JP2015157548A - Electric power steering device, resolver failure detection device, resolver failure detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which can accurately grasp a rotation angle of an electric motor without providing a mechanical positional displacement prevention mechanism.SOLUTION: An electric power steering device includes: a three-phase brushless electric motor 110 having a resolver 120; a motor rotation angle calculation part 35 which calculates a rotation angle of the electric motor 110 based on an output value from the resolver 120; a torque sensor for detecting a steering torque of a steering wheel; a target current calculation part 20 which conducts a predetermined direct current between two specific phases of the electric motor 110; a rotation angle correction part 36 which corrects a rotation angle calculated by the motor rotation angle calculation part 35 based on a difference between the rotation angle calculated by the motor rotation angle calculation part 35 and a predetermined angle when the target current calculation part conducts said predetermined direct current; and a motor drive control part 31 which controls drive of the electric motor 110 based on the corrected rotation angle after correction by the rotation angle correction part 36.

Description

  The present invention relates to an electric power steering device including an electric motor having a resolver, a resolver failure detection device, and a resolver failure detection method.

In recent years, there has been proposed an electric power steering device that includes an electric motor in a steering system of a vehicle and assists a driver's steering force with the power of the electric motor.
For example, the electric power steering device described in Patent Document 1 is configured as follows. That is, the microcomputer for controlling steering assist controls target electric current calculation means that receives signals from the torque sensor and the vehicle speed sensor and calculates and supplies current supplied to the brushless motor (electric motor), and the electric motor drive circuit. Drive control means. The microcomputer also calculates an electrical angle calculation means for calculating the rotational electrical angle of the brushless motor based on a signal from the resolver, and outputs a feedback current value based on the output of the electrical angle calculation means and the detected brushless motor current. Feedback current calculating means for calculating, and deviation calculating means for calculating a deviation ΔI between the feedback current value and the command current value from the target current calculating means are provided. The microcomputer also adds current control means for outputting the PI signal by adding the signals subjected to proportional control and integral control to the current deviation ΔI from the deviation calculating means, and calculating the PI signal and the electrical angle calculating means. Three-phase voltage command calculation means for generating a PWM signal for driving the brushless motor based on the rotating electrical angle and giving it to the motor drive circuit is provided.

  The electric power steering apparatus described in Patent Document 1 described above controls the driving of the electric motor using the rotation angle (electrical angle) of the electric motor (brushless motor) calculated based on the signal from the resolver. Therefore, it is desirable that the error between the rotation angle calculated based on the signal from the resolver and the actual rotation angle of the electric motor is small.

  On the other hand, in Patent Document 2, for the purpose of providing a brushless motor capable of obtaining a desired rotation characteristic by preventing relative positional deviation between the sensor rotor portion and the magnet, The described technique is disclosed. That is, the step part is formed in the rotor shaft which comprises the rotor of a brushless motor. A magnet, a resolver rotor portion, and an interposed member are fixed to the rotor shaft. The resolver rotor section detects the rotational position of the rotor shaft. The interposition member is disposed between the magnet and the resolver rotor portion. The magnet and the interposition member are engaged with each other in the circumferential direction by the first engaging portion. The interposition member and the resolver rotor portion are engaged with each other in the circumferential direction by the second engagement portion.

JP 2002-29432 A JP 2005-274484 A

From the viewpoint of simplification of the configuration and the like, the rotation angle of the electric motor can be accurately grasped based on the signal from the resolver without providing a mechanical displacement prevention mechanism like the technique described in Patent Document 2 described above. It is desirable to be able to do it. And thereby, drive control of an electric motor can be appropriately performed with a simple configuration.
An object of the present invention is to provide an electric power steering apparatus capable of appropriately performing drive control of an electric motor based on a signal from a resolver having a simple configuration. It is another object of the present invention to provide a resolver failure detection device and a resolver failure detection method that can detect a failure in a resolver with a simple configuration.

