JP2018113835A - Motor controller, electric power steering device and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller in which revolving-power of motor electric angle estimated from an induction voltage is improved, and to provide an electric power steering device and a vehicle.SOLUTION: A motor controller includes a current detector and a voltage detector for detecting the currents and voltages of a multi-phase coil in a polyphase electric motor, an induction voltage calculation unit for calculating the inter-phase induced voltage of the polyphase electric motor based on these currents and voltages, a virtual inter-phase induced voltage calculation unit for calculating the virtual inter-phase induced voltage having a phase or a frequency different from that of the inter-phase induced voltage based on the inter-phase induced voltage, a changeover timing detector for detecting a timing when a set of the magnitude relation and the sign relation of each of the inter-phase induced voltage and virtual inter-phase induced voltage or the virtual inter-phase induced voltage is changed over to other set of the magnitude relation and the sign relation, and a motor electric angle estimation unit for estimating the motor electric angle of the polyphase electric motor based on the detection results from the changeover timing detector.SELECTED DRAWING: Figure 16

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 an auxiliary steering force generated by a 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 Literature 1 estimates a motor electrical angle based on an induced voltage, and controls the motor based on the estimated motor electrical angle. As a result, the motor can be controlled when there is no motor rotation angle sensor (such as a resolver) or when the motor rotation angle sensor fails.

JP 2012-232624 A

  However, when the motor electrical angle is calculated based only on the induced voltage, there has been a limit to improving the accuracy of estimating the motor electrical angle. For this reason, even when there is no motor rotation angle sensor or when the motor rotation angle sensor fails, there has been a demand for a motor control device that improves the resolution of the motor electrical angle estimated from the induced voltage.

  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 electrical angle estimated from the induced voltage is improved. .

  In order to achieve the above object, a motor control device according to an aspect of the present invention includes a current detection unit that detects a current flowing through each of the multiphase coils included in the driven multiphase electric motor, A voltage detector that detects each voltage; and an induced voltage calculator that calculates an interphase induced voltage of the multiphase electric motor based on the current detected by the current detector and the voltage detected by the voltage detector; A virtual phase induced voltage calculation unit that calculates a virtual phase induced voltage having a phase or frequency different from that of the phase induced voltage based on the phase induced voltage calculated by the induced voltage calculation unit; and the phase induced voltage and the virtual phase induced voltage Switching timing detection for detecting the timing at which each of the voltages or the set of magnitude relations and sign relations of the induced voltage between virtual phases switches to another magnitude relation and sign relation set When, and a said switching motor electrical angle estimate unit that estimates a motor electric angle of the multi-phase electric motor based on the detection result by the timing detection unit.

  Thus, at the timing when the voltage magnitude / sign relation set switches to another magnitude / sign relation set, the voltage magnitude / sign relation set corresponds to the other magnitude relation / sign relation motor. It can be estimated that it is an electrical angle. Therefore, the motor control device can improve the resolution of the motor electrical angle estimated from the induced voltage without depending on the motor rotation angle sensor.

  As a desirable mode 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 detects each of the phase induced voltage and the virtual phase induced voltage. It is preferable to detect the timing at which a set of magnitude relation and code relation switches to another magnitude relation and sign relation set.

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

  As a desirable mode of the motor control device, the multiphase 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 interphase induced voltage corresponding to the trigonometric function obtained as described above, and the other of the two interphase induced voltages is a trigonometric function indicating a voltage obtained by shifting the phase of the interphase induced voltage by 37.5 degrees. A virtual interphase induced voltage corresponding to a trigonometric function obtained by applying the double angle formula is preferable.

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

  As a desirable mode of the motor control device, it is preferable that the virtual interphase induced voltage calculation unit 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 electrical angle can be estimated with a resolution twice that of the interphase induced voltage. Therefore, the motor control device can improve the resolution of the motor electrical angle estimated from the induced voltage without depending on the motor rotation angle sensor.

  An electric power steering apparatus according to an aspect of the present invention includes a steering having a multiphase electric motor that generates a steering assist force, a steering rudder angle detecting unit that detects a steering rudder angle, and any one of claims 1 to 4. The motor control device according to one aspect, a motor drive circuit that supplies a drive current to the multiphase electric motor, and a control arithmetic device that drives and controls the motor drive circuit based on a motor electrical angle of the multiphase electric motor; An electric power steering device comprising: the control arithmetic device based on a motor electrical angle estimated from the motor electrical angle estimation unit and a motor electrical angle estimated from the steering angle detected by the steering steering angle detection unit. The multiphase electric motor is driven by feedback control.

  Thereby, the motor electrical angle estimated by the motor electrical angle estimation unit or the motor electrical angle estimated from the steering angle detected by the steering steering angle detection unit is estimated more accurately than when only one of the motor electrical angles is used. The multiphase electric motor can be driven based on the motor electric angle.

  A motor control device according to an aspect of the present invention estimates a motor electrical angle of a multiphase electric motor that generates a steering assist force based on a steering angle detected by a steering angle detection unit that detects a steering angle of a steering. A motor electrical angle estimator; and a motor electrical angle corrector that corrects the motor electrical angle estimated by the motor electrical angle estimator. The motor electrical angle corrector includes: A current detector that detects a current flowing through each of the multiphase coils, a voltage detector that detects a voltage of each of the multiphase coils, and a current detected by the current detector and the voltage detector An induced voltage calculation unit that calculates an interphase induced voltage of the multiphase electric motor based on the obtained voltage, and an interphase induced voltage based on the interphase induced voltage calculated by the induced voltage calculation unit. A virtual phase induced voltage calculation unit that calculates a virtual phase induced voltage having a phase or frequency different from that of each other, and each of the phase induced voltage and the virtual phase induced voltage or a set of magnitude relations and sign relations of the virtual phase induced voltage is different in magnitude. A switching timing detection unit that detects the timing of switching to a set of relationship and sign relationship, and a correction unit that corrects the motor electrical angle estimated by the motor electrical angle estimation unit based on a detection result by the switching timing detection unit. Have.

  Thereby, the motor control device can obtain the estimated motor electrical angle based on the output shaft rotation angle. Further, the motor electrical angle estimated value can be corrected by the correction unit. Therefore, the motor control device can estimate the motor electrical angle with improved resolution.

  An electric power steering apparatus according to an aspect of the present invention includes a multiphase electric motor that generates a steering assist force for steering, a motor drive circuit that supplies a drive current to the multiphase electric motor, and a motor of the multiphase electric motor. An electric power steering apparatus comprising: a control arithmetic device that drives and controls the motor drive circuit based on an electrical angle; and a motor control device that outputs the motor electrical angle, wherein the motor control device is the motor control device described above. It is.

  The motor control device can improve the resolution of the motor electrical angle estimated from the induced voltage without depending on the motor rotation angle sensor. Therefore, the electric power steering apparatus can improve the resolution of the motor electrical 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 aspect of the electric power steering device, a steering angle detection unit that detects the steering angle of the steering, a torque detection unit that detects torque transmitted to the steering mechanism, and the rotation angle of the output shaft of the multiphase electric motor A motor electrical angle detection unit for detecting, and an abnormality detection unit for detecting an abnormality of the motor electrical angle detection unit, wherein the control arithmetic unit detects an abnormality of the motor electrical angle detection unit by the abnormality detection unit. If not, the motor drive circuit is driven and controlled based on the torque detected by the torque detection unit and the motor electrical angle detected by the motor electrical angle detection unit, and the abnormality detection unit detects an abnormality in the motor electrical angle detection unit. It is preferable to drive-control the motor drive circuit based on the motor electrical angle output by the motor control device when detected.

