between the size and inductance sensitivity of the bus bar 50. As a result of extensive research, the inventors of the present application have made the following discovery regarding the relationship between the size and inductance sensitivity of the bus bar 50.

[0061] As shown in FIGS. 9 and 10, the larger the width dimension W (mm) of the bus bar 50, the smaller the inductance sensitivity (nH) of the bus bar 50.

[0062] Basically, the longer the length dimension L (mm) of the busbar 50, the greater the inductance sensitivity (nH) of the busbar 50. However, as shown in the middle graph of FIG. 10 , there is a minimum value M in the relationship between the length dimension L (mm) and the inductance sensitivity (nH) of the busbar 50. As a result, the inductance sensitivity (nH) may be the same even when the length dimension L is different. Specifically, the inductance sensitivity (nH) of the busbar 50 (51, 52) is a function of the length dimension L (mm) from one end 51i, 52i (the bus plate 19c on one end side of the smoothing capacitor 19 or the bus plate 19d on the other end side) of the busbar 50 (51, 52) to the other end 51o, 52o (the input terminals 35, 36 of each power module 20). This function has a minimum value M so that the inductance sensitivity K (nH) is the same for different first and second lengths L1 (mm) and L2 (mm). The second length L2 (mm) is longer than the first length L1 (mm).

[0063] Furthermore, even if the thickness dimension t (mm) of the busbar 50 changes, the inductance sensitivity (nH) of the busbar 50 changes very little.

[0064] As shown in Fig. 7, the width of the negative busbar 51 and the width of the positive busbar 52 are substantially the same. As shown in Fig. 8, the length L- of the negative busbar 51 and the length L+ of the positive busbar 52 are different from each other. The length L- of the negative busbar 51 corresponds to the first length L1. The length L+ of the positive busbar 52 corresponds to the second length L2. The length L+ (second length L2) of the positive busbar 52 is longer than the length L- (first length L1) of the negative busbar 51. However, due to the presence of the minimum value M, the inductance of the negative busbar 51 and the inductance of the positive busbar 52 are equal to each other.

[0065] (cooling passage) FIG. 11 is a cross-sectional view of the cooling passage 61 of the inverter 15 as seen from the motor 3 side. As shown in FIGS. 8 and 11, the cooling passage (cooling jacket) 61 is provided inside the heat sink 60 as a cooling section. The cooling passage 61 is defined by an upper wall portion 60a, an outer peripheral wall portion 60b, a lower wall portion 60c, and an inner peripheral wall portion 60d. The cooling passage 61 is formed in a donut shape (annular, cylindrical) around the entire circumference when viewed in the axial direction of the motor 3 (inverter 15). The rotating shaft 3a of the motor 3 passes through the inside of the inner peripheral wall portion 60d. As described above, the upper surface of the upper wall portion 60a of the heat sink 60 is the mounting surface 65.

[0066] The cooling passage 61 is provided closer to the motor 3 than the mounting surface 65. A cooling medium H flows through the cooling passage 61. The cooling medium H is cooling water, cooling oil, or the like.

[0067] Furthermore, a plurality of fins 64 serving as a cooling section are provided inside the heat sink 60 (cooling passage 61). The fins 64 extend downward from the upper wall portion 60a inside the cooling passage 61. That is, the fins 64 are provided closer to the motor 3 than the mounting surface 65.

[0068] As shown in Figures 8 and 11, the cooling passage (cooling section) 61, when viewed in the axial direction of the motor 3 (inverter 15), faces the lower surface (first cooled surface) 31 of each power module 20 and all of the lower end side bus plate (third cooled surface) 19c of the smoothing capacitor 19.

[0069] Similarly, the fins (cooling section) 64, when viewed in the axial direction of the motor 3, face the lower surface (first cooled surface) 31 of each power module 20 and the entire lower end side bus plate (third cooled surface) 19c of the smoothing capacitor 19.

[0070] 11 , an inlet pipe 62 and an outlet pipe 63 are connected to an upper portion of the outer peripheral wall portion 42 of the inverter 15. The inlet pipe 62 and the outlet pipe 63 are in communication with a cooling passage 61. The cooling medium H introduced into the cooling passage 61 via the inlet pipe 62 is guided by the outer peripheral wall portion 42 and the boss portion 41, flows circumferentially within the cooling passage 61, and is then discharged to the outside via the outlet pipe 63. A guide plate 66 may be provided downstream of the inlet pipe 62.

[0071] (Effect of the first embodiment: Reduction and leveling of inductance) According to this embodiment, by increasing the width of each of the bus bars 51 and 52, the inductance of each of the bus bars 51 and 52 can be reduced.

