Drive device and electric power steering device

Abstract

A drive device according to the present disclosure comprises: a motor having a rotating shaft, a rotor fixed to the rotating shaft, and a winding that rotates the rotor about the motor shaft when a current flows through the winding; and a control unit attached to the motor to control the current to be supplied to the winding. The control unit comprises: an inverter circuit including a plurality of switching elements and capable of supplying a current to the winding; a rotation sensor that detects the rotation angle of the rotating shaft; and a circuit board on which the inverter circuit and the rotation sensor are mounted. In a plan view, the rotation sensor is located at a position that overlaps with the motor shaft, and the plurality of switching elements are located along the outer periphery of the circuit board.

Description

Drive unit and electric power steering device

[0001] The present disclosure relates to a drive unit and an electric power steering device.

[0002] Patent Document 1 discloses a drive device including a motor and an inverter circuit that controls the drive of the motor. The drive device also includes a rotation sensor that detects the rotation angle of the motor's rotating shaft. The inverter circuit and the rotation sensor are mounted on a wiring board.

[0003] Japanese Patent No. 7167635

[0004] In Patent Document 1, the switching elements of the inverter circuit are arranged in close proximity to the rotation sensor on the wiring board, which makes the rotation sensor susceptible to noise such as magnetic noise generated from the switching elements.

[0005] In view of the above circumstances, the present disclosure aims to provide a drive device and an electric power steering device that can reduce the effect of noise generated from switching elements of an inverter circuit on a rotation sensor.

[0006] One aspect of a drive device according to the present disclosure comprises a motor having a rotating shaft, a rotor fixed to the rotating shaft, and windings through which current flows to rotate the rotor about the motor shaft, and a control unit attached to the motor and controlling the current supplied to the windings, the control unit comprising an inverter circuit including a plurality of switching elements and capable of supplying current to the windings, a rotation sensor that detects the rotation angle of the rotating shaft, and a wiring board on which the inverter circuit and the rotation sensor are mounted, wherein, in a plan view, the rotation sensor is positioned so as to overlap with the motor shaft, and the plurality of switching elements are arranged along the outer periphery of the wiring board.

[0007] One aspect of an electric power steering device according to the present disclosure includes the drive device.

[0008] According to the present disclosure, it is possible to provide a drive device and an electric power steering device that can reduce the influence of noise generated from switching elements of an inverter circuit on a rotation sensor.

[0009] Fig. 1 is a circuit diagram of a drive device and an electric power steering device according to embodiment 1. Fig. 2 is a cross-sectional view showing the configuration of the drive device and the electric power steering device according to embodiment 1. Fig. 3 is a plan view of a wiring board according to embodiment 1. Fig. 4 is a circuit diagram of a drive device and an electric power steering device according to embodiment 2. Fig. 5 is a plan view of a wiring board according to embodiment 2. Fig. 6 is a plan view of a wiring board according to embodiment 3.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the scope of the present disclosure is not limited to the following embodiments and can be modified as desired within the scope of the technical concept of the present disclosure.

[0011] Embodiment 1. Fig. 1 is a circuit diagram of a drive device 1 and an electric power steering device 100 in embodiment 1. Fig. 2 is a cross-sectional view of the drive device 1. As shown in Fig. 1, the drive device 1 has a control unit 2 and a motor 4. The electric power steering device 100 is configured to use the torque generated by the motor 4 as an assist torque when steering the vehicle. Although detailed description will be omitted, a rotating shaft 43 of the motor 4 is connected to the steering system of the vehicle via a reducer or the like.

[0012] 1, the control unit 2 includes an inverter circuit 3a, a control circuit 5, a rotation sensor 14, etc. The control circuit 5 includes a CPU 10, an FET driver circuit 11 (pre-driver), an input circuit 12, a power supply circuit 13, etc.

[0013] 2 , the control unit 2 has a wiring board 20. The inverter circuit 3 a, the control circuit 5, the rotation sensor 14, etc. are mounted on the wiring board 20. The wiring board 20 has a first surface 20 a and a second surface 20 b. The wiring board 20 is covered by a cover 21.

[0014] As shown in Fig. 2, the motor 4 includes a motor body 40, a frame 45, a housing 46, a terminal group 44, etc. A permanent magnet synchronous motor, for example, can be used as the motor 4. The motor 4 according to this embodiment is a three-phase brushless motor. The three phases are a U phase, a V phase, and a W phase.

