JPWO2019142875A1 - Electric power steering device and method for detecting rotation angle of motor for electric power steering device - Google Patents

Abstract

Provided are an electric power steering device capable of detecting a rotation angle with high accuracy, and a rotation angle detection method. In the electric power steering device, a motor is provided on a steering column shaft, and the steering force of the steering is torque-controlled by drivingly controlling the motor using the rotation angle detected by the rotation angle detection device. The rotation angle detection device includes a ring-shaped resolver stator and a resolver rotor having a plurality of poles in which a gap d between the inner circumference of the resolver stator and the inner periphery of the resolver stator changes a plurality of times. A resolver that outputs a sine wave signal and a cosine wave signal of an electrical angle according to the rotation of the rotor, a position detection unit that detects the motor position based on the sine wave signal and the cosine wave signal, and a sine wave signal and a cosine wave signal A storage unit (EEPROM) for storing a first correction value and a second correction value for correcting

Description

  The present invention relates to an electric power steering device and a rotation angle detecting method.

  There is a so-called electric power steering (EPS) device in which steering is assisted by a motor in order to reduce the steering force of vehicles such as passenger cars and trucks. The electric power steering device has a steering assist control function for applying an assist steering force generated by a motor to a steering mechanism of a vehicle. In such an electric power steering apparatus, in order to improve the accuracy of the steering assist control, it is necessary to detect the position (rotation angle) of the motor with high accuracy. Further, as a position sensor for detecting the position (rotation angle) of a motor, a resolver is widely used because of its robustness and environmental resistance due to its simple configuration (for example, Patent Document 1).

JP, 2011-097679, A

  In particular, in a column-assist type electric power steering device that applies an auxiliary steering force to the steering through a speed reducer provided on a column shaft directly connected to the steering, vibration generated by torque ripple of a motor is transmitted to the steering. easy.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electric power steering device and a rotation angle detection method capable of detecting a rotation angle with high accuracy.

  In order to achieve the above object, in an electric power steering apparatus according to an aspect of the present invention, a motor is provided on a steering column shaft, and the motor is driven and controlled using a rotation angle detected by a rotation angle detection device. As a result, in the electric power steering device that controls the steering force of the steering wheel by torque, the rotation angle detection device includes an annular resolver stator and an inner circumference of the resolver stator per revolution around the axis. A resolver rotor having a plurality of poles in which the gap between them changes a plurality of times, and a resolver that outputs a sine wave signal and a cosine wave signal of an electrical angle in accordance with the rotation of the resolver rotor, and the sine wave signal and the cosine A position detection unit that detects the position of the motor based on a wave signal; and a storage unit that stores a first correction value and a second correction value for correcting the sine wave signal and the cosine wave signal. The position detecting unit calculates the first correction value and the second correction value, and corrects the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the first correction value, A correction calculation processing unit that corrects the phases of the sine wave signal and the cosine wave signal based on a second correction value, and an angle calculation unit that calculates the rotation angle of the motor based on the output signal of the correction calculation processing unit. In the correction value calculation process for calculating the first correction value and the second correction value, the correction calculation processing unit is configured to: based on the maximum value and the minimum value of the sine wave signal and the cosine wave signal, A first correction value is calculated, and a first sine wave signal and a first cosine wave signal in which the offset voltage and the gain of the sine wave signal and the cosine wave signal are corrected are obtained based on the first correction value, and the first correction value is obtained. The second sine wave signal and the second cosine wave signal obtained by advancing the phases of the sine wave signal and the first cosine wave signal by 45 electrical degrees are obtained, and the maximum of the second sine wave signal and the second cosine wave signal is obtained. In the correction process of calculating the second correction value based on the value and the minimum value and correcting the sine wave signal and the cosine wave signal, the sine wave signal and the cosine wave signal of the sine wave signal and the cosine wave signal are calculated based on the first correction value. A second sine wave signal obtained by obtaining a first sine wave signal and a first cosine wave signal whose offset voltage and gain are corrected, and advancing the phases of the first sine wave signal and the first cosine wave signal by 45 electrical degrees. And a second cosine wave signal, and at least a third sine wave signal and a third cosine wave signal in which the gains of the second sine wave signal and the second cosine wave signal are corrected based on the second correction value. , A fourth sine wave signal and a fourth cosine wave signal in which the phases of the third sine wave signal and the third cosine wave signal are delayed by an electrical angle of 45 degrees, respectively, and the angle calculation unit determines the fourth sine wave signal. The rotation angle of the motor is calculated based on the signal and the fourth cosine wave signal.

  Thereby, the first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal, and the second correction value for correcting the phases of the sine wave signal and the cosine wave signal can be obtained. . Moreover, the offset voltage, gain, and phase of the sine wave signal and the cosine wave signal can be corrected using the first correction value and the second correction value. Therefore, the angle calculation unit can calculate the position detection (rotation angle) of the motor with high accuracy. Therefore, the motor can be driven and controlled with high precision, and the precision of steering assist control in the electric power steering device can be improved.

  In order to achieve the above object, in an electric power steering apparatus according to an aspect of the present invention, a motor is provided on a steering column shaft, and the motor is driven and controlled using a rotation angle detected by a rotation angle detection device. As a result, in the electric power steering device that controls the steering force of the steering wheel by torque, the rotation angle detection device includes an annular resolver stator and an inner circumference of the resolver stator per revolution around the axis. A resolver rotor having a plurality of poles in which the gap between them changes a plurality of times, and a resolver that outputs a sine wave signal and a cosine wave signal of an electrical angle in accordance with the rotation of the resolver rotor, and the sine wave signal and the cosine A position detection unit that detects the position of the motor based on a wave signal; and a storage unit that stores a first correction value and a second correction value for correcting the sine wave signal and the cosine wave signal. The position detecting unit calculates the first correction value and the second correction value, and corrects the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the first correction value, A correction calculation processing unit that corrects the phases of the sine wave signal and the cosine wave signal based on a second correction value, and an angle calculation unit that calculates the rotation angle of the motor based on the output signal of the correction calculation processing unit. In the correction value calculation process for calculating the first correction value and the second correction value, the correction calculation processing unit is configured to: based on the maximum value and the minimum value of the sine wave signal and the cosine wave signal, A first correction value is calculated, and a first sine wave signal and a first cosine wave signal in which the offset voltage and the gain of the sine wave signal and the cosine wave signal are corrected are obtained based on the first correction value, and the first correction value is obtained. The second sine wave signal and the second cosine wave signal obtained by delaying the phases of the sine wave signal and the first cosine wave signal by 45 degrees in electrical angle are calculated, and the maximum of the second sine wave signal and the second cosine wave signal is obtained. In the correction process of calculating the second correction value based on the value and the minimum value and correcting the phases of the sine wave signal and the cosine wave signal, the sine wave signal and the cosine wave are calculated based on the first correction value. A second sine wave in which a first sine wave signal and a first cosine wave signal in which the offset voltage and the gain of the signal are corrected are obtained and the phases of the first sine wave signal and the first cosine wave signal are delayed by 45 degrees in electrical angle, respectively. Wave signal and second cosine wave signal are obtained, and at least the gain of the second sine wave signal and the second cosine wave signal is corrected based on the second correction value. A signal is obtained, a fourth sine wave signal and a fourth cosine wave signal obtained by advancing the phases of the third sine wave signal and the third cosine wave signal by 45 electrical degrees are obtained, and the angle calculation unit The rotation angle of the motor is calculated based on the four sine wave signal and the fourth cosine wave signal.

  Thereby, the first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal, and the second correction value for correcting the phases of the sine wave signal and the cosine wave signal can be obtained. . Moreover, the offset voltage, gain, and phase of the sine wave signal and the cosine wave signal can be corrected using the first correction value and the second correction value. Therefore, the angle calculation unit can calculate the position detection (rotation angle) of the motor with high accuracy. Therefore, the motor can be driven and controlled with high precision, and the precision of steering assist control in the electric power steering device can be improved.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit is SIN0_MAX, an average value of maximum values of the sine wave signals of a plurality of cycles detected in a predetermined cycle of a mechanical angle of the motor, and the sine of the plurality of cycles. When the average value of the minimum values of the wave signals is SIN0_MIN, the average value of the maximum values of the cosine wave signals of a plurality of cycles is COS0_MAX, and the average value of the minimum values of the cosine wave signals of a plurality of cycles is COS0_MIN, the following equation (1 ) And (2), it is preferable to calculate the first offset correction values SIN_OFFSET1 and COS_OFFSET1 that are the first correction values.

  SIN_OFFSET1=(SIN0_MAX+SIN0_MIN)/2 (1)

  COS_OFFSET1=(COS0_MAX+COS0_MIN)/2 (2)

  Thereby, the correction value for correcting the offset voltage of the sine wave signal and the cosine wave signal is obtained.

  As a desirable mode of the electric power steering device, the correction calculation processing unit calculates the first gain correction values SIN_GAIN1 and COS_GAIN1 that are the first correction values by using the following expressions (3) and (4), and In (3) and (4), N is preferably a natural number.

  SIN_GAIN1=N/(SIN0_MAX-SIN0_MIN) (3)

  COS_GAIN1=N/(COS0_MAX-COS0_MIN) (4)

  Thereby, the correction value for correcting the gains of the sine wave signal and the cosine wave signal is obtained.

  As a desirable aspect of the electric power steering apparatus, the correction calculation processing unit uses the following equations (5) and (6) when the sine wave signal is SIN0 and the cosine wave signal is COS0. It is preferable to calculate the signal SIN1 and the first cosine wave signal COS1.

  SIN1=SIN_GAIN1×(SIN0-SIN_OFFSET1) (5)

  COS1=COS_GAIN1×(COS0-COS_OFFSET1) (6)

  As a result, the offset voltage and gain of the sine wave signal and the cosine wave signal are corrected.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit calculates the second sine wave signal SIN2 and the second cosine wave signal COS2 by using the following equations (7) and (8), and calculates the second sine wave signal. When the maximum value of the wave signal is SIN2_MAX, the minimum value of the second sine wave signal is SIN2_MIN, the maximum value of the second cosine wave signal is COS2_MAX, and the minimum value of the second cosine wave signal is COS2_MIN, the following equation ( 9) and (10) are used to calculate the second offset correction values SIN_OFFSET2 and COS_OFFSET2, which are the second correction values using the following equations (11) and (12). It is preferable that the 2-gain correction values SIN_GAIN2 and COS_GAIN2 are calculated, and that N is a natural number in the following equations (11) and (12).

