Electric drive device and electric power steering device

Abstract

An electric drive device and an electric power steering device are provided that reduce noise superimposed on a detection value detected by a current detection element in a path from the current detection element to a control circuit. The electric drive device includes a motor and an electronic control device having a circuit board. A position on an axial extension line of a shaft is used as a reference position. From the reference position toward one side in the first direction, a mounting area for a first motor drive circuit, a mounting area for a first current detection element, a mounting area for a plurality of drive elements of a first inverter circuit, and a configuration area for a first coil wiring are sequentially arranged. From the reference position toward the other side in the first direction, a mounting area for a second motor drive circuit, a mounting area for a second current detection element, a mounting area for a plurality of drive elements of a second inverter circuit, and a configuration area for a second coil wiring are sequentially arranged.

Description

Technical Field

[0001] The present disclosure relates to an electric drive device and an electric power steering device including an electronic control device for controlling the rotation of a motor. Background Art

[0002] An electric power steering system that generates assist steering torque using a motor includes an electronic control unit that controls the motor (see Patent Documents 1 and 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-036244

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-188656 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The electric drive devices disclosed in Patent Documents 1 and 2 include a shunt resistor for detecting the current flowing through the motor coil. The detection value detected by the shunt resistor is amplified by a signal amplifier circuit.

[0009] The control circuit performs feedback control of the current supplied to the motor coil based on the detection value detected by the shunt resistor. Therefore, it is desirable to reduce the noise superimposed on the detection value detected by the shunt resistor in the path from the shunt resistor to the control circuit.

[0010] The present disclosure has been made in view of the above-mentioned problems, and an object thereof is to provide an electric drive device and an electric power steering device that reduce noise superimposed on a detection value detected by a current detection element in a path from the current detection element to a control circuit.

[0011] Solutions for solving problems

[0012] To achieve the above-mentioned object, an electric drive device of a technical solution comprises: an electric motor including a shaft extending axially from a load side to an opposite-load side, a motor rotor linked to the shaft, a motor stator including a stator core and a plurality of coil groups, and a cylindrical housing accommodating the motor rotor, the motor stator and the plurality of coil groups therein, the stator core rotating the motor rotor, the plurality of coil groups being divided into at least two systems of coil groups, a first coil group and a second coil group, for each of three phases, and the stator core being excited by a three-phase alternating current; a magnet provided at an end portion of the shaft on the opposite-load side for driving and controlling the electric motor; and an electronic control The device is located on the opposite side of the load of the shaft, including a circuit board arranged on the extension line of the axial direction of the shaft; a heat sink arranged between the circuit board and the electric motor; and a connector having terminals connected to the circuit board, the circuit board having: a configuration area for a detection circuit, the detection circuit including a magnetic sensor for detecting the rotation of the magnet, the magnetic sensor being located on the extension line of the axial direction of the magnet and mounted on the circuit board; a mounting area for multiple drive elements of a first inverter circuit, the first inverter circuit supplying current to the first coil group; a mounting area for multiple drive elements of a second inverter circuit, the second inverter circuit a mounting area for a first current detecting element, the first current detecting element detecting the current flowing in the first inverter circuit; a mounting area for a second current detecting element, the second current detecting element detecting the current flowing in the second inverter circuit; a mounting area for a first motor driving circuit, the first motor driving circuit having a first current detecting circuit for amplifying the detection value detected by the first current detecting element, and a first gate driving circuit for driving a plurality of driving elements of the first inverter circuit; a mounting area for a second motor driving circuit, the second motor driving circuit having a first current detecting circuit for amplifying the detection value detected by the second current detecting element a second current detection circuit for amplifying a detection value detected by the first current detection element by the first current detection circuit, and a second gate drive circuit for driving a plurality of drive elements of the second inverter circuit; a mounting area for a control circuit, the control circuit controlling the first gate drive circuit based on a current value obtained by amplifying the detection value detected by the first current detection element by the first current detection circuit, and controlling the second gate drive circuit based on a current value obtained by amplifying the detection value detected by the second current detection element by the second current detection circuit; a configuration area for first coil wiring, wherein each of the first coil wirings of the first coil group is connected to the substrate body of the circuit board;and a second coil wiring arrangement area, wherein each second coil wiring of the second coil group is connected to the substrate body of the circuit board. With a position on an extension line of the axial direction of the shaft as a reference position, the first motor drive circuit mounting area, the first current detection element mounting area, the first inverter circuit mounting area, and the first coil wiring arrangement area are sequentially arranged from the reference position toward one side in the first direction. The second motor drive circuit mounting area, the second current detection element mounting area, the second inverter circuit mounting area, and the second coil wiring arrangement area are sequentially arranged from the reference position toward the other side in the first direction. In a second direction intersecting the first direction, the control circuit mounting area and the connector terminals sandwich the reference position.

[0013] The mounting area of the first motor drive circuit is adjacent to the mounting area of the first current detection element. Furthermore, the mounting area of the second motor drive circuit is adjacent to the mounting area of the second current detection element. As a result, the wiring between the first motor drive circuit and the first current detection element is shortened, thereby reducing the noise of signal amplification within the first motor drive circuit. Furthermore, the wiring between the second motor drive circuit and the second current detection element is shortened, thereby reducing the noise of signal amplification within the second motor drive circuit. In this way, the electric drive device can reduce the noise superimposed on the detection value detected by the current detection element in the path from the current detection element to the control circuit. As a result, the control circuit drives the electric motor based on a current value with less noise, thereby suppressing torque fluctuations generated in the motor rotor.

[0014] As a preferred technical solution, the first current detection element detects the current flowing through the driver element of the lower arm of the plurality of driver elements in the first inverter circuit, and the second current detection element detects the current flowing through the driver element of the lower arm of the plurality of driver elements in the second inverter circuit. As a result, the mounting area of the first current detection element and the mounting area of the driver elements of the first inverter circuit are adjacent to each other, thereby shortening the wiring between the first current detection element and the driver elements of the first inverter circuit. The mounting area of the second current detection element and the mounting area of the driver elements of the second inverter circuit are adjacent to each other, thereby shortening the wiring between the second current detection element and the driver elements of the second inverter circuit.

[0015] As a preferred technical solution, the circuit board further includes a power circuit region in which a noise filter circuit and a power supply circuit are arranged. The power circuit region is positioned between the reference position and the connector terminals in the second direction. Thus, the power circuit region can be positioned near the connector terminals, with the wiring distance to the first inverter circuit and the wiring distance to the second inverter circuit being approximately the same.

[0016] As a desirable technical solution, the first motor drive circuit includes a boost circuit that boosts and generates a gate voltage for driving the multiple drive elements of the first inverter circuit, and the second motor drive circuit includes a boost circuit that boosts and generates a gate voltage for driving the multiple drive elements of the second inverter circuit. Compared to Patent Documents 1 and 2, this reduces the wiring distance between the first motor drive circuit and the multiple drive elements of the first inverter circuit, and reduces the wiring distance between the second motor drive circuit and the multiple drive elements of the second inverter circuit. As a result, the influence of wiring resistance on the time constant of the gate voltage signal waveform is reduced, making it possible to drive the first and second inverter circuits even when the gate voltage generated by the boost circuit is suppressed. Furthermore, the drive elements of the first and second inverter circuits can operate at high speed and stability.

[0017] As a preferred technical solution, the plurality of first coil wirings are arranged along the second direction, and the plurality of second coil wirings are arranged in the second direction in a reverse order to the phase arrangement of the plurality of first coil wirings. Thus, the power supply system supplied from the connector to the two coil groups is the same for each coil group.

