JP6825376B2 - Motor control device, electric power steering device and vehicle - Google Patents

Description

The present invention relates to a motor control device, an electric power steering device, and a vehicle.

The vehicle is equipped with an electric power steering device that assists steering by the auxiliary steering force generated by the motor. The electric power steering device includes a motor control device for controlling the motor. For example, Patent Document 1 describes an example of a motor control device. The motor control device described in Patent Document 1 estimates the motor electric angle based on the induced voltage, and controls the motor based on the estimated motor electric angle. As a result, it is possible to control the motor when there is no motor rotation angle sensor (resolver or the like) or when the motor rotation angle sensor fails.

Japanese Unexamined Patent Publication No. 2012-232624

However, when the motor electric angle is calculated based only on the induced voltage, there is a limit to improving the estimation accuracy of the motor electric angle. Therefore, even when there is no motor rotation angle sensor or when the motor rotation angle sensor fails, a motor control device having improved resolution of the motor electric angle estimated from the induced voltage has been required.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a motor control device, an electric power steering device, and a vehicle in which the resolution of the motor electric angle estimated from the induced voltage is improved. ..

In order to achieve the above object, the motor control device according to one aspect of the present invention includes a current detection unit that detects a current flowing through each of the polyphase coils of the driven polyphase electric motor, and the polyphase coil. A voltage detection unit that detects each voltage, and an induced voltage calculation unit that calculates the interphase induced voltage of the multi-phase electric motor based on the current detected by the current detection unit and the voltage detected by the voltage detection unit. , A virtual interphase induced voltage calculation unit that calculates a virtual interphase induced voltage whose phase or frequency is different from that of the interphase induced voltage based on the interphase induced voltage calculated by the induced voltage calculation unit, and the interphase induced voltage and virtual phase induced Based on the switching timing detection unit that detects the timing at which each of the voltages or the pair of magnitude relations and code relations of the virtual phase induced voltage switches to another pair of magnitude relations and code relations, and the detection result by the switching timing detection unit. It includes a motor electric angle estimation unit that estimates the motor electric angle of the multi-phase electric motor.

As a result, at the timing when the voltage magnitude-related and code-related sets are switched to other magnitude-related and code-related sets, the voltage magnitude-related and code-related sets correspond to the other magnitude-related and code-related sets. It can be estimated that it is an electric angle. Therefore, the motor control device can improve the resolution of the motor electric angle estimated from the induced voltage without depending on the motor rotation angle sensor.

As a desirable embodiment of the motor control device, the virtual phase induced voltage calculation unit calculates two virtual phase induced voltages having different phases, and the switching timing detection unit calculates each of the interphase induced voltage and the virtual phase induced voltage. It is preferable to detect the timing at which the magnitude relation and the code relation set are switched to another magnitude relation and the code relation set.

The motor electric angle can be estimated with higher resolution by combining the magnitude relation and the sign relation of the induced voltages between two virtual phases having different phases. Therefore, the motor control device can improve the resolution of the motor electric angle estimated from the induced voltage without depending on the motor rotation angle sensor.

As a preferred embodiment of the motor control device, the multi-phase electric motor is a three-phase electric motor, and one of the two virtual interphase induced voltages applies a double angle formula to a trigonometric function indicating the interphase induced voltage. The virtual interphase induced voltage corresponding to the trigonometric function thus obtained, and the other of the two virtual phase induced voltages is a trigonometric function indicating a voltage obtained by shifting the phase of the interphase induced voltage by 37.5 degrees. It is preferable that the virtual phase induced voltage corresponds to the trigonometric function obtained by applying the double angle formula.

As a result, the motor electric angle can be estimated with a resolution of 7.5 °.

As a desirable embodiment of the motor control device, it is preferable that the virtual phase-induced voltage calculation unit calculates the virtual-phase induced voltage having a frequency twice that of the interphase induced voltage.

By doubling the frequency of the virtual interphase induced voltage, the motor electric angle can be estimated with twice the resolution as compared with the interphase induced voltage. Therefore, the motor control device can improve the resolution of the motor electric angle estimated from the induced voltage without depending on the motor rotation angle sensor.

The electric power steering device according to one aspect of the present invention includes a steering having a multi-phase electric motor that generates a steering assist force, a steering angle detection unit that detects the steering angle of the steering, and any one of claims 1 to 4. The motor control device according to item 1, a motor drive circuit that supplies a drive current to the multi-phase electric motor, and a control calculation device that drives and controls the motor drive circuit based on the motor electric angle of the multi-phase electric motor. The control calculation device is based on the motor electric angle estimated by the motor electric angle estimation unit and the motor electric angle estimated from the steering angle detected by the steering steering angle detection unit. The multi-phase electric motor is driven by feedback control.

As a result, it is estimated more accurately than when only one of the motor electric angle estimated by the motor electric angle estimation unit and the motor electric angle estimated from the steering angle detected by the steering steering angle detection unit is used. A multi-phase electric motor can be driven based on the electric angle of the motor.

The motor control device according to one aspect of the present invention estimates the motor electric angle of a multi-phase electric motor that generates steering assist force based on the steering angle detected by the steering angle detection unit that detects the steering angle of the steering wheel. A motor electric angle estimation unit and a motor electric angle correction unit that corrects the motor electric angle estimated by the motor electric angle estimation unit are provided, and the motor electric angle correction unit is driven by the multi-phase electric motor. A current detection unit that detects the current flowing through each of the polyphase coils, a voltage detection unit that detects the voltage of each of the polyphase coils, a current detected by the current detection unit, and a voltage detection unit that detects the current. An induced voltage calculation unit that calculates the interphase induced voltage of the multi-phase electric motor based on the voltage, and a virtual phase or frequency different from the interphase induced voltage based on the interphase induced voltage calculated by the induced voltage calculation unit. The virtual phase-induced voltage calculation unit that calculates the phase-to-phase induced voltage, and each of the phase-to-phase induced voltage and the virtual phase-induced voltage, or the pair of the magnitude relation and the code relation of the virtual phase induced voltage becomes another set of magnitude relation and the code relation. It has a switching timing detection unit that detects the switching timing, and a correction unit that corrects the motor electric angle estimated by the motor electric angle estimation unit based on the detection result by the switching timing detection unit.

As a result, the motor control device can obtain an estimated motor electric angle based on the output shaft rotation angle. In addition, the correction unit can correct the estimated motor electric angle. Therefore, the motor control device can estimate the motor electric angle with a higher resolution.

The electric power steering device according to one aspect of the present invention includes a multi-phase electric motor that generates steering assisting force, a motor drive circuit that supplies a drive current to the multi-phase electric motor, and a motor of the multi-phase electric motor. An electric power steering device including a control calculation device that drives and controls the motor drive circuit based on the electric angle, and a motor control device that outputs the motor electric angle. The motor control device is the motor control device described above. Is.

The motor control device can improve the resolution of the motor electric angle estimated from the induced voltage without depending on the motor rotation angle sensor. Therefore, the electric power steering device can improve the resolution of the motor electric angle estimated from the induced voltage without depending on the motor rotation angle sensor, and can give an appropriate auxiliary steering torque to the output shaft.

As a desirable embodiment of the electric power steering device, a steering steering angle detecting unit that detects the steering angle of the steering, a torque detecting unit that detects the torque transmitted to the steering mechanism, and a rotation angle of the output shaft of the multi-phase electric motor are determined. The motor electric angle detecting unit for detecting and an abnormality detecting unit for detecting an abnormality in the motor electric angle detecting unit are provided, and the control calculation device detects an abnormality in the motor electric angle detecting unit in the abnormality detecting unit. If not, the motor drive circuit is driven and controlled based on the torque detected by the torque detection unit and the motor electric angle detected by the motor electric angle detection unit, and the abnormality detection unit detects an abnormality in the motor electric angle detection unit. It is preferable to drive and control the motor drive circuit based on the motor electric angle output by the motor control device when it is detected.

As a result, the electric power steering device can obtain the motor electric angle estimated value based on the output shaft rotation angle, so that the motor electric angle estimated value can be obtained even if an abnormality occurs in the motor rotation angle sensor. Therefore, the electric power steering device according to the present embodiment can estimate the motor electric angle with a higher resolution without depending on the motor rotation angle sensor.

The vehicle according to one aspect of the present invention includes the above-mentioned electric power steering device. According to the vehicle, even if an abnormality occurs in the motor rotation angle sensor, the operator can drive the vehicle with the same steering force as in the state before the above.

According to the present invention, it is possible to provide a motor control device, an electric power steering device, and a vehicle capable of improving the resolution of the motor electric angle estimated from the induced voltage without depending on the motor rotation angle sensor.

FIG. 1 is a perspective view schematically showing a vehicle equipped with the electric power steering device according to the first embodiment. FIG. 2 is a schematic view of the electric power steering device according to the first embodiment. FIG. 3 is a perspective view schematically showing the torque sensor according to the first embodiment. FIG. 4 is a side view schematically showing the torque sensor according to the first embodiment. FIG. 5 is a cross-sectional view taken along the line AA in FIG. FIG. 6 is a cross-sectional view taken along the line BB in FIG. FIG. 7 is a schematic view showing the torque sensor according to the first embodiment using a functional block. FIG. 8 is a schematic view showing the torque sensor according to the first embodiment using a functional block. FIG. 9 is a cross-sectional view of the motor according to the first embodiment. FIG. 10 is a schematic view showing the wiring of the motor according to the first embodiment. FIG. 11 is a schematic view showing the relationship between the motor and the ECU according to the first embodiment. FIG. 12 is a schematic view showing a motor electric angle calculation unit according to the first embodiment. FIG. 13 is a schematic view showing a relative offset amount estimation unit according to the first embodiment. FIG. 14 is a schematic view showing a motor electric angle correction unit according to the first embodiment. FIG. 15 is a schematic view showing an example of the relationship between the load torque and the amount of change in the motor electric angle due to the deformation characteristics of the mechanical element of the steering force assist mechanism. FIG. 16 is a diagram showing an example of the relationship between the interphase induced voltage and the virtual interphase induced voltage. FIG. 17 is a diagram showing an interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 18 is a diagram showing a magnitude relationship and a code relationship of the voltage of the interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 19 is a diagram showing an interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 20 is a diagram showing a magnitude relationship and a code relationship of the voltage of the interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 21 is a diagram showing a magnitude relationship and a code relationship of the voltage of the interphase induced voltage waveform and the virtual interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 22 is a diagram showing a magnitude relationship and a code relationship of the voltage of the interphase induced voltage waveform and the virtual interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 23 is a diagram showing the magnitude relation and the code relation of the voltage of the interphase induced voltage waveform and the virtual interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 24 is a diagram showing the magnitude relation and the code relation of the voltage of the interphase induced voltage waveform and the virtual interphase induced voltage waveform when the motor rotates in the forward direction. FIG. 25 is a schematic view showing correction of the motor electric angle estimated value by the correction unit according to the first embodiment. FIG. 26 is a schematic view showing a configuration example of the motor control device according to the second embodiment.