  As a result, the electric power steering apparatus can obtain the estimated motor electrical angle value based on the output shaft rotation angle, and therefore can obtain the estimated motor electrical angle value even if an abnormality occurs in the motor rotation angle sensor. Therefore, the electric power steering apparatus according to the present embodiment can estimate the motor electrical angle with improved resolution without depending on the motor rotation angle sensor.

  A vehicle according to an aspect of the present invention includes the above-described 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 a steering force equivalent to the state before the occurrence.

  ADVANTAGE OF THE INVENTION According to this invention, the motor control apparatus which can improve the resolution | decomposability of the motor electrical angle estimated from the induced voltage without depending on a motor rotation angle sensor, an electric power steering apparatus, and a vehicle can be provided.

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

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements 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 apparatus according to the first embodiment. FIG. 2 is a schematic diagram of the electric power steering apparatus 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. 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 in 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. One end of the output shaft 82 b is connected to the input shaft 82 a, and the other end of the output shaft 82 b is connected to the universal joint 84. In this 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). )) And other general steel materials.

  As shown in FIG. 2, the lower shaft 85 is a member connected to the output shaft 82 b 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. 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 linear motion by the rack 88b. The rack 88 b 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 drive three-phase AC motor. The speed reducer 92 is, for example, a worm speed reducer. Torque generated by the motor 93 is transmitted to the worm wheel via the worm inside the speed reducer 92 and rotates the worm wheel. The reduction gear 92 increases the torque generated by the motor 93 by a worm and a worm wheel (worm gear). The speed reducer 92 gives 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 82 b 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 and displaces the wheel.

  The ECU 90 is a device that controls the operation of the motor 93. Electric power is supplied to the ECU 90 from the power supply device 99 (for example, a vehicle-mounted battery) while the ignition switch 98 is on. 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 information output from the rotation detection unit 23a as operation information Y. The ECU 90 calculates an auxiliary steering command value based on the steering torque T, the vehicle speed V, and the operation information Y. The ECU 90 adjusts the power value X 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. 5 is a cross-sectional view taken along line AA in 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 multipolar ring magnet 10, a second multipolar ring magnet 11, an input shaft rotation angle sensor 12, and an output shaft rotation. And an angle sensor 13. The torsion bar 82c is an elastic member made of, for example, a steel material. The torsion bar 82c connects the input shaft 82a and the output shaft 82b.

  The first multipolar ring magnet 10 and the second multipolar ring magnet 11 have, for example, S poles and N poles arranged alternately on the outer peripheral surface. For the first multipolar ring magnet 10 and the second multipolar ring magnet 11, for example, a neodymium magnet, a ferrite magnet, a samarium cobalt magnet, or the like is used according to a necessary magnetic flux density. The first multipolar 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. For example, the second multipolar ring magnet 11 is attached to 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 an input shaft rotation angle θ _is (the rotation angle of the first multipolar 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 multipolar 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 are opposed to the outer peripheral surface of the first multipolar ring magnet 10. The first cos magnetic sensor 15 is disposed so as to have a phase difference of 90 ° in terms of the electrical angle of the first multipolar ring magnet 10 with respect to the first sin magnetic sensor 14. The first sin magnetic sensor 14 outputs sin θ _is according to the rotation angle of the first multipolar ring magnet 10. The first cos magnetic sensor 15 outputs cos θ _is according to the rotation angle of the first multipolar ring magnet 10.

The output shaft rotation angle sensor 13 detects the output shaft rotation angle θ _os (the rotation angle of the second multipolar 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 multipolar 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 are opposed to the outer peripheral surface of the second multipolar ring magnet 11. The second cos magnetic sensor 17 is disposed so as to have a phase difference of 90 ° in terms of the electrical angle of the second multipolar ring magnet 11 with respect to the second sin magnetic sensor 16. The second sin magnetic sensor 16 outputs sin θ _os according to the rotation angle of the second multipolar ring magnet 11. The second cos magnetic sensor 17 outputs cos θ _os according to the rotation angle of the second multipolar ring magnet 11.

  As 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 diagrams illustrating the torque sensor according to the first embodiment using functional blocks. 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 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 82 b with respect to the input shaft 82 a (the second multi-pole ring magnet 10 with respect to the second multi-pole ring magnet 10). pole calculates a relative angle) of the ring magnet 11, and outputs the torque calculation unit 19 an operation result as the relative angle [Delta] [theta] _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 calculation unit 181 receives sin θ _is output from the first sin magnetic sensor 14 and cos θ _is output from the first cos magnetic sensor 15. The input shaft rotation angle calculation unit 181 calculates the input shaft rotation angle θ _is (rad) by an arctangent function of a value obtained by dividing sin θ _is by cos θ _is, that _is , the following equation (1).

The output shaft rotation angle calculator 182 receives sin θ _os output from the second sin magnetic sensor 16 and cos θ _os output from the second cos magnetic sensor 17. The output shaft rotation angle calculation unit 182 calculates an output shaft rotation angle θ _os (rad) by an arctangent function of a value obtained by dividing sin θ _os by cos θ _os , that is, the following equation (2).

The difference calculation unit 183 receives 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. 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 calculator 19 calculates the steering torque T based on the relative angle Δθ _io input from the relative angle calculator 18. For example, the torque calculation unit 19 stores the relationship between the relative angle Δθ _io and the steering torque T determined by the characteristics of the torsion bar 82c. The torque calculator 19 calculates the steering torque T based on the relative angle Δθ _io input from the relative angle calculator 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 diagram illustrating 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. 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 eight, for example.

  As shown in FIG. 9, the first coil 37 is concentratedly wound around each of the plurality of teeth 931b. The first coil 37 is concentratedly wound around the outer periphery of the teeth 931b via an insulator. All the first coils 37 are included in a 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 such that the two first coils 37 are adjacent to each other in the circumferential direction. Three first coil groups Gr1 having adjacent first coils 37 as one group 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. Note that the number of the first coil groups Gr1 is not necessarily three, and it is sufficient if 3n are arranged at equal intervals in the circumferential direction when n is a natural number. Further, n is desirably an odd number.

  As shown in FIG. 9, the second coil 38 is concentratedly wound around each of the plurality of teeth 931b. The second coil 38 is concentratedly wound around the outer periphery of the teeth 931b via an insulator. The teeth 931b around which the second coil 38 is concentrated are different teeth 931b from the teeth 931b around which the first coil 37 is concentrated. All the second coils 38 are included in a second coil system that 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 such that the two second coils 38 are adjacent to each other in the circumferential direction. Three second coil groups Gr2 having the adjacent second coils 38 as one group 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. Note that the number of the second coil groups Gr2 is not necessarily three, and it is sufficient if 3n are arranged at equal intervals in the circumferential direction when n is a natural number. Further, n is desirably an odd number.

  As shown in FIG. 10, the six first coils 37 include two first U-phase coils 37Ua and a first U-phase coil 37Ub excited by a first U-phase current I1u, and two first coils 37Ub excited by a first V-phase current I1v. 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 are included. First U-phase coil 37Ub is connected in series to first U-phase coil 37Ua. First V-phase coil 37Vb is connected in series to first V-phase coil 37Va. First W-phase coil 37Wb is connected in series to first W-phase coil 37Wa. The winding direction of the first coil 37 around the teeth 931b is the same. The first U-phase coil 37Ub, the first V-phase coil 37Vb, and the first W-phase coil 37Wb are joined by a star connection (Y connection).