  For this purpose, the present invention provides a three-phase brushless electric motor having a resolver, calculation means for calculating a rotation angle of the electric motor based on an output value from the resolver, and detecting a steering torque of a steering wheel. A torque sensor that conducts a predetermined direct current between two specific phases of the electric motor, and a rotation angle calculated by the calculating means when the conductive means supplies the predetermined direct current. Correction means for correcting the rotation angle calculated by the calculation means based on the difference from the calculated angle, control means for controlling the drive of the electric motor based on the corrected rotation angle corrected by the correction means, An electric power steering apparatus comprising:

Here, the energization unit may energize the predetermined direct current when the steering torque detected by the torque sensor is equal to or less than a predetermined steering torque.
The electric motor may be set to have the predetermined angle when the predetermined direct current is applied between the specific two phases.

  From another point of view, the present invention is a resolver failure detection device that detects a failure of a resolver provided in a three-phase brushless electric motor, wherein the rotation angle of the electric motor is based on an output value from the resolver. Calculating means for calculating a current value, energizing means for energizing a predetermined DC current between two specific phases of the electric motor, and a rotation angle calculated by the calculating means when the energizing means energizes the predetermined DC current; A resolver failure detection apparatus comprising: a detecting unit that detects a failure of the resolver based on a difference from a predetermined angle.

Here, the detection unit may determine that the resolver has failed when a difference between a rotation angle calculated by the calculation unit and a predetermined angle is larger than a reference angle.
The energizing unit may energize the predetermined direct current when the steering torque of the steering wheel detected by the torque sensor is equal to or less than a predetermined steering torque.

  From another point of view, the present invention is a resolver failure detection method for detecting a failure of a resolver provided in a three-phase brushless electric motor, wherein a predetermined direct current is passed between specific two phases of the electric motor. When the difference between the rotation angle of the electric motor calculated based on the output value from the resolver and a predetermined angle is larger than a reference angle, the resolver failure is determined. It is a detection method.

  Here, the predetermined DC current may be applied when the steering torque of the steering wheel detected by the torque sensor is equal to or less than a predetermined steering torque.

According to invention of Claims 1-3, drive control of an electric motor can be appropriately performed based on the signal from the resolver of a simple structure.
According to the fourth to eighth aspects of the present invention, it is possible to detect a failure of a resolver having a simple configuration.

It is a figure showing the schematic structure of the electric power steering device concerning an embodiment. It is a schematic block diagram of a control apparatus. It is a schematic block diagram of a target current calculation part. It is the schematic of the control map which shows a response | compatibility with steering torque, vehicle speed, and base current. It is a schematic block diagram of a control part. It is a flowchart which shows the procedure of the failure detection process which a resolver failure detection part performs.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a schematic configuration of an electric power steering apparatus 100 according to an embodiment.
Electric power steering device 100 (hereinafter, also simply referred to as “steering device 100”) is a steering device for arbitrarily changing the traveling direction of a vehicle, and in this embodiment, an automobile as an example of the vehicle. The structure applied to is illustrated.

  The steering apparatus 100 includes a wheel-like steering wheel 101 that is operated by a driver to change the traveling direction of the automobile, and a steering shaft 102 that is provided integrally with the steering wheel 101. . The steering device 100 includes an upper connecting shaft 103 connected to the steering shaft 102 via a universal joint 103a, and a lower connecting shaft 108 connected to the upper connecting shaft 103 via a universal joint 103b. . The lower connecting shaft 108 rotates in conjunction with the rotation of the steering wheel 101.

  Steering device 100 includes tie rods 104 connected to left and right front wheels 150 as rolling wheels, and rack shaft 105 connected to tie rods 104. Further, the steering device 100 includes a pinion 106 a that constitutes a rack and pinion mechanism together with rack teeth 105 a formed on the rack shaft 105. The pinion 106 a is formed at the lower end portion of the pinion shaft 106. The rack shaft 105, the pinion shaft 106, and the like function as a transmission mechanism that transmits the rotational operation force of the steering wheel 101 as the rolling force of the front wheel 150. The pinion shaft 106 applies a driving force to roll the front wheel 150 by rotating with respect to the rack shaft 105 that rolls the front wheel 150.

  The steering device 100 also has a steering gear box 107 that houses the pinion shaft 106. The pinion shaft 106 is connected to the lower connection shaft 108 via the torsion bar 112 in the steering gear box 107. The steering gear box 107 has a steering torque T applied to the steering wheel 101 based on the relative rotation angle between the lower connecting shaft 108 and the pinion shaft 106, in other words, based on the twist amount of the torsion bar 112. Is provided.