  SIN2=SIN1-COS1 (7)

  COS2=COS1+SIN1 (8)

  SIN_OFFSET2=(SIN2_MAX+SIN2_MIN)/2 (9)

  COS_OFFSET2=(COS2_MAX+COS2_MIN)/2 (10)

  SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN) (11)

  COS_GAIN2=N/(COS2_MAX-COS2_MIN)...(12)

  Thereby, a correction value for correcting the phases of the sine wave signal and the cosine wave signal is obtained.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit calculates the third sine wave signal SIN3 and the third cosine wave signal COS3 by using the following equations (13) and (14), and the following equation (15) ) And (16), it is preferable to calculate the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4.

  SIN3=SIN_GAIN2×(SIN2-SIN_OFFSET1) (13)

  COS3=COS_GAIN2×(COS2-COS_OFFSET1) (14)

  SIN4=SIN3+COS3 (15)

  COS4=COS3-SIN3 (16)

  Thereby, the phases of the sine wave signal and the cosine wave signal are corrected.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit calculates the second sine wave signal SIN2 and the second cosine wave signal COS2 by using the following equations (17) and (18), and the following equation (19) ) And (20), the second gain correction values SIN_GAIN2 and COS_GAIN2, which are the second correction values, are calculated, and in the following equations (19) and (20), N is preferably a natural number.

  SIN2=SIN1-COS1 (17)

  COS2=COS1+SIN1 (18)

  SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN) (19)

  COS_GAIN2=N/(COS2_MAX-COS2_MIN) (20)

  Thereby, a correction value for correcting the phases of the sine wave signal and the cosine wave signal is obtained.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit calculates the third sine wave signal SIN3 and the third cosine wave signal COS3 using the following equations (21) and (22), and the following equation (23) ), (24) are used to calculate the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4.

  SIN3=SIN_GAIN2×SIN2 (21)

  COS3=COS_GAIN2×COS2 (22)

  SIN4=SIN3+COS3 (23)

  COS4=COS3-SIN3 (24)

  Thereby, the phases of the sine wave signal and the cosine wave signal are corrected.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit calculates the second sine wave signal SIN2 and the second cosine wave signal COS2 using the following equations (7)′ and (8)′, 2 When the maximum value of the sine wave signal is SIN2_MAX, the minimum value of the second sine wave signal is SIN2_MIN, the maximum value of the second cosine wave signal is COS2_MAX, and the minimum value of the second cosine wave signal is COS2_MIN: The second offset correction values SIN_OFFSET2 and COS_OFFSET2, which are the second correction values, are calculated using equations (9)′ and (10)′, and the second offset correction values SIN_OFFSET2 and COS_OFFSET2 are calculated using the following equations (11)′ and (12)′. It is preferable that the second gain correction values SIN_GAIN2 and COS_GAIN2, which are two correction values, are calculated, and N is a natural number in the following formulas (11)′ and (12)′.

  SIN2=SIN1+COS1 (7)'

  COS2=COS1-SIN1 (8)'

  SIN_OFFSET2=(SIN2_MAX+SIN2_MIN)/2 (9)'

  COS_OFFSET2=(COS2_MAX+COS2_MIN)/2 (10)'

  SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN)...(11)'

  COS_GAIN2=N/(COS2_MAX-COS2_MIN)...(12)'

  Thereby, a correction value for correcting the phases of the sine wave signal and the cosine wave signal is obtained.

  As a preferable mode of the electric power steering apparatus, the correction calculation processing unit calculates the third sine wave signal SIN3 and the third cosine wave signal COS3 using the following formulas (13)′ and (14)′, It is preferable to calculate the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 using (15)′ and (16)′.

  SIN3=SIN_GAIN2*(SIN2-SIN_OFFSET2)...(13)'

  COS3=COS_GAIN2×(COS2-COS_OFFSET2)...(14)'

  SIN4=SIN3-COS3 (15)'

  COS4=COS3+SIN3 (16)'

  Thereby, the phases of the sine wave signal and the cosine wave signal are corrected.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit calculates the second sine wave signal SIN2 and the second cosine wave signal COS2 by using the following equations (17)′ and (18)′, The second gain correction values SIN_GAIN2 and COS_GAIN2, which are the second correction values, are calculated using (19)′ and (20)′, and N is a natural number in the following equations (19)′ and (20)′. It is preferable.

  SIN2=SIN1+COS1 (17)'

  COS2=COS1-SIN1 (18)'

  SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN)...(19)'

  COS_GAIN2=N/(COS2_MAX-COS2_MIN)...(20)'

  Thereby, a correction value for correcting the phases of the sine wave signal and the cosine wave signal is obtained.

  As a desirable mode of the electric power steering apparatus, the correction calculation processing unit calculates the third sine wave signal SIN3 and the third cosine wave signal COS3 using the following formulas (21)′ and (22)′, It is preferable to calculate the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 using (23)′ and (24)′.

  SIN3=SIN_GAIN2×SIN2...(21)'

  COS3=COS_GAIN2×COS2 (22)'

  SIN4=SIN3-COS3 (23)'

  COS4=COS3+SIN3 (24)'

  Thereby, the phases of the sine wave signal and the cosine wave signal are corrected.

  As a desirable mode of the electric power steering device, it is preferable that the angle calculation unit calculates the rotation angle based on the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4.

  Accordingly, the position detection (rotation angle) of the motor can be calculated with high accuracy.

  In order to achieve the above object, a rotation angle detecting method according to an aspect of the present invention is a method in which a gap between an inner periphery of an annular resolver stator changes a plurality of times per revolution around an axis of a motor. A rotation angle detecting method for correcting a sine wave signal and a cosine wave signal of an electrical angle output according to the rotation of a resolver rotor having a pole, and detecting the rotation angle of the motor based on the correction result, A first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal is calculated based on the maximum value and the minimum value of the sine wave signal and the cosine wave signal, and is calculated as the first correction value. Based on the offset voltage and the gain of the sine wave signal and the cosine wave signal, the first sine wave signal and the first cosine wave signal are obtained, and the phases of the first sine wave signal and the first cosine wave signal are respectively calculated. A second sine wave signal and a second cosine wave signal advanced by 45 degrees in electrical angle are obtained, and the sine wave signal and the cosine signal are calculated based on the maximum and minimum values of the second sine wave signal and the second cosine wave signal. A correction value calculation processing step for calculating a second correction value for correcting the phase of the wave signal, and a first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the first correction value. A sine wave signal and a first cosine wave signal are obtained, and a second sine wave signal and a second cosine wave signal obtained by advancing the phases of the first sine wave signal and the first cosine wave signal by 45 electrical degrees are obtained, Based on the second correction value, at least a third sine wave signal and a third cosine wave signal obtained by correcting the gains of the second sine wave signal and the second cosine wave signal are obtained, and the third sine wave signal and the third sine wave signal are obtained. A correction processing step of obtaining a fourth sine wave signal and a fourth cosine wave signal in which the phase of the third cosine wave signal is delayed by 45 degrees in electrical angle, respectively, and based on the fourth sine wave signal and the fourth cosine wave signal, A rotation angle calculation step of calculating a rotation angle of the motor.

  Thereby, the first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal, and the second correction value for correcting the phases of the sine wave signal and the cosine wave signal can be obtained. . Moreover, the offset voltage, gain, and phase of the sine wave signal and the cosine wave signal can be corrected using the first correction value and the second correction value. Therefore, the angle calculation unit can calculate the position detection (rotation angle) of the motor with high accuracy.

  In order to achieve the above object, a rotation angle detecting method according to an aspect of the present invention is a method in which a gap between an inner periphery of an annular resolver stator changes a plurality of times per revolution around an axis of a motor. A rotation angle detecting method for correcting a sine wave signal and a cosine wave signal of an electrical angle output according to the rotation of a resolver rotor having a pole, and detecting the rotation angle of the motor based on the correction result, A first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal is calculated based on the maximum value and the minimum value of the sine wave signal and the cosine wave signal, and is calculated as the first correction value. Based on the offset voltage and the gain of the sine wave signal and the cosine wave signal, the first sine wave signal and the first cosine wave signal are obtained, and the phases of the first sine wave signal and the first cosine wave signal are respectively calculated. A second sine wave signal and a second cosine wave signal delayed by an electrical angle of 45 degrees are obtained, and the sine wave signal and the cosine wave are calculated based on the maximum and minimum values of the second sine wave signal and the second cosine wave signal. A correction value calculation processing step for calculating a second correction value for correcting the phase of the wave signal, and a first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the first correction value. A sine wave signal and a first cosine wave signal are obtained, and a second sine wave signal and a second cosine wave signal in which the phases of the first sine wave signal and the first cosine wave signal are delayed by an electrical angle of 45 degrees are obtained, Based on the second correction value, at least a third sine wave signal and a third cosine wave signal obtained by correcting the gains of the second sine wave signal and the second cosine wave signal are obtained, and the third sine wave signal and the third sine wave signal are obtained. On the basis of the correction processing step of obtaining a fourth sine wave signal and a fourth cosine wave signal obtained by advancing the phase of the third cosine wave signal by 45 electrical degrees, respectively, based on the fourth sine wave signal and the fourth cosine wave signal, A rotation angle calculation step of calculating a rotation angle of the motor.

  Thereby, the first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal, and the second correction value for correcting the phases of the sine wave signal and the cosine wave signal can be obtained. . Moreover, the offset voltage, gain, and phase of the sine wave signal and the cosine wave signal can be corrected using the first correction value and the second correction value. Therefore, the angle calculation unit can calculate the position detection (rotation angle) of the motor with high accuracy.

  According to the present invention, it is possible to provide an electric power steering apparatus and a rotation angle detection method capable of improving the accuracy of steering assist control.