[0018] As a desired technical solution, the substrate body of the circuit board is a double-sided mounting substrate, the multiple driving elements of the first inverter circuit and the multiple driving elements of the second inverter circuit are mounted on the first surface of the substrate body of the circuit board opposite to the heat sink, and the first motor drive circuit and the second motor drive circuit are mounted on the second surface of the substrate body of the circuit board, which is located on the side opposite to the first surface. The first motor drive circuit and the multiple driving elements of the first inverter circuit are electrically connected via the internal conductive layer of the circuit board. The second motor drive circuit and the multiple driving elements of the second inverter circuit are electrically connected via the internal conductive layer of the circuit board. Thus, the circuit board can be reduced in size. In addition, the heat generated by the multiple driving elements of the first inverter circuit and the multiple driving elements of the second inverter circuit is dissipated by the heat sink, thereby improving the reliability of the electric drive device.

[0019] As a desirable technical solution, an electric power steering system includes an electric drive device that generates an assist steering torque, thereby suppressing torque fluctuations of the electric motor and improving the operability of the electric power steering system.

[0020] Effects of the Invention

[0021] According to the present disclosure, it is possible to provide an electric drive device and an electric power steering device that reduce noise superimposed on a detection value detected by a current detection element in a path from the current detection element to a control circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a perspective view schematically showing a vehicle equipped with the electric power steering device according to the first embodiment.

[0023] Figure 2 This is a schematic diagram of the electric power steering system according to the first embodiment.

[0024] Figure 3 This is a cross-sectional view schematically showing a cross section of the motor according to the first embodiment.

[0025] Figure 4 This is a schematic diagram showing wiring of the motor according to the first embodiment.

[0026] Figure 5 This is a schematic diagram showing the relationship between the motor and the ECU in the first embodiment.

[0027] Figure 6 This is a side view of the electric drive device according to the first embodiment.

[0028] Figure 7 It is a plan view of the electric drive device according to the first embodiment.

[0029] Figure 8 Yes Figure 6 A sectional view of the cross section taken along the line VIII-VIII.

[0030] Figure 9 Yes Figure 7 A sectional view of the cross section taken along line IX-IX.

[0031] Figure 10 Yes Figure 7 A cross-sectional view of the section viewed in the direction XX.

[0032] Figure 11 Yes Figure 6 A cross-sectional view of the cross section viewed along the XI-XI line.

[0033] Figure 12 This is a perspective view illustrating the electric drive device according to the first embodiment with the cover and the circuit board removed.

[0034] Figure 13 yes Figure 12 Top view of .

[0035] Figure 14 This is a plan view showing a mounted state of electronic components on the first surface of the circuit board in the electric drive device according to the first embodiment.

[0036] Figure 15 This is a plan view showing a mounted state of electronic components on the second surface of the circuit board in the electric drive device according to the first embodiment.

[0037] Figure 16 This is a plan view showing the overlapping mounted states of electronic components on the first and second surfaces of the circuit board in the electric drive device according to the first embodiment.

[0038] Figure 17 This is a schematic diagram of an electric power steering device according to a second embodiment.

[0039] Figure 18 This is a schematic diagram of an electric power steering device according to a third embodiment.

[0040] Figure 19 This is a schematic diagram of an electric power steering device according to a fourth embodiment. DETAILED DESCRIPTION

[0041] The technical solutions (embodiments) for implementing the present disclosure are described in detail with reference to the accompanying drawings. The present disclosure is not limited to the contents described in the following embodiments. In addition, the structural elements described below include elements that can be easily thought of by those skilled in the art, and substantially the same elements. Moreover, the structural elements described below can be appropriately combined.

[0042] (Implementation 1)

[0043] Figure 1 It is a perspective view schematically showing a vehicle equipped with the electric power steering device according to the first embodiment. Figure 2 Schematic diagram of the electric power steering device of embodiment 1. Figure 1 As shown in FIG, a vehicle 101 is equipped with an electric power steering device 100. Figure 2 An overview of the electric power steering system 100 will be described.

[0044] The electric power steering system 100 includes a steering wheel 191, a steering shaft 192, a universal joint 196, an intermediate shaft 197, a universal joint 198, a first rack and pinion mechanism 199, and a tie rod 172, in the order in which the force applied by the driver (operator) is transmitted. Furthermore, the electric power steering system 100 includes a torque sensor 194 that detects the steering torque of the steering shaft 192, an electric motor 30, an electronic control unit (hereinafter referred to as the ECU (Electronic Control Unit)) 10 that controls the electric motor 30, and a reduction gear 175. The vehicle body is equipped with a vehicle speed sensor 182, a power supply unit 183 (e.g., an onboard battery), and an ignition switch 184. The vehicle speed sensor 182 detects the traveling speed of the vehicle 101. The vehicle speed sensor 182 outputs the detected vehicle speed signal SV to the ECU 10 via CAN (Controller Area Network) communication. When the ignition switch 184 is turned on, power is supplied from the power supply unit 183 to the ECU 10.

[0045] like Figure 2 As shown, the steering shaft 192 includes an input shaft 192A and an output shaft 192B. One end of the input shaft 192A is connected to the steering wheel 191, and the other end is connected to the torsion bar. One end of the output shaft 192B is connected to the torsion bar, and the other end is connected to the universal joint 196. Furthermore, a torque sensor 194 detects the steering torque applied to the steering shaft 192 by detecting the torsion of the torsion bar. The torque sensor 194 outputs a steering torque signal T corresponding to the detected steering torque to the ECU 10. The steering shaft 192 rotates in response to the steering force applied to the steering wheel 191.

[0046] Intermediate shaft 197 transmits torque from output shaft 192B. First rack-and-pinion mechanism 199 includes a first pinion shaft 199A, a first pinion 199B, a rack shaft 199C, and a first rack 199D. One end of first pinion shaft 199A is connected to intermediate shaft 197 via a universal joint 198, and the other end is connected to first pinion 199B. First rack 199D, formed on rack shaft 199C, meshes with first pinion 199B.

[0047] As described above, the rotation of the steering shaft 192 is transmitted to the first rack-and-pinion mechanism 199 via the intermediate shaft 197. This rotation is converted into linear motion of the rack shaft 199C by the first rack-and-pinion mechanism 199. The tie rods 172 are connected to both ends of the rack shaft 199C.

[0048] The electric motor 30 is a motor that generates an auxiliary steering torque for assisting the driver in steering. The electric motor 30 may be a brushless motor or a brushed motor having brushes and a commutator.

[0049] The ECU 10 includes a rotational angle sensor 23a. The rotational angle sensor 23a detects the rotational phase of the electric motor 30. The ECU 10 obtains a rotational phase signal from the electric motor 30 from the rotational angle sensor 23a, a steering torque signal T from the torque sensor 194, and a vehicle speed signal SV of the vehicle 101 from the vehicle speed sensor 182. The ECU 10 calculates an assist steering command value for the assist command based on the rotational phase signal, the steering torque signal T, and the vehicle speed signal SV. The ECU 10 supplies current to the electric motor 30 based on the calculated assist steering command value.

[0050] The electric drive device 1 includes an electric motor 30 and an ECU 10 fixed to the opposite-load side of the shaft of the electric motor 30 . The electric drive device 1 may also include an adapter for connecting the ECU 10 and the electric motor 30 .

[0051] The reduction gear 175 includes a worm shaft that rotates integrally with the shaft 31 of the electric motor 30, and a worm wheel that meshes with the worm shaft. Thus, the rotation of the shaft of the electric motor 30 is transmitted to the worm wheel via the worm shaft. In the first embodiment, the end of the motor shaft on the reduction gear 175 side is referred to as the load-side end, and the end of the motor shaft on the side opposite to the reduction gear 175 is referred to as the anti-load-side end.

[0052] The steering force input by the driver to the steering wheel 191 is transmitted to the first rack and pinion mechanism 199 via the steering shaft 192 and the intermediate shaft 197. The first rack and pinion mechanism 199 transmits the transmitted steering force to the rack shaft 199C as a force applied in the axial direction of the rack shaft 199C. At this time, the ECU 10 obtains the steering torque signal T input to the steering shaft 192 from the torque sensor 194. The ECU 10 obtains the vehicle speed signal SV from the vehicle speed sensor 182. The ECU 10 obtains the rotation phase signal of the electric motor 30 from the rotation angle sensor 23a. Then, the ECU 10 outputs a control signal to control the operation of the electric motor 30. The auxiliary steering torque generated by the electric motor 30 is transmitted to the output shaft 192B via the reduction gear 175. In this way, the electric power steering device 100 assists the driver in steering the steering wheel 191.