  Further, the steering device 100 includes an electric motor 110 supported by the steering gear box 107 and a speed reduction mechanism 111 that reduces the driving force of the electric motor 110 and transmits it to the pinion shaft 106. The speed reduction mechanism 111 includes, for example, a worm wheel (not shown) fixed to the pinion shaft 106, a worm gear (not shown) fixed to the output shaft of the electric motor 110, and the like. The electric motor 110 applies a driving force for rolling the front wheel 150 to the rack shaft 105 by applying a rotational driving force to the pinion shaft 106. Electric motor 110 according to the present embodiment is a three-phase brushless motor having resolver 120 that detects motor rotation angle θ, which is the rotation angle of electric motor 110. In addition, electric motor 110 according to the present embodiment is set such that motor rotation angle θ is zero when a DC current is applied to the U-V phase. Further, when the steering wheel 101 is in a neutral state (the steering angle is zero (deg)), the motor rotation angle θ of the electric motor 110 is set to be zero.

  In addition, the steering device 100 includes a control device 10 that controls the operation of the electric motor 110. An output signal from the torque sensor 109 described above is input to the control device 10. In addition, the control device 10 includes a vehicle speed sensor 170 that detects a vehicle speed Vc, which is a moving speed of the vehicle, via a network (CAN) that performs communication for sending signals for controlling various devices mounted on the vehicle. The output signal from is input.

  The steering device 100 configured as described above drives the electric motor 110 based on the detected torque detected by the torque sensor 109 and transmits the generated torque of the electric motor 110 to the pinion shaft 106. Thereby, the torque generated by the electric motor 110 assists the driver's steering force applied to the steering wheel 101.

Next, the control device 10 will be described.
FIG. 2 is a schematic configuration diagram of the control device 10.
The control device 10 is an arithmetic logic operation circuit including a CPU, a ROM, a RAM, an EEPROM (Electrically Erasable & Programmable Read Only Memory), and the like.
The control device 10 includes a torque signal Td obtained by converting the steering torque T detected by the torque sensor 109 described above into an output signal, and a vehicle speed signal obtained by converting the vehicle speed Vc detected by the vehicle speed sensor 170 into an output signal. v, a rotation angle signal θs that is an output signal corresponding to the motor rotation angle θ of the electric motor 110 from the resolver 120, and the like are input.

  Then, the control device 10 calculates (sets) a target current It necessary for the electric motor 110 to supply based on the torque signal Td, the vehicle speed signal v, and the like, and a target current calculation unit 20. Includes a control unit 30 that performs feedback control based on the target current It calculated by, and a resolver failure detection unit 70 as an example of a detection unit that detects a failure of the resolver 120.

Next, the target current calculation unit 20 will be described in detail.
FIG. 3 is a schematic configuration diagram of the target current calculation unit 20.
The target current calculation unit 20 calculates a base current calculation unit 21 that calculates a base current Ib that serves as a reference for setting the target current It, and inertia compensation that calculates an inertia compensation current Is for canceling the inertia moment of the electric motor 110. A current calculation unit 22 and a damper compensation current calculation unit 23 that calculates a damper compensation current Id that limits the rotation of the motor are provided. The target current calculation unit 20 includes a target current determination unit 25 that determines the target current It based on values calculated by the base current calculation unit 21, the inertia compensation current calculation unit 22, and the damper compensation current calculation unit 23. ing. In addition, the target current calculation unit 20 includes a phase compensation unit 26 that compensates for the phase of the steering torque T detected by the torque sensor 109.
The target current calculation unit 20 receives a torque signal Td, a vehicle speed signal v, a motor rotation speed signal Nms, which will be described later, and the like.

FIG. 4 is a schematic diagram of a control map showing the correspondence between the steering torque T, the vehicle speed Vc, and the base current Ib.
The base current calculation unit 21 calculates a base current Ib based on the torque signal Ts obtained by phase compensation of the torque signal Td by the phase compensation unit 26 and the vehicle speed signal v from the vehicle speed sensor 170. In other words, the base current calculation unit 21 calculates the base current Ib according to the steering torque T phase-compensated by the phase compensation unit 26 and the vehicle speed Vc. The base current calculation unit 21 is, for example, a phase-compensated steering torque T (torque signal Ts), vehicle speed Vc (vehicle speed signal v), and base current that are created in advance based on empirical rules and stored in the ROM. The base current Ib is calculated by substituting the steering torque T and the vehicle speed Vc into the control map illustrated in FIG. 4 illustrating the correspondence with Ib.