FIG. 1A is a diagram showing a configuration of an electric power steering device according to an embodiment. FIG. 1B is a perspective view of the electric power steering device according to the embodiment. FIG. 1C is an enlarged perspective view in which the electric motor and the ECU (control unit) shown in FIG. 1B are enlarged. FIG. 2 is a schematic diagram illustrating a hardware configuration of a control unit that controls the electric power steering device according to the embodiment. FIG. 3 is a functional block diagram showing a functional configuration of a control unit that controls the electric power steering device according to the embodiment. FIG. 4A is a schematic diagram showing a first example of a resolver. FIG. 4B is a schematic diagram showing a second example of the resolver. FIG. 5 is a diagram showing the relationship between the position detection signal and the phase angle in the resolver of the first example shown in FIG. 4A. FIG. 6 is a diagram showing an example of ideal sine wave signal waveforms and cosine wave signal waveforms and sine wave signal waveforms and cosine wave signal waveforms output from the resolver. FIG. 7 is a diagram illustrating an example of a schematic block configuration of a correction calculation processing unit in the position detection unit according to the embodiment. FIG. 8 is a flowchart showing an example of a correction value calculation processing procedure of the position detection signal in the initial calibration of the electric power steering apparatus according to the embodiment. FIG. 9 is a conceptual diagram of the offset correction value. FIG. 10 is a conceptual diagram of a gain correction value. FIG. 11 is a diagram showing an example of the primary correction processing result. FIG. 12 is a vector diagram after the phase conversion processing when there is no phase shift between the first sine wave signal and the first cosine wave signal in the embodiment. FIG. 13 is a vector diagram after the phase conversion processing in the case where the phase shift of α occurs between the first sine wave signal and the first cosine wave signal in the embodiment. FIG. 14 is a flowchart showing an example of a correction processing procedure of the position detection signal during actual operation of the electric power steering device according to the embodiment. FIG. 15 is a diagram showing a correction example by the second correction processing according to the embodiment. FIG. 16 is a diagram showing an example of the secondary correction processing result. FIG. 17 is a diagram showing an electrical angle error when the correction value calculation process and the correction process according to the embodiment are not performed. FIG. 18 is a diagram showing an electrical angle error when the primary correction process in the correction value calculation process and the correction process according to the embodiment is performed. FIG. 19 is a diagram illustrating an electrical angle error when the primary correction process and the secondary correction process in the correction value calculation process and the correction process according to the embodiment are performed. FIG. 20 is a diagram illustrating an example of a schematic block configuration of a correction calculation processing unit in the position detection unit according to the modified example of the embodiment. FIG. 21 is a vector diagram after the phase conversion process when there is no phase shift between the first sine wave signal and the first cosine wave signal in the modification of the embodiment. FIG. 22 is a vector diagram after the phase conversion processing when there is a phase shift of α between the first sine wave signal and the first cosine wave signal in the modification of the embodiment. FIG. 23 is a diagram illustrating a correction example by the second correction process according to the modified example of the embodiment.

  Hereinafter, modes for carrying out the invention (hereinafter, referred to as embodiments) will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Further, the constituent elements in the following embodiments include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that are within the equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be combined appropriately.

  FIG. 1A is a diagram showing a configuration of an electric power steering device according to an embodiment. FIG. 1B is a perspective view of the electric power steering device according to the embodiment. FIG. 1C is an enlarged perspective view in which the electric motor and the ECU (control unit) shown in FIG. 1B are enlarged. The electric power steering apparatus 100 includes a motor 20 that applies an auxiliary steering force to a steering mechanism of a vehicle, and controls the drive of the motor 20 based on a steering assist command value calculated using at least a steering torque for the steering mechanism and a vehicle speed. By doing so, the steering force of the steering wheel 1 is torque-controlled.

  As described above, the electric power steering device 100 is mounted on a vehicle to assist the driver of the vehicle in operating the steering wheel 1. The column shaft 2 of the steering wheel 1 is rotatably supported around a rotation center axis Z, and is connected to a tie rod 6 of a steered wheel via a reduction gear 3, universal joints 4a and 4b, and a rack and pinion mechanism 5. . A torque sensor 10 that detects a steering torque T of the steering 1 is provided on the column shaft 2. A reduction gear 3 is attached to the column shaft 2. The reduction gear 3 increases the torque generated by the motor 20 and transmits it to the column shaft 2. With such a structure, the steering force of the steering wheel 1 is assisted by the torque generated by the motor 20.

  In the present embodiment, the electric power steering device 100 is a column assist type device that transmits the torque of the motor 20 to the column shaft 2.

  The motor 20 is provided on the column shaft 2 of the steering 1. The motor 20 is, for example, a brushless motor or a brush motor. An ECU (Electronic Control Unit, hereinafter referred to as a control unit) 30 that controls the electric power steering device 100 receives electric power from a battery 14 via a power supply relay 13 incorporated therein, and transmits the electric power from an ignition switch 11. Receives an ignition signal. The control unit 30 also calculates a current command value for the motor 20 based on the steering torque T detected by the torque sensor 10 and the vehicle speed (vehicle speed) V detected by the vehicle speed sensor 12. The control unit 30 drives and controls the motor 20 based on the current value (current detection value) supplied to the motor 20 and the current command value so that the current detection value of the motor 20 follows the current command value. As described above, the control unit 30 is a device (control device for the electric power steering device) that controls the electric power steering device 100.

  As shown in FIGS. 1B and 1C, the motor 20 and the ECU 30 are arranged close to each other. The motor 20 includes a motor case 21 and a motor flange 22. The motor case 21 is a substantially cylindrical member, and is made of, for example, metal. The motor case 21 contains a rotor, a stator and the like (not shown). The rotor rotates about the axis X. A coil is wound around the stator. For example, a three-phase alternating current is supplied to the coil. The motor flange 22 is a member that closes an opening at one end of the motor case 21. The motor flange 22 is arranged at one end on the lower side of the motor case 21.

  The ECU 30 is built in a housing 32 formed of, for example, a metal in a box shape. The housing 32 has a fixing portion 32a. The fixing portion 32a is fixed to the motor flange 22 by a fastening member such as a bolt. As a result, the ECU 30 is arranged near the motor 20.

  The motor 20 is provided with a resolver 25 which is a position sensor for detecting the position (rotation angle) of the motor 20. The resolver 25 will be described later.

  FIG. 2 is a schematic diagram illustrating a hardware configuration of a control unit that controls the electric power steering device according to the embodiment. As shown in FIG. 2, the control unit 30 includes a power supply relay 13, a control computer (MCU) 110, a motor drive circuit 15, a motor current detection circuit 16, a position detection unit 17, and the like. A control computer 110 of the electric power steering apparatus 100 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102 as a first storage device, a ROM (Read Only Memory) 103 as a second storage device, and an EEPROM ( An Electrically Erasable Programmable ROM (104), an interface (I/F) 105, an A/D (Analog/Digital) converter 106, a PWM (Pulse Width Modulation) controller 107, etc. are provided, and these are connected to a bus 108. The CPU 101 corresponds to a processing device, and executes a control computer program (hereinafter, referred to as a control program) for the electric power steering device 100 stored in the ROM 103 to control the electric power steering device 100.

  The ROM 103 stores a control program, a diagnostic computer program for diagnosing the RAM 102 and the ROM 103 (hereinafter referred to as a diagnostic program), and data used for controlling and diagnosing the electric power steering device 100. Further, the RAM 102 is used as a work memory for operating the control program and the diagnostic program. The EEPROM 104 stores control data input/output by the control program. The control data is used on the control program expanded in the RAM 102 after the control unit 30 is powered on, and is overwritten in the EEPROM 104 at a predetermined timing.

  The ROM 103, the RAM 102, the EEPROM 104, and the like are storage devices that store information, and are storage devices (primary storage devices) that the CPU 101 can directly access. In addition, in the present embodiment, the EEPROM 104 uses the correction value calculation process and the correction process described later, and the average value and the minimum value of the maximum values of the position detection signals in each cycle of the electrical angle detected in one cycle of the mechanical angle of the motor 20. It functions as a storage unit that stores the average value, the first correction value, the second correction value, and the like. The position detection signal, the first correction value, and the second correction value will be described later.

  The A/D converter 106 inputs the steering torque T from the torque sensor 10, the current detection value Im of the motor 20 from the motor current detection circuit 16, the signal of the rotation angle θ of the motor 20 from the position detector 17, and the like. , Convert to digital signal. The interface 105 is connected to an in-vehicle network such as a CAN (Controller Area Network). The interface 105 is for receiving a signal (vehicle speed pulse) of the vehicle speed V from the vehicle speed sensor 12.

  The PWM controller 107 outputs a PWM control signal for each phase of UVW based on the current command value for the motor 20. The motor drive circuit 15 is composed of an inverter circuit and the like, and drives the motor 20 based on the signal output from the PWM controller 107. The motor current detection circuit 16 detects the value (current detection value) Im of the current supplied to the motor 20 and outputs it to the A/D converter 106.

  The position detection unit 17 performs position detection processing for obtaining the rotation angle θ of the motor 20 from the position detection signal output from the position sensor 25 (resolver in this embodiment), and outputs it to the A/D converter 106. In the present embodiment, the position detection unit 17 corrects the position detection signal output from the position sensor 25, and performs position detection processing based on the corrected signal. The position detection unit 17 may be configured by a circuit, or may be implemented by the control computer 110 shown in FIG. 2, more specifically by the CPU 101. The details of the correction method of the position detection signal in the position sensor 25 and the position detection unit 17 will be described later.

  FIG. 3 is a functional block diagram showing a functional configuration of a control unit that controls the electric power steering device according to the embodiment. The control of the electric power steering device 100 will be described with reference to FIG. As shown in FIG. 3, the control unit 30 has an assist function unit 31.

  The assist function unit 31 includes a current command value calculation unit 31a and a current control unit 31b. The current command value calculation unit 31a calculates a current command value I corresponding to the steering torque T and the vehicle speed V. The current controller 31b executes at least one of proportional control, differential control, and integral control so that the deviation between the current command value I and the detected current value Im approaches 0, and approaches the current command value I. The duty ratio D of the gate drive signal of the motor drive circuit 15 is calculated so that the current Im controlled by the above is generated. The motor drive circuit 15 outputs the current PWM-controlled to the motor 20 according to the duty ratio D calculated by the current controller 31b. The motor current detection circuit 16 detects a current Im flowing through the motor 20.

  The assist function unit 31 shown in FIG. 3 is realized by the control computer 110 shown in FIG. 2, more specifically, the CPU 101.

  FIG. 4A is a schematic diagram showing a first example of a resolver. FIG. 4B is a schematic diagram showing a second example of the resolver. A position detection signal which is a signal for detecting the position of the motor 20 is output from the resolver (position sensor) 25 shown in FIG. 4A or 4B. The resolver 25 includes, as a schematic configuration, an annular resolver stator 251, and a resolver rotor 252 that rotates around the axis X of the motor shaft 20a along the inner circumference of the resolver stator 251. In the first example shown in FIG. 4A, the resolver 25 having four poles is illustrated. In the second example shown in FIG. 4B, the resolver 25 having three poles is illustrated.

  The resolver stator 251 is configured by laminating a plurality of stator cores, and the armature winding 251b is wound around each of the plurality of teeth 251a that are equally arranged along the outer circumference of the resolver rotor 252. 4A and 4B exemplify the configuration having ten teeth 251a, the present disclosure is not limited by the number of teeth 251a.