Hereinafter, embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. In addition, the components in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, that is, those in a so-called equal range. Further, the components disclosed in the following embodiments can be appropriately combined.

(Embodiment 1)
FIG. 1 is a perspective view schematically showing a vehicle equipped with the electric power steering device according to the first embodiment. FIG. 2 is a schematic view of the electric power steering device according to the first embodiment. As shown in FIG. 1, the vehicle 101 is equipped with an electric power steering device 80. As shown in FIG. 2, the electric power steering device 80 includes a steering wheel 81, a steering shaft 82, a steering force assist mechanism 83, a universal joint 84, and a lower shaft 85 in the order in which the force given by the operator is transmitted. And a universal joint 86, which are joined to the pinion shaft 87. Further, the electric power steering device 80 includes an ECU (Electronic Control Unit) 90 as a motor control device and a torque sensor 94. The vehicle speed sensor 95 is provided on the vehicle body and outputs the vehicle speed V to the ECU 90 as a signal by CAN (Controller Area Network) communication.

As shown in FIG. 2, the steering shaft 82 includes an input shaft 82a and an output shaft 82b. One end of the input shaft 82a is connected to the steering wheel 81, and the other end of the input shaft 82a is connected to the output shaft 82b. Further, one end of the output shaft 82b is connected to the input shaft 82a, and the other end of the output shaft 82b is connected to the universal joint 84. In the present embodiment, the input shaft 82a and the output shaft 82b are made of carbon steel for machine structure (SC material (Carbon Steel for Machine Structural Use)) or carbon steel tube for machine structure (so-called STKM material (Carbon Steel Tubes for Machine Structural Purposes)). )) Is formed from general steel materials.

As shown in FIG. 2, the lower shaft 85 is a member connected to the output shaft 82b via the universal joint 84. One end of the lower shaft 85 is connected to the universal joint 84 and the other end is connected to the universal joint 86. Further, one end of the pinion shaft 87 is connected to the universal joint 86, and the other end of the pinion shaft 87 is connected to the steering gear 88.

As shown in FIG. 2, the steering gear 88 includes a pinion 88a and a rack 88b. The pinion 88a is connected to the pinion shaft 87. The rack 88b meshes with the pinion 88a. The steering gear 88 converts the rotational motion transmitted to the pinion 88a into a straight motion by the rack 88b. The rack 88b is connected to the tie rod 89.

As shown in FIG. 2, the steering force assist mechanism 83 includes a speed reducing device 92 and a motor 93. The motor 93 is, for example, a brushless motor. The motor 93 is a sine wave-driven three-phase AC motor. The speed reducer 92 is, for example, a worm speed reducer. The torque generated by the motor 93 is transmitted to the worm wheel via the worm inside the speed reducer 92 to rotate the worm wheel. The speed reducer 92 increases the torque generated by the motor 93 by means of a worm and a worm wheel (worm gear). Then, the reduction gear 92 applies an auxiliary steering torque to the output shaft 82b. The electric power steering device 80 is a column assist system.

The steering torque (including auxiliary steering torque) output via the output shaft 82b is transmitted to the lower shaft 85 via the universal joint 84, and further transmitted to the pinion shaft 87 via the universal joint 86. The steering torque transmitted to the pinion shaft 87 is transmitted to the tie rod 89 via the steering gear 88 to displace the wheels.

The ECU 90 is a device that controls the operation of the motor 93. With the ignition switch 98 turned on, power is supplied to the ECU 90 from the power supply device 99 (for example, an in-vehicle battery). The ECU 90 acquires signals from the torque sensor 94, the vehicle speed sensor 95, and the rotation detection unit 23a (see FIG. 11). Specifically, the ECU 90 acquires the steering torque T from the torque sensor 94. The ECU 90 acquires the vehicle speed V of the vehicle body from the vehicle speed sensor 95. The ECU 90 acquires the information output from the rotation detection unit 23a as the operation information Y. The ECU 90 calculates the auxiliary steering command value based on the steering torque T, the vehicle speed V, and the operation information Y. Then, the ECU 90 adjusts the power value X to be supplied to the motor 93 based on the calculated auxiliary steering command value.

FIG. 3 is a perspective view schematically showing the torque sensor according to the first embodiment. FIG. 4 is a side view schematically showing the torque sensor according to the first embodiment. FIG. 5 is a cross-sectional view taken along the line AA in FIG. FIG. 6 is a cross-sectional view taken along the line BB in FIG. The torque sensor 94 detects the steering torque T transmitted to the input shaft 82a. Specifically, as shown in FIG. 3, the torque sensor 94 includes a torsion bar 82c, a first multi-pole ring magnet 10, a second multi-pole ring magnet 11, an input shaft rotation angle sensor 12, and an output shaft rotation. It includes an angle sensor 13. The torsion bar 82c is, for example, an elastic member made of a steel material. The torsion bar 82c connects the input shaft 82a and the output shaft 82b.

The first multi-pole ring magnet 10 and the second multi-pole ring magnet 11 have, for example, alternately arranged S poles and N poles on the outer peripheral surface. For the first multi-pole ring magnet 10 and the second multi-pole ring magnet 11, for example, neodymium magnets, ferrite magnets, samarium-cobalt magnets, and the like are used depending on the required magnetic flux density. The first multi-pole ring magnet 10 is attached to, for example, the end of the input shaft 82a on the output shaft 82b side, and rotates together with the input shaft 82a. The second multi-pole ring magnet 11 is attached to, for example, the end of the output shaft 82b on the input shaft 82a side, and rotates together with the output shaft 82b.

The input shaft rotation angle sensor 12 detects the input shaft rotation angle θ _is (rotation angle of the first multipole ring magnet 10), which is the rotation angle of the input shaft 82a. The input shaft rotation angle sensor 12 is fixed to the vehicle body, for example. The input shaft rotation angle sensor 12 outputs a sin signal and a cos signal according to the rotation angle of the first multi-pole ring magnet 10. As shown in FIG. 3, the input shaft rotation angle sensor 12 includes a first sin magnetic sensor 14 and a first cos magnetic sensor 15. The first sin magnetic sensor 14 and the first cos magnetic sensor 15 face the outer peripheral surface of the first multipole ring magnet 10. The first cos magnetic sensor 15 is arranged so as to have a phase difference of 90 ° with respect to the first sin magnetic sensor 14 at the electric angle of the first multipole ring magnet 10. The first sin magnetic sensor 14 outputs sin θ _is according to the rotation angle of the first multi-pole ring magnet 10. The first cos magnetic sensor 15 outputs cos θ _is according to the rotation angle of the first multi-pole ring magnet 10.

The output shaft rotation angle sensor 13 detects the output shaft rotation angle θ _os (rotation angle of the second multipole ring magnet 11), which is the rotation angle of the output shaft 82b. The output shaft rotation angle sensor 13 is fixed to the vehicle body, for example. The output shaft rotation angle sensor 13 outputs a sin signal and a cos signal according to the rotation angle of the second multipole ring magnet 11. As shown in FIG. 3, the output shaft rotation angle sensor 13 includes a second sin magnetic sensor 16 and a second cos magnetic sensor 17. The second sin magnetic sensor 16 and the second cos magnetic sensor 17 face the outer peripheral surface of the second multipole ring magnet 11. The second cos magnetic sensor 17 is arranged so as to have a phase difference of 90 ° with respect to the second sin magnetic sensor 16 at the electric angle of the second multipole ring magnet 11. The second sin magnetic sensor 16 outputs sin θ _os according to the rotation angle of the second multipole ring magnet 11. The second cos magnetic sensor 17 outputs cos θ _os according to the rotation angle of the second multipole ring magnet 11.

For the first sin magnetic sensor 14, the first cos magnetic sensor 15, the second sin magnetic sensor 16, and the second cos magnetic sensor 17, for example, a Hall element, a Hall IC, an MR (Magneto Resistance effect) sensor, or the like is used.

7 and 8 are schematic views showing the torque sensor according to the first embodiment using a functional block. As shown in FIG. 7, a relative angle calculation unit 18 and a torque calculation unit 19 are provided.

The relative angle calculation unit 18 is based on the signals input from the input shaft rotation angle sensor 12 and the output shaft rotation angle sensor 13, and the relative angle of the output shaft 82b with respect to the input shaft 82a (the second multiple with respect to the first multi-pole ring magnet 10). The relative angle of the pole ring magnet 11) is calculated, and the calculation result is output to the torque calculation unit 19 as the relative angle Δθ _io . Specifically, as shown in FIG. 8, the relative angle calculation unit 18 includes an input shaft rotation angle calculation unit 181, an output shaft rotation angle calculation unit 182, and a difference calculation unit 183.

The input shaft rotation angle computing unit 181, cos [theta] _IS output from the sin [theta _IS and the 1cos magnetic sensor 15 output from the first 1sin magnetic sensor 14 is inputted. The input shaft rotation angle calculation unit 181 calculates the input shaft rotation angle θ _is (rad) by the inverse tangent function of the value obtained by dividing sin θ _is by cos θ _is, that _is , the following equation (1).

The output shaft rotation angle computing unit 182, cos [theta] _os output from the sin [theta _os and the 2cos magnetic sensor 17 output from the first 2sin magnetic sensor 16 are inputted. The output shaft rotation angle calculation unit 182 calculates the output shaft rotation angle θ _os (rad) by the inverse trigonometric function of the value obtained by dividing sin θ _os by cos θ _os , that is, the following equation (2).

The input shaft rotation angle θ _is output from the input shaft rotation angle calculation unit 181 and the output shaft rotation angle θ _os output from the output shaft rotation angle calculation unit 182 are input to the difference calculation unit 183. The difference calculation unit 183 outputs the difference between the input shaft rotation angle θ _is and the output shaft rotation angle θ _{os to} the torque calculation unit 19 as a relative angle Δθ _io .

The torque calculation unit 19 calculates the steering torque T based on the relative angle Δθ _io input from the relative angle calculation unit 18. For example, the torque calculation unit 19 stores the relationship between the relative angle Δθ _io and the steering torque T, which is determined by the characteristics of the torsion bar 82c. The torque calculation unit 19 calculates the steering torque T based on the relative angle Δθ _io input from the relative angle calculation unit 18 and the relationship between the stored relative angle Δθ _io and the steering torque T.