[0072] Since the smoothing capacitor 19 and each of the power modules 20u, 20v, and 20w are mounted on the same mounting surface 65, the distance between each of the bus bars 51 and 52 connecting the smoothing capacitor 19 and each of the power modules 20u, 20v, and 20w is shortened, thereby reducing the inductance of each of the bus bars 51 and 52.

[0073] Since the motor 3 and the inverter 15 are disposed adjacent to each other in the axial direction, the length of the electrical path between each of the power modules 20u, 20v, 20w and each of the coils 17u, 17v, 17w is shortened, thereby reducing the inductance of the electrical path (including the output bus bar 54) connecting each of the power modules 20u, 20v, 20w and each of the coils 17u, 17v, 17w.

[0074] Since the power modules 20u, 20v, and 20w are lined up in the circumferential direction of the motor 3 on the outer side of the smoothing capacitor 19, the distance between the smoothing capacitor 19 and each of the power modules 20u, 20v, and 20w can be made equal to one another. Furthermore, by widening the width of each of the bus bars 51 and 52 so that the width is aligned with the circumferential direction of the motor 3, the inductance of the electrical path between the smoothing capacitor 19 and each of the power modules 20u, 20v, and 20w in each of the bus bars 51 and 52 can be leveled.

[0075] By utilizing the above-mentioned minimum value M (see FIG. 10), the inductance of the negative side busbar 51 and the inductance of the positive side busbar 52 can be equalized to each other, even though the length dimension L- (first length L1) of the negative side busbar 51 and the length dimension L+ (second length L2) of the positive side busbar 52 are different from each other.

[0076] In particular, by setting the arrangement pattern of each power module 20 and the nearby unit capacitors 45 to be equal to each other, and by setting the distance (wiring connection distance between the electrodes and terminals) between each power module 20 and at least the unit capacitor 45 closest to each power module 20 to be equal to each other, it is possible to more easily reduce the inductance of the connecting wiring between the smoothing capacitor 19 and each power module 20, and / or level out the inductance by making the wiring lengths equal.

[0077] (Effects of the first embodiment: improved cooling performance, etc.) Furthermore, the large-area lower surface (first cooled surface) 31 of the wide, flat power module 20 faces the cooling passage 61 and fins 64 as cooling sections, so the cooling area of ​​the power module 20 by the cooling sections 61, 64 can be increased. As a result, even if only one surface (lower surface, first cooled surface) 31 of the power module 20 is cooled by the cooling sections 61, 64, sufficient cooling capacity can be ensured.

[0078] The lower surfaces (first cooled surfaces) 31 of the power modules 20 (U-phase power module 20u, V-phase power module 20v, and W-phase power module 20w) are mounted side by side on the same mounting surface 65 perpendicular to the axial direction of the motor 3, which allows the axial length of the inverter 15 to be shortened. Furthermore, since the cooling units 61, 64 only need to be provided on one surface (lower surface, first cooled surface) 31 of the power modules 20, the inverter 15 can be made smaller than when the cooling units 61, 64 are provided on both surfaces of the power modules 20.

[0079] As described above, the drive unit A composed of the motor 3 and the inverter 15 can be made smaller while the power module 20 is cooled sufficiently.

[0080] By flowing the cooling medium H through the cooling passage 61 as the cooling section, the cooling capacity of the power module 20 by the cooling section can be increased.

[0081] Since the size of the SiC-MOSFET chip 24 included in the power module 20 is small, the size of the copper block 25 as a heat transfer block placed on the SiC-MOSFET chip 24 is also small (see FIG. 5 ). For this reason, to effectively cool the power module 20 on both sides, it is necessary to place expensive ceramic substrates (e.g., SiN) on both sides of the SiC-MOSFET chip 24. Therefore, it is more cost-effective to cool the power module 20 on one side and improve the effect of the one-sided cooling than to cool the power module 20 on both sides.

[0082] The smoothing capacitor 19 as well as each power module 20 can be cooled by the cooling units 61 and 64.

[0083] The width of the negative bus bar 51 can be easily increased by arranging the power modules 20 side by side in the circumferential direction of the motor 3 on the outer peripheral side of the smoothing capacitor 19 and extending the width direction W of the negative bus bar 51 in the circumferential direction of the motor 3. This makes it possible to easily increase the heat dissipation area from the negative bus bar 51 to the cooling units 61, 64.

[0084] Since the cooling units 61, 64 are provided on the motor 3 side, this is also advantageous for cooling the wiring (for example, the output bus bar 54) connecting the motor 3 and each power module 20.

[0085] As shown by the two-dot chain line in Fig. 1, conventionally, inverter 15' has often been disposed near second battery unit 12b' of battery 12'. According to this embodiment, inverter 15 can be disposed adjacent to motor 3 in the axial direction, so it is no longer necessary to dispose inverter 15 near second battery unit 12b. This increases the degree of freedom in the layout of second battery unit 12b, allowing second battery unit 12b to be larger.