  The resolver rotor 252 is configured by stacking a plurality of rotor cores. When the resolver rotor 252 rotates around the axis X of the motor shaft 20a, the gap d between the resolver stator 251 and the resolver rotor 252 changes, and the sine wave supplied to the armature winding 251b of the resolver stator 251 is changed. A sine wave signal and a cosine wave signal corresponding to the wavy excitation signal are output as the position detection signal of the electrical angle.

  FIG. 5 is a diagram showing the relationship between the position detection signal and the phase angle in the resolver of the first example shown in FIG. 4A. 5A shows an ideal waveform of a sine wave signal as a position detection signal, and FIG. 5B shows an ideal waveform of a cosine wave signal as a position detection signal, 5C shows the electrical angle of the position detection signal, and FIG. 5D shows the mechanical angle of the motor 20.

  In the example shown in FIG. 5, in one cycle Tm of the mechanical angle θm of the motor 20, the resolver 25 detects the position detection signals (sine wave signal sin θe, cosine wave signal cos θe) for 4 cycles of 4 Te in electrical angle. The number of cycles Te of the position detection signal of the electrical angle detected in one cycle Tm of the mechanical angle θm of the motor 20 is determined by the shape of the resolver rotor 252 viewed in the axial direction. In the case of the resolver 25 of the first example shown in FIG. 4A, the gap d between the resolver stator 251 and the resolver rotor 252 changes four times in one cycle Tm of the mechanical angle θm of the motor 20. That is, the resolver 25 of the first example shown in FIG. 4A is a 4-pole resolver that outputs a position detection signal for 4 cycles of 4 Te in electrical angle in one cycle Tm of the mechanical angle θm of the motor 20. Further, in the case of the resolver 25 of the second example shown in FIG. 4B, the gap d between the resolver stator 251 and the resolver rotor 252 changes three times in one cycle Tm of the mechanical angle θm of the motor 20. That is, the resolver 25 of the second example illustrated in FIG. 4B is a three-pole resolver that outputs a position detection signal for three Te cycles in electrical angle in one cycle Tm of the mechanical angle θm of the motor 20. In this embodiment, the case where the number of poles of the resolver 25 is two or more is targeted, and the number of poles of the resolver 25 may be two poles or plural poles of five poles or more.

  FIG. 6 is a diagram showing an example of ideal sine wave signal waveforms and cosine wave signal waveforms and sine wave signal waveforms and cosine wave signal waveforms output from the resolver. In FIG. 6, ideal sine wave signal waveforms and cosine wave signal waveforms when the four-pole resolver 25 of the first example shown in FIG. 4A is used, and actual sine wave signal waveforms and cosine wave output from the resolver 25 are shown. The signal waveform is illustrated. 6A shows the waveform of the ideal sine wave signal sin θid, FIG. 6B shows the waveform of the ideal cosine wave signal cos θid, and FIG. 6C shows the waveform. , An example of the actual sine wave signal sin θre output from the resolver 25, and FIG. 6D shows an example of the actual cosine wave signal cos θre output from the resolver 25. 6C and 6D show an example in which the resolver 25 with four poles of the first example shown in FIG. 4A is eccentric from the axis X of the motor shaft 20a (see FIG. 4A).

  As shown in (c) and (d) of FIG. 6, the actual sine wave signal sin θre and the actual cosine wave signal cos θre output from the resolver 25 are the ideal sine wave signal sin θid and the ideal cosine wave signal. A phase shift α and offsets sin_offset and cos_offset are included with respect to cos θid. Further, when the resolver 25 is eccentric, the actual sine wave signal sin θre and the actual cosine wave signal cos θre output from the resolver 25 are maximum values sin_max1, 2 for each cycle Te of the electrical angle θe. , 3, 4, cos_max 1, 2, 3, 4, and minimum values sin_min 1, 2, 3, 4, cos_min 1, 2, 3, 4, are different values.

  In the present embodiment, for example, in the example shown in FIG. 6, at least in one cycle Tm of the mechanical angle θm of the motor 20, the maximum values sin_max1, 2, 3, of the sinusoidal signal sin θre for four cycles Te in the electrical angle θe. 4 and the minimum values sin_min1, 2, 3, 4, and the maximum values cos_max1, 2, 3, 4 and the minimum values cos_min1, 2, 3, 4 of the cosine wave signal cos θre. Then, the average value of the maximum values sin_max1, 2, 3, 4, of the sine wave signal sin θre for these four cycles Te and the average value of the minimum values sin_min 1, 2, 3, 4, and the maximum value cos_max1, of the cosine wave signal cos θre. The average value of 2, 3, 4 and the minimum value cos_min 1, 2, 3, 4 are calculated and stored in the EEPROM 104. The cycle of the mechanical angle θm of the motor 20 for detecting the maximum value and the minimum value of the sine wave signal sin θre and the maximum value and the minimum value of the cosine wave signal cos θre may be two or more cycles. For example, in 2 cycles 2Tm of the mechanical angle θm of the motor 20, the maximum value and the minimum value of the sine wave signal sin θre for 8 cycles 8Te at the electrical angle θe and the maximum value and the minimum value of the cosine wave signal cos θre are detected, In a mode in which the average value of the maximum values and the average value of the minimum values of these sine wave signals sinθre for 8 cycles and 8Te and the average value of the maximum values and the minimum values of the cosine wave signal cosθre are obtained and stored in the EEPROM 104. It may be. The present disclosure is not limited by the cycle of the mechanical angle θm of the motor 20 that detects the maximum and minimum values of the sine wave signal sin θre and the maximum and minimum values of the cosine wave signal cos θre.

  In the present embodiment, the average value of the maximum value and the average value of the minimum value of the sine wave signal sin θre for a plurality of cycles detected in the predetermined cycle of the mechanical angle θm of the motor 20, and the average value of the maximum value of the cosine wave signal cos θre. By performing the following correction value calculation processing and correction processing on the actual sine wave signal sin θre and the actual cosine wave signal cos θre output from the resolver 25 using the average value of the values and the minimum value, The ideal sine wave signal sin θid and the ideal cosine wave signal cos θid shown in (a) and (b) of FIG.

  Next, a correction value calculation process of the electric power steering device according to the embodiment will be described.

  FIG. 7 is a diagram illustrating an example of a schematic block configuration of a correction calculation processing unit in the position detection unit according to the embodiment. FIG. 8 is a flowchart showing an example of a correction value calculation processing procedure in the initial calibration of the electric power steering apparatus according to the embodiment. Hereinafter, the correction value calculation processing procedure according to the embodiment will be described with reference to FIGS. 7 and 8. Here, an example of the correction value calculation processing procedure when the 4-pole resolver 25 of the first example shown in FIG. 4A is used will be described.

  As shown in FIG. 7, in the present embodiment, the position detection unit 17 includes a correction calculation processing unit 171 and an angle calculation unit 172.

  The correction calculation processing unit 171 performs correction value calculation processing and correction processing for the position detection signal output from the resolver 25. The processing in the correction calculation processing unit 171 includes a primary correction processing 1711 and a secondary correction processing 1712.

  The angle calculation unit 172 calculates position information (rotation angle θ) used for controlling the motor 20 based on the signal output from the correction calculation processing unit 171.

  In the initial calibration of the electric power steering apparatus 100, the ECU 30 rotates the steering wheel 1 in a predetermined direction from the steering neutral position P0 at a predetermined speed (for example, the rotation speed of the motor 20 is a low rotation speed of about 100 rms). The sine wave signal SIN0 and the cosine wave signal COS0 detected by the resolver 25 are input to the position detector 17. The correction calculation processing unit 171 acquires the input sine wave signal SIN0 and cosine wave signal COS0 (step S101).

  The correction calculation processing unit 171 obtains the average value of the maximum values and the average value of the minimum values of the acquired sine wave signal SIN0, and the average value of the maximum values and the minimum values of the cosine wave signal COS0, and stores them in the EEPROM 104. Yes (step S102). Specifically, the correction calculation processing unit 171 performs sampling processing on the input sine wave signal SIN0 and cosine wave signal COS0, and calculates the average value of the maximum values and the average value of the minimum values of these sine wave signals SIN0 and the cosine wave signal. The average value of the maximum value and the average value of the minimum value of the signal COS0 is obtained and stored in the EEPROM 104.

  The correction calculation processing unit 171 performs a correction value calculation process on the input sine wave signal SIN0 and cosine wave signal COS0.

  The correction calculation processing unit 171 includes a first offset correction value and a first gain correction value for the sine wave signal SIN0 and the cosine wave signal COS0 (hereinafter, the first offset correction value and the first gain correction value are collectively referred to as “first correction value”). (Also referred to as “”) and stored in the EEPROM 104 (step S103).

  The first offset correction values (SIN_OFFSET1, COS_OFFSET1) in step S103 are SIN0_MAX, the average of the maximum values of the sine wave signal SIN0, SIN0_MIN, the average of the minimum values of the sine wave signal SIN0, and the average of the maximum values of the cosine wave signal COS0. When the value is COS0_MAX and the average value of the minimum values of the cosine wave signal COS0 is COS0_MIN, they are expressed by the following equations (1) and (2).

  SIN_OFFSET1=(SIN0_MAX+SIN0_MIN)/2 (1)

  COS_OFFSET1=(COS0_MAX+COS0_MIN)/2 (2)

  FIG. 9 is a conceptual diagram of the offset correction value. The first offset correction value SIN_OFFSET1 is equal to the offset voltage of the sine wave signal SIN0. That is, the offset voltage of the sine wave signal SIN0 is corrected by subtracting the first offset correction value SIN_OFFSET1 from the sine wave signal SIN0.

  Also in the cosine wave signal COS0, similarly, the first offset correction value COS_OFFSET1 is equal to the offset voltage of the cosine wave signal COS0. That is, the offset voltage of the cosine wave signal COS0 is corrected by subtracting the first offset correction value COS_OFFSET1 from the cosine wave signal COS0.

  The first gain correction value (SIN_GAIN1, COS_GAIN1) in step S102 is expressed by the following equations (3) and (4). In the following expressions (3) and (4), N is a natural number.

  SIN_GAIN1=N/(SIN0_MAX-SIN0_MIN) (3)

  COS_GAIN1=N/(COS0_MAX-COS0_MIN) (4)

  FIG. 10 is a conceptual diagram of the gain correction value. The gain of the sine wave signal SIN0 is corrected by multiplying the value obtained by subtracting the first offset correction value SIN_OFFSET1 from the sine wave signal SIN0 by the first gain correction value SIN_GAIN1. Here, when N=2, the sine wave signal SIN0 is normalized to the level “1”.