FIG. 9 is a cross-sectional view of the motor according to the first embodiment. FIG. 10 is a schematic view showing the wiring of the motor according to the first embodiment. As shown in FIG. 9, the motor 93 includes a housing 930, a stator 931 and a rotor 932. The stator 931 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 peripheral surface of the back yoke 931a. Twelve teeth 931b are arranged in the circumferential direction. The 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 number of magnets 932b is, for example, eight.

As shown in FIG. 9, the first coil 37 is centrally wound around each of the plurality of teeth 931b. The first coil 37 is centrally wound around the outer circumference of the teeth 931b via an insulator. All the first coils 37 are included in the first coil system, which is a system excited by the first inverter 27 (see FIG. 11). The first coil system includes, for example, six first coils 37. The six first coils 37 are arranged so that the two first coils 37 are adjacent to each other in the circumferential direction. Three first coil groups Gr1 in which adjacent first coils 37 are grouped are arranged at equal intervals in the circumferential direction. That is, the first coil system includes three first coil groups Gr1 arranged at equal intervals in the circumferential direction. The first coil group Gr1 does not necessarily have to be three, and it is sufficient that three first coil groups Gr1 are arranged at equal intervals in the circumferential direction when n is a natural number. Further, it is desirable that n is an odd number.

As shown in FIG. 9, the second coil 38 is centrally wound around each of the plurality of teeth 931b. The second coil 38 is centrally wound around the outer circumference of the teeth 931b via an insulator. The teeth 931b in which the second coil 38 is centrally wound is a teeth 931b different from the teeth 931b in which the first coil 37 is centrally wound. All the second coils 38 are included in the second coil system, which is a system excited by the second inverter 29 (see FIG. 11). The second coil system includes, for example, six second coils 38. The six second coils 38 are arranged so that the two second coils 38 are adjacent to each other in the circumferential direction. Three second coil groups Gr2, in which adjacent second coils 38 are grouped together, are arranged at equal intervals in the circumferential direction. That is, the second coil system includes three second coil groups Gr2 arranged at equal intervals in the circumferential direction. The number of the second coil groups Gr2 does not necessarily have to be three, and it is sufficient that three second coil groups Gr2 are arranged at equal intervals in the circumferential direction when n is a natural number. Further, it is desirable that n is an odd number.

As shown in FIG. 10, the six first coils 37 are the two first U phase coils 37Ua and the first U phase coil 37Ub excited by the first U phase current I1u and the two excited by the first V phase current I1v. It includes a first V-phase coil 37Va and a first V-phase coil 37Vb, and two first W-phase coils 37Wa and a first W-phase coil 37Wb excited by a first W-phase current I1w. The 1st U phase coil 37Ub is connected in series with the 1st 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 directions of the first coil 37 with respect to the teeth 931b are all the same. Further, the 1st U phase coil 37Ub, the 1st V phase coil 37Vb and the 1st W phase coil 37Wb are joined by a star connection (Y connection).

As shown in FIG. 10, the six second coils 38 are the two second U phase coils 38Ua and the second U phase coil 38Ub excited by the second U phase current I2u and the two excited by the second V phase current I2v. It includes a second V-phase coil 38Va and a second V-phase coil 38Vb, and two second W-phase coils 38Wa and a second W-phase coil 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 directions of the second coil 38 with respect to the teeth 931b are all the same, and are the same as the winding direction of the first coil 37. Further, the second U-phase coil 38Ub, the second V-phase coil 38Vb, and the second W-phase coil 38Wb are joined by a star connection (Y connection).

As shown in FIG. 9, the three first coil groups Gr1 are composed of the first UV coil group Gr1UV, the first VW coil group Gr1VW, and the 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 adjacent to each other in the circumferential direction. The first VW coil group Gr1VW includes a first V-phase coil 37Vb and a first W-phase coil 37Wa that are adjacent to each other in the circumferential direction. The first UW coil group Gr1UW includes a first U-phase coil 37Ua and a first W-phase coil 37Wb that are adjacent to each other in the circumferential direction.

As shown in FIG. 9, the three second coil groups Gr2 are composed of 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 adjacent to each other in the circumferential direction. The second VW coil group Gr2VW includes a second V-phase coil 38Vb and a second W-phase coil 38Wa that are adjacent to each other in the circumferential direction. The second UW coil group Gr2UW includes a second U-phase coil 38Ua and a second W-phase coil 38Wb that are adjacent to each other in the circumferential direction.

The first coil 37 excited by the first U-phase current I1u faces the second coil 38 excited by the second U-phase current I2u 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. For example, as shown in FIG. 9, the first U-phase coil 37Ua faces the second U-phase coil 38Ua in the radial direction, and the first U-phase coil 37Ub faces the second U-phase coil 38Ub.

The first coil 37, which is excited by the first V-phase current I1v, faces the second coil 38, which is excited by the second V-phase current I2v, in the radial direction. For example, as shown in FIG. 9, the first V-phase coil 37Va faces the second V-phase coil 38Va and the first V-phase coil 37Vb faces the second V-phase coil 38Vb in the radial direction.

The first coil 37 excited by the first W phase current I1w faces the second coil 38 excited by the second W phase current I2w in the radial direction. For example, as shown in FIG. 9, the first W-phase coil 37Wa faces the second W-phase coil 38Wa and the first W-phase coil 37Wb faces the second W-phase coil 38Wb in the radial direction.

FIG. 11 is a schematic view showing the relationship between the motor and the ECU according to the first embodiment. As shown in FIG. 11, the ECU 90 includes a current command value calculation unit 24, a motor electric angle calculation unit 23, a first gate drive circuit 25, a second gate drive circuit 26, a first inverter 27, and a second. It includes an inverter 28. The current command value calculation unit 24 calculates the motor current command value. The motor electric angle calculation unit 23 calculates the motor electric angle θ _m and outputs it to the current command value calculation unit 24. The motor current command value output from the current command value calculation unit 24 is input to the first gate drive circuit 25 and the second gate drive circuit 26.

As shown in FIG. 11, the motor 93 includes a rotation detection unit 23a as a motor rotation angle sensor. The rotation detection unit 23a is, for example, a resolver. The detection value of the rotation detection unit 23a is supplied to the motor electric angle calculation unit 23. The motor electric angle calculation unit 23 calculates the motor electric angle θ _m based on the detection value of the rotation detection unit 23a, and outputs the motor electric angle θ _m to the current command value calculation unit 24.

The current command value calculation unit 24 includes a steering torque T detected by the torque sensor 94, a vehicle speed V detected by the vehicle speed sensor 95, and a motor electric angle θ _m output from the motor electric angle calculation unit 23. Entered. The current command value calculation unit 24 calculates the current command value based on the steering torque T, the vehicle speed V, and the motor electric angle θ _m , and outputs the current command value to the first gate drive circuit 25 and the second gate drive circuit 26.

The first gate drive circuit 25 calculates the first pulse width modulation signal based on the current command value and outputs it to the first inverter 27. The first inverter 27 switches the electric field effect transistor so as to have a three-phase current value according to the duty ratio of the first pulse width adjustment signal, and the first U phase current I1u, the first V phase current I1v, and the first W. Generates a three-phase AC including the phase current I1w. The 1st U phase current I1u excites the 1st U phase coil 37Ua and the 1st U phase coil 37Ub, the 1st V phase current I1v excites the 1st V phase coil 37V and the 1st V phase coil 37Vb, and the 1st W phase current I1w excites the 1st W. The phase coil 37Wa and the first W phase coil 37Wb are excited.

The second gate drive circuit 26 calculates the second pulse width modulation signal based on the current command value and outputs it to the second inverter 28. The second inverter 28 switches the electric field effect transistor so as to have a three-phase current value according to the duty ratio of the second pulse width adjustment signal, and the second U phase current I2u, the second V phase current I2v, and the second W Generates a three-phase AC including the 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. The phase coil 38Wa and the second W phase coil 38Wb are excited.

As shown in FIG. 11, the electric power steering device 80 includes a first current sensor 31u, a first current sensor 31v, a first current sensor 31w, and a second current sensor 33u for detecting the current value of each phase of the motor 93. , A second current sensor 33v and a second current sensor 33w are provided. For example, the first current sensor 31u, the first current sensor 31v, the first current sensor 31w, the second current sensor 33u, the second current sensor 33v, and the second current sensor 33w each have a shunt resistance. The first current sensor 31u detects the first U phase current value I _dct1U and outputs it to the motor electric angle calculation unit 23. The first current sensor 31v detects the first V phase current value I _dct1V and outputs it to the motor electric angle calculation unit 23. The first current sensor 31w detects the first W phase current value I _dct1W and outputs it to the motor electric angle calculation unit 23. The second current sensor 33u detects the second U phase current value I _dct2U and outputs it to the motor electric angle calculation unit 23. The second current sensor 33v detects the second V phase current value I _dct2V and outputs it to the motor electric angle calculation unit 23. The second current sensor 33w detects the second W phase current value I _dct2W and outputs it to the motor electric angle calculation unit 23.

In the following description, when it is not necessary to distinguish between the 1st U phase current value I _dct1U , the 1st V phase current value I _dct1V, and the 1st W phase current value I _dct1W , it may be described as the 1st current value I _d1. is there. When it is not necessary to distinguish between the second U phase current value I _dct2U , the second V phase current value I _dct2V, and the second W phase current value I _dct2W , it may be described as the second current value I _d2 . When it is not necessary to distinguish between the first current sensor 31u, the first current sensor 31v, and the first current sensor 31w, it may be described as the first current sensor 31. When it is not necessary to distinguish between the second current sensor 33u, the second current sensor 33v, and the second current sensor 33w, it may be described as the second current sensor 33.

As shown in FIG. 11, the electric power steering device 80 includes a first voltage sensor 32u, a first voltage sensor 32v, a first voltage sensor 32w, and a second voltage sensor 34u for detecting each phase voltage value of the motor 93. A second voltage sensor 34v and a second voltage sensor 34w are provided. The first voltage sensor 32u detects the first U phase voltage value V _dct1U and outputs it to the motor electric angle calculation unit 23. The first voltage sensor 32v detects the first V phase voltage value V _dct1V and outputs it to the motor electric angle calculation unit 23. The first voltage sensor 32w detects the first W phase voltage value V _dct1W and outputs it to the motor electric angle calculation unit 23. The second voltage sensor 34u detects the second U phase voltage value V _dct2U and outputs it to the motor electric angle calculation unit 23. The second voltage sensor 34v detects the second V phase voltage value V _dct2V and outputs it to the motor electric angle calculation unit 23. The second voltage sensor 34w detects the second W phase voltage value V _dct2W and outputs it to the motor electric angle calculation unit 23.