[0053] like Figure 2 As shown, the electric power steering system 100 is a column assist type that applies assist force to an output shaft 192B of a steering shaft 192 .

[0054] Figure 3 This is a cross-sectional view schematically showing a cross section of the motor according to the first embodiment. Figure 4Schematic diagram showing the wiring of the motor of Embodiment 1. In this Embodiment 1, the circumferential direction refers to the direction along the concentric circle centered on the axis 31. The radial direction refers to the direction away from the axis 31 in a plane orthogonal to the axial direction Ax. Figure 3 As shown, the electric motor 30 includes a housing 930, a motor rotor 932, and a motor stator having a stator core 931. The motor stator includes a cylindrical stator core 931, a plurality of first coils 37, and a plurality of second coils 38. The stator core 931 includes an annular back yoke 931a and a plurality of teeth 931b protruding from the inner circumferential surface of the back yoke 931a. There are 12 teeth 931b arranged in the circumferential direction. The motor rotor 932 includes a rotor yoke 932a and magnets 932b. The magnets 932b are provided on the outer circumferential surface of the rotor yoke 932a. The number of magnets 932b is, for example, eight. The rotation of the motor rotor 932 is linked to the rotation of the shaft 31.

[0055] like Figure 3 As shown, the first coils 37 are concentratedly wound around the plurality of teeth 931b. The first coils 37 are concentratedly wound around the outer periphery of the teeth 931b via an insulator. All the first coils 37 are included in the first coil system. The first coil system of the first embodiment is provided by the first inverter circuit 251A (see FIG. 2 ) included in the first power circuit 25A. Figure 5 ) and is supplied with current and excited. The first coil system includes, for example, six first coils 37. The six first coils 37 are arranged in a manner that two first coils 37 are adjacent to each other in the circumferential direction. The adjacent first coils 37 are regarded as a group of first coil groups Gr1, and three are arranged at equal intervals in the circumferential direction. That is, the first coil system has three first coil groups Gr1 arranged at equal intervals in the circumferential direction. In addition, the first coil groups Gr1 do not necessarily have to be three. When n is a natural number, 3n can be arranged at equal intervals in the circumferential direction. In addition, it is desirable that n is an odd number. As described above, in this embodiment 1, there are multiple coil groups, which are divided into at least two systems, the first coil group Gr1 and the second coil group Gr2, for each of the three phases, and the stator core is excited by three-phase AC.

[0056] like Figure 3 As shown, the second coils 38 are concentratedly wound around a plurality of teeth 931b. The second coils 38 are concentratedly wound around the outer periphery of the teeth 931b via an insulator. The teeth 931b around which the second coils 38 are concentratedly wound are different from the teeth 931b around which the first coils 37 are concentratedly wound. All the second coils 38 are included in the second coil system. The second coil system is provided by the second inverter circuit 251B (see FIG. 2 ) included in the second power circuit 25B. Figure 5) and is supplied with current and excited. The second coil system includes, for example, six second coils 38. The six second coils 38 are arranged in a manner that two second coils 38 are adjacent to each other in the circumferential direction. Three second coil groups Gr2, which regard adjacent second coils 38 as a group, are arranged at equal intervals in the circumferential direction. That is, the second coil system has three second coil groups Gr2 arranged at equal intervals in the circumferential direction. In addition, the number of second coil groups Gr2 does not necessarily have to be three. When n is a natural number, 3n second coil groups Gr2 can be arranged at equal intervals in the circumferential direction. In addition, it is desirable that n is an odd number.

[0057] like Figure 4 As shown, the six first coils 37 include: two first U-phase coils 37Ua and 37Ub, excited by the first U-phase current I1u; two first V-phase coils 37Va and 37Vb, excited by the first V-phase current I1v; and two first W-phase coils 37Wa and 37Wb, excited by the first W-phase current I1w. The first U-phase coil 37Ub is connected in series with the first U-phase coil 37Ua. The first V-phase coil 37Vb is connected in series with the first V-phase coil 37Va. The first W-phase coil 37Wb is connected in series with the first W-phase coil 37Wa. The winding direction of all first coils 37 is the same with respect to the teeth 931b. Furthermore, the first U-phase coil 37Ub, the first V-phase coil 37Vb, and the first W-phase coil 37Wb are connected in a star connection (Y connection).

[0058] like Figure 4 As shown, the six second coils 38 include: two second U-phase coils 38Ua and 38Ub, excited by the second U-phase current I2u; two second V-phase coils 38Va and 38Vb, excited by the second V-phase current I2v; and two second W-phase coils 38Wa and 38Wb, excited by the second W-phase current I2w. The second U-phase coil 38Ub is connected in series with the second U-phase coil 38Ua. The second V-phase coil 38Vb is connected in series with the second V-phase coil 38Va. The second W-phase coil 38Wb is connected in series with the second W-phase coil 38Wa. The winding direction of all second coils 38 with respect to the teeth 931b is the same as the winding direction of the first coil 37. Furthermore, the second U-phase coil 38Ub, the second V-phase coil 38Vb, and the second W-phase coil 38Wb are connected in a star connection (Y connection).

[0059] like Figure 3As shown, the three first coil groups Gr1 include a first UV coil group Gr1UV, a first VW coil group Gr1VW, and a first UW coil group Gr1UW. The first UV coil group Gr1UV includes a first U-phase coil 37Ub and a first V-phase coil 37Va, which are circumferentially adjacent to each other. The first VW coil group Gr1VW includes a first V-phase coil 37Vb and a first W-phase coil 37Wa, which are circumferentially adjacent to each other. The first UW coil group Gr1UW includes a first U-phase coil 37Ua and a first W-phase coil 37Wb, which are circumferentially adjacent to each other.

[0060] like Figure 3 As shown, the three second coil groups Gr2 include a second UV coil group Gr2UV, a second VW coil group Gr2VW, and a second UW coil group Gr2UW. The second UV coil group Gr2UV includes a second U-phase coil 38Ub and a second V-phase coil 38Va, which are circumferentially adjacent to each other. The second VW coil group Gr2VW includes a second V-phase coil 38Vb and a second W-phase coil 38Wa, which are circumferentially adjacent to each other. The second UW coil group Gr2UW includes a second U-phase coil 38Ua and a second W-phase coil 38Wb, which are circumferentially adjacent to each other.

[0061] The first coil 37 excited by the first U-phase current I1u and the second coil 38 excited by the second U-phase current I2u are opposite to each other in the radial direction of the stator core 931. In the following description, the radial direction of the stator core 931 is simply described as the radial direction. Figure 3 As shown, in the radial direction, the first U-phase coil 37Ua and the second U-phase coil 38Ua face each other, and the first U-phase coil 37Ub and the second U-phase coil 38Ub face each other.

[0062] The first coil 37 excited by the first V-phase current I1v and the second coil 38 excited by the second V-phase current I2v are radially opposed to each other. Figure 3 As shown, in the radial direction, the first V-phase coil 37Va and the second V-phase coil 38Va face each other, and the first V-phase coil 37Vb and the second V-phase coil 38Vb face each other.

[0063] The first coil 37 excited by the first W-phase current I1w and the second coil 38 excited by the second W-phase current I2w are radially opposed to each other. Figure 3 As shown, in the radial direction, the first W-phase coil 37Wa and the second W-phase coil 38Wa face each other, and the first W-phase coil 37Wb and the second W-phase coil 38Wb face each other.

[0064] Figure 5 Schematic diagram showing the relationship between the motor and ECU in Embodiment 1. Figure 5As shown in FIG. 1 , the ECU 10 includes a detection circuit 23, a control circuit 24, a first power circuit 25A, a second power circuit 25B, a power management circuit 27, a cut-off drive circuit 243, and a power relay drive circuit 246. Figure 5 In the figure, circuits that do not require explanation are omitted as appropriate.