  Similarly, in the cosine wave signal COS0, the gain of the cosine wave signal COS0 is corrected by multiplying the first gain correction value COS_GAIN1 by the value obtained by subtracting the first offset correction value COS_OFFSET1 from the cosine wave signal COS0. Here, when N=2, the cosine wave signal COS0 is also normalized to the level "1".

  Subsequently, the correction calculation processing unit 171 acquires again the input sine wave signal SIN0 and cosine wave signal COS0 (step S104).

  The correction calculation processing unit 171 corrects the acquired sine wave signal SIN0 and cosine wave signal COS0 using the first correction value calculated in step S103 (hereinafter, also referred to as “first correction processing”) (step S105). .. Specifically, the sine wave signal SIN0 and the cosine wave signal COS0 are corrected using the following equations (5) and (6), and the first sine wave signal SIN1 and the first cosine wave signal COS1 are obtained. The first correction process using these formulas (5) and (6) is the primary correction process 1711 shown in FIG. 7.

  SIN1=SIN_GAIN1×(SIN0-SIN_OFFSET1) (5)

  COS1=COS_GAIN1×(COS0-COS_OFFSET1) (6)

  FIG. 11 is a diagram showing an example of the primary correction processing result. In FIG. 11, the primary correction processing 1711 shows the first sine wave signal SIN1 in which the offset voltage and the gain of the sine wave signal SIN0, which is the position detection signal, are corrected. An example in which a phase shift occurs is shown. Similarly, the first cosine wave signal COS1 also has a phase shift of α.

  Subsequently, the correction calculation processing unit 171 uses the following equations (7) and (8) to calculate the first sine wave signal SIN1 and the first cosine wave signal obtained from the above equations (5) and (6). Phase conversion processing of COS1 is performed (step S106), and the second sine wave signal SIN2 and the second cosine wave signal COS2 are calculated.

  SIN2=SIN1-COS1 (7)

  COS2=COS1+SIN1 (8)

  As a result, the phases of the second sine wave signal SIN2 and the second cosine wave signal COS2 obtained by advancing the phases of the first sine wave signal SIN1 and the first cosine wave signal COS1 by 45 degrees are obtained.

  FIG. 12 is a vector diagram after the phase conversion processing when there is no phase shift between the first sine wave signal and the first cosine wave signal in the embodiment. FIG. 13 is a vector diagram after the phase conversion processing in the case where the phase shift of α occurs between the first sine wave signal and the first cosine wave signal in the embodiment.

  As shown in FIG. 12, when there is no phase shift between the first sine wave signal SIN1 and the first cosine wave signal COS1, the vector (SIN1-COS1) of the above equation (7) The magnitude of the vector (COS1+SIN1) in the equation (8) is equal.

  On the other hand, as shown in FIG. 13, when the first cosine wave signal COS1 has a phase shift of α with respect to the first sine wave signal SIN1, the vector (SIN1-COS1( −α)) becomes larger than the vector (COS1(−α)+SIN1) in the above equation (8).

  In the present embodiment, offset correction and gain correction are performed on the first sine wave signal SIN2 that is the result of the above expression (7) and the first cosine wave signal COS2 that is the result of the above expression (8). By doing so, correction is performed so that the vector sizes of the signals after the offset correction and the gain correction become equal.

  The correction calculation processing unit 171 includes a second offset correction value and a second gain correction value (hereinafter referred to as a second offset correction value and a second gain) that are correction values for the phase conversion processing results of the expressions (7) and (8). The correction values are collectively calculated as a “second correction value”), stored in the EEPROM 104 (step S107), and the correction value calculation process ends.

  For the second offset correction values (SIN_OFFSET2, COS_OFFSET2) in step S107, the maximum value of the second sine wave signal SIN2 is SIN2_MAX, the minimum value of the second sine wave signal SIN2 is SIN2_MIN, and the maximum value of the second cosine wave signal COS2 is COS2_MAX. , Where COS2_MIN is the minimum value of the second cosine wave signal COS2, it is expressed by the following equations (9) and (10).

  SIN_OFFSET2=(SIN2_MAX+SIN2_MIN)/2 (9)

  COS_OFFSET2=(COS2_MAX+COS2_MIN)/2 (10)

  Further, the second gain correction value (SIN_GAIN2, COS_GAIN2) in step S107 is expressed by the following equations (11) and (12). In the following equations (11) and (12), N is a natural number.

  SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN) (11)

  COS_GAIN2=N/(COS2_MAX-COS2_MIN)...(12)

  In the correction process during the actual operation of the electric power steering device 100, which will be described later, the first sine wave signal SIN1 and the first cosine wave signal COS1 after the primary correction process are calculated by using the formulas (7) and (8) described above. The phase conversion process is performed, and the offset correction and the gain correction are performed on the second sine wave signal SIN2 and the second cosine wave signal COS2 after the phase conversion process by using the above formulas (11) and (12). Further, by performing the phase conversion processing in the opposite direction to the above equations (7) and (8) on the signal after the offset correction and the gain correction, the phase shift between the sine wave signal and the cosine wave signal is caused. It can be resolved.

  Next, a correction process during actual operation of the electric power steering device 100 according to the embodiment will be described with reference to FIGS. 7 and 14. In the present embodiment, the actual operation indicates that the vehicle actually travels after the vehicle equipped with the electric power steering device 100 according to the embodiment is shipped or delivered to the user. FIG. 14 is a flowchart showing an example of a correction processing procedure during actual operation of the electric power steering device according to the embodiment.

  During actual operation of the electric power steering apparatus 100 according to the embodiment, the sine wave signal SIN0 and the cosine wave signal COS0 detected by the resolver 25 are input to the position detection unit 17. The correction calculation processing unit 171 acquires the input sine wave signal SIN0 and cosine wave signal COS0 (step S201).

  The correction calculation processing unit 171 performs the first correction processing described in the above-described correction value calculation processing on the acquired sine wave signal SIN0 and cosine wave signal COS0 (step S202). Specifically, the sine wave signal SIN0 and the cosine wave signal COS0 are corrected using the above equations (5) and (6) to obtain the first sine wave signal SIN1 and the first cosine wave signal COS1. The first correction process using these equations (5) and (6) corresponds to the primary correction process 1711 shown in FIG.

  Subsequently, the correction calculation processing unit 171 uses the above-mentioned equations (7) and (8) to calculate the first sine wave signal SIN1 and the first cosine wave signal obtained by the above equations (5) and (6). Phase conversion processing of COS1 is performed (step S203).

  As a result, the second sine wave signal SIN2 and the second cosine wave signal COS2 in which the phases of the first sine wave signal SIN1 and the first cosine wave signal COS1 are advanced by 45 degrees are obtained.

  Subsequently, the correction calculation processing unit 171 corrects the second sine wave signal SIN2 and the second cosine wave signal COS2 obtained in step S203 using the second correction value calculated in the correction value calculation process described above (hereinafter, "Second correction process") (step S204). Specifically, the second sine wave signal SIN2 and the second cosine wave signal COS2 are corrected using the following expressions (13) and (14), and the third sine wave signal SIN3 and the third cosine wave signal COS3 are corrected. Ask for.

  SIN3=SIN_GAIN2×(SIN2-SIN_OFFSET2) (13)

  COS3=COS_GAIN2×(COS2-COS_OFFSET2) (14)

  FIG. 15 is a diagram showing a correction example by the second correction processing according to the embodiment. As shown in FIG. 15, the magnitudes of the second sine wave signal SIN2 and the second cosine wave signal COS2 are corrected. As a result, the magnitudes of the corrected third sine wave signal SIN3 and the third cosine wave signal COS3 are normalized.

  Subsequently, the correction calculation processing unit 171 uses the following equations (15) and (16) to obtain the third sine wave signal SIN3 and the third cosine wave signal obtained by the equations (13) and (14). The COS3 is subjected to reverse phase conversion processing in the opposite direction to the above equations (7) and (8) (step S205), and the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 are calculated.

  SIN4=SIN3+COS3 (15)

  COS4=COS3-SIN3 (16)

  As a result, the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 in which the phases of the third sine wave signal SIN3 and the third cosine wave signal COS3 are delayed by 45 degrees are obtained. That is, in step S203, the phase advanced by 45 degrees is returned.

  The processes of steps S203, S204, and S205 described above correspond to the secondary correction process 1712 shown in FIG. 7.

  FIG. 16 is a diagram showing an example of the secondary correction processing result. FIG. 16 shows an example in which the phase shift of the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 is eliminated by the secondary correction processing 1712.

  The sine wave signal and the cosine wave signal detected by the resolver 25 are corrected by the above processing from step S201 to step S205. Specifically, the primary correction processing 1711 of the correction calculation processing unit 171 corrects the offset voltage and the gain of the sine wave signal and the cosine wave signal, and the secondary correction processing 1712 of the correction calculation processing unit 171 corrects the sine wave signal and The phase shift of the cosine wave signal is corrected.

  The fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 corrected by the correction calculation processing unit 171 are output to the angle calculation unit 172. The angle calculation unit 172 calculates the rotation angle θ that is the position information of the motor 20 based on the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 output from the correction calculation processing unit 171.

  In the present embodiment, as described above, in the initial calibration of the electric power steering apparatus 100, the first correction value (first offset correction value, first gain correction value) and the secondary correction processing 1712 used in the primary correction processing 1711. The second correction value (the second offset correction value, the second gain correction value) used in step 1 is obtained. Then, during the actual operation of the electric power steering device 100, the first correction value (first offset correction value, first gain correction value) and the second correction value (second offset correction value, second gain correction value) are used. Then, the input sine wave signal and cosine wave signal are corrected.

  As a result, the angle calculation unit 172 can calculate the position detection (rotation angle) of the motor with high accuracy. Therefore, the accuracy of the steering assist control in the electric power steering device 100 can be improved.

  In the above-described embodiment, an example in which the secondary offset correction value is used for correction in the secondary offset correction processing 1712 is shown. However, the offset voltage can be sufficiently corrected by the first offset offset correction value in the primary offset correction processing 1711. For example, it is not always necessary to perform the secondary correction processing 1712 using the second offset correction value. Hereinafter, an aspect in which the second offset correction value is not used in the secondary correction processing 1712 will be described. Although the following description will be given with reference to FIGS. 8 and 14, the description of the same processes as those described above will be omitted, and only different processes will be described.