  As shown in FIG. 10, the six second coils 38 include two second U-phase coils 38Ua and second U-phase coils 38Ub excited by the second U-phase current I2u, and 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 a second W-phase current I2w. Second U-phase coil 38Ub is connected in series to second U-phase coil 38Ua. Second V-phase coil 38Vb is connected in series to second V-phase coil 38Va. Second W-phase coil 38Wb is connected in series to second W-phase coil 38Wa. The winding direction of the second coil 38 around the teeth 931 b is the same direction, and is the same as the winding direction of the first coil 37. The second U-phase coil 38Ub, the second V-phase coil 38Vb, and the second W-phase coil 38Wb are joined by star connection (Y connection).

  As shown in FIG. 9, the three first coil groups Gr1 include a first UV coil group Gr1UV, a first VW coil group Gr1VW, and a first UW coil group Gr1UW. The first UV coil group Gr1UV includes a first U-phase coil 37Ub and a first V-phase coil 37Va that are adjacent to each other in the circumferential direction. 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 include a second UV coil group Gr2UV, a second VW coil group Gr2VW, and a second UW coil group Gr2UW. The second UV coil group Gr2UV includes a second U-phase coil 38Ub and a second V-phase coil 38Va that are adjacent to each other in the circumferential direction. 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. Second UW coil group Gr2UW includes second U-phase coil 38Ua and 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 referred to as the radial direction. For example, as shown in FIG. 9, in the radial direction, the first U-phase coil 37Ua faces the second U-phase coil 38Ua, and the first U-phase coil 37Ub faces the second U-phase coil 38Ub.

  The first coil 37 excited by the first V-phase current I1v is opposed to the second coil 38 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 is opposed to the second coil 38 excited by the second W-phase current I2w in the radial direction. For example, as shown in FIG. 9, in the radial direction, 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.

FIG. 11 is a schematic diagram illustrating a 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 electrical angle calculation unit 23, a first gate drive circuit 25, a second gate drive circuit 26, a first inverter 27, a second And an inverter 28. The current command value calculation unit 24 calculates a motor current command value. The motor electrical angle calculator 23 calculates the motor electrical angle θ _m and outputs it to the current command value calculator 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 detector 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 23 a is supplied to the motor electrical angle calculation unit 23. The motor electrical angle calculator 23 calculates the motor electrical angle θ _m based on the detection value of the rotation detector 23 a and outputs it to the current command value calculator 24.

The current command value calculating section 24, the steering torque T detected by the torque sensor 94, a vehicle speed V detected by the vehicle speed sensor 95, a motor electric angle theta _m outputted from the motor electrical angle computation section 23, but Entered. Current command value calculating section 24, the steering torque T, and calculates a current command value based on the vehicle speed V and motor electrical angle theta _m, and outputs to the first gate driving circuit 25 and the second gate driving circuit 26.

  The first gate drive circuit 25 calculates a first pulse width modulation signal based on the current command value and outputs the first pulse width modulation signal to the first inverter 27. The first inverter 27 switches the field effect transistor so as to obtain a three-phase current value according to the duty ratio of the first pulse width modulation signal, and thereby the first U-phase current I1u, the first V-phase current I1v, and the first W A three-phase alternating current including the phase current I1w is generated. The first U-phase current I1u excites the first U-phase coil 37Ua and the first U-phase coil 37Ub, the first V-phase current I1v excites the first V-phase coil 37Va and the first V-phase coil 37Vb, and the first W-phase current I1w becomes the first W The phase coil 37Wa and the first W-phase coil 37Wb are excited.

  The second gate drive circuit 26 calculates a 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 field effect transistor so as to obtain a three-phase current value according to the duty ratio of the second pulse width modulation signal, and thereby performs the second U-phase current I2u, the second V-phase current I2v, and the second W A three-phase alternating current including the phase current I2w is generated. 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 becomes the second W-phase. 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. The second current sensor 33v and the 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 include a shunt resistor. The first current sensor 31u detects the first U-phase current value I _dct1U and outputs it to the motor electrical angle calculation unit 23. The first current sensor 31v detects the first V-phase current value I _dct1V and outputs it to the motor electrical angle calculator 23. The first current sensor 31 w detects the first W-phase current value I _dct1 W and outputs it to the motor electrical angle calculation unit 23. The second current sensor 33u detects the second U-phase current value I _dct2U and outputs it to the motor electrical angle calculation unit 23. The second current sensor 33v detects the second V-phase current value I _dct2V and outputs it to the motor electrical angle calculator 23. The second current sensor 33w detects the second W-phase current value I _dct2W and outputs it to the motor electrical angle calculator 23.

In the following description, when it is not necessary to distinguish between the first U-phase current value I _dct1U , the first V-phase current value I _dct1V and the first W-phase current value I _dct1W , the first current value I _d1 may be described. is there. The 2U-phase current value _{I dct2U,} when there is no need to distinguish the first 2V phase current value _{I Dct2V} and the 2W-phase current value _{I dct2W,} which may be described as a second current value _{I d2.} When there is no need to distinguish between the first current sensor 31u, the first current sensor 31v, and the first current sensor 31w, the current sensor 31u may be described as one current sensor 31. When there is no need to distinguish between the second current sensor 33u, the second current sensor 33v, and the second current sensor 33w, the second current sensor 33u may be described as the second current sensor 33.

As shown in FIG. 11, the electric power steering apparatus 80 includes a first voltage sensor 32u, a first voltage sensor 32v, a first voltage sensor 32w, a second voltage sensor 34u, and the like 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 electrical angle calculator 23. The first voltage sensor 32v detects the first V-phase voltage value V _dct1V and outputs it to the motor electrical angle calculator 23. The first voltage sensor 32 w detects the first W-phase voltage value V _dct1 W and outputs it to the motor electrical angle calculator 23. The second voltage sensor _{34 u} detects the second U-phase voltage value V _dct2 U and outputs it to the motor electrical angle calculation unit 23. The second voltage sensor _{34 v} detects the second V-phase voltage value V _dct2 V and outputs it to the motor electrical angle calculation unit 23. The second voltage sensor _{34 w} detects the second W-phase voltage value V _dct2 W and outputs it to the motor electrical 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 , the first voltage value V _d1 may be described. is there. The 2U-phase voltage value _{V dct2U,} when there is no need to distinguish the first 2V phase voltage value _{V Dct2V} and the 2W-phase voltage value _{V dct2W,} sometimes described as the second voltage value _{V d2.} When there is no need to distinguish between the first voltage sensor 32u, the first voltage sensor 32v, and the first voltage sensor 32w, the first voltage sensor 32u may be described as the first voltage sensor 32. When there is no need to distinguish between the second voltage sensor 34u, the second voltage sensor 34v, and the second voltage sensor 34w, the second voltage sensor 34u may be described as the second voltage sensor 34.

FIG. 12 is a schematic diagram illustrating a motor electrical angle calculation unit according to the first embodiment. As shown in FIG. 12, the motor electrical angle calculator 23 includes a main motor electrical angle calculator 23b, a sub motor electrical angle calculator 23c, an electrical angle selector 23d, a RAM 50, and a ROM 51. The main motor electrical angle calculation unit 23 b includes an angle calculation unit 60 and a rotation detection abnormality diagnosis unit 61. The angle calculator 60 calculates the first motor electrical angle θ _m1 based on a sin signal and a cos signal corresponding to the rotation angle of the motor 93 output from the rotation detector 23a. Then, the calculated first motor electrical angle θ _m1 is output to the electrical angle selector 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 sub motor electrical angle calculation unit 23c calculates the second motor electrical angle θ _m2 as an estimated value without using the information output from the rotation detection unit 23a. As shown in FIG. 12, the sub motor electrical angle calculation unit 23c includes a relative offset amount estimation unit 62, a motor electrical angle estimation unit 63, and a motor electrical angle correction unit 64.