  The inertia compensation current calculation unit 22 calculates the inertia compensation current Is based on the torque signal Ts and the vehicle speed signal v obtained by phase compensation of the torque signal Td by the phase compensation unit 26. In other words, the inertia compensation current calculation unit 22 calculates the inertia compensation current Is according to the steering torque T phase-compensated by the phase compensation unit 26 and the vehicle speed Vc. Note that the inertia compensation current calculation unit 22, for example, a phase-compensated steering torque T (torque signal Ts) and vehicle speed Vc (vehicle speed signal v) and inertia, which are created based on empirical rules and stored in the ROM in advance. The inertia compensation current Is is calculated by substituting the phase-compensated steering torque T and the vehicle speed Vc into the control map indicating the correspondence with the compensation current Is.

  The damper compensation current calculation unit 23 calculates the damper compensation current Id based on the torque signal Ts, the vehicle speed signal v, the motor rotation speed signal Nms, and the like, in which the torque signal Td is phase compensated by the phase compensation unit 26. In other words, the damper compensation current calculation unit 23 calculates the damper compensation current Id according to the steering torque T phase-compensated by the phase compensation unit 26, the vehicle speed Vc, and the motor rotation speed Nm. The damper compensation current calculation unit 23 is, for example, a phase-compensated steering torque T (torque signal Ts), vehicle speed Vc (vehicle speed signal v), and motor, which are previously created based on empirical rules and stored in the ROM. By substituting the phase-compensated steering torque T, vehicle speed Vc, and motor rotational speed Nm into the control map indicating the correspondence between the rotational speed Nm (motor rotational speed signal Nms) and the damper compensation current Id, the damper compensation current Id is obtained. calculate.

The target current determination unit 25 includes the base current Ib calculated by the base current calculation unit 21, the inertia compensation current Is calculated by the inertia compensation current calculation unit 22, and the damper compensation calculated by the damper compensation current calculation unit 23. A target current It is determined based on the current Id. For example, the target current determination unit 25 determines the current obtained by adding the inertia compensation current Is to the base current Ib and subtracting the damper compensation current Id as the target current It.
Further, when the target current determination unit 25 acquires from the resolver failure detection unit 70 an instruction command (command) for energizing a predetermined DC current to the U-V phase of the electric motor 110 as described later. The predetermined direct current is determined as the target current It. As described above, the target current determination unit 25 functions as an example of an energization unit that energizes a predetermined DC current between two specific phases of the electric motor 110.

Next, the control unit 30 will be described in detail.
FIG. 5 is a schematic configuration diagram of the control unit 30.
As shown in FIG. 5, the control unit 30 actually includes a motor drive control unit 31 as an example of a control unit that controls the operation of the electric motor 110, a motor drive unit 32 that drives the electric motor 110, and the electric motor 110. And a motor current detector 33 for detecting the actual current Im flowing through the motor. In addition, the control unit 30 corrects the motor rotation angle θ calculated by the motor rotation angle calculation unit 35 and the motor rotation angle calculation unit 35 as an example of a calculation unit that calculates the motor rotation angle θ of the electric motor 110. A rotation angle correction unit 36 as an example of means, and a motor rotation speed calculation unit 37 that calculates the motor rotation speed Nm of the electric motor 110 based on the corrected rotation angle θc corrected by the rotation angle correction unit 36. doing. The control unit 30 also includes a feedback current calculation unit 38 that calculates the feedback current If based on the actual current Im detected by the motor current detection unit 33 and the corrected rotation angle θc corrected by the rotation angle correction unit 36. doing.

  The motor drive control unit 31 performs feedback control based on a deviation between the target current It finally determined by the target current calculation unit 20 and the feedback current If calculated by the feedback current calculation unit 38 ( F / B) The control unit 40 and the PWM signal generation unit 60 that generates a PWM (pulse width modulation) signal for PWM driving the electric motor 110 are included.

  The feedback control unit 40 includes a deviation calculating unit 41 for obtaining a deviation between the target current It finally determined by the target current calculating unit 20 and the feedback current If calculated by the feedback current calculating unit 38, and the deviation is A feedback (F / B) processing unit 42 that performs feedback processing so as to be zero.