  In step S106 of the correction value calculation process illustrated in FIG. 8, the correction calculation processing unit 171 uses the following formulas (17) and (18) in the same manner as the above formulas (7) and (8). In step S105 of the correction value calculation process shown in FIG. 7, the phase conversion process of the first sine wave signal SIN1 and the first cosine wave signal COS1 obtained by the formulas (5) and (6) is performed, and the second sine wave signal SIN2 and The cosine wave signal COS2 is calculated.

  SIN2=SIN1-COS1 (17)

  COS2=COS1+SIN1 (18)

  Further, in step S107 of the correction value calculation process shown in FIG. 8, the correction calculation processing section 171 outputs the second gain correction value (second correction value) which is a correction value for the phase conversion processing result of the equations (17) and (18). A correction value) is calculated and stored in the EEPROM 104. The second gain correction value (SIN_GAIN2, COS_GAIN2) in step S107 is expressed by the following equations (19) and (20). In the following equations (19) and (20), N is a natural number.

  SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN) (19)

  COS_GAIN2=N/(COS2_MAX-COS2_MIN) (20)

  In addition, in step S204 of the correction processing illustrated in FIG. 14, the correction calculation processing unit 171 calculates the second sine wave signal SIN2 and the second cosine wave signal COS2 by the second gain correction value (second Correction value). Specifically, the second sine wave signal SIN2 and the second cosine wave signal COS2 are corrected using the following equations (21) and (22), and the third sine wave signal SIN3 and the third cosine wave signal COS3 are corrected. Ask for.

  SIN3=SIN_GAIN2×SIN2 (21)

  COS3=COS_GAIN2×COS2 (22)

  Subsequently, in step S205 of the correction process illustrated in FIG. 14, the correction calculation processing unit 171 uses the following formulas (23) and (24) as in the above formulas (15) and (16), For the third sine wave signal SIN3 and the third cosine wave signal COS3 obtained by the above equations (21) and (22), the phase conversion processing in the opposite direction to the above equations (17) and (18) is performed. , The fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 are calculated.

  SIN4=SIN3+COS3 (23)

  COS4=COS3-SIN3 (24)

  As a result, the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 in which the phases of the third sine wave signal SIN3 and the third cosine wave signal COS3 are delayed by 45 degrees are obtained. That is, in step S203, the phase advanced by 45 degrees is returned.

  FIG. 17 is a diagram showing an electrical angle error when the correction value calculation process and the correction process according to the embodiment are not performed. FIG. 18 is a diagram showing an electrical angle error when the primary correction process in the correction value calculation process and the correction process according to the embodiment is performed. FIG. 19 is a diagram illustrating an electrical angle error when the primary correction process and the secondary correction process in the correction value calculation process and the correction process according to the embodiment are performed.

  As shown in FIG. 17, when the correction value calculation process and the correction process according to the embodiment are not performed, the electrical angle error changes within a range of ±1.2 [deg].

  On the other hand, when the primary correction process is performed in the correction value calculation process and the correction process according to the embodiment, the electrical angle error changes within a range of ±0.8 [deg] as shown in FIG. There is.

  As described above, the electrical angle error can be reduced by performing the primary correction process in the correction value calculation process and the correction process according to the embodiment.

  Further, when the primary correction process and the secondary correction process are performed in the correction value calculation process and the correction process according to the embodiment, as shown in FIG. 19, the electrical angle error is within ±0.4 [deg]. It is changing.

  As described above, by performing the primary correction processing and the secondary correction processing in the correction value calculation processing and the correction processing according to the embodiment, it is possible to further reduce the electrical angle error.

  In addition, when the 4-pole resolver of the first example shown in FIG. 4A is adopted for a brassless motor having four pole pairs, the electrical angle of the motor and the electrical angle of the resolver are divided into four quadrants in terms of mechanical angle. It has a high affinity because it can correspond to.

  For example, when a TMR (Tunnel Magnet Resistance) sensor is used as a position sensor for a brassless motor having four pole pairs, it is necessary to divide the mechanical angle into four to determine the quadrant. This is not necessary when the 4-pole resolver of one example is used as the position sensor.

  On the other hand, if the angular velocity or angular acceleration of the rotation of the motor is obtained from the detected value of the resolver and it is attempted to use it for the control of the motor, the error component of the detected value of the resolver affects as the fluctuation of the angular velocity or angular acceleration of the rotation of the motor The control accuracy of the motor may decrease. On the other hand, in this embodiment, high detection accuracy can be obtained by performing offset correction and gain correction in the primary correction processing and further performing phase correction in the secondary correction processing.

  Further, for example, when the configuration using the three-pole resolver of the second example shown in FIG. 4B is changed to the configuration using the four-pole resolver of the first example shown in FIG. 4A, a three-pole resolver is used. The inclination of the electrical angle becomes larger than that of the configuration used, and accordingly, the sensitivity to the error component of the detected value of the resolver becomes higher. As a result, the influence of fluctuations in the angular velocity and angular acceleration of the rotation of the motor increases, and the control accuracy of the motor is likely to decrease. On the other hand, in the present embodiment, as described above, high offset detection accuracy can be obtained by performing offset correction and gain correction in the primary correction processing and further performing phase correction in the secondary correction processing.

  Particularly, the primary correction processing and the secondary correction processing according to the present embodiment are effective when the accuracy of the sine wave signal and the cosine wave signal output from the resolver is low. Therefore, the degree of freedom in selecting a resolver is increased, and a lower cost resolver can be adopted.

  When applied to a motor of a column assist type electric power steering device, low frequency noise components such as road noise and floor noise when the vehicle is running are superimposed on the sine wave signal and cosine wave signal output from the resolver. easy. Even in such a configuration, high detection accuracy can be obtained by the primary correction processing and the secondary correction processing according to the present embodiment.

(Modification)
FIG. 20 is a diagram illustrating an example of a schematic block configuration of a correction calculation processing unit in the position detection unit according to the modified example of the embodiment. The same components as those of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

  As shown in FIG. 20, in the modified example of the present embodiment, the position detection unit 17a includes a correction calculation processing unit 171a and an angle calculation unit 172.

  The correction calculation processing unit 171a performs a correction value calculation process and a correction process of the position detection signal output from the resolver 25. The processing in the correction calculation processing unit 171a includes a primary correction processing 1711 and a secondary correction processing 1712a.

  The modified example of the embodiment is different from the above-described embodiment in the processing of step S106 in the correction value calculation processing procedure and the processing of step S205 in the correction processing procedure. Although the following description will be given with reference to FIGS. 8 and 14, the description of the same processes as those described above will be omitted, and only different processes will be described.

  In step S106 of the correction value calculation process illustrated in FIG. 8, the correction calculation processing unit 171a uses the following equations (7)′ and (8)′ to obtain the equations (5) and (6). Phase conversion processing is performed on the first sine wave signal SIN1 and the first cosine wave signal COS1 (step S106), and the second sine wave signal SIN2 and the second cosine wave signal COS2 are calculated.

  SIN2=SIN1+COS1 (7)'

  COS2=COS1-SIN1 (8)'

  As a result, the phases of the second sine wave signal SIN2 and the second cosine wave signal COS2 in which the phases of the first sine wave signal SIN1 and the first cosine wave signal COS1 are delayed by 45 degrees are obtained.

  FIG. 21 is a vector diagram after the phase conversion process when there is no phase shift between the first sine wave signal and the first cosine wave signal in the modification of the embodiment. FIG. 22 is a vector diagram after the phase conversion processing when there is a phase shift of α between the first sine wave signal and the first cosine wave signal in the modification of the embodiment.

  As shown in FIG. 21, when there is no phase shift between the first sine wave signal SIN1 and the first cosine wave signal COS1, the vector (SIN1+COS1) of the equation (7)′ and the above The magnitude of the vector (COS1-SIN1) in the equation (8)' is equal.

  On the other hand, as shown in FIG. 22, when the first cosine wave signal COS1 has a phase shift of α with respect to the first sine wave signal SIN1, the vector (SIN1(-SIN1(- α)+COS1) becomes larger than the vector (COS1-SIN1(−α)) of the above equation (8)′.

  In the modified example of the present embodiment, the offset correction is performed on the first sine wave signal SIN2 which is the result of the expression (7)′ and the first cosine signal COS2 which is the result of the expression (8)′. By performing the gain correction and the gain correction, the vector sizes of the signals after the offset correction and the gain correction are corrected to be equal. The following correction value calculation processing procedure is the same as that of the above-described embodiment.

  FIG. 23 is a diagram illustrating a correction example by the second correction process according to the modified example of the embodiment. As shown in FIG. 23, the magnitudes of the second sine wave signal SIN2 and the second cosine wave signal COS2 are corrected. As a result, the magnitudes of the corrected third sine wave signal SIN3 and the third cosine wave signal COS3 are normalized.

  Further, the correction calculation processing unit 171a uses the following equations (15)′ and (16)′ in step S107 of the correction value calculation processing shown in FIG. The obtained third sine wave signal SIN3 and the third cosine wave signal COS3 are subjected to reverse phase conversion processing in the opposite direction of the above equations (7)' and (8)' (step S205), and the fourth sine The wave signal SIN4 and the fourth cosine wave signal COS4 are calculated.

  SIN4=SIN3-COS3 (15)'

  COS4=COS3+SIN3 (16)'

  As a result, the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 in which the phases of the third sine wave signal SIN3 and the third cosine wave signal COS3 are advanced by 45 degrees are obtained. That is, the phases delayed by 45 degrees are returned in step S203.

  Note that, in the modified example of the above-described embodiment, similar to the embodiment, an example of performing correction using the second offset correction value in the secondary correction processing 1712a has been described, but according to the first offset correction value in the primary correction processing 1711. Similar to the above-described embodiment, it is not always necessary to perform the secondary correction processing 1712a using the second offset correction value as long as the offset voltage of the position detection signal can be sufficiently corrected.

  In addition, in the above-described embodiment and the modification of the embodiment, the resolver 25, the position detection unit 17, and the EEPROM 104 constitute a rotation angle detection device.

  In addition, in the above-described embodiment and modified examples of the embodiment, the rotation angle detection device constitutes a motor control device that drives and controls the motor 20.