[0065] The control circuit 24 includes a control arithmetic circuit 241, a first motor drive circuit 26A, and a second motor drive circuit 26B. Input and output signals such as the steering torque signal T and the vehicle speed signal SV are transmitted to the control arithmetic circuit 241 via a connector CNT. Because the circuit board 20 is a multilayer resin substrate having multiple conductive layers, the wiring electrically connecting the connector CNT to the control arithmetic circuit 241 of the control circuit 24 is routed through the conductive layers within the circuit board 20.

[0066] Power is supplied via the wiring PW from the power supply device 183 via the connector CNT. The noise filter circuit 90 includes a choke coil 91 and a capacitor 92, which remove high-frequency components superimposed on the power supplied from the wiring PW. The connection wiring PWS routed on the circuit board 20 is connected to the wiring PW from the power supply device 183. One end of the connection wiring PWS is connected to the noise filter circuit 90 (choke coil 91, capacitor 92), and the other end of the connection wiring is connected to the first inverter circuit 251A of the first power circuit 25A or the second inverter circuit 251B of the second power circuit 25B via the power supply circuit 256. In addition, when describing the first inverter circuit 251A and the second inverter circuit 251B without distinguishing between them, they are simply described as the inverter circuit 251.

[0067] Power supply circuit 256 is positioned between noise filter circuit 90 and inverter circuit 251. It includes a power cutoff element 257 and a reverse polarity protection element 258. Both power cutoff element 257 and reverse polarity protection element 258 are field effect transistors (FETs). The forward direction of the parasitic diode of reverse polarity protection element 258 is opposite to the forward direction of the parasitic diode of power cutoff element 257. Therefore, even if power of the opposite polarity is mistakenly supplied from power supply device 183, reverse polarity protection element 258 will cut off the power of the opposite polarity, protecting inverter circuit 251.

[0068] The power management circuit 27 is a switching IC that controls the on / off switching of power to the circuits mounted on the circuit board 20 and the distribution of power. For example, the power management circuit 27 controls the distribution of power used by the control circuit 24. One end of the connection wiring is connected to the noise filter circuit 90 (choke coil 91, capacitor 92), and the other end of the connection wiring is connected to the power management circuit 27.

[0069] The detection circuit 23 includes two rotation angle sensors 23a and a sensor control unit 23b. Even if one rotation angle sensor 23a fails, the detection circuit 23 can continue to function. The first power circuit 25A includes a first inverter circuit 251A and a current cutoff circuit 255. The second power circuit 25B includes a second inverter circuit 251B and a current cutoff circuit 255.

[0070] The first motor drive circuit 26A includes a first gate drive circuit 242a, a plurality of first current detection circuits 244, and a boost circuit 245. The second motor drive circuit 26B includes a second gate drive circuit 242b, a plurality of second current detection circuits 244, and a boost circuit 245. The boost circuit 245 supplies boosted power to the first gate drive circuit 242a, the second gate drive circuit 242b, the cutoff drive circuit 243, and the power supply relay drive circuit 246.

[0071] When the power supply relay driving circuit 246 turns on the power cutoff element 257 and the reverse connection protection element 258 based on the control of the control calculation circuit 241 , the power from the power supply device 183 is supplied to the inverter circuit 251 .

[0072] In addition, the inverter circuit 251 includes multiple drive elements 252. The drive elements 252 are field effect transistors (FETs), also known as switching elements. The drive element 252 connected to the high potential side constitutes the upper arm, and the drive element 252 connected to the low potential side constitutes the lower arm. A shunt resistor SR is connected to each of the three drive elements 252 in the lower arm. Although a shunt resistor SR is connected to each of the three drive elements 252, the three drive elements 252 may be connected to only one shunt resistor SR.

[0073] The control calculation circuit 241 controls the first motor drive circuit 26A or the second motor drive circuit 26B. For example, the control calculation circuit 241 calculates a motor current command value and uses the motor current command value to control the first motor drive circuit 26A or the second motor drive circuit 26B. The sensor control unit 23b calculates the motor electrical angle θm based on the detection value of the rotation angle sensor 23a and outputs it to the control calculation circuit 241. The first gate drive circuit 242a controls the first power circuit 25A based on the motor current command value. The second gate drive circuit 242b controls the second power circuit 25B based on the motor current command value. In this way, the current flowing into the first coil 37 and the current flowing into the second coil 38 are independently controlled by the control calculation circuit 241.

[0074] like Figure 5As shown, the ECU 10 includes a rotation angle sensor 23a. The rotation angle sensor 23a is, for example, a magnetic sensor. The detection value of the rotation angle sensor 23a is supplied to the sensor control unit 23b. Based on the detection value of the rotation angle sensor 23a, the sensor control unit 23b outputs an output value corresponding to the motor electrical angle θm to the control calculation circuit 241.

[0075] The control calculation circuit 241 receives inputs including a steering torque signal T detected by the torque sensor 194, a vehicle speed signal SV detected by the vehicle speed sensor 182, and an output value corresponding to the motor electrical angle θm output from the sensor control unit 23b. The control calculation circuit 241 calculates a motor current command value based on the steering torque signal T, the vehicle speed signal SV, and the motor electrical angle θm calculated from these output values, and outputs the value to the first gate drive circuit 242a and the second gate drive circuit 242b.

[0076] The first gate drive circuit 242a calculates a first pulse-width modulated signal based on the motor current command value and outputs the gate drive signal to the first inverter circuit 251A of the first power circuit 25A. The gate drive signal is a pulse signal generated based on the gate voltage boosted by the boost circuit 245. The first inverter circuit 251A switches the drive element 252 according to the duty cycle of the first pulse-width modulated signal to form three-phase current values, generating a three-phase AC current consisting of a first U-phase current I1u, a first V-phase current I1v, and a first W-phase current I1w. The first U-phase current I1u excites the first U-phase coil 37Ua and the first U-phase coil 37Ub, the first V-phase current I1v excites the first V-phase coil 37Va and the first V-phase coil 37Vb, and the first W-phase current I1w excites the first W-phase coil 37Wa and the first W-phase coil 37Wb.

[0077] The second gate drive circuit 242b calculates a second pulse-width modulated signal based on the motor current command value and outputs the gate drive signal to the second inverter circuit 251b of the second power circuit 25B. The gate drive signal is generated based on the voltage boosted by the boost circuit 245. The second inverter circuit 251b switches the drive element 252 according to the duty cycle of the second pulse-width modulated signal to form three-phase current values, thereby generating a three-phase AC current including a second U-phase current I2u, a second V-phase current I2v, and a second W-phase current I2w. The second U-phase current I2u excites the second U-phase coil 38Ua and the second U-phase coil 38Ub, the second V-phase current I2v excites the second V-phase coil 38Va and the second V-phase coil 38Vb, and the second W-phase current I2w excites the second W-phase coil 38Wa and the second W-phase coil 38Wb.

[0078] Inverter circuit 251 is a power conversion circuit that converts DC power into AC power. As described above, inverter circuit 251 includes multiple drive elements 252. Drive elements 252 are, for example, field-effect transistors. Smoothing capacitor 253 is connected in parallel with inverter circuit 251. Capacitor 253 is, for example, an electrolytic capacitor. In other words, circuit board 20 includes multiple electrolytic capacitors connected in parallel.

[0079] Furthermore, the current detection circuit 244 is connected to, for example, a shunt resistor SR. The shunt resistor SR is an example of a current detection element. The current detection element may also be a Hall effect element, etc. The current detection circuit 244 uses an operational amplifier and includes a differential amplifier circuit and a low-pass filter. The differential amplifier circuit of the current detection circuit 244 amplifies the detection value detected by the shunt resistor SR. The amplified detection value is passed through a low-pass filter to attenuate components higher than the cutoff frequency. The detection value detected by the shunt resistor SR is then transmitted as a current value to the control operation circuit 241.