[0015] The motor body 40 has a stator 41, a rotor 42, and a rotating shaft 43. The stator 41 has three-phase windings (three-phase coils, first three-phase windings). In FIG. 1 , the three-phase windings are represented by symbols Ua, Va, and Wa. The three-phase windings Ua, Va, and Wa are delta-connected. The three-phase windings Ua, Va, and Wa may also be star-connected. The rotor 42 is fixed to the rotating shaft 43. The rotating shaft 43 rotates relative to the stator 41 around the motor axis C.

[0016] (Directional Definition) In this specification, the direction along the motor axis C is referred to as the axial direction. The axial direction also coincides with the thickness direction of the wiring board 20. As shown in FIG. 2, the wiring board 20 and the rotor 42 are arranged side by side in the axial direction. In the axial direction, the side on which the wiring board 20 is arranged is referred to as the upper side, and the side on which the rotor 42 is arranged is referred to as the lower side. The wiring board 20 extends so as to intersect (substantially perpendicular to) the axial direction. In the wiring board 20, the first surface 20a faces upward, and the second surface 20b faces downward. That is, the first surface 20a faces toward the cover 21, and the second surface 20b faces toward the rotor 42. A view from the axial direction is referred to as a plan view. A view from the axial direction is referred to as a plan view. Note that the axial direction does not have to coincide with the vertical direction. A direction perpendicular to the axial direction is referred to as a first orthogonal direction X (see FIG. 3, etc.). The direction perpendicular to both the axial direction and the first orthogonal direction X is referred to as a second orthogonal direction Y (see FIG. 3, etc.).

[0017] As shown in FIG. 3 , the wiring substrate 20 has a substantially rectangular shape in a plan view and includes a first side edge 20c, a second side edge 20d, a third side edge 20e, and a fourth side edge 20f. The first side edge 20c, the second side edge 20d, the third side edge 20e, and the fourth side edge 20f form the outer periphery of the wiring substrate 20. The first side edge 20c and the second side edge 20d are parallel to the first orthogonal direction X. The third side edge 20e is parallel to the second orthogonal direction Y. The fourth side edge 20f has a central edge parallel to the second orthogonal direction Y and a pair of connecting edges connecting the central edge to the first side edge 20c and the second side edge 20d, respectively. In the first orthogonal direction X, the side closer to the third side edge 20e is referred to as the +X side, and the side closer to the fourth side edge 20f is referred to as the −X side. In the second orthogonal direction Y, the side closer to the second side edge 20d is referred to as the +Y side, and the side closer to the first side edge 20c is referred to as the -Y side.

[0018] As shown in Figure 2, the frame 45 is cylindrical. The motor body 40 is housed inside the frame 45. A through hole is formed in the center of the bottom of the frame 45, and a lower bearing 47b is fixed inside this through hole. The lower end of the rotary shaft 43 is inserted into the lower bearing 47b.

[0019] The housing 46 is provided on top of the motor 4. The housing 46 is fitted inside the upper end of the cylindrical frame 45. The housing 46 prevents foreign matter from entering the inside of the motor 4. A through hole is formed in the center of the housing 46, and an upper bearing 47a is fixed inside this through hole. The upper end of the rotary shaft 43 is inserted into the upper bearing 47a.

[0020] The upper bearing 47a and the lower bearing 47b hold the rotating shaft 43 so that the rotating shaft 43 can rotate smoothly. A sensor magnet 48 is attached to the upper end of the rotating shaft 43. The sensor magnet 48 has at least one north pole and one south pole.

[0021] The wiring board 20 is disposed above the housing 46. The stator 41 (three-phase windings Ua, Va, Wa) is disposed below the housing 46. The terminal group 44 electrically connects the wiring board 20 to the three-phase windings Ua, Va, Wa. Specifically, the housing 46 has a through hole extending in the axial direction. The terminal group 44 is inserted into the through hole of the housing 46. The terminal group 44 includes three first terminals corresponding to the three-phase windings Ua, Va, Wa, respectively.

[0022] 3 , three current supply holes 22au, 22av, and 22aw (three-phase first current supply holes) corresponding to the U, V, and W phases are formed in the wiring substrate 20. The three current supply holes 22au, 22av, and 22aw are arranged on the outer periphery of the wiring substrate 20. In a plan view, the three current supply holes 22au, 22av, and 22aw are arranged along the first side edge 20c (the outer periphery of the wiring substrate 20). The three current supply holes 22au, 22av, and 22aw are arranged in the first orthogonal direction X.