  As described above, in the electric power steering apparatus 100 according to the embodiment and the modified example of the embodiment, the motor 20 is provided on the column shaft 2 of the steering 1, and the motor is provided by using the rotation angle detected by the rotation angle detection device. By controlling the driving of the steering wheel 20, the steering force of the steering wheel 1 is torque-controlled. The rotation angle detection device includes a ring-shaped resolver stator 251 and a resolver rotor 252 having a plurality of poles in which the gap d between the inner circumference of the resolver stator 251 changes a plurality of times per revolution around the axis. A resolver 25 that includes a sine wave signal and a cosine wave signal of an electrical angle according to the rotation of the resolver rotor 252, and position detection units 17 and 17a that detect the position of the motor 20 based on the sine wave signal and the cosine wave signal. And a storage unit (EEPROM 104) in which the first correction value and the second correction value for correcting the sine wave signal and the cosine wave signal are stored. The position detection units 17 and 17a calculate the first correction value and the second correction value, and correct the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the first correction value to obtain the second correction value. Based on the correction calculation processing units 171, 171a for correcting the phases of the sine wave signal and the cosine wave signal, and an angle calculation unit 172 for calculating the rotation angle of the motor 20 based on the output signals of the correction calculation processing units 171, 171a. Equipped with.

  Specifically, in the correction value calculation process for calculating the first correction value and the second correction value, the correction calculation processing unit 171 calculates the first correction value based on the maximum and minimum values of the sine wave signal and the cosine wave signal. The first sine wave signal and the first cosine wave signal are calculated and the offset voltage and the gain of the sine wave signal and the cosine wave signal are corrected based on the first correction value to obtain the first sine wave signal and the first cosine wave signal. The second sine wave signal and the second cosine wave signal obtained by advancing the phase of each by 45 electrical degrees are obtained, and the second correction value is calculated based on the maximum and minimum values of the second sine wave signal and the second cosine wave signal. calculate.

  Alternatively, specifically, in the correction value calculation process of calculating the first correction value and the second correction value, the correction calculation processing unit 171a performs the first correction based on the maximum value and the minimum value of the sine wave signal and the cosine wave signal. The first sine wave signal and the first cosine wave signal are obtained by calculating the values and obtaining the first sine wave signal and the first cosine wave signal in which the offset voltage and the gain of the sine wave signal and the cosine wave signal are corrected based on the first correction value. A second sine wave signal and a second cosine wave signal in which the phase of the wave signal is delayed by 45 electrical degrees are obtained, and the second correction is performed based on the maximum value and the minimum value of the second sine wave signal and the second cosine wave signal. Calculate the value.

  Further, specifically, in the correction processing for correcting the sine wave signal and the cosine wave signal, the correction calculation processing unit 171 corrects the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the first correction value. The first sine wave signal and the first cosine wave signal are obtained, and the second sine wave signal and the second cosine wave signal obtained by advancing the phases of the first sine wave signal and the first cosine wave signal by 45 electrical degrees are obtained. Based on the two correction values, at least the third sine wave signal and the third cosine wave signal in which the gains of the second sine wave signal and the second cosine wave signal are corrected are obtained, and the third sine wave signal and the third cosine wave signal are calculated. A fourth sine wave signal and a fourth cosine wave signal whose phases are delayed by 45 electrical degrees are obtained. The angle calculator 172 calculates the rotation angle of the motor 20 based on the fourth sine wave signal and the fourth cosine wave signal.

  Alternatively, specifically, in the correction processing for correcting the sine wave signal and the cosine wave signal, the correction calculation processing unit 171a corrects the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the first correction value. The first sine wave signal and the first cosine wave signal are obtained, and the second sine wave signal and the second cosine wave signal obtained by delaying the phases of the first sine wave signal and the first cosine wave signal by an electrical angle of 45 degrees are calculated. Based on the two correction values, at least the third sine wave signal and the third cosine wave signal in which the gains of the second sine wave signal and the second cosine wave signal are corrected are obtained, and the third sine wave signal and the third cosine wave signal are calculated. A fourth sine wave signal and a fourth cosine wave signal whose phases are advanced by 45 electrical degrees are obtained. The angle calculator 172 calculates the rotation angle of the motor 20 based on the fourth sine wave signal and the fourth cosine wave signal.

  Further, the rotation angle detecting method according to the embodiment has a resolver rotor having a plurality of poles in which the gap d between the inner periphery of the annular resolver stator 251 changes a plurality of times per revolution around the axis of the motor 20. A method for detecting a rotation angle of a motor 20 based on a correction result of a sine wave signal and a cosine wave signal of an electrical angle output according to the rotation of 252. A first correction value for correcting the offset voltage and gain of the sine wave signal and the cosine wave signal is calculated based on the maximum value and the minimum value of the signal, and the sine wave signal and the cosine wave signal of the sine wave signal are calculated based on the first correction value. The first sine wave signal and the first cosine wave signal with the offset voltage and the gain corrected are obtained, and the phases of the first sine wave signal and the first cosine wave signal are advanced by 45 degrees in electrical angle, respectively. A correction value for calculating the second cosine wave signal and calculating a second correction value for correcting the phases of the sine wave signal and the cosine wave signal based on the maximum value and the minimum value of the second sine wave signal and the second cosine wave signal. The first sine wave signal and the first cosine wave signal are obtained by correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the calculation processing step and the first correction value. The second sine wave signal and the second cosine wave signal obtained by advancing the phase of the wave signal by 45 electrical degrees are obtained, and at least the gains of the second sine wave signal and the second cosine wave signal are calculated based on the second correction value. The corrected third sine wave signal and the third cosine wave signal are obtained, and the fourth sine wave signal and the fourth cosine wave signal obtained by delaying the phases of the third sine wave signal and the third cosine wave signal by 45 degrees in electrical angle There is a correction processing step to be obtained, and a rotation angle calculation step for calculating the rotation angle of the motor 20 based on the fourth sine wave signal and the fourth cosine wave signal.

  Alternatively, the rotation angle detection method according to the embodiment has a resolver rotor having a plurality of poles in which the gap d between the inner periphery of the annular resolver stator 251 changes a plurality of times per revolution around the axis of the motor 20. A method for detecting a rotation angle of a motor 20 based on a correction result of a sine wave signal and a cosine wave signal of an electrical angle output according to the rotation of 252. A first correction value for correcting the offset voltage and gain of the sine wave signal and the cosine wave signal is calculated based on the maximum value and the minimum value of the signal, and the sine wave signal and the cosine wave signal of the sine wave signal are calculated based on the first correction value. The first sine wave signal and the first cosine wave signal with the offset voltage and the gain corrected are obtained, and the phases of the first sine wave signal and the first cosine wave signal are delayed by 45 degrees in electrical angle, respectively, and A correction value for calculating the second cosine wave signal and calculating a second correction value for correcting the phases of the sine wave signal and the cosine wave signal based on the maximum value and the minimum value of the second sine wave signal and the second cosine wave signal. The first sine wave signal and the first cosine wave signal are obtained by correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal based on the calculation processing step and the first correction value. The second sine wave signal and the second cosine wave signal obtained by delaying the phase of the wave signal by 45 degrees in electrical angle are obtained, and at least the gains of the second sine wave signal and the second cosine wave signal are calculated based on the second correction value. The corrected third sine wave signal and the third cosine wave signal are obtained, and the fourth sine wave signal and the fourth cosine wave signal obtained by advancing the phases of the third sine wave signal and the third cosine wave signal by 45 electrical degrees are obtained. There is a correction processing step to be obtained, and a rotation angle calculation step for calculating the rotation angle of the motor 20 based on the fourth sine wave signal and the fourth cosine wave signal.

  According to the electric power steering apparatus 100 and the rotation angle detection method according to the embodiment and the modification of the embodiment, the first correction value for correcting the offset voltage and the gain of the sine wave signal SIN0 and the cosine wave signal COS0, and A second correction value for correcting the phases of the sine wave signal and the cosine wave signal can be obtained. Also, the offset voltage, gain, and phase of the sine wave signal SIN0 and the cosine wave signal COS0 can be corrected using the first correction value and the second correction value. Therefore, the angle calculation unit 172 can calculate the position detection (rotation angle θ) of the motor 20 with high accuracy. Therefore, the motor 20 can be driven and controlled with high accuracy, and the accuracy of steering assist control in the electric power steering device 100 can be improved.

  In addition, in the above-described embodiment and the modified example of the embodiment, the configuration in which the correction calculation processing units 171 and 171a are provided in the position detection unit 17 is illustrated, but the correction calculation processing units 171 and 171a include the position detection units 17 and 17a. May be different components. Further, although the first correction value and the second correction value are stored in the EEPROM 104 by way of example, a storage unit other than the EEPROM 104 is provided, and the storage unit stores the first correction value and the second correction value. May be The present disclosure is not limited to the configurations of the correction calculation processing units 171 and 171a and the manner in which the first correction value and the second correction value are stored.

1 Steering 2 Column shaft 3 Reduction gear 3a Gear (column shaft)
3b Gear (shaft (motor))
4a, 4b Universal joint 10 Torque sensor 11 Ignition switch 12 Vehicle speed sensor 14 Battery 15 Motor drive circuit 16 Motor current detection circuit 17,17a Position detection part 20 Motor 20a Motor shaft 21 Motor case 22 Motor flange 25 Position sensor (resolver)
30 Control Unit (ECU)
31 Assist Function Section 31a Current Command Value Calculation Section 31b Current Control Section 32 Housing 32a Fixed Section 100 Electric Power Steering Device (EPS)
101 CPU
105 Interface 106 A/D Converter 107 PWM Controller 110 Control Computer (MCU)
171, 171a Correction calculation processing section 172 Angle calculation section 251 Resolver stator 251a Teeth 251b Armature winding 252 Resolver rotor 1711 Primary correction processing 1712, 1712a Secondary correction processing

Claims (14)