The feedback (F / B) processing unit 42 performs feedback control so that the target current It and the feedback current If match. For example, the feedback (F / B) processing unit 42 is proportional to the deviation calculated by the deviation calculating unit 41. Is proportionally processed, integrated by an integral element, and these values are added by an addition operation unit.
The PWM signal generation unit 60 performs PWM (pulse width modulation) driving of the electric motor 110 based on the output value from the feedback control unit 40 and the corrected rotation angle θc corrected by the rotation angle correction unit 36. And outputs the generated PWM signal.

The motor drive unit 32 is a so-called inverter, and includes, for example, six independent transistors (FETs) as switching elements. Three of the six transistors are a positive line of a power source, an electric coil of each phase, The other three transistors are connected to the electric coil of each phase and the negative side (ground) line of the power source. Then, the driving of the electric motor 110 is controlled by driving the gates of two transistors selected from the six and switching the transistors.
The motor current detection unit 33 detects the value of the actual current Im flowing through the electric motor 110 from the voltage generated at both ends of the shunt resistor connected to the motor drive unit 32.

The motor rotation angle calculation unit 35 calculates the motor rotation angle θ based on the output signal of the resolver 120. The rotation angle correction unit 36 will be described in detail later. The motor rotation speed calculation unit 37 calculates the motor rotation speed Nm of the electric motor 110 based on the corrected rotation angle θc corrected by the rotation angle correction unit 36, and the calculated motor rotation speed Nm is converted into an output signal. A motor rotation speed signal Nms is output.
The feedback current calculation unit 38 is based on the arithmetic expression stored in advance in the ROM, the actual current Im detected by the motor current detection unit 33, and the corrected rotation angle θc corrected by the rotation angle correction unit 36. If is calculated.

Next, the resolver failure detection unit 70 (see FIG. 2) will be described in detail.
The resolver failure detection unit 70 calculates a motor rotation angle θ (hereinafter referred to as “detection rotation angle θd”) calculated based on an output signal from the resolver 120 and an actual motor rotation angle θ (hereinafter referred to as “actual rotation angle θa”). When the absolute value of the difference from the reference angle θb is greater than a predetermined reference angle θb, it is determined that a failure has occurred in the resolver 120.

More specifically, the actual rotation angle θa of the electric motor 110 when a predetermined direct current is applied to the U-V phase of the electric motor 110 according to the present embodiment is set to be zero. In view of this, the resolver failure detection unit 70 has an absolute value of the difference between the detected rotation angle θd and the actual rotation angle θa of zero when the predetermined DC current is applied to the U-V phase larger than the reference angle θb. It is determined that a failure has occurred.
The resolver failure detection unit 70 stores the difference between the detected rotation angle θd and the actual rotation angle θa in the EEPROM when the absolute value of the difference between the detected rotation angle θd and the actual rotation angle θa is equal to or smaller than the reference angle θb. To do.

Next, a procedure of failure detection processing performed by the resolver failure detection unit 70 will be described using a flowchart.
FIG. 6 is a flowchart showing a procedure of failure detection processing performed by the resolver failure detection unit 70. The resolver failure detection unit 70 repeatedly executes this failure detection process every predetermined period (for example, every 1 millisecond).

  First, the resolver failure detection unit 70 sets the sign of the steering torque T when the steering wheel 101 is rotated in one direction from the neutral state to the plus, and the sign of the steering torque T when rotated in the other direction is minus. It is determined whether or not the absolute value of the steering torque T most recently detected by the torque sensor 109 is equal to or less than a predetermined reference steering torque Tb (step (hereinafter simply referred to as “S”) 101). . The reference steering torque Tb can be exemplified in the map shown in FIG. 4 as a value within the range of the steering torque T at which the base current Ib is determined to be zero. In other words, the process of S101 determines whether or not the steering torque T detected by the torque sensor 109 is a value within the dead zone region.