[0080] The current cutoff circuit 255 is disposed between the inverter circuit 251 and the first coil 37 or the second coil 38. If the current value detected by the current detection circuit 244 is determined to be abnormal, the control calculation circuit 241 drives the current cutoff circuit 255 via the cutoff drive circuit 243, thereby cutting off the current flowing from the inverter circuit 251 to the first coil 37. Furthermore, the control calculation circuit 241 drives the current cutoff circuit 255 via the cutoff drive circuit 243, thereby cutting off the current flowing from the inverter circuit 251 to the second coil 38. If the current value detected by the current detection circuit 244 is determined to be abnormal, the control calculation circuit 241 disconnects the power supply cutoff element 257 and the reverse connection protection element 258 via the power supply relay drive circuit 246, thereby protecting the inverter circuit 251.

[0081] Figure 6 This is a side view of the electric drive device according to the first embodiment. Figure 7 It is a plan view of the electric drive device according to the first embodiment. Figure 8 Yes Figure 6 A sectional view of the cross section taken along the line VIII-VIII. Figure 9 Yes Figure 7 A sectional view of the cross section taken along line IX-IX. Figure 10 Yes Figure 7 A cross-sectional view of the section viewed in the direction XX. Figure 11 Yes Figure 6 A cross-sectional view of the cross section viewed along the XI-XI line. Figure 12 This is a perspective view illustrating the electric drive device according to the first embodiment with the cover and the circuit board removed. Figure 13 yes Figure 12 A top view of the . Figure 6 and Figure 7 As shown, the electric drive device 1 includes an electric motor 30 and an ECU 10 disposed on the opposite side of the electric motor 30 from the load.

[0082] like Figure 6 and Figure 7 As shown in FIG. 1 , the ECU 10 includes a radiator 40 and a cover 50 covering the opposite side of the radiator 40 from the load. Figure 8 As shown, the heat sink 40 supports the circuit board 20, and the cover 50 covers the circuit board 20. Figure 9 As shown, the circuit board 20 and the connector CNT are mounted on the heat sink 40. When viewed from the axial direction Ax, the connector CNT is positioned so that the connector terminals of the wiring harness can be inserted and removed from the radially outer side of the shaft 31 of the electric motor 30. As described above, the ECU 10 includes the circuit board 20, the heat sink 40 supporting the circuit board 20, the connector CNT, and the cover 50.

[0083] like Figure 8 As shown, the electric motor 30 includes a housing 930. The motor rotor 932 includes a rotor yoke 932a and a magnet 932b. The magnet 932b is provided on the outer peripheral surface of the rotor yoke 932a. The housing 930 is cylindrical and contains the motor rotor 932, the shaft 31, and the stator. The stator includes a plurality of coil groups divided into two systems for each of the three phases, for example, the first coil group Gr1 and the second coil group Gr2 (see FIG. Figure 3 ).

[0084] like Figure 8 As shown, the circuit board 20 has a substrate body 21 and a plurality of electronic components mounted on the substrate body 21. The substrate body 21 is, for example, a printed circuit board formed of resin or the like. Inside the circuit board 20 is a multilayer substrate provided with a plurality of conductive layers, and the circuit board 20 is a double-sided mounting substrate capable of double-sided mounting. Among the multiple electronic components mounted on one substrate body 21, for example, there are a central processing unit (CPU), an application specific integrated circuit (ASIC), a field effect transistor (FET), a magnetic sensor, an electrolytic capacitor, a resistor element, a diode, and a thermistor. The above-mentioned multiple electronic components constitute Figure 5 The detection circuit 23, the control circuit 24, the first power circuit 25A and the second power circuit 25B are shown.

[0085] like Figure 8 and Figure 9As shown, the heat sink 40 supports the circuit board 20. The circuit board 20 is fixed to one surface (the side opposite to the load) of the heat sink 40. The heat sink 40 is made of a metal material with high heat dissipation properties such as aluminum and copper, and effectively dissipates heat generated by the circuit board 20 to the outside.

[0086] like Figure 8 As shown, shaft 31 is rotatably supported by bearings 33 and 34. Bearing 33 is interposed between heat sink 40 and shaft 31. Heat sink 40 has a bearing support portion 411 on the load side thereof, and a hollow portion 45H of heat sink 40 through which shaft 31 passes. Bearing 33 is disposed within hollow portion 45H surrounded by bearing support portion 411. Bearing 34 is interposed between housing 930 and shaft 31.

[0087] like Figure 8 and Figure 9 As shown, a magnet 32 is mounted on one end of the shaft 31 using a magnet bender 32A. When viewed in the axial direction Ax, half of the magnet 32 is magnetized to an S pole and the other half to an N pole. Alternatively, the magnet 32 may have alternating S and N poles on its outer circumferential surface when viewed in the circumferential direction. Due to the high precision of the bearing 33 components, the position of the magnet 32 in the axial direction Ax, located on the opposite side of the heat sink 40 from the load, is constant. The end with the magnet 32 is the end of the shaft 31 on the opposite side from the load.

[0088] The other end of the shaft 31 is provided with a reduction gear 175 (see Figure 2 ) The motor gear 31G that transmits the rotation. The end portion having the motor gear 31G is the end portion of the shaft 31 on the load side.

[0089] The substrate body 21 has a first surface 21 b and a second surface 21 a located on the opposite side of the first surface 21 b . Figure 5 The detection circuit 23, control circuit 24, first power circuit 25A, and second power circuit 25B shown are composed of one or more electronic components mounted on the first surface 21b or the second surface 21a. For example, the rotation angle sensor 23a is composed of a single electronic component mounted on the second surface 21a of the substrate body 21.

[0090] also, Figure 5 The control circuit 24 shown is composed of a plurality of electronic components mounted on the first surface 21b of the substrate body 21. The circuit board 20 also includes a capacitor 253 mounted on the first surface 21b of the substrate body 21.

[0091] The rotation angle sensor 23a is located on the opposite side of the load of the shaft 31 and is arranged on an extension line of the axial direction Ax of the magnet 32. The substrate body 21 uses a plane perpendicular to the axial direction Ax as the mounting surface of the rotation angle sensor 23a. The rotation angle sensor 23a is mounted on the substrate body 21 in a manner capable of sensing changes in the magnetic field of the magnet 32. It is desirable that the magnet 32 and the rotation angle sensor 23a are opposite to each other in the axial direction Ax. The rotation angle sensor 23a may be mounted on the second surface 21a instead of the first surface 21b of the substrate body 21, or may be mounted on both the first surface 21b and the second surface 21a of the substrate body 21.

[0092] The rotation angle sensor 23a is, for example, a spin valve sensor. A spin valve sensor is a sensor that can detect changes in the direction of magnetic flux using an element composed of a fixed layer of ferromagnetic material and a free layer of ferromagnetic material sandwiched between a non-magnetic layer. The magnetization direction of the ferromagnetic material is fixed by an antiferromagnetic layer, etc. Spin valve sensors include GMR (Giant Magneto Resistance) sensors and TMR (Tunnel Magneto Resistance) sensors. In addition, the rotation angle sensor 23a can be any sensor that can detect the rotation of the magnet 32. The rotation angle sensor 23a can also be, for example, an AMR (Anisotropic Magneto Resistance) sensor or a Hall sensor.

[0093] The cover 50 is made of metal or resin, and prevents foreign matter or moisture from entering the interior of the electric drive device 1. Figure 8 As shown, the cover 50 is fixed by being sandwiched between the support columns 451 protruding toward the anti-load side of the heat sink 40 and the bolts CT serving as fixing members.

[0094] like Figure 9 、 Figure 10 as well as Figure 11 As shown, the heat sink 40 includes a base portion 44 that supports the connector CNT. The base portion 44 protrudes radially outward from the inner wall of the housing 930. The connector CNT is arranged on the opposite side of the base portion 44 to the load.

[0095] Connector CNT includes terminals CNTP, which include a power supply terminal, a communication terminal for CAN communication, and input / output terminals for inputting and outputting data using methods other than CAN communication. The resin material of connector CNT is, for example, polybutylene terephthalate (PBT). Terminals CNTP of connector CNT are electrically connected to circuit board 20.