[0086] (First Modification of the First Embodiment) Fig. 12 is a view corresponding to Fig. 11 according to a first modified example of the first embodiment. According to this modified example, the cooling section (cooling passage 61 and fins 64) does not face at all one end side bus plate (third cooled surface) 19c on the lower side of the smoothing capacitor 19.

[0087] Since the amount of heat generated by the smoothing capacitor 19 is small compared to the amount of heat generated by the power module 20, there may be no problem even if the smoothing capacitor 19 is not cooled by the cooling units 61 and 64.

[0088] (Second Modification of the First Embodiment) FIG. 13 is a view corresponding to FIG. 7 relating to a second modified example of the first embodiment. The inverter 16 according to this modified example is arranged adjacent to the in-wheel motor 14 in the axial direction (vehicle width direction) of the in-wheel motor 14 (see FIG. 1). The inverter 16 does not have a shaft through-hole 40 or a boss portion 41. The smoothing capacitor 19 also has a unit capacitor 45 arranged near the center. The heat sink 60 does not have an inner circumferential wall portion 60d. The cooling passage 61 is circular and has no holes when viewed in the axial direction of the motor 3.

[0089] (Other Modifications of the First Embodiment) The cooling medium H flowing through the cooling passages 61 may be, for example, air. Furthermore, the cooling portion may not include the cooling passages 61 and may be composed of, for example, only the fins 64. The cooling portion may also be a solid cooling member.

[0090] The cooling section does not need to be provided over the entire circumference, but may be provided only in a portion facing each power module 20 in the circumferential direction.

[0091] Instead of the negative bus bar 51, the positive bus bar 52 may have a second cooled surface on one side (one side in the thickness direction) that faces the motor 3 and is placed on the placement surface 65.

[0092] Although not shown, each output bus bar 54 may be configured to be wide so as to extend along the circumferential direction of the motor 3. In other words, the width direction of the output bus bar 54 may extend in the circumferential direction (in an arc shape). The output bus bar 54 may also be fan-shaped. This makes it easier to make the output bus bar 54 wide, which makes it easier to reduce the inductance of the output bus bar 54 (see FIG. 10).

[0093] The mounting surface 65 may be configured with a plurality of surfaces positioned on the same plane perpendicular to the axial direction of the motor 3 .

[0094] <Second embodiment> Fig. 14 is a diagram corresponding to Fig. 7 according to the second embodiment, and is a horizontal cross-sectional view of the inverter 15 as seen from the opposite side to the motor 3. Fig. 15 is a diagram corresponding to Fig. 8 according to the second embodiment, and is a vertical cross-sectional view of the inverter 15. Hereinafter, detailed description of the same configuration as in the above embodiments may be omitted.

[0095] In this embodiment, the power modules 20 (U-phase power module 20u, V-phase power module 20v, and W-phase power module 20w) are arranged on the outer circumferential side of the smoothing capacitor 19. The power modules 20 are arranged side by side in the circumferential direction of the motor 3 on the outer circumferential side of the smoothing capacitor 19.

[0096] The input terminals 35, 36 (first end face 33) and output terminal 37 (second end face 34) of each power module 20 face in the radial direction of the motor 3 (inverter 15). Specifically, the input terminals 35, 36 (first end face 33) of each power module 20 face the inner circumferential side. The output terminal 37 (second end face 34) of each power module 20 faces the outer circumferential side. The power modules 20 are arranged radially, starting from the center O of the inverter 15 (motor 3).

[0097] As in the above embodiment, the lower surface (first cooled surface) 31 of each power module 20 and the lower end bus plate (third cooled surface) 19c of the smoothing capacitor 19 are placed on the placement surface 65.

[0098] As shown in Fig. 14, the width dimension of the negative bus bar 51 is the same as the width dimension of the positive bus bar 52. As shown in Fig. 15, the length dimension L- of the negative bus bar 51 is the same as the length dimension L+ of the positive bus bar 52. Therefore, the inductance of the negative bus bar 51 is the same as the inductance of the positive bus bar 52.

[0099] The other configurations are the same as those in the first embodiment.

[0100] <Third embodiment> Fig. 16 is a diagram corresponding to Fig. 7 according to the third embodiment, and is a horizontal cross-sectional view of the inverter 15 as seen from the opposite side to the motor 3. Fig. 17 is a diagram corresponding to Fig. 8 according to the third embodiment, and is a vertical cross-sectional view of the inverter 15. Hereinafter, detailed description of the same configuration as in the above embodiments may be omitted.

[0101] 16 and 17 , the negative input terminal 35 is connected to the lower side of the first end face 33 of each power module 20. The positive input terminal 36 is connected to the lower side of the second end face 34 of each power module 20. The output terminal 37 is connected to the center of the upper face 32 of each power module 20.