The relative offset amount estimation unit 62 estimates the relative offset amount θ _off of the reference value θ _osr of the output shaft rotation angle θ _os with respect to the origin θ _md of the motor electrical angle θ _m . In the following description, the origin θ _md of the motor electrical angle θ _m may be described as the motor electrical angle origin θ _md . The reference value θ _osr is the output shaft rotation angle θ _os at the time of system start-up (time when the ignition switch 98 is turned on from OFF). Then, the relative offset amount estimation unit 62 outputs the estimated relative offset amount θ _off to the motor electrical angle estimation unit 63.

FIG. 13 is a schematic diagram illustrating 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 an output shaft rotation angle θ _os detected by the output shaft rotation angle sensor 13 and a main motor electrical angle calculation unit when the rotation detection unit 23a and the angle calculation unit 60 are normal. A first relative offset amount θ _off1 is estimated based on the first motor electrical angle θ _m1 detected at 23b. Then, the estimated first relative offset amount θ _off1 is stored in the _RAM 50.

When the rotation detection unit 23a and the angle calculation unit 60 are normal, the first relative offset amount estimation unit 621 can acquire the motor electrical angle origin θ _md, and thus easily _obtain the first relative offset amount θ _off1 . Can be estimated. 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 electrical angle origin _θmd . 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 SAr 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 is turned on from the OFF state). When it is a value, the second relative offset amount θ _off2 is estimated. Specifically, the second relative offset amount estimation unit 622 estimates the motor electrical angle origin θ _md and estimates the second relative offset amount θ _off2 based on the estimated motor electrical angle origin θ _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 electrical angle θ _m is the assumed motor electrical angle θ _X and inputs a step-wave current corresponding to the assumed motor electrical 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-wave current corresponding to the assumed motor electrical angle θ _X to the motor 93 in response to the input of the current output command I _oi from the sub motor electrical angle calculation unit 23 c. The second relative offset amount estimation unit 622 acquires the steering torque T detected by the torque sensor 94 according to the input of the step-wave 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. When the system is activated, there is a possibility that the steering torque T is not zero when the driver is applying force to the steering wheel 81 when the ignition switch 98 is turned on. The second relative offset amount estimation unit 622 stores in advance the steering torque T at the time of system startup as a torque offset amount Toff and subtracts it from the steering torque T detected after the system startup.

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 the amplitudes of the torque waveforms are positive and negative and are equal. The second relative offset amount estimation unit 622 estimates that the motor electrical angle θ _m is the motor electrical angle origin θ _md when the amplitudes are determined to be positive and negative and equal.

On the other hand, when it is determined that the amplitude of the torque waveform is not equal in the steering torque T after subtraction and is not equal (not output according to the torque command), the motor electrical angle θ _{m at} that time is the motor electrical angle origin θ _md . Absent. In this case, the second relative offset amount estimating section 622, assuming the motor amplitude from the shape of the different torque waveform in positive and negative, and assuming motor electrical angle theta _X updating the assumed motor electrical angle theta _X by a predetermined angle shift and the updated A current output command I _oi is output to the current command value calculation unit 24 so that a step-wave current corresponding to the electrical angle θ _X is input to the motor 93. The second relative offset amount estimation unit 622 repeatedly performs such processing until the amplitude of the torque waveform is positive and negative and is determined to be equivalent.

The relative offset amount selection unit 623 selects the first relative offset amount θ _off1 when the abnormality detection signal SAr becomes a value indicating that there is an abnormality during system startup. 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, it 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 electrical angle estimator 63 outputs 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 estimating unit 62, the motor electrical angle estimated value θ _me is calculated. Then, the calculated motor electrical angle estimated value θ _me is output to the motor electrical angle correction unit 64.

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

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

  FIG. 14 is a schematic diagram illustrating a motor electrical angle correction unit according to the first embodiment. FIG. 15 is a schematic diagram illustrating an example of the relationship between the load torque and the change amount of the motor electrical angle due to the deformation characteristics of the mechanical elements of the steering force assist mechanism. FIG. 16 is a schematic diagram illustrating correction of the estimated motor electrical angle value by the correction unit according to the first embodiment. As shown in FIG. 14, the motor electrical 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 speed reducer 92 is interposed between the output shaft 82 b and the motor 93. For example, the compliance characteristic of the worm gear has nonlinearity and hysteresis as shown in FIG. In FIG. 15, the X-axis is load torque (motor output torque), and the Y-axis is the change amount δθ _m of the motor electrical angle θ _m . Therefore, the motor electric angle theta _m is not a one-to-one correspondence with the output shaft rotation angle theta _os. As the output of the motor 93 increases, the error between the estimated motor electrical angle θ _me and the actual motor electrical angle θ _m increases.

When the compliance characteristic of the worm gear is not taken into account, a deviation occurs between the actual motor electrical angle θ _m and the estimated motor electrical angle θ _{me due} to the output of the motor 93. Therefore, the motor electrical angle correction unit 64 corrects the motor electrical angle estimated value θ _me based on the induced voltage.

The induced voltage calculation unit 641 includes an induced voltage e _UV between the UV phase between the U phase and the V phase, an induced voltage e _VW between the V phase and the W phase between the V phase and the W phase, and between the W phase and the U phase. The WU-phase induced voltage _eWU is calculated.

The inductance by the first U-phase coil 37Ua and the first U-phase coil 37Ub (FIG. 10) is L (H), and the resistance is 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 first U-phase current value I _dct1U , the first V-phase current value I _dct1V , and the first 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. 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 phase induced voltage e _UV (V) is expressed by the following formula (4). The VW interphase induced voltage e _VW (V) is represented by the following formula (5). The WU-phase induced voltage e _WU (V) is represented by the following formula (6).

  Expressions (4), (5), and (6) include a term that differentiates the detected current value. When the induced voltage calculation unit 641 solves the differential equation, the differential equation is approximated by a difference equation. However, if the method of approximating the differential equation with the difference equation is used for the current detection value that easily includes noise, the difference between the calculation result by the induced voltage calculation unit 641 and the actual induced voltage value may be increased. There is sex.

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

  On the other hand, the motor electrical angle calculation unit 23 according to the first embodiment reduces the divergence between the calculation results obtained by the equations (4), (5), and (6) and the actual induced voltage value. Can do.

The _peak values of the first U-phase current value I _dct1U , the first V-phase current value I _dct1V , and the first W-phase current value I _dct1w are I _p , and the motor electrical angle is θ _m (rad). At this time, the first U-phase current value I _dct1U (A) is expressed by the following formula (7). The first V-phase current value I _dct1V (A) is expressed by the following formula (8). The first W-phase current value I _dct1W (A) is expressed by the following formula (9).

When Expression (7) and Expression (8) are applied to Expression (4), the last term on the right side of Expression (4) is transformed as shown in Expression (10) below. In the equation (10), Δθ _m is a term obtained by time differentiation of θ _m . Δθ _m is the electrical angle change rate of the motor 93 (amount of change in electrical angle per unit time). Then, when Expression (10) is substituted into Expression (4), Expression (11) is obtained. Thus, the term for differentiating the detected current value is replaced with the electrical angle change rate Δθ _m (rad / s) of the motor 93. Similarly, when Expression (8) and Expression (9) are substituted into Expression (5), the following Expression (12) is obtained. Substituting Equation (7) and Equation (9) into Equation (6) yields Equation (13) below.