[0096] like Figure 8As shown, the circuit board 20 is arranged on the opposite side of the heat sink 40 from the load.

[0097] like Figure 12 and Figure 13 As shown, the heat sink 40 has a height difference between the first surface 41 and the second surface 42 on the opposite side of the heat sink body. Furthermore, the first surface 41 does not have to be flat; it only needs to be lower than the second surface 42 in the axial direction Ax. The mounting surface 441 is located on the load side relative to the first surface, and the second surface 42 is located on the opposite side of the load relative to the first surface.

[0098] like Figure 12 As shown, the heat sink 40 includes support columns 451 and 452 protruding from the first surface 41 toward the opposite side of the load. The support columns 451 and 452 each have an internal threaded portion extending from the upper surface on the opposite side of the load in the axial direction Ax. Figure 8 As shown, the support column 451 protrudes beyond the circuit board 20. Figure 8 As shown, the bolts CT passing through the cover 50 are fastened to the internal threaded portion of the support column 451 , thereby fixing the cover 50 to the heat sink 40 .

[0099] like Figure 9 As shown, the bolt BT1 passing through the circuit board 20 is fastened to Figure 12 The internal thread portion of the support column 452 is shown. Thus, the circuit board 20 is fixed so as not to deviate relative to the heat sink 40.

[0100] like Figure 9 As shown, the connector CNT is sandwiched between the heat sink 40 and the circuit board 20 , and the circuit board 20 and the connector CNT are fixed by bolts BT2 .

[0101] Bolts BT1 are located adjacent to bolts BT2 to secure the circuit board 20 and heat sink 40. Since bolts BT1 (the second bolt) and BT2 (the third bolt) are located close together, even if the connector CNT sways, the tightening force of bolts BT1, in addition to the tightening force of bolts BT2, can suppress the swaying of the connector CNT.

[0102] like Figure 12 As shown, the electric drive device 1 includes a first coil wiring 321 connecting the first coil group Gr1 and the circuit board 20, and a second coil wiring 322 connecting the second coil group Gr2 and the circuit board 20. The first coil wiring 321 and the second coil wiring 322 may be included in the ECU 10 or in the electric motor 30.

[0103] like Figure 12As shown, the first coil wiring 321 and the second coil wiring 322 are inserted into the through-holes of the circuit board 20 , and the circuit board 20 and the first coil wiring 321 and the second coil wiring 322 are electrically connected.

[0104] like Figure 12 and Figure 13 As shown, in order to dissipate heat generated by the circuit board 20, the second surface 42 faces the circuit board 20. Furthermore, a heat dissipation material is applied between the circuit board 20 and the second surface 42 of the heat sink 40. Heat dissipation material, for example, is a material made by mixing a thermally conductive filler into a silicone polymer, known as a TIM (Thermal Interface Material). The heat dissipation material may be other materials than those listed above, as long as its thermal conductivity is greater than that of the substrate body 21 of the circuit board 20.

[0105] like Figure 11 、 Figure 12 as well as Figure 13 As shown, on the load-opposite side of the base portion 44, there are: a loading surface 441, on which the connector CNT is mounted; a protrusion 442, which protrudes toward the load-opposite side compared to the loading surface 441; a recess 443, which is the base of the protrusion 442, and the recess 443 is recessed toward the load side compared to the loading surface 441; and a recess 444, which is recessed toward the load side compared to the loading surface 441, and accommodates the head of the bolt BBT serving as a fixing member.

[0106] like Figure 9 and Figure 11 As shown, connector CNT has a recess CNTR on the load side. Protrusion 442 engages with recess CNTR. When viewed radially from shaft 31, recess CNTR is located midway between the two ends of connector CNT. This minimizes the volume of recess CNTR, ensuring sufficient space for the connector's conductors.

[0107] like Figure 12 As shown, the protrusion 442 is shaped like a prism. Each surface of the prism exerts a counterforce against the blocking force, further suppressing the swinging of the connector CNT. Since the protrusion 442 is made of metal, it can support the connector CNT even though it is small.

[0108] like Figure 10 and Figure 12 As shown, the bolts BBT passing through the base portion 44 are fastened to the internal thread portion of the flange portion 933 of the electric motor 30 , thereby fixing the heat sink 40 to the electric motor 30 .

[0109] Figure 14 This is a plan view showing a mounted state of electronic components on the first surface of the circuit board in the electric drive device according to the first embodiment. Figure 15This is a plan view showing a mounted state of electronic components on the first surface of the circuit board in the electric drive device according to the first embodiment. Figure 16 1 is a top view showing the overlapping mounting state of electronic components on the first and second surfaces of the circuit board in the electric drive device of embodiment 1. Figure 16 In FIG. 2 , the electronic components mounted on the second surface 21a of the substrate body 21 are indicated by dotted lines. Figures 14 to 16 In the figure, the substrate body 21 is parallel to a PX-PY plane that is orthogonal to a third direction PZ that is parallel to the axial direction Ax.

[0110] like Figure 14 As shown, the arrangement region A25A for the first power circuit 25A and the arrangement region A25B for the second power circuit 25B are spaced apart in the first direction PX of the substrate body 21. The capacitor 253 of the first power circuit 25A is arranged in the arrangement region A25A. The capacitor 253 of the second power circuit 25B is arranged in the arrangement region A25B. Between the arrangement region A25A for the first power circuit 25A and the arrangement region A25B for the second power circuit 25B in the first direction PX are the mounting region A26A for the first motor drive circuit 26A and the mounting region A26B for the second motor drive circuit 26B.

[0111] like Figure 14 As shown, the control circuit mounting area A241 houses the control arithmetic circuit 241 and the power management circuit 27. The control circuit mounting area A241 and the terminal arrangement area ACNT for connecting to the terminals CNTP of the connector CNT sandwich a reference position on an extension of the axial direction Ax of the shaft 31 in a second direction PY intersecting the first direction PX. Furthermore, the control circuit mounting area A241 and the terminal arrangement area ACNT for connecting to the terminals CNTP of the connector CNT sandwich a mounting area A26A for the first motor drive circuit 26A and a mounting area A26B for the second motor drive circuit 26B in a second direction PY intersecting the first direction PX.

[0112] like Figure 15 As shown in FIG. 2 , a choke coil 91 and a power supply circuit 256 are arranged in the power circuit region A90 on the second surface 21a of the substrate body 21. Figure 14 As shown, the capacitor 92 is arranged in the power circuit region A90 of the first surface 21b of the substrate body 21. Thus, the noise filter circuit 90 is mounted in the power circuit region A90.

[0113] With the position on the extension line of the axial direction Ax as a reference position, the mounting area ASRA for the shunt resistor SR, the mounting area A251A for the plurality of driver elements of the inverter circuit 251 included in the first power circuit 25A, and the mounting area A255A for the current interruption circuit 255 are arranged in this order from the reference position toward one side in the first direction PX. The mounting area ASRB for the shunt resistor SR, the mounting area A251B for the plurality of driver elements of the inverter circuit 251 included in the second power circuit 25B, and the mounting area A255B for the current interruption circuit 255 are arranged in this order from the same reference position toward the other side in the first direction PX.

[0114] As described above, the electric drive device 1 of the first embodiment includes an electric motor 30, an ECU 10 located on the opposite-load side of the shaft 31 for driving and controlling the electric motor 30, and a connector CNT. The ECU 10 includes a magnet 32 at the opposite-load side end of the shaft 31, and a circuit board 20 located on the opposite-load side of the shaft 31 and arranged along an extension of the axial direction (e.g., axial direction Ax) of the shaft 31. The circuit board 20 includes a detection circuit 23, which includes a rotation angle sensor 23a that detects the rotation of the magnet 32. The rotation angle sensor 23a is a magnetic sensor that detects the rotation of the magnet 32.