In the following description, when it is not necessary to distinguish between the first U phase voltage value V _dct1U , the first V phase voltage value V _dct1V, and the first W phase voltage value V _dct1W , it may be described as the first voltage value V _d1. is there. When it is not necessary to distinguish between the second U phase voltage value V _dct2U , the second V phase voltage value V _dct2V, and the second W phase voltage value V _dct2W , it may be described as the second voltage value V _d2 . When it is not necessary to distinguish between the first voltage sensor 32u, the first voltage sensor 32v, and the first voltage sensor 32w, it may be described as the first voltage sensor 32. When it is not necessary to distinguish between the second voltage sensor 34u, the second voltage sensor 34v, and the second voltage sensor 34w, it may be described as the second voltage sensor 34.

FIG. 12 is a schematic view showing a motor electric angle calculation unit according to the first embodiment. As shown in FIG. 12, the motor electric angle calculation unit 23 includes a main motor electric angle calculation unit 23b, a submotor electric angle calculation unit 23c, an electric angle selection unit 23d, a RAM 50, and a ROM 51. The main motor electric angle calculation unit 23b includes an angle calculation unit 60 and a rotation detection abnormality diagnosis unit 61. The angle calculation unit 60 calculates the first motor electric angle θ _m1 based on the sin signal and the cos signal corresponding to the rotation angle of the motor 93 output from the rotation detection unit 23a. Then, the calculated first motor electric angle θ _m1 is output to the electric angle selection unit 23d. The rotation detection abnormality diagnosis unit 61 detects an abnormality in the rotation detection unit 23a and the angle calculation unit 60, and outputs an abnormality detection signal SAr.

The submotor electric angle calculation unit 23c calculates the second motor electric angle θ _m2 as an estimated value without using the information output from the rotation detection unit 23a. As shown in FIG. 12, the submotor electric angle calculation unit 23c includes a relative offset amount estimation unit 62, a motor electric angle estimation unit 63, and a motor electric angle correction unit 64.

Relative offset amount estimating section 62 estimates a reference value theta _osr relative offset theta _off of the output shaft rotation angle theta _os to the origin theta _md motor electrical angle theta _m. In the following description, the origin θ _md of the motor electric angle θ _m may be described as the motor electric angle origin θ _md . The reference value θ _osr is the output shaft rotation angle θ _os when the system is started (the time when the ignition switch 98 is turned from OFF to ON). Then, the relative offset amount estimation unit 62 outputs the estimated relative offset amount θ _off to the motor electric angle estimation unit 63.

FIG. 13 is a schematic view showing a relative offset amount estimation unit according to the first embodiment. As shown in FIG. 13, the relative offset amount estimation unit 62 includes a first relative offset amount estimation unit 621, a second relative offset amount estimation unit 622, and a relative offset amount selection unit 623. The first relative offset amount estimation unit 621 includes the output shaft rotation angle θ _os detected by the output shaft rotation angle sensor 13 and the main motor electric angle calculation unit when the rotation detection unit 23a and the angle calculation unit 60 are normal. The first relative offset amount θ _{off 1} is estimated based on the first motor electric angle θ _m1 detected at 23b. Then, the estimated first relative offset amount θ _off1 is stored in the _RAM 50.

When the rotation detecting unit 23a and the angle calculation unit 60 is normal, the first relative offset amount estimating section 621, it is possible to obtain a motor electric angle origin theta _md, facilitating a first relative offset theta _off1 Can be estimated to. When there is an abnormality in the rotation detection unit 23a or the angle calculation unit 60, the first relative offset amount estimation unit 621 cannot acquire the motor electric angle origin θ _md . A second relative offset amount estimation unit 622 and a relative offset amount selection unit 623 are provided in case there is an abnormality in the rotation detection unit 23a or the angle calculation unit 60.

The second relative offset amount estimation unit 622 indicates that the abnormality detection signal SA is abnormal in the initial diagnosis by the rotation detection abnormality diagnosis unit 61 when the system is restarted (the time when the ignition switch 98 changes from the OFF state to the ON state). When it is a value, the second relative offset amount θ _off2 is estimated. Specifically, the second relative offset amount estimating section 622 is configured to estimate the motor electric angle origin theta _md, it estimates a second relative offset theta _off2 based on the estimated motor electric angle origin theta _md. Then, storing a second relative offset theta _off2 estimated to RAM 50.

The second relative offset amount estimation unit 622 stores the steering torque T detected by the torque sensor 94 when the system is restarted in the RAM 50 as the torque offset amount Toff.

Next, the second relative offset amount estimation unit 622 assumes that the current motor electric angle θ _m is assumed motor electric angle θ _X, and inputs a step wave-like current corresponding to the assumed motor electric angle θ _X to the motor 93. The current output command I _oi is output to the current command value calculation unit 24 as described above. The current command value calculation unit 24 inputs a step wavy current corresponding to the assumed motor electric angle θ _X to the motor 93 in response to the input of the current output command I _oi from the submotor electric angle calculation unit 23c. The second relative offset amount estimation unit 622 acquires the steering torque T detected by the torque sensor 94 in response to the input of the step wavy current to the motor 93.

Next, the second relative offset amount estimation unit 622 subtracts the torque offset amount Toff from the acquired steering torque T. There is a possibility that the steering torque T is not 0 when the driver applies force to the steering wheel 81 when the ignition switch 98 is turned on at the time of system startup. The second relative offset amount estimation unit 622 stores the steering torque T at the time of system startup as the torque offset amount Toff in advance, and subtracts it from the steering torque T detected after the system is started.

Next, the second relative offset amount estimation unit 622 determines the symmetry of the torque waveform with respect to the steering torque T after the torque offset amount Toff is subtracted. The second relative offset amount estimation unit 622 determines whether or not the amplitudes of the torque waveforms are positive and negative and are equivalent. The second relative offset amount estimation unit 622 estimates that the motor electric angle θ _m when it is determined that the amplitudes are positive and negative and is equivalent is the motor electric angle origin θ _md .

On the other hand, when it is determined that the amplitudes of the torque waveforms are positive and negative in the steering torque T after subtraction and are not the same (the output is not as per the torque command), the motor electric angle θ _{m at} that time is the motor electric angle origin θ _md . Absent. In this case, the second relative offset amount estimation unit 622 sets the assumed motor electric angle θ _X as the assumed motor electric angle θ _X updated by shifting the assumed motor electric angle θ _X by a predetermined angle from the shapes of torque waveforms having different positive and negative amplitudes, and updates the assumed motor. The current output command I _oi is output to the current command value calculation unit 24 so that the step wavy current corresponding to the electric angle θ _X is input to the motor 93. The second relative offset amount estimation unit 622 repeatedly executes such processing until the amplitudes of the torque waveforms are determined to be positive and negative and equivalent.

Relative offset amount selector 623, when the abnormality detection signal SAr becomes a value indicating that there is abnormality during system startup, selects the first relative offset theta _off1. Relative offset amount selector 623, if the initial diagnosis abnormality detection signal SAr after a system restart is a value indicating that there is abnormality, selects the second relative offset theta _off2. The better choice of the first relative offset theta _off1 and second relative offset theta _off2 read from RAM 50, and outputs it as a relative offset theta _off the motor electrical angle estimate unit 63.

The motor electric angle estimation unit 63 includes the output shaft rotation angle θ _os detected by the output shaft rotation angle sensor 13, the reduction ratio RGr of the reduction gear 92 (see FIG. 2) and the rotor 932 (see FIG. 9) stored in advance in the ROM 51. ) And the relative offset amount θ _off estimated by the relative offset amount estimation unit 62, the motor electric angle estimated value θ _me is calculated. Then, the calculated motor electric angle estimated value θ _me is output to the motor electric angle correction unit 64.

Specifically, the motor electric angle estimation unit 63 calculates the motor electric angle estimated value θ _me (rad) according to the following equation (3).

The motor electric angle correction unit 64 corrects the motor electric angle estimated value θ _me based on the induced voltage of the motor 93. Then, the corrected motor electric angle estimated value is output to the electric angle selection unit 23d as the second motor electric angle θ _m2 .

FIG. 14 is a schematic view showing a motor electric angle correction unit according to the first embodiment. FIG. 15 is a schematic view showing an example of the relationship between the load torque and the amount of change in the motor electric angle due to the deformation characteristics of the mechanical element of the steering force assist mechanism. FIG. 16 is a schematic view showing correction of the motor electric angle estimated value by the correction unit according to the first embodiment. As shown in FIG. 14, the motor electric angle correction unit 64 includes an induced voltage calculation unit 641, a switching timing detection unit 642, an angle error calculation unit 643, and a correction unit 644.

A mechanical element such as a worm gear of the reduction gear 92 is interposed between the output shaft 82b and the motor 93. For example, the compliance characteristics of a worm gear are non-linear and have hysteresis, as shown in FIG. 15, the X axis is a load torque (motor output torque), Y axis is the change amount .delta..theta _m of the motor electrical angle theta _m. Therefore, the motor electric angle θ _m does not correspond one-to-one with the output shaft rotation angle θ _os . As the output of the motor 93 increases, the error between the estimated motor electric angle θ _me and the actual motor electric angle θ _m increases.

If the compliance characteristics of the worm gear are not taken into consideration, the output of the motor 93 causes a discrepancy between the actual motor electric angle θ _m and the motor electric angle estimated value θ _me . Therefore, the motor electric angle correction unit 64 corrects the motor electric angle estimated value θ _me based on the induced voltage.

Induced voltage calculation unit 641, between the UV phase induced voltage e _UV between the U-phase and V-phase, and VW phase induced voltage e _VW between the V phase and the W-phase, and W-phase and U-phase The WU interphase induced voltage e _WU is calculated.

Let the inductance of the first U-phase coil 37Ua and the first U-phase coil 37Ub (FIG. 10) be L (H) and the resistance be R (Ω). It is assumed that the inductance and resistance of the first V-phase coil 37Va and the first V-phase coil 37Vb and the inductance and resistance of the first W-phase coil 37Wa and the first W-phase coil 37Wb are equal to L (H) and R (Ω). The 1st U phase current value I _dct1U , the 1st V phase current value I _dct1V , and the 1st W phase current value I _dct1W shown in FIG. 11 are I _dct1U (A), I _dct1V (A), and I _dct1W (A), respectively. Suppose there is. It is _assumed that the first U phase voltage value V _dct1U , the first V phase voltage value V _dct1V , and the first W phase voltage value V _dct1W are V _dct1U (V), V _dct1V (V), and V _dct1W (V), respectively. At this time, the UV interphase induced voltage _eUV (V) is represented by the following equation (4). The VW interphase induced voltage e _VW (V) is represented by the following equation (5). The WU interphase induced voltage e _WU (V) is represented by the following equation (6).