If the rotation detection unit 23a is normal, the induced voltage calculation unit 641 can calculate the electrical 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 electrical angle change rate Δθ _m when the rotation detection unit 23a is abnormal.

The induced voltage calculation unit 641 calculates the electrical angle change rate Δθ _m based on the output shaft rotation angle θ _os detected by the torque sensor 94, for example. As illustrated 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 and stored in the RAM 50. The RAM 50 outputs the previously stored output shaft rotation angle θ _os to the induced voltage calculation unit 641 as the previous output shaft rotation angle θ _osp . The induced voltage calculation unit 641 calculates the electrical angle change rate Δθ _m based on the difference between the previous output shaft rotation angle θ _osp and the current output shaft rotation angle θ _os . Specifically, when the calculation cycle of the relative angle calculation unit 18 is t (s), the induced voltage calculation unit 641 calculates the electrical angle change rate Δθ _m by the following equation (14).

The induced voltage calculation unit 641 substitutes Equation (14) into Equation (4), Equation (5), and Equation (6) to induce UV phase induced voltage e _UV , VW phase induced voltage e _VW , and WU phase induced. The voltage e _WU is calculated. As shown in FIG. 16, the UV phase induced voltage e _UV , the VW phase induced voltage e _VW , and the WU phase induced voltage e _WU are sine waves shifted from each other by 120 °. As shown in FIG. 14, the induced voltage calculation unit 641 switches the calculated UV phase induced voltage e _UV , VW phase induced voltage e _VW , and WU phase induced voltage e _WU to output 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 induced voltage between virtual phases will be described with reference to FIG. The virtual interphase induced voltage is a voltage including a zero cross point different from the zero cross point of the interphase induced voltage. The zero-cross point is a timing at which the UV-phase induced voltage e _UV , the VW-phase induced voltage e _VW and the WU-phase induced voltage e _WU become the reference induced voltage (for example, 0 [V]). In the present embodiment, by calculating the virtual interphase induced voltage from the interphase induced voltage, more zero cross points than the zero cross point indicated by only the interphase induced voltage can be obtained. In the present embodiment, the virtual interphase induced voltage calculation unit 645 calculates the virtual interphase induced voltage for the purpose of obtaining information indicated by these zero cross points.

FIG. 16 is a diagram illustrating an example of the relationship between the interphase induced voltage and the virtual interphase induced voltage. Note that the vertical axis of the graph of one interphase induced voltage waveform and 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 electrical angle ([deg]). Assuming that the phase induced voltage estimated from the voltage equation is a sine wave, the phase induced voltage waveform drawn by the UV phase induced voltage e _UV , the VW phase induced voltage e _VW and the WU phase induced voltage e _WU represents the motor electrical angle of the motor 93. θ can be represented by a trigonometric function as in the following Expression (15), Expression (16), and Expression (17), and can be illustrated as in the upper left graph of FIG.

By applying the double angle formula to Equation (15), Equation (16), and Equation (17), an equation indicating an induced voltage between virtual phases having more zero cross points can be obtained. The double angle formula can be expressed as the following equation (18). sin (θ) can be the UV-phase induced voltage e _UV expressed by the equation (15). Further, cos (θ) can be calculated by combining trigonometric functions represented by the following equation (19). From equation (19), cos (θ) can be calculated from the VW-phase induced voltage e _VW and the WU-phase induced voltage e _WU represented by equations (16) and (17).

The formula of the double angle expressed by the equation (18) is expressed by the UV phase induced voltage e _UV , the VW phase induced voltage e _VW and the WU phase induced voltage e _WU represented by the equations (15), (16) and (17). (20), (21), and (22) are obtained. Equations (20), (21), and (22) are obtained by applying a double angle formula to a trigonometric function indicating the UV phase induced voltage e _UV , the VW phase induced voltage e _VW, and the WU phase induced voltage e _WU. The induced voltage between virtual phases corresponding to the obtained trigonometric function is shown, and can be illustrated as a graph in the lower left of FIG. 16, for example.

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

Next, a case will be described in which another equation is obtained in which the zero cross timing does not overlap with the equations (20), (21), and (22). By manipulating the trigonometric function representing the interphase induced voltage (see equations (15), (16), and (17)), a trigonometric function representing the interphase induced voltage having different phases can be obtained. The following formulas (23), (24), and (25) are expressed by the following equations (15), (16), and (17): UV-phase induced voltage e _UV and VW-phase induced voltage e _VW And a trigonometric function in which the phase of the induced voltage _eWU between the _WU phases is shifted by 37.5 °, and can be illustrated as a graph on the upper right 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) are obtained. Expressions (26), (27), and (28) correspond to the trigonometric functions obtained by applying the double angle formula to the trigonometric functions indicating the voltages obtained by shifting the phase of the interphase induced voltage by 37.5 °. The virtual interphase induced voltage is represented, and can be illustrated, for example, as in the lower right graph of FIG.

The virtual interphase induced voltage calculation unit 645 according to 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 formula (20), formula (21), and formula (22), and the above formula (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 formula (20), formula (21), formula (22), formula (26), formula (27), and formula (28) is the UV phase induced voltage e _UV , the VW phase This is a virtual interphase induced voltage having a frequency twice that of the induced voltage _eVW and the interphase induced voltage _eWU . Note that 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 formula (20), formula (21), and formula (22). Further, the order of operations related to the derivation of (26), Expression (27), and Expression (28) is not limited to the above example. For example, the phase operation may be performed on the equations (20), (21), and (22) (26) to derive the equations (27) and (28). The virtual interphase induced voltage calculation unit 645 outputs the calculated virtual interphase induced power 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 denoted by reference numeral VI.

The switching timing detection unit 642 detects the timing at which the magnitude relationship between the phase induced voltage and the virtual phase induced voltage or the voltage between the virtual phase induced voltage and the sign relationship is switched to another magnitude relationship and the sign relationship. The magnitude relationship is a magnitude relationship between the voltage values of each of a plurality of phases of a single-phase multiphase electric motor (for example, the motor 93). For example, when comparing each of the UV phase induced voltage e _UV , the VW phase induced voltage e _VW , and the WU phase induced voltage e _WU in the motor 93 of a certain motor electrical angle, the UV phase induced voltage e _UV , VW phase induced voltage _e VW, when the WU phase induced voltage _{e WU,} UV phase induced voltage _{e UV} has a magnitude relationship of greater than VW phase induced voltage _{e VW} and WU phase induced voltage _{e WU.} At this time, the VW-phase induced voltage e _VW has a magnitude relationship that is larger than the UV-phase induced voltage e _UV and larger than the WU-phase induced voltage e _WU . At this time, WU phase induced voltage _{e WU} has a magnitude relationship of less than UV phase induced voltage _{e UV} and VW phase induced voltage _e VW, WU phase induced voltage _{e WU.} The sign relationship is a positive / negative combination of voltage values of a plurality of phases of a single-phase multiphase electric motor (for example, motor 93). For example, when the voltage values of the UV phase induced voltage e _UV , the VW phase induced voltage e _VW , and the WU phase induced voltage e _WU in the motor 93 of a certain motor electrical angle are schematically shown, (e _UV , E _VW , e _WU ) = (+, +, +). Further, when the voltage values of the UV phase induced voltage e _UV , the VW phase induced voltage e _VW , and the WU phase induced voltage e _WU in the motor 93 of a certain motor electrical angle are schematically shown, (e _UV , E _VW , e _WU ) = (−, −, −). Hereinafter, the relationship between the motor electrical angle and the set of the magnitude relationship and the code relationship that are the detection targets by the switching timing detection unit 642 will be described with reference to FIGS.