[0115] like Figure 16 As shown, if the installation status of the electronic components on the first surface 21b and the second surface 21a of the overlapping circuit board 20 is used, the position on the extension line of the axial direction Ax of the shaft 31 is used as the reference position, and from the reference position to one side of the first direction PX, the installation area A26A of the first motor drive circuit 26A, the installation area ASRA of the first current detection element, the installation area A251A of the multiple drive elements of the first inverter circuit 251A and the configuration area A321 of the first coil wiring 321 are sequentially arranged.

[0116] From the same reference position to the other side of the first direction PX, there are arranged in sequence the mounting area A26B of the second motor drive circuit 26B, the mounting area ASRB of the second current detection element, the mounting area A251B of multiple drive elements of the second inverter circuit 251B, and the configuration area A322 of the second coil wiring 322.

[0117] In the second direction PY, the mounting area A241 of the control arithmetic circuit 241 of the control circuit 24 and the terminal CNTP of the connector sandwich the reference position (the position on the extension line of the axial direction Ax of the shaft 31). Figure 16As shown, the mounting area A26A of the first motor driver circuit 26A and the mounting area A26B of the second motor driver circuit 26B are separated in the first direction PX, with reference line LYAx, which passes through a reference position in the second direction (a position on an extension of the axial direction Ax of the shaft 31). Consequently, the mounting area ASRA of the shunt resistor SR and the mounting area ASRB of the shunt resistor SR are separated in the first direction PX, with reference line LYAx serving as the boundary. Similarly, the mounting area A251A of the multiple driver elements of the inverter circuit 251 included in the first power circuit 25A and the mounting area A251B of the multiple driver elements of the inverter circuit 251 included in the second power circuit 25B are separated in the first direction PX, with reference line LYAx serving as the boundary. Since the mounting region A251A for the plurality of driving elements of the inverter circuit 251 included in the first power circuit 25A and the mounting region A251B for the plurality of driving elements of the inverter circuit 251 included in the second power circuit 25B are separated, heat generated by the driving elements is dispersed.

[0118] The mounting area A26A of the first motor drive circuit 26A is adjacent to the mounting area ASRA of the first current detection element. Furthermore, the mounting area A26B of the second motor drive circuit 26B is adjacent to the mounting area ASRB of the second current detection element. This shortens the wiring between the first motor drive circuit 26A and the shunt resistor SR, which serves as the first current detection element, thereby reducing noise associated with signal amplification within the first motor drive circuit 26A. Furthermore, the wiring between the second motor drive circuit 26B and the shunt resistor SR, which serves as the second current detection element, is shortened, thereby reducing noise associated with signal amplification within the second motor drive circuit 26B. In this manner, the electric drive device 1 can reduce the noise that is superimposed on the detection value detected by the shunt resistor SR in the path from the shunt resistor SR, which serves as the current detection element, to the control calculation circuit 241 of the control circuit 24. As a result, the control circuit 24 drives the electric motor 30 based on a current value with less noise, thereby suppressing torque ripple generated in the motor rotor.

[0119] like Figure 5 As shown, the shunt resistor SR as the first current detection element detects the current flowing to the driving element of the lower arm among the multiple driving elements of the first inverter circuit 251A. Similarly, the shunt resistor SR as the second current detection element detects the current flowing to the driving element of the lower arm among the multiple driving elements of the second inverter circuit 251B. Figure 16As shown, the mounting area ASRA for the first current sensing element is adjacent to the mounting area A251A for the driver element of the first inverter circuit. This shortens the wiring between the shunt resistor SR and the driver element of the first inverter circuit 251A. The mounting area ASRB for the second current sensing element is adjacent to the mounting area for the driver element of the second inverter circuit 251B. This shortens the wiring between the shunt resistor SR and the driver element of the second inverter circuit.

[0120] The circuit board 20 includes a power supply circuit region A90 in which the noise filter circuit 90 and the power supply circuit 256 are arranged. The power supply circuit region A90 is arranged at the reference position (the position on the extension line of the axial direction Ax of the shaft 31) and Figure 14 Thus, the power circuit region A90 can be arranged near the terminal CNTP of the connector CNT, with the wiring distance to the first inverter circuit 251A and the wiring distance to the second inverter circuit 251B being similar.

[0121] In addition, if Figure 5 As shown, the first motor drive circuit 26A includes a booster circuit 245, which boosts and generates a gate voltage for driving a plurality of drive elements of the first inverter circuit 251A. The second motor drive circuit 26B includes a booster circuit 245, which boosts and generates a gate voltage for driving a plurality of drive elements of the second inverter circuit 251B. Figure 14 As shown, the first motor drive circuit 26A and the first inverter circuit 251A are adjacent, while the second motor drive circuit 26B and the second inverter circuit 251B are adjacent. As a result, the influence of the wiring resistance of the wiring connecting the multiple drive elements from the first motor drive circuit 26A to the first inverter circuit 251A on the time constant of the gate voltage signal waveform is reduced. Furthermore, even if the gate voltage generated by the booster circuit 245 is suppressed, the first inverter circuit 251A can still be driven. Similarly, the influence of the wiring resistance of the wiring connecting the multiple drive elements from the second motor drive circuit 26B to the second inverter circuit 251B on the time constant of the gate voltage signal waveform is reduced. Furthermore, even if the gate voltage generated by the booster circuit 245 is suppressed, the second inverter circuit 251B can still be driven. Furthermore, the operation of the drive elements of the first inverter circuit 251A and the second inverter circuit 251B is facilitated by high-speed and stable operation.

[0122] like Figures 14 to 16As shown, the U-phase coil wiring 321u, V-phase coil wiring 321v, and W-phase coil wiring 321w of the plurality of first coil wirings 321 are arranged in the second direction PY. Furthermore, the U-phase coil wiring 322u, V-phase coil wiring 322v, and W-phase coil wiring 322w of the plurality of second coil wirings 322 are arranged in the second direction PY. The phase arrangement of the plurality of first coil wirings 321 is in the opposite order to the phase arrangement of the plurality of second coil wirings 322. Thus, the power supply path for supplying the first U-phase current I1u, the first V-phase current I1v, and the first W-phase current I1w is identical to the power supply path for supplying the second U-phase current I2u, the second V-phase current I2v, and the second W-phase current I2w.

[0123] As described above, the substrate body 21 of the circuit board 20 is a double-sided mounting substrate. Figure 15 As shown, the plurality of driving elements of the first inverter circuit 251A and the plurality of driving elements of the second inverter circuit 251B are mounted on the first surface 21b of the substrate body 21 facing the heat sink 40. Figure 14 As shown, the first motor drive circuit 26A and the second motor drive circuit 26B are mounted on the second surface 21a of the substrate body 21, and the second surface 21a is located on the side opposite to the first surface 21b. The first motor drive circuit 26A and the multiple drive elements of the first inverter circuit 251A are electrically connected via the internal conductive layer of the circuit board 20. The second motor drive circuit 26B and the multiple drive elements of the second inverter circuit 251B are electrically connected via the internal conductive layer of the circuit board 20. As a result, the mounting density of electronic components is improved and the circuit board 20 is reduced in size. In addition, since the heat generated by the multiple drive elements of the first inverter circuit 251A and the multiple drive elements of the second inverter circuit 251B is dissipated by the heat sink 40, the reliability of the electric drive device 1 is improved.

[0124] Furthermore, the electric power steering system 100 includes the electric drive device 1 described above, and the electric drive device 1 generates an assist steering torque, thereby suppressing torque fluctuations of the electric motor 30 and improving operability of the electric power steering system 100 .

[0125] (Implementation Method 2)

[0126] Figure 17 Schematic diagram of an electric power steering system according to Embodiment 2. Components identical to those described in Embodiment 1 are denoted by the same reference numerals, and redundant descriptions are omitted.

[0127] like Figure 17As shown, the electric power steering system 100A employs a rack-and-pinion parallel system. The shaft 31 of the electric motor 30 is connected to a power transmission mechanism 173. This power transmission mechanism 173 includes a pulley 176 and a belt 177. The rotation of the belt 177 rotates the nut of a ball screw assembly 178. This rotation of the shaft 31 of the electric motor 30 applies assist force to the rack shaft 199C.