[0023] The U-phase first terminal corresponding to the winding Ua is inserted into the U-phase current supply hole 22au. The V-phase first terminal corresponding to the winding Va is inserted into the V-phase current supply hole 22av. The W-phase first terminal corresponding to the winding Wa is inserted into the W-phase current supply hole 22aw. Current is supplied from the inverter circuit 3a of the wiring board 20 to the three-phase windings Ua, Va, and Wa via the three current supply holes 22au, 22av, and 22aw and the three first terminals. This causes the rotating shaft 43 to rotate. The three first terminals may be ends of the three-phase windings Ua, Va, and Wa, or may be relay members electrically connected to the ends of the three-phase windings Ua, Va, and Wa.

[0024] The rotation sensor 14 detects the rotation angle of the rotating shaft 43. An MR (magnetoresistance) sensor can be used as the rotation sensor 14. The rotation sensor 14 detects the rotation angle of the rotating shaft 43 by detecting the magnetic field generated by the sensor magnet 48. The rotation sensor 14 is disposed to face the sensor magnet 48. More specifically, as shown in FIG. 2 , the rotation sensor 14 is mounted on the second surface 20b of the wiring board 20. The rotation sensor 14 is disposed in a position overlapping the sensor magnet 48 in a plan view. This arrangement improves the accuracy with which the rotation angle is detected by the rotation sensor 14, thereby improving the controllability of the motor 4 by the control unit 2. However, the rotation sensor 14 may be disposed on the first surface 20a of the wiring board 20 as long as the desired detection accuracy can be achieved.

[0025] As shown in FIG. 2 , a connector assembly 50 is disposed above the cover 21. The connector assembly 50 is a component in which connectors, metal bus bars, terminals, etc., and a holding member 51 that holds them are integrally molded. The holding member 51 is made of, for example, resin. The connector assembly 50 connects power lines and ground lines required for controlling and driving the motor 4 to the wiring board 20. The connector assembly 50 also connects signal transmission lines that transmit signals such as torque sensor signals and vehicle communication signals to the wiring board 20. The connector assembly 50 may electrically connect the power lines, ground lines, signal transmission lines, etc., to the control unit 2 all at once. Alternatively, a connector separate from the connector assembly 50 may be provided for connecting the power lines, ground lines, etc.

[0026] The connector assembly 50 has a plurality of connector terminals 52 extending downward from a holding member 51. The plurality of connector terminals 52 are inserted into a plurality of connector through-holes 23 (see FIG. 3 ) formed in the wiring board 20. Furthermore, each connector terminal 52 is electrically connected to a circuit pattern formed on the wiring board 20.

[0027] The wiring board 20 is fixed to the housing 46 with screws or the like. The wiring board 20 may be fixed to the cover 21, the connector assembly 50, or the like.

[0028] Next, we will explain the outline of the operation of each part of the control unit 2. The power supply circuit 13 uses power supplied from the battery 9 (power supply) to generate a power supply voltage for normal operation of each electronic component (CPU 10, FET driver circuit 11, input circuit 12, rotation sensor 14, etc.) that constitutes the control unit 2.

[0029] The input circuit 12 inputs various pieces of information that the control unit 2 receives from the sensors 8, the rotation sensor 14, etc., to the CPU 10. Although detailed illustration is omitted, the input circuit 12 includes a torque sensor interface circuit and a vehicle communication interface circuit. The torque sensor interface circuit is a circuit for detecting the steering torque of the driver in the electric power steering device 100 and acquiring steering torque information. The vehicle communication interface circuit is a circuit for receiving various pieces of information from the vehicle system.

[0030] The CPU 10 calculates a control amount for supplying power to the motor 4 based on the above-mentioned various information input from the input circuit 12. The FET driver circuit 11 drives the inverter circuit 3a based on the calculation result of the CPU 10.

[0031] The inverter circuit 3a supplies power to the three-phase windings Ua, Va, and Wa of the motor 4 based on the calculation results of the CPU 10. The inverter circuit 3a has three upper arms and three lower arms corresponding to the U, V, and W phases, respectively. In the inverter circuit 3a, the circuit configurations for the U, V, and W phases are similar. Therefore, the following description will focus on the U phase as a representative of these three phases. In other words, the following description also applies to the V and W phases. Furthermore, FIG. 1 shows the components of the inverter circuit 3a that correspond to the U phase. However, in reality, the inverter circuit 3a also has components corresponding to the V and W phases. In other words, FIG. 1 omits the components of the inverter circuit 3a that correspond to the V and W phases.