  FIG. 17 is a diagram showing an interphase induced voltage waveform when the motor 93 rotates forward. FIG. 18 is a diagram illustrating the magnitude relationship and the sign relationship of the voltage of the interphase induced voltage waveform when the motor 93 rotates forward. FIG. 19 is a diagram showing an interphase induced voltage waveform when the motor 93 rotates forward. FIG. 20 is a diagram illustrating the magnitude relationship and the sign relationship of the voltage of the interphase induced voltage waveform when the motor 93 rotates forward. 18, 20, and FIGS. 21 to 24 to be described later, the range of the motor electrical angle specified from the set of the magnitude relationship and the sign relationship of the phase induced voltage waveform and the virtual phase induced voltage waveform is expressed by α to β. If the motor electrical angle is θ, for example, α ≦ θ <β.

The UV phase induced voltage e _UV , the VW phase induced voltage e _VW, and the WU phase induced voltage e _WU have predetermined voltage magnitude relationships and sign relationships in a predetermined angle range (for example, a range of 30 °). Become a relationship. In other words, in the motor 93, the magnitude relationship and the sign relationship of the interphase induced voltage corresponding to the motor electrical angle (θ) are uniquely determined. That is, the set of the magnitude relationship and the sign relationship of the voltage is a combination of the magnitude relationship and the sign relationship that are uniquely determined according to the motor electrical angle (θ). In the case of a three-phase electric motor like the motor 93 of this embodiment, when the motor electrical 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 electrical angle (θ). The magnitude relation and the sign relation set are different from each other. In the case of FIG. 17, the UV phase induced voltage e _UV is the largest (“large” in FIG. 18) and the VW phase induced voltage e _VW is in the range of the motor electrical angle 0 to 30 ° when the motor 93 rotates forward. The second largest ("middle" in FIG. 18), and the WU-phase induced voltage _eWU is the smallest ("small" in FIG. 18). Further, in the range of the motor electrical angle of 30 to 60 ° when the motor 93 is rotated forward, the UV phase induced voltage e _UV is the second largest (“middle” in FIG. 18), and the VW phase induced voltage e _VW is the highest. Large (“large” in FIG. 18) and the WU-phase induced voltage e _WU is the smallest (“small” in FIG. 18). As described above, the magnitude relationship among the UV phase induced voltage e _UV , the VW phase induced voltage e _VW and the WU phase induced voltage e _WU changes in units of 30 °. However, in the example shown in FIG. 17, in the motor electrical angle range of 180 to 210 °, the same voltage magnitude relationship as in the motor electrical angle range of 0 to 30 ° is obtained. Moreover, in the range of motor electrical angles 210-240 degrees, it becomes the same magnitude relationship of the voltage as the range of motor electrical angles 30-60 degrees. Thus, the period of the magnitude relationship of the voltage is 180 °.

Here, paying attention to the signs (positive and negative) of the UV phase induced voltage e _UV , the VW phase induced voltage e _VW and the WU phase induced voltage e _WU , the motor electrical angle in the range of 0 to 30 ° when the motor 93 rotates in the positive direction. , The UV-phase induced voltage e _UV is “+”, the VW-phase induced voltage e _VW is “−”, and the WU-phase induced voltage e _WU is “+”. That is, it can be considered that it has a sign relationship of (e _UV , e _VW , e _WU ) = (+, −, +). On the other hand, in the motor electrical angle range of 180 to 210 ° when the motor 93 rotates forward, the UV phase induced voltage e _UV is “−”, the VW phase induced voltage e _VW is “+”, and the WU phase induced voltage e _WU is “−”. That is, it can be considered that it has a sign relationship of (e _UV , e _VW , e _WU ) = (−, +, −). As described above, the range of the two motor electrical angles having the same voltage magnitude relationship is different in the sign relationship. For this reason, in the motor electrical angle range of 0 to 360 °, discrimination is possible in units of 30 ° by a combination of the voltage magnitude relationship and the sign relationship. In other words, the range of the motor electrical angle can be specified in units of 30 ° by detecting the magnitude relation and positive / negative of the voltages of the UV phase induced voltage e _UV , the VW phase induced voltage e _VW and the WU phase induced voltage e _WU. it can. This is the same when the motor 93 rotates in the reverse direction as shown in FIGS.

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

  FIGS. 21 to 24 are diagrams showing the magnitude relationship and the sign relationship of the voltages of the interphase induced voltage waveform and the virtual interphase induced voltage waveform when the motor 93 rotates forward. In FIG. 21 to FIG. 24, serial numbers (1 to 48) are assigned to the sets of magnitude relations and sign relations of the voltages of the interphase induced voltage waveform and the virtual interphase induced voltage waveform. In addition, in FIGS. 21 to 24, the interphase induced voltages represented by the above formulas (15) to (17) and the virtual interphase induced voltages represented by the formulas (20) to (28) are expressed by formula numbers. Show.

  The virtual interphase induced voltage represented by the equations (20) to (22) and the virtual interphase induced voltage represented by the equations (26) to (28) are respectively independent of the motor electrical angle with a resolution of 15 °. The magnitude relation and sign relation of the voltage that can specify the range are shown. Further, the virtual interphase induced voltage represented by the equations (20) to (22) and the virtual interphase induced voltage represented by the equations (26) to (28) are shifted in phase by 37.5 °. For this reason, whenever the motor electrical angle changes by 7.5 °, the magnitude relationship of the virtual interphase induced voltage expressed by the equations (20) to (22) or the virtual relationship expressed by the equations (26) to (28). One of the magnitude relations of the interphase induced voltage changes. Further, the sign relationship of the interphase induced voltage is different between the range of the motor electrical angle of 0 to 180 °, the range of the motor electrical angle of 0 to 180 °, and the range of the motor electrical angle of 180 to 360 °. Accordingly, as shown in FIGS. 21 to 24, in the range of the motor electrical angle of 0 to 360 °, a set of magnitude relations and sign relations of the voltages of the interphase induced voltage waveform and the virtual interphase induced voltage waveform, which are assigned different serial numbers, respectively. When collating each other, there is no case where the magnitude relationship and the sign relationship of the voltages are completely the same. Thereby, in this embodiment, the range of the motor electrical angle can be specified with a resolution of 7.5 °.

  18 is different from the magnitude relationship and sign relationship of voltages in the case of forward rotation and the magnitude relationship and sign relationship of voltages in the case of reverse rotation shown in FIG. 20, but the magnitude relationship of voltages in each rotation direction. In addition, by preparing in advance data indicating a set of code relationships, the range of the motor electrical angle can be specified regardless of the rotation direction of the motor 93. This is not limited to the case where the set of the magnitude relation and sign relation of the voltage is based only on the interphase induced voltage, but the magnitude relation between the voltages of the interphase induced voltage and the virtual interphase induced voltage described with reference to FIGS. The same applies to the code-related group.

Maps corresponding to both forward rotation and reverse rotation as map data for specifying the motor electrical angle θ _mz based on the set of voltage magnitude and sign relationships based on the concept described with reference to FIGS. 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 electrical angle θ _mz with reference to the map data according to the timing at which the magnitude relationship or the sign relationship of the voltage changes, and the identified motor electrical angle θ _mz is output to the angle error calculator 643. For example, when a transition is made from the magnitude relationship and the sign relationship of the serial number 1 to the magnitude relationship and the sign relationship of the serial number 2, the switching timing detection unit 642 specifies that the motor electrical angle θ _mz = 7.5 ° (FIG. 21).