[0128] (Implementation 3)

[0129] Figure 18 It is a schematic diagram of an electric power steering system according to Embodiment 3. Components identical to those described in Embodiments 1 and 2 are denoted by the same reference numerals, and redundant descriptions are omitted. Figure 18 The electric power steering system 100B shown is a pinion assist system in which an auxiliary steering torque is applied to a first pinion shaft 199A. In the electric power steering system 100B, a torque sensor 194 is connected to the first pinion shaft 199A.

[0130] The electric motor 30 rotates the reduction gear 175 of the worm shaft. The worm wheel of the reduction gear 175 rotates integrally with the first pinion shaft 199A. Therefore, the electric motor 30 can rotate the first pinion 199B. The first pinion 199B is engaged with the first rack 199D. As a result, the electric drive device 1 applies an assist force to the first rack 199D via the reduction gear 175. In addition, the first pinion 199B can be arranged orthogonally to the first rack 199D, or it can be arranged obliquely with an offset from the orthogonal position. As described above, the electric power steering device 100B of embodiment 3 is a single pinion assist method.

[0131] (Implementation 4)

[0132] Figure 19 This is a schematic diagram of an electric power steering system according to Embodiment 4. Components identical to those described in Embodiments 1 to 3 are denoted by the same reference numerals, and duplicate descriptions are omitted. The electric power steering system 100C includes an output shaft 192B and a second pinion 171B in addition to a first pinion shaft 199A and a first pinion 199B. The electric power steering system 100C employs a dual-pinion assist system. A torque sensor 194 detects torque between the pinion shaft 195 and the first pinion 199B.

[0133] The electric motor 30 rotates the reduction gear 175 of the worm shaft. The worm wheel of the reduction gear 175 rotates integrally with the output shaft 192B. Therefore, the electric motor 30 can rotate the second pinion 171B. The second pinion 171B meshes with the second rack 171C. As a result, the electric drive device 1 applies an assist force to the second rack 171C via the reduction gear 175. In addition, the second pinion 171B can be arranged orthogonally to the second rack 171C, or it can be arranged obliquely offset from the orthogonal position. The electric power steering device 100C of embodiment 4 is a double pinion assist method.

[0134] Description of Reference Numerals

[0135] 1. Electric drive device; 10. ECU; 20. Circuit board; 21. Substrate body; 21a. Second surface; 21b. First surface; 23. Detection circuit; 23a. Rotation angle sensor; 23b. Sensor control unit; 24. Control circuit; 25A. First power circuit; 25B. Second power circuit; 26A. First motor drive circuit; 26B. Second motor drive circuit; 27. Power management circuit; 30. Electric motor; 31. Shaft; 32. Magnet; 37. First coil; 38. Second coil; 40. Radiator; 41. First surface; 42. Second surface; 90. Noise filter circuit; 91. Choke coil; 92. Capacitor; 100, 100A, 100B, 100C, electric power steering device; 244, current detection circuit; 245, boost circuit; 246, power relay drive circuit; 251, inverter circuit; 252, drive element; 253, capacitor; 255, current cutoff circuit; 256, power supply circuit; 257, power cutoff element; 258, reverse connection protection element; 321, first coil wiring; 321u, 321v, 321w, coil wiring; 322, second coil wiring; 322u, 322v, 322w, coil wiring; 930, housing; 931, stator core; 932, motor rotor.

Claims

1. An electric drive device, wherein: The electric drive device has: An electric motor comprising a shaft extending axially from a load side to an opposite load side, a motor rotor coupled to the shaft, a motor stator having a stator core and a plurality of coil groups, and a cylindrical housing accommodating the motor rotor, the motor stator, and the plurality of coil groups, wherein the stator core rotates the motor rotor, the plurality of coil groups being divided into at least two coil groups, a first coil group and a second coil group, for each of three phases, and the stator core being excited by a three-phase alternating current. a magnet provided at an end portion of the shaft on the opposite side to the load in order to drive and control the electric motor; an electronic control device located on the opposite side of the shaft from the load side and including a circuit board arranged on an extension line of the axial direction of the shaft; a heat sink disposed between the circuit board and the electric motor; and a connector having terminals connected to the circuit board, The circuit board has: a configuration area for a detection circuit, the detection circuit including a magnetic sensor for detecting the rotation of the magnet, the magnetic sensor being located on an extension line of the axial direction of the magnet and mounted on the circuit board; a mounting area for a plurality of driving elements of a first inverter circuit that supplies current to the first coil group; a mounting area for a plurality of driving elements of a second inverter circuit that supplies current to the second coil group; a mounting area for a first current detection element that detects a current flowing in the first inverter circuit; a mounting area for a second current detection element that detects a current flowing in the second inverter circuit; a mounting area for a first motor drive circuit including a first current detection circuit for amplifying a detection value detected by the first current detection element and a first gate drive circuit for driving a plurality of drive elements of the first inverter circuit; a mounting area for a second motor drive circuit including a second current detection circuit for amplifying a detection value detected by the second current detection element and a second gate drive circuit for driving a plurality of drive elements of the second inverter circuit; a mounting area for a control circuit that controls the first gate drive circuit based on a current value obtained by amplifying a detection value detected by the first current detection element using the first current detection circuit, and controls the second gate drive circuit based on a current value obtained by amplifying a detection value detected by the second current detection element using the second current detection circuit; a first coil wiring arrangement area, wherein each of the first coil wirings of the first coil group is connected to a substrate body of the circuit board; as well as The second coil wiring arrangement area, each of the second coil wirings of the second coil group is connected to the substrate body of the circuit board, Taking the position on the axial extension line of the shaft as a reference position, the mounting area of the first motor drive circuit, the mounting area of the first current detection element, the mounting areas of the plurality of drive elements of the first inverter circuit, and the arrangement area of the first coil wiring are arranged in sequence from the reference position toward one side in the first direction. The mounting area of the second motor drive circuit, the mounting area of the second current detection element, the mounting area of the plurality of drive elements of the second inverter circuit, and the arrangement area of the second coil wiring are sequentially arranged from the reference position toward the other side of the first direction. In a second direction intersecting the first direction, the mounting region of the control circuit and the terminals of the connector sandwich the reference position.

2. The electric drive device according to claim 1, wherein: The first current detection element detects current flowing through a driver element of a lower arm among the plurality of driver elements of the first inverter circuit, and the second current detection element detects current flowing through a driver element of a lower arm among the plurality of driver elements of the second inverter circuit.

3. The electric drive device according to claim 1, wherein: The circuit board also includes a power supply circuit area for configuring a noise filter circuit and a power supply circuit. The power circuit region is arranged between the reference position and the terminal of the connector in the second direction.

4. The electric drive device according to claim 1, wherein: The first motor drive circuit includes a boost circuit that boosts and generates a gate voltage for driving a plurality of drive elements of the first inverter circuit. The second motor drive circuit includes a booster circuit that boosts and generates a gate voltage for driving a plurality of drive elements of the second inverter circuit.

5. The electric drive device according to claim 1, wherein: The plurality of first coil wirings are arranged along the second direction, The plurality of second coil wires are arranged along the second direction such that the phase arrangement of the plurality of second coil wires is in the reverse order of the phase arrangement of the plurality of first coil wires.

6. The electric drive device according to claim 1, wherein: The substrate body of the circuit board is a double-sided mounting substrate, The multiple driving elements of the first inverter circuit and the multiple driving elements of the second inverter circuit are mounted on the first surface of the substrate body of the circuit board opposite to the heat sink, and the first motor driving circuit and the second motor driving circuit are mounted on the second surface of the substrate body of the circuit board, which is located on the side opposite to the first surface.

7. An electric power steering device, wherein: The electric power steering device includes the electric drive device according to any one of claims 1 to 6, The electric drive device generates an assistive steering torque.

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