[0032] As shown in FIG. 1 , the inverter circuit 3a includes a smoothing capacitor 30au, an upper-arm switching element 31au, a lower-arm switching element 32au, a motor relay switching element 33au, and a shunt resistor 34au. The upper-arm switching element 31au is disposed in the upper arm, and the lower-arm switching element 32au is disposed in the lower arm. The upper-arm switching element 31au is electrically connected to the positive electrode of the battery 9, and the lower-arm switching element 32au is electrically connected to the negative electrode of the battery 9. The upper-arm switching element 31au and the lower-arm switching element 32au are connected in series. The motor relay switching element 33au is connected between the upper-arm switching element 31au and the lower-arm switching element 32au. The motor relay switching element 33au has a relay function. That is, the motor relay switching element 33au switches on and off the power supply from the portion between the upper-arm switching element 31au and the lower-arm switching element 32au to the winding Ua of the motor 4. The upper-arm switching element 31au and the lower-arm switching element 32au are operated by the FET driver circuit 11 based on the results of calculations by the CPU 10. As an example, the upper-arm switching element 31au, the lower-arm switching element 32au, and the motor relay switching element 33au may be a field effect transistor (FET). Note that the motor relay switching element 33au may be omitted.

[0033] The smoothing capacitor 30au is connected near the upper-arm switching element 31au and the lower-arm switching element 32au. The smoothing capacitor 30au has the function of suppressing power supply voltage fluctuations and noise during switching. The shunt resistor 34au is connected between the lower-arm switching element 32au and ground. The shunt resistor 34au is used to detect the drive current flowing through the winding Ua of the motor 4. The inverter circuit 3a may include a choke coil that suppresses noise emission to the outside of the drive device 1 and noise inflow to the inside of the drive device 1.

[0034] Next, the arrangement of each component included in the drive device 1 will be described. As shown in FIG. 2 , the CPU 10, FET driver circuit 11, input circuit 12, and power supply circuit 13 of the control circuit 5 are mounted on the wiring board 20. The CPU 10 and power supply circuit 13 are mounted on the first surface 20a of the wiring board 20. The FET driver circuit 11 and input circuit 12 are mounted on the second surface 20b of the wiring board 20. Note that the CPU 10 may also be mounted on the second surface 20b. The power supply circuit 13 may also be mounted on the second surface 20b. The FET driver circuit 11 may also be mounted on the first surface 20a. The input circuit 12 may also be mounted on the first surface 20a.

[0035] 3 is a plan view showing the schematic shape of the wiring board 20 and the arrangement of components mounted on the wiring board 20. Note that FIG. 3 is a view of the wiring board 20 as seen from the first surface 20a side. Components mounted on the first surface 20a are indicated by solid lines, and components mounted on the second surface 20b are indicated by dashed lines. In FIG. 3, the components of the control circuit 5 are not shown.

[0036] Three upper-arm switching elements 31au, 31av, and 31aw and three lower-arm switching elements 32au, 32av, and 32aw corresponding to the U, V, and W phases are mounted on the first surface 20a of the wiring board 20. The upper-arm switching elements 31au, 31av, and 31aw and the lower-arm switching elements 32au, 32av, and 32aw are arranged on the outer periphery of the wiring board 20. In a plan view, the upper-arm switching elements 31au, 31av, and 31aw and the lower-arm switching elements 32au, 32av, and 32aw are arranged along the first side edge 20c and the fourth side edge 20f (the outer periphery of the wiring board 20). A rotation sensor 14 is mounted on the second surface 20b of the wiring board 20. The rotation sensor 14 is arranged in the center of the wiring board 20. In a plan view, the rotation sensor 14 is disposed at a position overlapping the motor shaft C. That is, the upper arm switching elements 31au, 31av, 31aw and the lower arm switching elements 32au, 32av, 32aw are disposed at a distance from the rotation sensor 14.

[0037] When a motor relay switching element is provided, the motor relay switching element is mounted on the first surface 20a of the wiring board 20. For example, the motor relay switching element may be disposed between the current supply holes 22au, 22av, 22aw and the rotation sensor 14. The motor relay switching element is preferably disposed in a position close to the current supply holes 22au, 22av, 22aw.