The angle error calculation unit 643 calculates an angle error θ _err for correcting the motor electrical angle estimated value θ _me based on the motor electrical angle θ _mz . Specifically, when the motor electrical angle θmz is input, the angle error calculation unit 643 calculates the difference between the motor electrical angle θ _mz and the estimated motor electrical angle θ _me as the angle error θ _err . That is, the angle error θ _err is calculated so that the motor electrical angle θ _mz is derived when the angle error θ _err is applied to the estimated motor electrical angle value θ _me . Angle error calculation unit 643 stores the RAM50 the calculated difference as the angle error theta _err. In FIG. 25, motor electrical angles θ _mz1 , θ _mz2 , θ _mz3 , θ _mz4 , θ _mz5 , θ _mz6 are used as the motor electrical angles θ _mz corresponding to the resolution of 7.5 degrees input from the switching timing detection unit 642. Illustrated.

FIG. 25 is a schematic diagram illustrating correction of the estimated motor electrical angle value by the correction unit according to the first embodiment. The correction unit 644 corrects the motor electrical angle estimation value θ _me input from the motor electrical angle estimation unit 63 with the angle error θ _err stored in the RAM 50, as shown in FIG. The correction unit 644 corrects the estimated motor electrical angle θ _me with 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 in FIG. 16 represents the estimated motor electrical angle θ _me (second motor electrical 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 electrical angle θ _mz (motor electrical angle θ _mz1 to motor electrical angle θ _mz6 ) is the angle error θ _err . The correcting unit 644 outputs the corrected motor electrical angle estimated value θ _me as the second motor electrical angle θ _m2 to the electrical angle selecting unit 23d (see FIG. 12). If it is attempted to obtain the motor electrical angle θmz based only on the magnitude relationship and the sign relationship of the interphase induced voltage, the resolution becomes 30 degrees, so that the motor electrical angle estimated value θ _me is updated as in RV in FIG. The frequency becomes 1/4. Thus, according to the present embodiment, it is possible to obtain the motor electrical angle θ _mz for correcting the motor electrical angle estimated value θ _me with higher resolution.

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

The current command value calculation unit 24 calculates a current command value based on the steering torque T, the vehicle speed V, and the motor electrical angle θ _m (the first motor electrical angle θ _m1 or the second motor electrical angle θ _m2 ). Thereby, even if it is a case where abnormality arises in the rotation detection part 23a, ECU90 can control the motor 93 appropriately.

The induced voltage calculation unit 641 necessarily calculates the UV phase induced voltage e _UV , the VW phase induced voltage e _VW , and the WU phase 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 that the motor 93 has may be one. Further, the rotation detection unit 23a is not necessarily a resolver, and may be another sensor such as a rotary encoder or an MR sensor.

As described above, according to this embodiment, the ECU 90 controls the steering assist force based on the steering angle detected by the steering angle detection unit (for example, the output shaft rotation angle sensor 13) that detects the steering angle of the steering. Motor electrical angle estimation unit 63 for estimating motor electrical angle estimation value θ _me of the multiphase electric motor that generates the motor, and motor electrical angle correction unit for correcting motor electrical angle estimation value θ _me estimated by motor electrical angle estimation unit The motor electrical angle correction unit 64 includes a current detection unit (a first current sensor 31 and a second current sensor 33) that detects a current flowing through each of the multiphase coils included in the driven multiphase electric motor. The voltage detectors (first voltage sensor 32 and second voltage sensor 34) for detecting the respective voltages of the multiphase coils, and the current and voltage detectors detected by the current detectors An induced voltage calculation unit 641 that calculates an interphase induced voltage of the multiphase electric motor based on the pressure, and a virtual interphase induced voltage whose phase is different from the phase induced voltage based on the phase induced voltage calculated by the induced voltage calculation unit 641 A virtual phase induced voltage calculation unit 645 for calculating the phase detection voltage, and a timing at which each of the phase induced voltage and the virtual phase induced voltage or a set of magnitude relation and sign relation of the virtual phase induced voltage is switched to another magnitude relation and sign relation set. And a correction unit 644 that corrects the estimated motor electrical angle θ _me estimated by the motor electrical angle estimation unit based on the detection result of the switching timing detection unit 642.

Thus, at the timing when the voltage magnitude / sign relation set switches to another magnitude / sign relation set, the voltage magnitude / sign relation set corresponds to the other magnitude relation / sign relation motor. The motor electrical angle estimated value θ _me can be corrected based on the estimation that the electrical angle θ _mz has been reached. Therefore, the ECU 90 can estimate the motor electrical angle θ _mz with higher accuracy without depending on the motor rotation angle sensor. In addition, by calculating the virtual phase induced voltage and using the relationship between the magnitude of each phase induced voltage and the virtual phase induced voltage and the set of sign relationship and the motor electrical angle, the motor electrical angle θ _mz can be obtained with higher resolution. Can be determined. That is, the correction of the motor electrical angle estimated value θ _me can be performed more finely. Note that the motor electrical angle estimated value θ _me output from the motor electrical angle estimating unit 63 is based on the steering torque T detected by the torque sensor 94, and therefore between the detection target of the torque sensor 94 and the motor 93. A mechanical error may occur due to a mechanical configuration (for example, the speed reducer 92). On the other hand, since the motor electrical angle θ _mz is based on an electrical signal from the motor 93, there is no mechanical error that may occur in the estimated motor electrical angle θ _me . That is, in the present embodiment, by correcting the motor electrical angle estimated value θ _me with the motor electrical angle θ _mz , it is possible to suppress mechanical errors that may be involved in the derivation of the second motor electrical angle θ _m2. it can. Therefore, the second motor electrical angle θ _m2 can be derived with higher accuracy. As described above, according to the present embodiment, the angle can be estimated more finely, so that the correction can be made before the accumulation of the angle error becomes large, and the steering feeling can be further improved.

Moreover, it is preferable that the virtual interphase induced voltage calculation unit 645 calculates a 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 electrical angle estimated value θ _me can be estimated with a resolution twice that of the interphase induced voltage, and the ECU 90 does not depend on the motor rotation angle sensor. Therefore, the motor electrical angle θ _mz can be estimated with higher accuracy. Further, since the angle error can be corrected with higher accuracy, the accumulation (integration) of the estimated angle error of the motor electrical angle can be suppressed. Therefore, the estimation accuracy of the motor electrical 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 other combinations of magnitude relationships and sign relationships between the interphase induced voltage and the virtual interphase induced voltage. It is preferable to detect the timing of switching to a set of magnitude relationship and code relationship. The motor electrical angle estimated value θ _me can be estimated with higher resolution by combining the magnitude relationship and the sign relationship between the two virtual phase induced voltages having different phases. Therefore, the ECU 90 can estimate the motor electrical angle θ _mz with higher accuracy without depending on the motor rotation angle sensor.

The motor 93 is a three-phase electric motor, and one of the two virtual interphase induced voltages is a virtual interphase induced voltage corresponding to a trigonometric function obtained by applying a double angle formula to the trigonometric function indicating the interphase induced voltage. The other of the two virtual interphase induced voltages is a virtual corresponding to a trigonometric function obtained by applying a double angle formula to a trigonometric function indicating a voltage obtained by shifting the phase of the interphase induced voltage by 37.5 °. A phase-induced voltage is preferable. Thereby, the motor electrical angle θ _mz can be estimated with a resolution of 7.5 °.

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

The electric power steering device 80 also includes a motor that generates steering assist 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 first motor drive circuit. 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} An electric power steering apparatus provided. The electric power steering apparatus 80 can estimate the motor electrical angle θ _mz with high accuracy without depending on the motor rotation angle sensor, and can provide an appropriate auxiliary steering torque to the output shaft.