Equations (4), (5) and (6) include terms for differentiating the current detection value. When solving the differential equation, the induced voltage calculation unit 641 approximates the differential equation with the difference equation. However, if the method of approximating the differential equation with the difference equation is used for the current detection value that tends to contain noise, the discrepancy between the calculation result by the induced voltage calculation unit 641 and the actual induced voltage value may increase. There is sex.

In the prior art, the derivative term is considered sufficiently smaller than the other terms and may be ignored. Alternatively, a low-pass filter may be used for the solution of the difference equation. However, in any case, there is a limit to reducing the dissociation between the calculation result and the actual induced voltage value.

On the other hand, the motor electric angle calculation unit 23 according to the first embodiment reduces the discrepancy between the calculation results of the equations (4), (5) and (6) and the actual induced voltage value. Can be done.

The 1U-phase current value _{I dct1U,} the 1V-phase current value _{I dct1V,} and the peak value of the 1W phase current value _{I Dct1w} and _{I p,} the motor electric angle and θ _m (rad). At this time, the first U phase current value I _dct1U (A) is represented by the following equation (7). The first V phase current value I _dct1V (A) is represented by the following equation (8). The first W phase current value I _dct1W (A) is represented by the following equation (9).

When the equations (7) and (8) are applied to the equation (4), the last term on the right side of the equation (4) is transformed as in the following equation (10). In the equation (10), Δθ _m is a term obtained by differentiating θ _m with respect to time. Δθ _m is the rate of change in the electric angle of the motor 93 (the amount of change in the electric angle per unit time). Then, by substituting the equation (10) into the equation (4), the equation (11) is obtained. In this way, the term that differentiates the current detection value is replaced with the electric angle change rate Δθ _m (rad / s) of the motor 93. Similarly, by substituting the equations (8) and (9) into the equation (5), the following equation (12) is obtained. Substituting the equations (7) and (9) into the equation (6) gives the following equation (13).

If the rotation detection unit 23a is normal, the induced voltage calculation unit 641 can calculate the electric angle change rate Δθ _m based on the information obtained from the rotation detection unit 23a. However, the induced voltage calculation unit 641 needs to calculate the electric angle change rate Δθ _m when there is an abnormality in the rotation detection unit 23a.

The induced voltage calculation unit 641 calculates the electric angle change rate Δθ _m based on, for example, the output shaft rotation angle θ _os detected by the torque sensor 94. As shown in FIG. 14, the output shaft rotation angle θ _os is input to the induced voltage calculation unit 641 from the output shaft rotation angle calculation unit 182 (see FIG. 8) of the torque sensor 94. Further, the output shaft rotation angle θ _os is input to and stored in the RAM 50. RAM50 outputs an output shaft rotation angle theta _os stored last time, the induced voltage calculation unit 641 as the previous output shaft rotation angle theta _osp. The induced voltage calculation unit 641 calculates the electric angle change rate Δθ _m based on the difference between the previous output shaft rotation angle θ _os and the current output shaft rotation angle θ _os . Specifically, assuming that the calculation cycle of the relative angle calculation unit 18 is t (s), the induced voltage calculation unit 641 calculates the electric angle change rate Δθ _m by the following equation (14).

By substituting the equation (14) into the equations (4), (5) and (6), the induced voltage calculation unit 641 induces the UV interphase induced voltage _eUV , the VW interphase induced voltage _eVW , and the WU interphase induction. Calculate the voltage e _WU . As shown in FIG. 16, the UV interphase induced voltage _eUV , the VW interphase induced voltage _eVW , and the WU interphase induced voltage _eWU are sinusoidal waves displaced by 120 ° from each other. As shown in FIG. 14, the induced voltage calculation unit 641 switches the calculated UV interphase induced voltage _eUV , VW interphase induced voltage _eVW , and WU interphase induced voltage _eWU to the timing detection unit 642.

The virtual interphase induced voltage calculation unit 645 calculates a virtual interphase induced voltage having a phase different from that of the interphase induced voltage based on the interphase induced voltage calculated by the induced voltage calculation unit 641. Here, the virtual interphase induced voltage will be described with reference to FIG. The virtual interphase induced voltage is a voltage including a zero crossing point different from the zero crossing point of the interphase induced voltage. The zero crossing point is the timing at which the UV interphase induced voltage _eUV , the VW interphase induced voltage _eVW, and the WU interphase induced voltage _eWU become reference induced voltages (for example, 0 [V]), respectively. In the present embodiment, by calculating the virtual interphase induced voltage from the interphase induced voltage, it is possible to obtain more zero cross points than the zero cross points indicated only by the interphase induced voltage. In the present embodiment, the virtual interphase induced voltage calculation unit 645 calculates the virtual interphase induced voltage for the purpose of obtaining the information indicated by these zero cross points.

FIG. 16 is a diagram showing an example of the relationship between the interphase induced voltage and the virtual interphase induced voltage. The vertical axis of the graph of the one interphase induced voltage waveform and the three virtual interphase voltage waveforms shown in FIG. 16 indicates the positive / negative and magnitude of the induced voltage, and the horizontal axis indicates the motor electric angle ([deg]). Assuming that the interphase induced voltage estimated from the voltage equation is a sine wave, the interphase induced voltage waveform drawn by the UV interphase induced voltage _eUV , VW interphase induced voltage _eVW and WU interphase induced voltage _eWU is the motor electric angle of the motor 93. As θ, it can be represented by a trigonometric function as in the following equations (15), (16) and (17), and can be illustrated as shown in the upper left graph of FIG.

By applying the double angle formulas to Eqs. (15), (16) and (17), it is possible to obtain an equation showing a virtual interphase induced voltage having more zero cross points. The double angle formula can be expressed as the following equation (18). sin (theta) can be a UV phase induced voltage _{e UV} represented by the formula (15). Further, cos (θ) can be calculated by synthesizing trigonometric functions represented by the following equation (19). From the equation (19), cos (θ) can be calculated from the VW interphase induced voltage e _VW and the WU interphase induced voltage e _WU represented by the equations (16) and (17).

The double angle formula represented by the formula (18) is expressed by the formulas (15), (16) and (17). UV interphase induced voltage e _UV , VW interphase induced voltage e _VW and WU interphase induced voltage e _WU When applied to, the equations (20), (21) and (22) are obtained. Equations (20), (21) and (22) are obtained by applying the double angle formula to the trigonometric functions showing the UV interphase induced voltage e _UV , the VW interphase induced voltage e _VW and the WU interphase induced voltage e _WU. It represents the virtual interphase induced voltage corresponding to the trigonometric function, and can be illustrated as shown in the lower left graph of FIG. 16, for example.

The above shows an example of applying the double angle (n = 2) formula among n double angles (n is a natural number of 2 or more), but the present invention is not limited to this. For example, it may be a triple angle (n = 3) or quadruple angle (n = 4) formula. Specifically, in the case of a trigonometric angle, it can be expressed as sin (3θ) = 3sin (θ) cos ² (θ) −sin ³ (θ). Further, in the case of a quadruple angle, it can be expressed as sin (4θ) = 4sin (θ) cos ³ (θ) -4sin ³ (θ) cos (θ). The sin (θ) on the right side in these equations is obtained from the above equation (15). Further, the cos (θ) on the right side in these equations is obtained from the above equation (19). Therefore, both the n-fold angle formulas can be derived based on the above equation (15) and the above equation (19).

Next, a case where another equation whose zero cross timing does not overlap with the equations (20), (21), and (22) is obtained will be described. By manipulating the trigonometric functions representing the interphase induced voltages (see equations (15), (16) and (17)), trigonometric functions representing the interphase induced voltages having different phases can be obtained. The following equations (23), (24) and (25) are expressed by (Equation (15), equation (16) and equation (17), UV interphase induced voltage _eUV , VW interphase induced voltage e _VW. It is a trigonometric function in which the phases of the WU interphase induced voltage e _WU are shifted by 37.5 °, and can be illustrated as shown in the upper right graph of FIG. 16, for example.

By applying the double angle formula to the above equations (23), (24) and (25), the following equations (26), (27) and (28) can be obtained. Equations (26), (27) and (28) correspond to trigonometric functions obtained by applying the double angle formula to a trigonometric function indicating a voltage in which the phase of the interphase induced voltage is shifted by 37.5 °. It represents the virtual interphase induced voltage and can be illustrated, for example, as shown in the lower right graph of FIG.

The virtual interphase induced voltage calculation unit 645 of the present embodiment calculates two virtual interphase induced voltages having different phases. Specifically, the virtual interphase induced voltage calculation unit 645 of the present embodiment includes the virtual interphase induced voltage represented by the above equations (20), (21) and (22), and the above equation (23). , The virtual interphase induced voltage represented by the equations (24) and (25), and the virtual interphase induced voltage represented by the above equations (26), (27) and (28) are calculated. The virtual interphase induced voltage represented by the above equations (20), (21) and (22) and the equations (26), (27) and (28) is the UV interphase induced voltage _eUV , VW interphase. Induced voltage e _VW and WU Interphase induced voltage This is a virtual interphase induced voltage having twice the frequency as compared with e _WU . The virtual interphase induced voltage calculated by the virtual interphase induced voltage calculation unit 645 is not limited to this. For example, the virtual interphase induced voltage calculation unit 645 may calculate only the virtual interphase induced voltage represented by the above equations (20), (21) and (22). Further, the order of operations related to the derivation of equations (26), equation (27) and equation (28) is not limited to the above example. For example, the equations (20), (21) and (22) may be phase-operated to derive the equations (27) and (28). The virtual interphase induced voltage calculation unit 645 switches the calculated virtual interphase induced power and outputs it to the timing detection unit 642. In FIG. 14, the virtual interphase induced power output from the virtual interphase induced voltage calculation unit 645 to the switching timing detection unit 642 is illustrated with a reference numeral VI.