[0038] As described above, the drive device 1 according to this embodiment includes a motor 4 having a rotating shaft 43, a rotor 42 fixed to the rotating shaft 43, and three-phase windings Ua, Va, and Wa that rotate the rotor 42 about the motor axis C when a current flows through them, and a control unit 2 attached to the motor 4 and controlling the current supplied to the three-phase windings Ua, Va, and Wa. The control unit 2 includes an inverter circuit 3a that includes a plurality of switching elements 31au, 31av, 31aw, 32au, 32av, and 32aw and is capable of supplying current to the three-phase windings Ua, Va, and Wa, a rotation sensor 14 that detects the rotation angle of the rotating shaft 43, and a wiring board 20 on which the inverter circuit 3a and the rotation sensor 14 are mounted. In a plan view, the rotation sensor 14 is disposed at a position overlapping the motor shaft C, and the multiple switching elements 31au, 31av, 31aw, 32au, 32av, 32aw are disposed along the outer periphery of the wiring board 20. The electric power steering device 100 according to this embodiment also includes a drive device 1.

[0039] With this configuration, the switching elements 31au, 31av, 31aw, 32au, 32av, and 32aw can be disposed at a distance from the rotation sensor 14. Therefore, the influence of noise generated from the switching elements 31au, 31av, 31aw, 32au, 32av, and 32aw of the inverter circuit 3a on the rotation sensor 14 can be reduced.

[0040] Control unit 2 also has an FET driver circuit 11 that outputs a signal to drive inverter circuit 3a, an input circuit 12 that receives an external signal, a CPU 10 that controls FET driver circuit 11 based on the signal from input circuit 12, and a power supply circuit 13 that supplies power supply voltage to FET driver circuit 11, input circuit 12, and CPU 10. FET driver circuit 11, input circuit 12, CPU 10, and power supply circuit 13 are mounted on wiring board 20. Because FET driver circuit 11, input circuit 12, CPU 10, and power supply circuit 13 are also mounted on wiring board 20 on which inverter circuit 3a and rotation sensor 14 are mounted, drive device 1 can be made smaller.

[0041] Embodiment 2 Next, a description will be given of a drive unit and an electric power steering device according to embodiment 2. The drive unit and electric power steering device according to this embodiment have the same basic configuration as the drive unit and electric power steering device according to embodiment 1, and therefore differences will be mainly described.

[0042] As shown in FIG. 4 , in this embodiment, the motor 4 has two sets of three-phase windings (three-phase coils). Specifically, the motor 4 has second three-phase windings Ub, Vb, and Wb in addition to three-phase windings Ua, Va, and Wa. The second three-phase windings Ub, Vb, and Wb are delta-connected. The second three-phase windings Ub, Vb, and Wb may also be star-connected. The drive device 1 further includes a second inverter circuit 3b that supplies power to the second three-phase windings Ub, Vb, and Wb, and a second FET driver circuit 15 (second pre-driver) that drives the second inverter circuit 3b. In the example shown in FIG. 4 , the inverter circuit 3a and the second inverter circuit 3b are connected to a common battery 9 and ground. However, the second inverter circuit 3b may be connected to a battery and ground of a different system.

[0043] The terminal group 44 of the motor 4 includes three first terminals corresponding to the three-phase windings Ua, Va, and Wa, respectively, as well as three second terminals corresponding to the second three-phase windings Ub, Vb, and Wb, respectively.

[0044] 5 , in addition to the three current supply holes 22au, 22av, and 22aw, the wiring substrate 20 is formed with three second current supply holes 22bu, 22bv, and 22bw (three-phase second current supply holes) corresponding to the U, V, and W phases, respectively. The three second current supply holes 22bu, 22bv, and 22bw are arranged on the outer periphery of the wiring substrate 20. In a plan view, the three second current supply holes 22bu, 22bv, and 22bw are arranged along the second side edge 20d (the outer periphery of the wiring substrate 20). The three second current supply holes 22bu, 22bv, and 22bw are arranged in the first orthogonal direction X.

[0045] The U-phase second terminal corresponding to the second winding Ub is inserted into the U-phase second current supply hole 22bu. The V-phase second terminal corresponding to the second winding Vb is inserted into the V-phase second current supply hole 22bv. The W-phase second terminal corresponding to the second winding Wb is inserted into the W-phase second current supply hole 22bw. Current is supplied from the second inverter circuit 3b to the second three-phase windings Ub, Vb, and Wb via the three second current supply holes 22bu, 22bv, and 22bw and the three second terminals. This causes the rotating shaft 43 to rotate. The three second terminals may be ends of the second three-phase windings Ub, Vb, and Wb, or may be relay members electrically connected to the ends of the second three-phase windings Ub, Vb, and Wb.