An electric power steering device, wherein a motor is provided on a column shaft of a steering wheel, and the steering force of the steering wheel is torque-controlled by drivingly controlling the motor using a rotation angle detected by a rotation angle detection device,
The rotation angle detection device,
An annular resolver stator and a resolver rotor having a plurality of poles each having a gap between the inner circumference of the resolver stator and a plurality of poles per revolution around the axis are provided, and the resolver rotor is rotated according to the rotation of the resolver rotor. A resolver that outputs a sine wave signal and a cosine wave signal of an electrical angle,
A position detection unit that detects the position of the motor based on the sine wave signal and the cosine wave signal;
A storage unit that stores a first correction value and a second correction value for correcting the sine wave signal and the cosine wave signal;
Equipped with
The position detection unit,
The offset voltage and the gain of the sine wave signal and the cosine wave signal are corrected based on the first correction value while calculating the first correction value and the second correction value, and based on the second correction value, A correction calculation processing unit that corrects the phases of the sine wave signal and the cosine wave signal,
An angle calculation unit that calculates a rotation angle of the motor based on an output signal of the correction calculation processing unit;
Equipped with
The correction calculation processing unit,
In the correction value calculation process for calculating the first correction value and the second correction value,
The first correction value is calculated based on the maximum value and the minimum value of the sine wave signal and the cosine wave signal, and the offset voltage and the gain of the sine wave signal and the cosine wave signal are calculated based on the first correction value. The corrected first sine wave signal and the first cosine wave signal are obtained, and the phases of the first sine wave signal and the first cosine wave signal are advanced by 45 degrees in terms of electrical angle. A signal is obtained, and the second correction value is calculated based on the maximum value and the minimum value of the second sine wave signal and the second cosine wave signal,
In a correction process for correcting the sine wave signal and the cosine wave signal,
The first sine wave signal and the first cosine wave signal are obtained by correcting the offset voltage and gain of the sine wave signal and the cosine wave signal based on the first correction value, and the first sine wave signal and the first cosine wave are obtained. The second sine wave signal and the second cosine wave signal obtained by advancing the phase of the wave signal by 45 degrees in electrical angle are obtained, and based on the second correction value, at least the second sine wave signal and the second cosine wave signal. The third sine wave signal and the third cosine wave signal whose gains are corrected are obtained, and the phases of the third sine wave signal and the third cosine wave signal are delayed by 45 degrees in electrical angle, and a fourth sine wave signal and a third cosine wave signal, respectively. Find the 4 cosine wave signal,
The angle calculation unit,
An electric power steering device that calculates a rotation angle of the motor based on the fourth sine wave signal and the fourth cosine wave signal. The correction calculation processing unit,
SIN0_MAX is an average value of the maximum values of the sine wave signals of a plurality of cycles, SIN0_MIN is an average value of the minimum values of the sine wave signals of a plurality of cycles, which are detected in a predetermined cycle of the mechanical angle of the motor, and the cosine of a plurality of cycles When the average value of the maximum values of the wave signals is COS0_MAX and the average value of the minimum values of the cosine wave signals of a plurality of cycles is COS0_MIN, the first correction value is obtained using the following formulas (1) and (2). The electric power steering apparatus according to claim 1, wherein the first offset correction values SIN_OFFSET1 and COS_OFFSET1 are calculated.
SIN_OFFSET1=(SIN0_MAX+SIN0_MIN)/2 (1)
COS_OFFSET1=(COS0_MAX+COS0_MIN)/2 (2) The correction calculation processing unit,
The first gain correction values SIN_GAIN1 and COS_GAIN1 that are the first correction values are calculated using the following equations (3) and (4), and in the following equations (3) and (4), N is a natural number. 2. The electric power steering device according to item 2.
SIN_GAIN1=N/(SIN0_MAX-SIN0_MIN) (3)
COS_GAIN1=N/(COS0_MAX-COS0_MIN) (4) The correction calculation processing unit,
When the sine wave signal is SIN0 and the cosine wave signal is COS0, the first sine wave signal SIN1 and the first cosine wave signal COS1 are calculated using the following equations (5) and (6). The electric power steering device described.
SIN1=SIN_GAIN1×(SIN0-SIN_OFFSET1) (5)
COS1=COS_GAIN1×(COS0-COS_OFFSET1) (6) The correction calculation processing unit,
The following equations (7) and (8) are used to calculate the second sine wave signal SIN2 and the second cosine wave signal COS2,
When the maximum value of the second sine wave signal is SIN2_MAX, the minimum value of the second sine wave signal is SIN2_MIN, the maximum value of the second cosine wave signal is COS2_MAX, and the minimum value of the second cosine wave signal is COS2_MIN. Using the following equations (9) and (10), the second offset correction values SIN_OFFSET2 and COS_OFFSET2 that are the second correction values are calculated,
The second gain correction values SIN_GAIN2 and COS_GAIN2, which are the second correction values, are calculated using the following equations (11) and (12), and in the following equations (11) and (12), N is a natural number. The electric power steering device according to item 4.
SIN2=SIN1-COS1 (7)
COS2=COS1+SIN1 (8)
SIN_OFFSET2=(SIN2_MAX+SIN2_MIN)/2 (9)
COS_OFFSET2=(COS2_MAX+COS2_MIN)/2 (10)
SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN) (11)
COS_GAIN2=N/(COS2_MAX-COS2_MIN)...(12) The correction calculation processing unit,
The following equations (13) and (14) are used to calculate the third sine wave signal SIN3 and the third cosine wave signal COS3,
The electric power steering apparatus according to claim 5, wherein the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 are calculated using the following equations (15) and (16).
SIN3=SIN_GAIN2×(SIN2-SIN_OFFSET2) (13)
COS3=COS_GAIN2×(COS2-COS_OFFSET2) (14)
SIN4=SIN3+COS3 (15)
COS4=COS3-SIN3 (16) The correction calculation processing unit,
The following equations (17) and (18) are used to calculate the second sine wave signal SIN2 and the second cosine wave signal COS2,
The second gain correction values SIN_GAIN2 and COS_GAIN2 that are the second correction values are calculated using the following equations (19) and (20), and N is a natural number in the following equations (19) and (20). The electric power steering device according to item 4.
SIN2=SIN1-COS1 (17)
COS2=COS1+SIN1 (18)
SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN) (19)
COS_GAIN2=N/(COS2_MAX-COS2_MIN) (20) The correction calculation processing unit,
The following equations (21) and (22) are used to calculate the third sine wave signal SIN3 and the third cosine wave signal COS3,
The electric power steering device according to claim 7, wherein the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 are calculated using the following equations (23) and (24).
SIN3=SIN_GAIN2×SIN2 (21)
COS3=COS_GAIN2×COS2 (22)
SIN4=SIN3+COS3 (23)
COS4=COS3-SIN3 (24) The correction calculation processing unit,
The second sine wave signal SIN2 and the second cosine wave signal COS2 are calculated using the following equations (7)′ and (8)′,
When the maximum value of the second sine wave signal is SIN2_MAX, the minimum value of the second sine wave signal is SIN2_MIN, the maximum value of the second cosine wave signal is COS2_MAX, and the minimum value of the second cosine wave signal is COS2_MIN. , Using the following equations (9)′ and (10)′, the second offset correction values SIN_OFFSET2 and COS_OFFSET2 that are the second correction values are calculated.
The second gain correction values SIN_GAIN2 and COS_GAIN2, which are the second correction values, are calculated using the following equations (11)′ and (12)′, and in the following equations (11)′ and (12)′, N is a natural number. The electric power steering device according to claim 4.
SIN2=SIN1+COS1 (7)'
COS2=COS1-SIN1 (8)'
SIN_OFFSET2=(SIN2_MAX+SIN2_MIN)/2 (9)'
COS_OFFSET2=(COS2_MAX+COS2_MIN)/2 (10)'
SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN)...(11)'
COS_GAIN2=N/(COS2_MAX-COS2_MIN)...(12)' The correction calculation processing unit,
The following equations (13)′ and (14)′ are used to calculate the third sine wave signal SIN3 and the third cosine wave signal COS3,
The electric power steering device according to claim 9, wherein the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 are calculated using the following equations (15)′ and (16)′.
SIN3=SIN_GAIN2×(SIN2-SIN_OFFSET2)...(13)′
COS3=COS_GAIN2×(COS2-COS_OFFSET2) (14)'
SIN4=SIN3-COS3 (15)'
COS4=COS3+SIN3 (16)' The correction calculation processing unit,
The following equations (17)' and (18)' are used to calculate the second sine wave signal SIN2 and the second cosine wave signal COS2,
The second gain correction values SIN_GAIN2 and COS_GAIN2, which are the second correction values, are calculated using the following equations (19)′ and (20)′, and in the following equations (19)′ and (20)′, N is a natural number. The electric power steering device according to claim 4.
SIN2=SIN1+COS1 (17)'
COS2=COS1-SIN1 (18)'
SIN_GAIN2=N/(SIN2_MAX-SIN2_MIN)...(19)'
COS_GAIN2=N/(COS2_MAX-COS2_MIN)...(20)' The correction calculation processing unit,
The following equations (21)' and (22)' are used to calculate the third sine wave signal SIN3 and the third cosine wave signal COS3,
The electric power steering device according to claim 11, wherein the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4 are calculated using the following equations (23)' and (24)'.
SIN3=SIN_GAIN2×SIN2...(21)'
COS3=COS_GAIN2×COS2 (22)'
SIN4=SIN3-COS3 (23)'
COS4=COS3+SIN3 (24)' The angle calculation unit,
The electric power steering according to any one of claims 6, 8, 10 and 12, wherein the rotation angle is calculated based on the fourth sine wave signal SIN4 and the fourth cosine wave signal COS4. apparatus. A sine wave signal of an electrical angle output according to the rotation of a resolver rotor having a plurality of poles whose gap between the inner circumference of an annular resolver stator changes a plurality of times per revolution around the axis of the motor, and A rotation angle detection method for correcting a cosine wave signal and detecting the rotation angle of the motor based on the correction result,
A first correction value for correcting the offset voltage and the gain of the sine wave signal and the cosine wave signal is calculated based on the maximum value and the minimum value of the sine wave signal and the cosine wave signal, and the first correction value is calculated. On the basis of the offset voltage and gain of the sine wave signal and the cosine wave signal, the first sine wave signal and the first cosine wave signal are obtained, and the phases of the first sine wave signal and the first cosine wave signal are calculated. A second sine wave signal and a second cosine wave signal that are advanced by 45 electrical degrees are obtained, and the sine wave signal and the second cosine wave signal are calculated based on the maximum value and the minimum value of the second sine wave signal and the second cosine wave signal. A correction value calculation processing step of calculating a second correction value for correcting the phase of the cosine wave signal,
Based on the first correction value, offset voltage and gain of the sine wave signal and the cosine wave signal are corrected to obtain a first sine wave signal and a first cosine wave signal, and the first sine wave signal and the first cosine wave are obtained. A second sine wave signal and a second cosine wave signal obtained by advancing the phase of the wave signal by 45 electrical degrees are obtained, and based on the second correction value, at least the second sine wave signal and the second cosine wave signal. The third sine wave signal and the third cosine wave signal whose gains have been corrected are obtained, and the phases of the third sine wave signal and the third cosine wave signal are delayed by an electrical angle of 45 degrees, respectively, and A correction processing step for obtaining a 4 cosine wave signal,
A rotation angle calculating step of calculating a rotation angle of the motor based on the fourth sine wave signal and the fourth cosine wave signal,
A rotation angle detection method having.

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