The switching timing detection unit 642 detects the timing at which the pair of magnitude relations and code relations between the phase-to-phase induced voltage and the virtual interphase induced voltage or the virtual interphase induced voltage is switched to another pair of magnitude relations and code relations. The magnitude relationship is the magnitude relationship of the voltage values of each of the plurality of phases of the multi-phase electric motor (for example, the motor 93) of one system. Eg, UV phase induced voltage _e UV in the motor 93 of a motor electric angle, VW phase induced voltage _e VW, when comparing each of the WU phase induced voltage _{e WU,} UV phase induced voltage _{e UV} in order of voltage value greater, When the VW interphase induced voltage e _VW and the WU interphase induced voltage e _WU are obtained, the UV interphase induced voltage e _UV has a magnitude relationship that is larger than the VW interphase induced voltage e _VW and the WU interphase induced voltage e _WU . At this time, VW phase induced voltage _{e VW} is greater than the UV phase induced voltage _{e UV,} and has a magnitude relationship of greater than WU interphase induced voltage _{e WU.} Further, at this time, the WU interphase induced voltage e _WU has a magnitude relationship smaller than the UV interphase induced voltage e _{UV, the} VW interphase induced voltage e _VW , and the WU interphase induced voltage e _WU . The sign relationship is a combination of positive and negative voltage values of each of a plurality of phases of a multi-phase electric motor (for example, a motor 93) of one system. Eg, UV phase induced voltage _e UV in the motor 93 of a motor electric angle, VW phase induced voltage _e VW, when the when the voltage value of each of the WU phase induced voltage _{e WU} is positive schematically showing, _{(e UV} , E _VW , e _WU ) = (+, +, +) can be regarded as having a sign relationship. Further, UV phase induced voltage _e UV in the motor 93 of a motor electric angle, VW phase induced voltage _e VW, when the when the voltage value of each of the WU phase induced voltage _{e WU} is negative schematically showing, _{(e UV} , E _VW , e _WU ) = (-,-,-) can be regarded as having a sign relationship. Hereinafter, the relationship between the magnitude relation and the set of the code relations to be detected by the switching timing detection unit 642 and the motor electric angle will be described with reference to FIGS. 17 to 24.

FIG. 17 is a diagram showing an interphase induced voltage waveform when the motor 93 rotates in the forward direction. FIG. 18 is a diagram showing a voltage magnitude relationship and a code relationship of the interphase induced voltage waveform when the motor 93 rotates in the forward direction. FIG. 19 is a diagram showing an interphase induced voltage waveform when the motor 93 rotates in the forward direction. FIG. 20 is a diagram showing a voltage magnitude relationship and a code relationship of the interphase induced voltage waveform when the motor 93 rotates in the forward direction. In FIGS. 18 and 20, and FIGS. 21 to 24 described later, the range of the motor electric angle specified from the set of the voltage magnitude relation and the code relation of the interphase induced voltage waveform and the virtual interphase induced voltage waveform is α to β. It is represented by, and if the motor electric angle is θ, for example, α ≦ θ <β.

UV interphase induced voltage e _UV , VW interphase induced voltage e _VW and WU Interphase induced voltage e _WU have predetermined voltage magnitude relations and code relations in a predetermined angular range (for example, 30 ° range). Become a relationship. In other words, in the motor 93, the magnitude relation and the sign relation of the interphase induced voltage corresponding to the motor electric angle (θ) are uniquely determined. That is, the set of the magnitude relation and the code relation of the voltage is a combination of the magnitude relation and the code relation uniquely determined according to the motor electric angle (θ). In the case of a three-phase electric motor such as the motor 93 of the present embodiment, when the motor electric angle (θ) changes in the range of 30 degrees or more and less than 330 degrees, the interphase induced voltage before and after the change of the motor electric angle (θ). The pair of magnitude relations and code relations is different from each other. In the case of FIG. 17, in the range of the motor electric angle of 0 to 30 ° when the motor 93 rotates in the forward direction, the UV interphase induced voltage _eUV is the largest (“large” in FIG. 18), and the VW interphase induced voltage _eVW is It is the second largest (“medium” in FIG. 18) and has the smallest WU interphase induced voltage _eWU (“small” in FIG. 18). Further, in the range of the motor electric angle of 30 to 60 ° when the motor 93 rotates in the forward direction, the UV interphase induced voltage _eUV is the second largest (“middle” in FIG. 18), and the VW interphase induced voltage _eVW is the largest. Large (“Large” in FIG. 18) and the smallest WU interphase induced voltage _eWU (“Small” in FIG. 18). In this way, the magnitude relationship between the UV interphase induced voltage _eUV , the VW interphase induced voltage _eVW, and the WU interphase induced voltage _eWU changes in units of 30 °. However, in the example shown in FIG. 17, in the range of the motor electric angle of 180 to 210 °, the magnitude relationship of the voltage is the same as that of the range of the motor electric angle of 0 to 30 °. Further, in the range of the motor electric angle of 210 to 240 °, the magnitude relationship of the voltage is the same as that of the range of the motor electric angle of 30 to 60 °. As described above, the period of the magnitude relation of the voltage is 180 °.

Here, focusing on the signs (positive and negative) of the UV interphase induced voltage e _UV , the VW interphase induced voltage e _VW, and the WU interphase induced voltage e _WU , in the range of the motor electric angle of 0 to 30 ° when the motor 93 rotates in the forward direction. , UV interphase induced voltage e _UV is "+", VW interphase induced voltage e _VW is "-", WU interphase induced voltage e _WU is "+". _{That, (e UV, e VW,} e WU) = - can be regarded as having a sign relation (+, +). On the other hand, in the range of the motor electric angle of 180 to 210 ° when the motor 93 rotates in the forward direction, the UV interphase induced voltage e _UV is "-", the VW interphase induced voltage e _VW is "+", and the WU interphase induced voltage e _WU is It becomes "-". _{That, (e UV, e VW,} e WU) = (-, +, -) can be considered as having a sign relation. As described above, the ranges of the electric angles of the two motors having the same magnitude relationship of the voltage have different sign relationships. Therefore, in the range of the motor electric angle of 0 to 360 °, it is possible to discriminate in units of 30 ° by the combination of the magnitude relation and the sign relation of the voltage. In other words, the range of the motor electric angle can be specified in units of 30 ° by detecting the magnitude relationship and positive / negative of the UV interphase induced voltage _eUV , VW interphase induced voltage _eVW and WU interphase induced voltage _eWU. it can. This also applies when the motor 93 rotates in the reverse direction as shown in FIGS. 19 and 20.

In this way, the range of the motor electric angle can be specified with a resolution of 30 ° based on the UV interphase induced voltage e _UV , the VW interphase induced voltage e _VW, and the WU interphase induced voltage e _WU. By using the voltage, the resolution of the motor electric angle that can be calculated can be further improved. Specifically, for example, the resolution can be increased n times by applying the n-fold angle formula. Furthermore, the resolution is 2n by giving a phase shift to one of the two virtual phase induced voltages to which the n-fold angle formula is applied and treating it as a set of magnitude relation and code relation of two virtual phase induced voltages having different phases. Can be doubled. However, the period of the voltage magnitude relation and the sign relation at the virtual phase induced voltage to which the n-fold angle formula is applied is 1 / n before the n-fold angle formula is applied. Therefore, the magnitude relationship and code relationship of the voltage indicated by the interphase induced voltage (or the magnitude relationship and code relationship of the voltage indicated by the virtual interphase induced voltage having the same magnification as the interphase induced voltage) and the magnitude of the voltage indicated by the virtual interphase induced voltage. By combining the relationship and the sign relationship, it is possible to obtain a resolution (for example, 2n times) based on the virtual phase induced voltage to which the formula of the n times angle is applied in the range of the motor electric angle of 0 to 360 °.

21 to 24 are diagrams showing the magnitude relation and the code relation of the voltage of the interphase induced voltage waveform and the virtual interphase induced voltage waveform when the motor 93 rotates in the forward direction. In FIGS. 21 to 24, serial numbers (1 to 48) are assigned to the set of the voltage magnitude relation and the code relation of the interphase induced voltage waveform and the virtual interphase induced voltage waveform. Further, in FIGS. 21 to 24, the interphase induced voltage represented by the above equations (15) to (17) and the virtual interphase induced voltage represented by the equations (20) to (28) are represented by the equation numbers. Shown.

The virtual interphase induced voltage represented by the formulas (20) to (22) and the virtual interphase induced voltage represented by the formulas (26) to (28) are independently of the motor electric angle with a resolution of 15 °. The magnitude relation and the code relation of the voltage which can specify the range are shown. Further, the phase of the virtual interphase induced voltage represented by the equations (20) to (22) and the virtual phase induced voltage represented by the equations (26) to (28) are out of phase by 37.5 °. Therefore, every time the motor electric angle changes by 7.5 °, the magnitude relation of the virtual phase induced voltage represented by the equations (20) to (22) or the virtual represented by the equations (26) to (28). One of the magnitude relations of the interphase induced voltage will change. Further, the sign relationship of the interphase induced voltage is different between the range of the motor electric angle of 0 to 180 °, the range of the motor electric angle of 0 to 180 °, and the range of the motor electric angle of 180 to 360 °. Therefore, as shown in FIGS. 21 to 24, a set of voltage magnitude relations and code relations of the interphase induced voltage waveform and the virtual interphase induced voltage waveform with different serial numbers in the range of the motor electric angle 0 to 360 °. When collating each other, there is no one in which the magnitude relation and the code relation of the voltage completely match. Thereby, in the present embodiment, the range of the motor electric angle can be specified with a resolution of 7.5 ° unit.

Although the magnitude relationship and code relationship of the voltage in the case of forward rotation shown in FIG. 18 and the magnitude relationship and code relationship of the voltage in the case of reverse rotation shown in FIG. 20 are different, the magnitude relationship of the voltage in each rotation direction is different. By preparing data indicating a set of code relations in advance, the range of the motor electric angle can be specified regardless of the rotation direction of the motor 93. This is not limited to the case where the set of voltage magnitude relation and code relation is based only on the interphase induced voltage, and the magnitude relation of each voltage of the interphase induced voltage and the virtual interphase induced voltage described with reference to FIGS. 21 to 24. The same applies to the set of code relations.

Maps corresponding to both forward rotation and reverse rotation are used as map data for specifying the motor electric angle _θmz based on the set of voltage magnitude relation and code relation according to the concept described with reference to FIGS. 21 to 24. The data is stored in the ROM 51 in advance. Timing detection unit 642 switches the motor motor electric angle theta _mz corresponding to a set of front and rear magnitude relationship and sign relationship between the rotational direction switching timing of the read from the ROM 51, the read motor electric angle theta _mz angular error calculating section 643 Output to. Specifically, the switching timing detection unit 642 identifies the motor electric angle θ _mx by referring to the map data according to the timing when the voltage magnitude relation or the code relation occurs, and the specified motor electric angle θ _{The mz} is output to the angle error calculation unit 643. For example, when transitioning from the magnitude relationship and code relationship of the voltage of serial number 1 to the magnitude relationship and code relationship of the voltage of serial number 2, the switching timing detection unit 642 specifies that the motor electric angle θ _mz = 7.5 ° (FIG. 21).