[0046] In plan view, the current supply holes 22au, 22av, 22aw are arranged in the following order toward the +X side (one side in the first orthogonal direction X): U-phase current supply hole 22au, V-phase current supply hole 22av, W-phase current supply hole 22aw. In plan view, the three second current supply holes 22bu, 22bv, 22bw are arranged in the following order toward the −X side (the other side in the first orthogonal direction X): U-phase second current supply hole 22bu, V-phase second current supply hole 22bv, W-phase second current supply hole 22bw. In plan view, the three current supply holes 22au, 22av, 22aw and the three second current supply holes 22bu, 22bv, 22bw are arranged such that the first current supply hole and the second current supply hole of the corresponding phase are point-symmetrical with respect to the motor axis C. More specifically, in a plan view, the U-phase current supply hole 22au and the second current supply hole 22bu are arranged symmetrically with respect to a point around the motor axis C, the V-phase current supply hole 22av and the second current supply hole 22bv are arranged symmetrically with respect to a point around the motor axis C, and the W-phase current supply hole 22aw and the second current supply hole 22bw are arranged symmetrically with respect to a point around the motor axis C. Note that it is only necessary that the first current supply hole and the second current supply hole of the corresponding phase are arranged symmetrically with respect to a point around the motor axis C in a plan view, and the arrangement order of the current supply holes 22au, 22av, and 22aw toward the +X side is not limited to the U-phase, V-phase, and W-phase order, and the arrangement order of the second current supply holes 22bu, 22bv, and 22bw toward the −X side is not limited to the U-phase, V-phase, and W-phase order.

[0047] The circuit configuration of the second inverter circuit 3b is similar to that of the inverter circuit 3a. Specifically, the second inverter circuit 3b has three upper arms and three lower arms corresponding to the U, V, and W phases. The circuit configurations for the U, V, and W phases in the second inverter circuit 3b are similar. The U phase will be described as a representative of the three phases. The second inverter circuit 3b includes a second smoothing capacitor 30bu, a second upper-arm switching element 31bu, a second lower-arm switching element 32bu, a second motor relay switching element 33bu, and a second shunt resistor 34bu. The second upper-arm switching element 31bu is disposed in the upper arm, and the second lower-arm switching element 32bu is disposed in the lower arm. The second upper-arm switching element 31bu is electrically connected to the positive electrode of the battery 9, and the second lower-arm switching element 32bu is electrically connected to the negative electrode of the battery 9. The second upper-arm switching element 31bu and the second lower-arm switching element 32bu are connected in series. The second motor relay switching element 33bu is connected between the second upper-arm switching element 31bu and the second lower-arm switching element 32bu. The second motor relay switching element 33bu has a relay function. That is, the second motor relay switching element 33bu switches on and off the power supply from the portion between the second upper-arm switching element 31bu and the second lower-arm switching element 32bu to the winding Ub of the motor 4. The second upper-arm switching element 31bu and the second lower-arm switching element 32bu are operated by the second FET driver circuit 15 based on the results of calculations by the CPU 10. As an example of the second upper-arm switching element 31bu, the second lower-arm switching element 32bu, and the second motor relay switching element 33bu, a field effect transistor (FET) can be adopted. Note that the second motor relay switching element 33bu may be omitted.

[0048] The second smoothing capacitor 30bu is connected near the second upper-arm switching element 31bu and the second lower-arm switching element 32bu. The second smoothing capacitor 30bu has a function of suppressing power supply voltage fluctuations and noise during switching. The second shunt resistor 34bu is connected directly between the second lower-arm switching element 32bu and ground. The second shunt resistor 34bu is used to detect the drive current flowing through the second winding Ub of the motor 4. The second inverter circuit 3b may include a choke coil that suppresses noise emission to the outside of the drive device 1 and noise inflow to the inside of the drive device 1.