The electric power steering device 80 includes a steering angle detector (for example, an output shaft rotation angle sensor 13) that detects the steering angle of the steering, a torque sensor 94 that detects torque transmitted to the steering mechanism, and a motor A rotation detection unit 23a that detects the rotation angle of the output shaft and a rotation detection abnormality diagnosis unit 61 that detects an abnormality of the rotation detection unit 23a. abnormality drives and controls the motor drive circuit based on the motor electric angle theta _m detected by the torque and the rotation detecting unit 23a detected by the torque sensor 94 when not detected, the rotation detecting unit 23a by the rotation detecting abnormality diagnosing section 61 When the abnormality is detected, the motor drive circuit is driven and controlled based on the second motor electrical angle θ _m2 output by the motor electrical angle calculator 23.

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

The induced voltage calculation unit 641 does not necessarily calculate the electrical 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 electrical 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 electrical 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, when the calculation cycle of the relative angle calculation unit 18 is t (s), the induced voltage calculation unit 641 calculates the electrical angle change rate Δθ _m by the following equation (29).

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

(Embodiment 2)
FIG. 26 is a schematic diagram illustrating 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 electrical angle estimation unit 63 may not be provided. In the second embodiment, the relative offset amount estimation unit 62 and the motor electrical angle estimation unit 63 are omitted. Also, in this case, the switching timing detection unit 642 detects the timing at which the magnitude relationship between the phase induced voltage and the virtual phase induced voltage or the voltage between the virtual phase induced voltages and the sign relation set switches to another magnitude relation and the sign relation set. Then, an output PI indicating the set of the magnitude relationship and the sign relationship between the voltages before and after the switching is performed to the motor electrical angle estimation unit 649. The motor electrical angle estimator 649 outputs the motor electrical angle θ _mz corresponding to the set of the magnitude relationship and the sign relationship before and after the switching indicated by the output PI as the estimated second motor electrical angle θ _m2 .

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

DESCRIPTION OF SYMBOLS 10 1st multipolar ring magnet 11 2nd multipolar ring magnet 12 Input shaft rotation angle sensor 13 Output shaft rotation angle sensor 23 Motor electrical angle calculation part 23a Rotation detection part 23b Main motor electrical angle calculation part 23c Sub motor electrical angle calculation part 23d Electrical angle selector 31, 31u, 31v, 31w First current sensor 32, 32u, 32v, 32w First voltage sensor 33, 33u, 33v, 33w Second current sensor 34, 34u, 34v, 34w Second voltage sensor 64 Motor Electrical 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 Decelerator 93 Motor 94 Torque sensor 95 Vehicle speed sensor 98 Ignition switch 99 Power supply device 101 Vehicle 641 Induced voltage calculator 642 Switching timing detector 643 Angle error calculator 644 Corrector 645 Virtual phase induced voltage calculator

Claims (9)

A current detector for detecting a current flowing in each of the multiphase coils of the driven multiphase electric motor;
A voltage detector for detecting the voltage of each of the multiphase coils;
An induced voltage calculator that calculates an interphase induced voltage of the multiphase electric motor based on the current detected by the current detector and the voltage detected by the voltage detector;
Based on the interphase induced voltage calculated by the induced voltage calculator, a virtual interphase induced voltage calculator that calculates a virtual interphase induced voltage that is different in phase or frequency from the interphase induced voltage, and
A switching timing detection unit for detecting a timing at which each of the interphase induced voltage and the virtual interphase induced voltage or the set of magnitude relations and sign relations of the virtual interphase induced voltage switches to another magnitude relation and sign relation set;
A motor control device comprising: a motor electrical angle estimation unit that estimates a motor electrical angle of the multiphase electric motor based on a detection result by the switching timing detection unit. The virtual interphase induced voltage calculation unit calculates two virtual interphase induced voltages having different phases,
2. The motor control according to claim 1, wherein the switching timing detection unit detects a timing at which each magnitude relation and sign relation set of the interphase induced voltage and virtual interphase induced voltage switches to another magnitude relation and sign relation set. apparatus. The multi-phase electric motor is a three-phase electric motor,
One of the two virtual phase induced voltages is a virtual phase induced voltage corresponding to a trigonometric function obtained by applying a double angle formula to a trigonometric function indicating the phase induced voltage,
The other of the two virtual phase induced voltages is a virtual phase corresponding to a trigonometric function obtained by applying a double angle formula to a trigonometric function indicating a voltage obtained by shifting the phase of the phase induced voltage by 37.5 degrees. The motor control device according to claim 2, wherein the motor control device is an induced voltage. The motor control device according to any one of claims 1 to 3, 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 having a multi-phase electric motor for generating steering assist force;
A steering angle detector that detects the steering angle of the steering;
The motor control device according to any one of claims 1 to 4,
A motor drive circuit for supplying a drive current to the multiphase electric motor;
An electric power steering device comprising: a control arithmetic device that drives and controls the motor drive circuit based on a motor electrical angle of the multiphase electric motor;
The control arithmetic device controls the multiphase electric motor by feedback control based on the motor electrical angle estimated by the motor electrical angle estimation unit and the motor electrical angle estimated from the steering angle detected by the steering angle detection unit. Electric power steering device to drive. A motor electrical angle estimator that estimates a motor electrical angle of a multiphase electric motor that generates a steering assist force based on a steering angle detected by a steering angle detector that detects a steering angle;
A motor electrical angle correction unit that corrects the motor electrical angle estimated by the motor electrical angle estimation unit;
The motor electrical angle correction unit is
A current detector for detecting a current flowing in each of the multiphase coils of the driven multiphase electric motor;
A voltage detector for detecting the voltage of each of the multiphase coils;
An induced voltage calculator that calculates an interphase induced voltage of the multiphase electric motor based on the current detected by the current detector and the voltage detected by the voltage detector;
Based on the interphase induced voltage calculated by the induced voltage calculator, a virtual interphase induced voltage calculator that calculates a virtual interphase induced voltage that is different in phase or frequency from the interphase induced voltage, and
A switching timing detection unit for detecting a timing at which each of the interphase induced voltage and the virtual interphase induced voltage or the set of magnitude relations and sign relations of the virtual interphase induced voltage switches to another magnitude relation and sign relation set;
A motor control device comprising: a correction unit that corrects the motor electrical angle estimated by the motor electrical angle estimation unit based on a detection result by the switching timing detection unit. A multiphase electric motor for generating steering assist force of the steering;
A motor drive circuit for supplying a drive current to the multiphase electric motor;
A control arithmetic device that drives and controls the motor drive circuit based on a motor electrical angle of the multiphase electric motor;
An electric power steering device comprising: a motor control device that outputs the motor electrical angle;
The said motor control apparatus is a motor control apparatus of any one of Claim 1 to 5. Electric power steering apparatus. A steering angle detector that detects the steering angle of the steering;
A torque detector for detecting torque transmitted to the steering mechanism;
A motor electrical angle detector that detects a rotation angle of an output shaft of the multiphase electric motor;
An abnormality detection unit for detecting an abnormality of the motor electrical angle detection unit,
The control arithmetic device is based on the torque detected by the torque detector and the motor electrical angle detected by the motor electrical angle detector when the abnormality detector does not detect the abnormality of the motor electrical angle detector. The drive control of the motor drive circuit is performed, and the motor drive circuit is driven and controlled based on the motor electrical angle output by the motor control device when the abnormality detection unit detects an abnormality of the motor electrical angle detection unit. Item 8. The electric power steering device according to Item 7.   A vehicle comprising the electric power steering device according to claim 7 or 8.

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