Angle error calculation unit 643, based on the motor electric angle theta _mz, calculates an angle error theta _err for correcting the motor electrical angle estimate value theta _me. Specifically, the angle error calculation unit 643, the motor electric angle θmz is inputted, calculates the difference between the motor electrical angle theta _mz and the motor electrical angle estimate value theta _me as the angle error theta _err. That is, the angle error θ _err is calculated so that the motor electric angle θ _mx is derived when the angle error θ _err is applied to the motor electric angle estimated value θ _me . The angle error calculation unit 643 stores the calculated difference as an angle error θ _err in the RAM 50. In FIG. 25, the motor electric angles θ _mz1 , θ _mz2 , θ _mz3 , θ _mz4 , θ _mz5 , and θ _mz6 are set as the motor electric angles θ _mz corresponding to the resolution of 7.5 degrees input from the switching timing detection unit 642. It is illustrated.

FIG. 25 is a schematic view showing correction of the motor electric angle estimated value by the correction unit according to the first embodiment. As shown in FIG. 25, the correction unit 644 corrects the motor electric angle estimation value θ _me input from the motor electric angle estimation unit 63 with the angle error θ _err stored in the RAM 50. The correction unit 644 corrects the motor electric angle estimated value θ _me by the angle error θ _err currently stored in the RAM 50 until the next zero cross timing is detected. The solid line in the upper graph of FIG. 16 is the motor electric angle estimated value θ _me (second motor electric angle θ _m2 ) after being corrected by the correction unit 644. For example, the difference between the peak value of the solid line at the zero cross timing and the motor electric angle θ _mz (motor electric angle θ _mz1 to motor electric angle θ _mz6 ) is the angle error θ _err . The correction unit 644 outputs the corrected motor electric angle estimated value θ _me to the electric angle selection unit 23d (see FIG. 12) as the second motor electric angle θ _m2 . If the motor electric angle θmz is to be obtained based only on the magnitude relation and the sign relation of the interphase induced voltage, the resolution will be 30 degrees. Therefore, the motor electric angle estimated value θ _me is updated as shown in RV in FIG. The frequency is reduced to 1/4. As described above, according to the present embodiment, it is possible to obtain the motor electric angle θ _mz for correcting the motor electric angle estimated value θ _me with higher resolution.

The electric angle selection unit 23d (see FIG. 12) is the first motor electric angle output from the main motor electric angle calculation unit 23b when the abnormality detection signal SAr output from the rotation detection abnormality diagnosis unit 61 indicates that there is no abnormality. Select θ _m1 . The electric angle selection unit 23d outputs the first motor electric angle θ _m1 to the current command value calculation unit 24 (see FIG. 11) as the motor electric angle θ _m . On the other hand, the electric angle selection unit 23d selects the second motor electric angle θ _m2 output from the submotor electric angle calculation unit 23c when the abnormality detection signal SAr indicates that there is an abnormality. The electric angle selection unit 23d outputs the second motor electric angle θ _m2 to the current command value calculation unit 24 (see FIG. 11) as the motor electric angle θ _m .

Then, the current command value calculation unit 24 calculates the current command value based on the steering torque T, the vehicle speed V, and the motor electric angle θ _m (first motor electric angle θ _m1 or second motor electric angle θ _m2 ). As a result, even if an abnormality occurs in the rotation detection unit 23a, the ECU 90 can appropriately control the motor 93.

The induced voltage calculation unit 641 calculates the UV interphase induced voltage e _UV , the VW interphase induced voltage e _VW , and the WU interphase induced voltage e _WU based on the first current value I _d1 and the first voltage value V _d1. It does not have to be. The induced voltage calculation unit 641 may use the second current value I _d2 and the second voltage value V _d2 of the second coil system instead of the first current value I _d1 and the first voltage value V _d1 .

The motor 93 does not necessarily have to include the first coil system and the second coil system. That is, the number of coil systems included in the motor 93 may be one. Further, the rotation detection unit 23a does not necessarily have to be a resolver, and may be another sensor such as a rotary encoder or an MR sensor.

As described above, according to the present embodiment, the ECU 90 has a steering assist force based on the steering angle detected by the steering steering angle detecting unit (for example, the output shaft rotation angle sensor 13) that detects the steering angle of the steering wheel. The motor electric angle estimation unit 63 that estimates the motor electric angle estimated value θ _me of the multi-phase electric motor that generates the above, and the motor electric angle correction unit that corrects the motor electric angle estimated value θ _me estimated by the motor electric angle estimation unit. The motor electric angle correction unit 64 includes 64, and the motor electric angle correction unit 64 includes a current detection unit (first current sensor 31 and second current sensor 33) that detects a current flowing through each of the polyphase coils of the driven multi-phase electric motor. , Based on the voltage detection unit (first voltage sensor 32 and second voltage sensor 34) that detects the voltage of each of the polyphase coils, the current detected by the current detection unit, and the voltage detected by the voltage detection unit. Based on the induced voltage calculation unit 641 that calculates the interphase induced voltage of the phase electric motor and the interphase induced voltage calculated by the induced voltage calculation unit 641, the virtual phase interphase that calculates the virtual interphase induced voltage whose phase is different from the interphase induced voltage. The induced voltage calculation unit 645 and the switching timing detection unit that detects the timing at which each of the interphase induced voltage and the virtual phase induced voltage or the set of the magnitude relation and the code relation of the virtual phase induced voltage is switched to the other magnitude relation and the set of the code relation. It has 642 and a correction unit 644 that corrects the motor electric angle estimated value θ _me estimated by the motor electric angle estimating unit based on the detection result by the switching timing detecting unit 642.

As a result, at the timing when the voltage magnitude-related and code-related sets are switched to other magnitude-related and code-related sets, the voltage magnitude-related and code-related sets correspond to the other magnitude-related and code-related sets. The motor electric angle estimated value θ _me can be corrected based on the estimation that the electric angle θ _mz is reached. Therefore, the ECU 90 can estimate the motor electric angle _θmz with higher accuracy without depending on the motor rotation angle sensor. In addition, by calculating the virtual interphase induced voltage and using the magnitude relationship between the interphase induced voltage and the virtual interphase induced voltage and the relationship between the set of sign relationships and the motor electric angle, the motor electric angle θ _mz with higher resolution. Can be determined. That is, the motor electric angle estimated value θ _me can be corrected more finely. Since the motor electric angle estimation value θ _me output from the motor electric angle estimation unit 63 is based on the steering torque T detected by the torque sensor 94, it is between the detection target of the torque sensor 94 and the motor 93. Mechanical errors may occur due to the mechanical configuration (for example, speed reducer 92, etc.). On the other hand, since the motor electric angle θ _mz is based on the electric signal from the motor 93, it does not cause a mechanical error that may occur in the motor electric angle estimated value θ _me . That is, in the present embodiment, by correcting the motor electric angle estimated value θ _me with the motor electric angle θ _mz , it is possible to suppress the mechanical error that may occur in the derivation of the second motor electric angle θ _m 2. it can. Therefore, the second motor electric angle θ _m2 can be derived with higher accuracy. As described above, according to the present embodiment, since the angle can be estimated more finely, it is possible to correct the angle error before the accumulation becomes large, and the steering feeling can be further improved.

Further, it is preferable that the virtual interphase induced voltage calculation unit 645 calculates the virtual interphase induced voltage having a frequency twice that of the interphase induced voltage. By doubling the frequency of the virtual interphase induced voltage, the motor electric angle estimated value θ _me can be estimated with twice the resolution of the interphase induced voltage, and the ECU 90 depends on the motor rotation angle sensor. The motor electric angle _θmz can be estimated with higher accuracy without the need for it. Further, since the angle error can be corrected with higher accuracy, the accumulation (integration) of the estimated angle error of the motor electric angle can be suppressed. Therefore, the estimation accuracy of the motor electric angle can be improved.

Further, the virtual interphase induced voltage calculation unit 645 calculates two virtual interphase induced voltages having different phases, and the switching timing detection unit 642 has another set of magnitude relation and code relation of the interphase induced voltage and the virtual interphase induced voltage. It is preferable to detect the timing of switching to the magnitude relation and the code relation set. By combining the magnitude relation and the code relation of the two virtual phase induced voltages having different phases, the motor electric angle estimated value θ _me can be estimated with higher resolution. Therefore, the ECU 90 can estimate the motor electric angle _θmz with higher accuracy without depending on the motor rotation angle sensor.

Further, the motor 93 is a three-phase electric motor, and one of the two virtual interphase induced voltages corresponds to the trigonometric function obtained by applying the double angle formula to the trigonometric function indicating the interphase induced voltage. It is a voltage, and the other of the two virtual interphase induced voltages corresponds to the trigonometric function obtained by applying the double angle formula to the trigonometric function showing the voltage obtained by shifting the phase of the interphase induced voltage by 37.5 °. It is preferably an interphase induced voltage. As a result, the motor electric angle _θmz can be estimated with a resolution of 7.5 °.

Further, the control calculation device (ECU 90) including the current command value calculation unit 24 corrects the motor electric angle and the motor electric angle corrected from the steering angle detected by the steering steering angle detection unit (for example, the output shaft rotation angle sensor 13). The motor 93 is driven by feedback control based on the motor electric angle output by the unit 64. Specifically, the motor electric angle estimation unit 63 includes the output shaft rotation angle θ _os detected by the output shaft rotation angle sensor 13, the reduction ratio RGr and the rotor of the reduction gear 92 (see FIG. 2) stored in the ROM 51 in advance. The motor electric angle estimated value θ _me is calculated based on the pole pair number P of 932 (see FIG. 9) and the relative offset amount θ _off estimated by the relative offset amount estimation unit 62. Then, the calculated motor electric angle estimated value θ _me is output to the motor electric angle correction unit 64. The motor electric angle correction unit 64 corrects the motor electric angle estimated value θ _me based on the induced voltage of the motor 93. Then, the corrected motor electric angle estimated value is output to the electric angle selection unit 23d as the second motor electric angle θ _m2 . The current command value calculation unit 24 drives the motor 93 by calculating the current command value based on the motor electric angle θ _m (for example, the second motor electric angle θ _m2 ) or the like. As a result, when only the motor electric angle θ _me estimated from the steering angle detected by the steering steering angle detection unit is used, and simply the magnitude relationship between the phase-to-phase induced voltage and the virtual phase-induced voltage, or the voltage of the virtual-phase induced voltage, and The motor electric angle corresponding to the voltage magnitude relationship and the code relationship set before and after the switching indicated by the timing at which the code relationship set is switched to another magnitude relationship and the code relationship set (for example, the motor electric angle θ of the second embodiment described later). _The motor 93 can be driven based on the motor electric angle θ _mz estimated more accurately than when only _mz ) is used.