[0049] 5 , three second upper-arm switching elements 31bu, 31bv, and 31bw and three second lower-arm switching elements 32bu, 32bv, and 32bw corresponding to the U, V, and W phases are mounted on the first surface 20a of the wiring substrate 20. The three second upper-arm switching elements 31bu, 31bv, and 31bw and the three second lower-arm switching elements 32bu, 32bv, and 32bw are arranged on the outer periphery of the wiring substrate 20. In a plan view, the three second upper-arm switching elements 31bu, 31bv, and 31bw and the three second lower-arm switching elements 32bu, 32bv, and 32bw are arranged along the second side edge 20d and the fourth side edge 20f (the outer periphery of the wiring substrate 20). That is, the three second upper-arm switching elements 31bu, 31bv, and 31bw and the three second lower-arm switching elements 32bu, 32bv, and 32bw are arranged at a distance from the rotation sensor 14.

[0050] As described above, in this embodiment, the control unit 2 further includes a second inverter circuit 3b that includes a plurality of second switching elements 31bu, 31bv, 31bw, 32bu, 32bv, and 32bw and is capable of supplying current to the motor 4 via a path different from that of the inverter circuit 3a. In a plan view, the plurality of second switching elements 31bu, 31bv, 31bw, 32bu, 32bv, and 32bw are arranged along the outer periphery of the wiring board 20. This allows the motor 4 to continue to be driven even if a malfunction occurs in one inverter circuit, ensuring system redundancy. Furthermore, the second switching elements 31bu, 31bv, 31bw, 32bu, 32bv, and 32bw can be arranged away from the rotation sensor 14. Therefore, the influence of noise generated from the second switching elements 31bu, 31bv, 31bw, 32bu, 32bv, and 32bw of the second inverter circuit 3b on the rotation sensor 14 can be reduced.

[0051] The wiring board 20 also has three-phase current supply holes 22au, 22av, 22aw electrically connected to the three-phase windings Ua, Va, Wa, and three-phase second current supply holes 22bu, 22bv, 22bw electrically connected to the second three-phase windings Ub, Vb, Wb. The three-phase current supply holes 22au, 22av, 22aw and the three-phase second current supply holes 22bu, 22bv, 22bw are provided such that the first current supply hole and the second current supply hole of the corresponding phase are arranged point-symmetrically with respect to the motor axis C in a plan view. This causes the magnetic field generated from the wiring (e.g., the first terminal) corresponding to the current supply holes 22au, 22av, and 22aw to cancel out the magnetic field generated from the wiring (e.g., the second terminal) corresponding to the second current supply holes 22bu, 22bv, and 22bw, thereby reducing the effect of the magnetic field on the rotation sensor 14.

[0052] Furthermore, in a plan view, the three-phase current supply holes 22au, 22av, 22aw and the three-phase second current supply holes 22bu, 22bv, 22bw are arranged along the outer periphery of the wiring board 20. This allows the three-phase current supply holes 22au, 22av, 22aw and the three-phase second current supply holes 22bu, 22bv, 22bw to be arranged apart from the rotation sensor 14. This reduces the effect on the rotation sensor 14 of noise generated from the current supply holes 22au, 22av, 22aw and the second current supply holes 22bu, 22bv, 22bw and the wiring corresponding thereto.

[0053] Embodiment 3 Next, a description will be given of a drive unit and an electric power steering device according to Embodiment 3. The drive unit and electric power steering device according to this embodiment have the same basic configuration as the drive unit and electric power steering device according to Embodiment 2, and therefore differences will be mainly described.

[0054] In this embodiment, FET driver circuit 11, second FET driver circuit 15, input circuit 12, CPU 10, and power supply circuit 13 of control circuit 5 are arranged in region R1 shown in Fig. 6 on wiring board 20. Region R1 is a region on wiring board 20 that is surrounded by switching elements 31au, 31av, 31aw, 32au, 32av, and 32aw of inverter circuit 3a, current supply holes 22au, 22av, and 22aw, second switching elements 31bu, 31bv, 31bw, 32bu, 32bv, and 32bw of second inverter circuit 3b, and second current supply holes 22bu, 22bv, and 22bw. This allows the FET driver circuit 11, second FET driver circuit 15, input circuit 12, CPU 10, and power supply circuit 13 of the control circuit 5 to be arranged in the center of the wiring board 20, making effective use of the board area.