[0102] The negative bus bar 51 connects one end bus plate 19c of the smoothing capacitor 19 to the negative input terminal 35 of each power module. The positive bus bar 52 connects the other end bus plate 19d of the smoothing capacitor 19 to the positive input terminal 36 of each power module 20.

[0103] The positive bus bar 52 starts from the other-end bus plate 19d (one end 52i) of the smoothing capacitor 19 and extends along the top surface 32 from the first end surface 33 to the second end surface 34 of each power module 20. The positive bus bar 52 then bends downward and extends along the second end surface 34 to the lower positive input terminal 36 (the other end 52o). In other words, the positive bus bar 52 extends while wrapping around each power module 20 from the top surface 32. Each output bus bar 54 starts from the output terminal 37 on the top surface 32 of each power module 20 and extends upward. The positive bus bar 52 has three openings through which the three output bus bars 54 extending upward can pass.

[0104] As in the above embodiment, the lower surface (first cooled surface) 31 of each power module 20 and the lower end bus plate (third cooled surface) 19c of the smoothing capacitor 19 are placed on the placement surface 65.

[0105] As shown in FIG. 16, the width of the negative busbar 51 and the width of the positive busbar 52 are the same. As shown in FIG. 17, the length (L-) of the negative busbar 51 and the length (the sum of La+ and Lb+) of the positive busbar 52 are different. The length (L-) of the negative busbar 51 corresponds to the first length L1. The length (the sum of La+ and Lb+) of the positive busbar 52 corresponds to the second length L2. The length (the sum of La+ and Lb+, the second length L2) of the positive busbar 52 is longer than the length (L-, the first length L1) of the negative busbar 51. However, due to the presence of the minimum value M (see FIG. 10), the inductance sensitivity of the negative busbar 51 and the inductance of the positive busbar 52 are equal to each other.

[0106] The conditions (materials, etc.) of the negative bus bar 51 and the positive bus bar 52 according to this embodiment are different from those of the above embodiment. Therefore, the aspect of the minimum value M (see FIG. 10) is also different. Specifically, the distance (difference) between the first length L1 and the second length L2 is larger than in the above embodiment.

[0107] The other configurations are the same as those in the second embodiment.

[0108] <Other embodiments> In the above embodiments, examples have been shown in which three power modules 20 are arranged close to each other on the circumference, but this is not limiting, and for example, they may be arranged so as to form a central angle of 120° with the unit capacitors 45 also arranged in a corresponding rotationally symmetric pattern as shown in Fig. 18. Such an arrangement makes it easier to further equalize the inductance.

[0109] Although the present disclosure has been described above with reference to preferred embodiments, such description is not limiting and various modifications are possible. [Explanation of symbols]

[0110] 1 vehicle 2 engines 3 Drive motor 12 Battery 14 In-wheel motor 15 Inverter 17u, 17v, 17w coil 18 Motor side terminal block 19 Smoothing capacitor 19a one end 19b other end 19c One end bus plate 19d Other end bus plate 20 Power Module 20u, 20v, 20w power module 24 SiC-MOSFET chips 31 Bottom side 32 Top side 33 First end surface 34 Second end face 35 Negative input terminal 36 Positive input terminal 37 Output terminal 45 unit capacitor 50 Input bus bar 51 Negative bus bar 51a Bottom side 51i,52i One end 51o, 52o other end 52 Positive bus bar 54 Output bus bar 65 Placement surface (top)

Claims

1. An inverter structure of an inverter having a smoothing capacitor and a plurality of power modules, the smoothing capacitor comprises a plurality of columnar unit capacitors each having an electrode on both ends, a one-end bus plate which is flat over the entire area and connected to the electrode at one end of each unit capacitor, and a plate-like other-end bus plate which is connected to the electrode at the other end, the plurality of unit capacitors being arranged so that their axial directions are parallel to each other and so that they are aligned in a direction along a plane perpendicular to the axial direction, The plurality of unit capacitors are arranged at positions equidistant from a predetermined center, and An inverter structure characterized in that the distances between each power module and at least the unit capacitors closest to each power module are set equal to each other.

2. 2. The inverter structure of claim 1, The inverter structure is characterized in that the one end side bus plate and the other end side bus plate have flat plate-like outer shapes.

3. The inverter structure according to any one of claims 1 and 2, The inverter structure further comprises a flat input bus bar connecting outer edges of the one end bus plate and the other end bus plate to the power module.

4. The inverter structure according to any one of claims 1 and 2, An inverter structure, wherein an outer edge of at least one of the one end bus plate and the other end bus plate is connected to the power module.

5. The inverter structure according to any one of claims 1 to 4, an outer surface of at least one of the one end bus plate and the other end bus plate and an outer surface of the power module are arranged to be located on the same plane.

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