Further, the electric power steering device 80 includes a motor that generates steering assisting force for steering, a motor drive circuit (first gate drive circuit 25 and second gate drive circuit 26) that supplies a drive current to the motor, and a motor. and second control arithmetic unit for driving and controlling the motor driving circuit based on motor electrical angle theta _{m @ 2} (current command value calculation unit 24), and ECU90 comprising a motor electrical angle calculation unit 23 for outputting a second motor electric angle theta _{m @ 2} It is an electric power steering device provided. The electric power steering device 80 can estimate the motor electric angle _θmz with high accuracy without depending on the motor rotation angle sensor, and can apply an appropriate auxiliary steering torque to the output shaft.

Further, the electric power steering device 80 includes a steering steering angle detecting unit (for example, an output shaft rotation angle sensor 13) that detects the steering angle of the steering wheel, a torque sensor 94 that detects the torque transmitted to the steering mechanism, and a motor. The rotation detection unit 23a for detecting the rotation angle of the output shaft and the rotation detection abnormality diagnosis unit 61 for detecting the abnormality of the rotation detection unit 23a are provided, and the control calculation device is the rotation detection abnormality diagnosis unit 61 of the rotation detection unit 23a. When no abnormality is detected, the motor drive circuit is driven and controlled based on the torque detected by the torque sensor 94 and the motor electric angle θ _m detected by the rotation detection unit 23a, and the rotation detection abnormality diagnosis unit 61 drives and controls the rotation detection unit 23a. The motor drive circuit is driven and controlled based on the second motor electric angle θ _m2 output by the motor electric angle calculation unit 23 when the abnormality is detected.

As a result, the electric power steering device 80 can obtain the motor electric angle estimated value based on the output shaft rotation angle, so that the motor electric angle estimated value can be obtained even if an abnormality occurs in the motor rotation angle sensor. Therefore, the electric power steering device 80 according to the present embodiment can estimate the second motor electric angle θ _m2 with high accuracy without depending on the motor rotation angle sensor.

The induced voltage calculation unit 641 does not necessarily have to calculate the electric angle change rate Δθ _m based on the output shaft rotation angle θ _os . For example, the induced voltage calculation unit 641 may calculate the electric angle change rate Δθ _m based on the input shaft rotation angle θ _is . In this case, the induced voltage calculation unit 641 calculates the electric angle change rate Δθ _m based on the difference between the previous input shaft rotation angle θ _isp and the current input shaft rotation angle θ _is . Specifically, assuming that the calculation cycle of the relative angle calculation unit 18 is t (s), the induced voltage calculation unit 641 calculates the electric angle change rate Δθ _m by the following equation (29).

Further, the rotation detection unit 23a may not be provided. When there is no rotation detection unit 23a, the main motor electric angle calculation unit 23b and the electric angle selection unit 23d are omitted. Further, in this case, the second motor electric angle θ _m2 calculated by the submotor electric angle calculation unit 23c is treated as the motor electric angle θ _m .

(Embodiment 2)
FIG. 26 is a schematic view showing a configuration example of the motor control device according to the second embodiment. Of the configurations described with reference to FIGS. 1 to 25, the motor electric angle estimation unit 63 may not be provided. In the second embodiment, the relative offset amount estimation unit 62 and the motor electric angle estimation unit 63 are omitted. Further, in this case, the switching timing detection unit 642 detects the timing at which the magnitude relation and the code relation set of the interphase induced voltage and the virtual phase induced voltage or the virtual phase induced voltage are switched to another magnitude relation and the code relation set. Then, an output PI indicating a set of voltage magnitude relations and code relations before and after switching is performed on the motor electric angle estimation unit 649. The motor electric angle estimation unit 649 outputs the motor electric angle θ _mz corresponding to the set of the magnitude relation and the code relation of the voltage before and after the switching indicated by the output PI as the estimated second motor electric angle θ _m2 .

Further, the motor 93 is a two-system motor 93 having a first coil system L1 and a second coil system L2, but the number of systems included in the motor 93 may be 3 or more. Further, the number of phases of the motor included in one system is not limited to 3, and may be, for example, 4 or more, or 1 or 2.

10 1st multi-pole ring magnet 11 2nd multi-pole ring magnet 12 Input shaft rotation angle sensor 13 Output shaft rotation angle sensor 23 Motor electric angle calculation unit 23a Rotation detection unit 23b Main motor Electric angle calculation unit 23c Submotor Electric angle calculation unit 23d Electric angle selection unit 31, 31u, 31v, 31w 1st current sensor 32, 32u, 32v, 32w 1st voltage sensor 33, 33u, 33v, 33w 2nd current sensor 34, 34u, 34v, 34w 2nd voltage sensor 64 motor Electric angle correction unit 80 Electric power steering device 81 Steering wheel 82 Steering shaft 82a Input shaft 82b Output shaft 82c Torsion bar 90 ECU (motor control device)
92 Deceleration device 93 Motor 94 Torque sensor 95 Vehicle speed sensor 98 Ignition switch 99 Power supply device 101 Vehicle 641 Induced voltage calculation unit 642 Switching timing detection unit 643 Angle error calculation unit 644 Correction unit 645 Virtual phase-to-phase induced voltage calculation unit

Claims (8)

A current detector that detects the current flowing through each of the multi-phase coils of the driven multi-phase electric motor,
A voltage detector that detects the voltage of each of the polyphase coils,
An induced voltage calculation unit that calculates the interphase induced voltage of the multi-phase electric motor based on the current detected by the current detection unit and the voltage detected by the voltage detection unit.
A virtual interphase induced voltage calculation unit that calculates a virtual interphase induced voltage whose phase or frequency is different from that of the interphase induced voltage based on the interphase induced voltage calculated by the induced voltage calculation unit.
A switching timing detection unit that detects the timing at which each of the interphase induced voltage and the virtual interphase induced voltage or the pair of the magnitude relation and the code relation of the virtual phase induced voltage is switched to another pair of magnitude relation and the code relation.
It is provided with a motor electric angle estimation unit that estimates the motor electric angle of the multi-phase electric motor based on the detection result by the switching timing detection unit .
The virtual phase induced voltage calculation unit calculates two virtual phase induced voltages having different phases, and calculates the induced voltage between the virtual phases.
The switching timing detection unit, the inter-phase induced voltage and the virtual inter-phase induced voltage of each of the magnitude relationship and code related set of other magnitude relation and a motor control apparatus that detect the timing of switching the set of code relations of. The multi-phase electric motor is a three-phase electric motor.
One of the two virtual interphase induced voltages is a virtual interphase induced voltage corresponding to the trigonometric function obtained by applying the double angle formula to the trigonometric function indicating the interphase induced voltage.
The other of the two virtual phase-induced voltages is between the virtual phases corresponding to the trigonometric function obtained by applying the double angle formula to the trigonometric function indicating the voltage obtained by shifting the phase of the interphase induced voltage by 37.5 degrees. The motor control device according to claim 1 , which is an induced voltage. The motor control device according to claim 1 or 2 , wherein the virtual interphase induced voltage calculation unit calculates the virtual interphase induced voltage having a frequency twice that of the interphase induced voltage. Steering with a multi-phase electric motor that generates steering assist force,
And the steering angle detector for detecting a steering angle of the steering wheel,
And motors control device,
A motor drive circuit that supplies a drive current to the multi-phase electric motor,
An electric power steering device including a control arithmetic unit that drives and controls the motor drive circuit based on the motor electric angle of the multi-phase electric motor.
The motor control device is
A current detector that detects the current flowing through each of the multi-phase coils of the driven multi-phase electric motor,
A voltage detector that detects the voltage of each of the polyphase coils,
An induced voltage calculation unit that calculates the interphase induced voltage of the multi-phase electric motor based on the current detected by the current detection unit and the voltage detected by the voltage detection unit.
A virtual interphase induced voltage calculation unit that calculates a virtual interphase induced voltage whose phase or frequency is different from that of the interphase induced voltage based on the interphase induced voltage calculated by the induced voltage calculation unit.
A switching timing detection unit that detects the timing at which each of the interphase induced voltage and the virtual interphase induced voltage or the pair of the magnitude relation and the code relation of the virtual phase induced voltage is switched to another pair of magnitude relation and the code relation.
With the motor electric angle estimation unit that estimates the motor electric angle of the multi-phase electric motor based on the detection result by the switching timing detection unit.
With
The control calculation device controls the multi-phase electric motor by feedback control based on the motor electric angle estimated by the motor electric angle estimation unit and the motor electric angle estimated from the steering angle detected by the steering steering angle detection unit. An electric power steering device that drives. A motor electric angle estimation unit that estimates the motor electric angle of a multi-phase electric motor that generates steering assist force based on the steering angle detected by the steering steering angle detection unit that detects the steering angle.
It is provided with a motor electric angle correction unit that corrects the motor electric angle estimated by the motor electric angle estimation unit.
The motor electric angle correction unit
A current detection unit that detects the current flowing through each of the multi-phase coils of the driven multi-phase electric motor, and
A voltage detector that detects the voltage of each of the polyphase coils,
An induced voltage calculation unit that calculates the interphase induced voltage of the multi-phase electric motor based on the current detected by the current detection unit and the voltage detected by the voltage detection unit.
A virtual interphase induced voltage calculation unit that calculates a virtual interphase induced voltage whose phase or frequency is different from that of the interphase induced voltage based on the interphase induced voltage calculated by the induced voltage calculation unit.
A switching timing detection unit that detects the timing at which each of the interphase induced voltage and the virtual interphase induced voltage or the pair of the magnitude relation and the code relation of the virtual phase induced voltage is switched to another pair of magnitude relation and the code relation.
A motor control device including a correction unit that corrects the motor electric angle estimated by the motor electric angle estimation unit based on a detection result by the switching timing detection unit. A multi-phase electric motor that generates steering assist force for steering,
A motor drive circuit that supplies a drive current to the multi-phase electric motor,
A control arithmetic unit that drives and controls the motor drive circuit based on the motor electric angle of the multi-phase electric motor.
An electric power steering device including a motor control device that outputs the motor electric angle.
The motor control device is an electric power steering device that is the motor control device according to any one of claims 1 to 3 . Steering angle detection unit that detects the steering angle and
A torque detector that detects the torque transmitted to the steering mechanism,
A motor electric angle detection unit that detects the rotation angle of the output shaft of the multi-phase electric motor,
It is provided with an abnormality detection unit that detects an abnormality in the motor electric angle detection unit.
The control calculation device is based on the torque detected by the torque detection unit and the motor electric angle detected by the motor electric angle detection unit when the abnormality detection unit does not detect an abnormality of the motor electric angle detection unit. A claim that drives and controls the motor drive circuit and drives and controls the motor drive circuit based on the motor electric angle output by the motor control device when an abnormality of the motor electric angle detection unit is detected by the abnormality detection unit. Item 6. The electric power steering device according to Item 6 . A vehicle provided with the electric power steering device according to claim 6 or 7 .

Images