[0055] The technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

[0056] For example, a power supply relay switching element and a reverse connection protection relay switching element may be provided in series between the battery 9 and the inverter circuit 3a. The parasitic diode of the reverse connection protection relay switching element is connected in the opposite direction to the parasitic diode of the power supply relay switching element. The power supply relay switching element switches between supplying and cutting off current from the battery 9 to the inverter circuit 3a. The reverse connection protection relay switching element protects the inverter circuit 3a from reverse current flow if the battery 9 voltage (+B) and ground are mistakenly connected in reverse when the battery 9 is installed in a vehicle. In this case, in the second and third embodiments, the inverter circuit 3a and the second inverter circuit 3b may use a common power supply relay switching element and reverse connection protection relay switching element, or two systems of power supply relay switching elements and reverse connection protection relay switching elements may be used.

[0057] For example, the drive device 1 may be used for purposes other than the electric power steering device 100. In addition, the above-described embodiments and modifications may be combined as appropriate.

[0058] DESCRIPTION OF SYMBOLS 1... Drive device 2... Control unit 3a... Inverter circuit 3b... Second inverter circuit 4... Motor 10... CPU 11... FET driver circuit (pre-driver) 12... Input circuit 13... Power supply circuit 14... Rotation sensor 15... Second FET driver circuit (second pre-driver) 20... Wiring board 22au, 22av, 22aw... Current supply hole (first power supply hole) 22bu, 22bv, 22bw... Second current supply hole 31au, 31av, 31aw... Upper arm switching element (switching element) 32au, 32av, 32aw... Lower arm switching element (switching element) 31bu, 31bv, 31bw... Second upper arm switching element (second switching element) 32bu, 32bv, 32bw... Second lower arm switching element (second switching element) 41... Stator 42... Rotor 43... Rotating shaft Ua, Va, Wa... Windings (first windings) Ub, Vb, Wb... Second windings

Claims

1. A motor having a rotating shaft, a rotor fixed to the rotating shaft, and a winding that rotates the rotor about a motor axis when an electric current flows through it; A control unit attached to the motor and controlling the current supplied to the winding; Comprising: The control unit: An inverter circuit including a plurality of switching elements and capable of supplying current to the winding; A rotation sensor that detects the rotation angle of the rotating shaft; A wiring board on which the inverter circuit and the rotation sensor are mounted; Comprising: In a plan view, the rotation sensor is disposed at a position overlapping the motor axis, and the plurality of switching elements are disposed along the outer peripheral edge of the wiring board. A drive device.

2. The control unit: A pre-driver that outputs a signal for driving the inverter circuit; An input circuit to which an external signal is input; A CPU that controls the pre-driver based on a signal from the input circuit; A power supply circuit that supplies a power supply voltage to the pre-driver, the input circuit, and the CPU; Further comprising: The pre-driver, the input circuit, the CPU, and the power supply circuit are mounted on the wiring board. The drive device according to claim 1.

3. The control unit: Further comprising a second inverter circuit including a plurality of second switching elements and capable of supplying current to the motor through a path different from that of the inverter circuit; Further comprising: In a plan view, the plurality of second switching elements are disposed along the outer peripheral edge of the wiring board. The drive device according to claim 1 or 2.

4. The winding includes a first three-phase winding to which current is supplied from the inverter circuit and a second three-phase winding to which current is supplied from the second inverter circuit; The wiring board has three-phase first current supply holes electrically connected to the first three-phase winding and three-phase second current supply holes electrically connected to the second three-phase winding; The three-phase first current supply holes and the three-phase second current supply holes are provided such that, in a plan view, the first current supply hole and the second current supply hole of the corresponding phase are disposed point-symmetrically about the motor axis. The drive device according to claim 3.

5. In a plan view, the three-phase first current supply holes and the three-phase second current supply holes are disposed along the outer peripheral edge of the wiring board. The drive device according to claim 4.

6. The control unit includes: a pre-driver that outputs a signal for driving the inverter circuit; a second pre-driver that outputs a signal for driving the second inverter circuit; an input circuit to which a signal from the outside is input; a CPU that controls the pre-driver and the second pre-driver based on the signal from the input circuit; a power supply circuit that supplies a power supply voltage to the rotation sensor, the pre-driver, the second pre-driver, the input circuit, and the CPU; and further includes: the pre-driver, the second pre-driver, the input circuit, the CPU, and the power supply circuit are mounted on the wiring board; in a plan view, the pre-driver, the second pre-driver, the input circuit, the CPU, and the power supply circuit are arranged in a region surrounded by the plurality of switching elements, the three-phase first current supply holes, the plurality of second switching elements, and the three-phase second current supply holes; The driving device according to claim 5.

7. An electric power steering device including the driving device according to claim 1 or 2.