When the detected absolute value of the steering torque T is equal to or less than the reference steering torque Tb (Yes in S101), the target current calculation unit 20 is configured so that a predetermined direct current is supplied to the U-V phase of the electric motor 110. An instruction command (command) is sent to (S102). Upon receiving this instruction command, the target current determining unit 25 of the target current calculating unit 20 determines a predetermined direct current as the target current It.
Thereafter, it is determined whether or not a predetermined direct current has been applied to the U-V phase of the electric motor 110 for a predetermined time (S103). When a predetermined direct current is energized for a predetermined time (Yes in S103), the detected rotation angle θd calculated based on the output signal from the resolver 120 is read, and the read detection rotation angle θd and actual rotation angle θa are read. An angle difference Δθ from (zero) (deg) is calculated (S104). On the other hand, when the predetermined direct current is not energized for a predetermined time (No in S103), the processes after S102 are performed again.

  Thereafter, it is determined whether or not the absolute value of the angle difference Δθ calculated in S104 is equal to or smaller than the reference angle θb (S105). If the absolute value of the angle difference Δθ is equal to or smaller than the reference angle θb (Yes in S105), the angle difference Δθ between the detected rotation angle θd and the actual rotation angle θa is stored in the EEPROM (S106). On the other hand, when the absolute value of the angle difference Δθ is larger than the reference angle θb (No in S105), it is determined that a failure has occurred in the resolver 120, and the function as the steering device 100 is stopped (S107). As a method of stopping the function of the steering device 100, the power supplied to the control device 10 that sends an instruction command (command) for setting the target current It to be supplied to the electric motor 110 to zero is sent to the target current calculation unit 20. For example, the relay may be turned off to stop.

  On the other hand, when the detected absolute value of the steering torque T is not less than or equal to the reference steering torque Tb (No in S101), a predetermined value to the U-V phase of the electric motor 110 is executed in order to execute control of the normal electric motor 110. DC current is not energized (S108).

Next, the rotation angle correction unit 36 will be described in detail.
The rotation angle correction unit 36 corrects the motor rotation angle θ calculated based on the output signal from the resolver 120 by the angle difference Δθ calculated by the resolver failure detection unit 70 and stored in the EEPROM. That is, when the detected rotation angle θd is advanced from the actual rotation angle θa, the rotation angle correction unit 36 corrects the rotation angle after correcting the value obtained by subtracting the absolute value of the angle difference Δθ from the detected rotation angle θd. Output as θc. On the other hand, when the detected rotation angle θd is retarded from the actual rotation angle θa, the rotation angle correction unit 36 corrects the value obtained by adding the absolute value of the angle difference Δθ to the detected rotation angle θd. Output as θc.

  In the control device 10 configured as described above, since the rotation angle correction unit 36 corrects the motor rotation angle θ calculated based on the output signal from the resolver 120, the motor drive control unit 31 determines that the actual rotation angle θa is It becomes easy to acquire the same value. That is, the motor drive control unit 31 can easily grasp the motor rotation angle θ with high accuracy. Thereby, the motor drive control part 31 can output the control signal for carrying out drive control of the electric motor 110 appropriately. As described above, according to the control device 10 according to the present embodiment, the resolver 120 is not provided with a mechanical mechanism for preventing a deviation of the detected rotation angle θd from the actual rotation angle θa, and the signal from the resolver 120 is received. Based on this, the rotation angle of the electric motor 110 (motor rotation angle θ) can be grasped with high accuracy, and drive control of the electric motor 110 can be performed appropriately.

Moreover, according to the control apparatus 10 which concerns on this Embodiment, the failure of the resolver 120 can be detected with high precision. As described above, the control device 10 functions as a resolver failure detection device that detects a failure of the resolver 120 using the resolver failure detection method shown in the flowchart shown in FIG.
In addition, when the detected absolute value of the steering torque T is equal to or less than the reference steering torque Tb, a predetermined DC current is applied to the U-V phase of the electric motor 110, so that the steering is performed when the automobile is traveling straight. The wheel 101 is easily held in a neutral state. Therefore, the neutral position of the steering wheel 101 becomes clear, and the center feeling during straight traveling is improved.

  In the above-described embodiment, the electric motor 110 is set so that the motor rotation angle θ when the direct current is applied to the U-V phase is zero, but is not particularly limited to such a mode. The electric motor 110 may be set so that the motor rotation angle θ becomes zero when a direct current is applied to the VW phase or the WU phase. In such a case, when the resolver failure detection unit 70 executes the failure detection process, a predetermined DC current is applied to the V-W phase or W-U phase set so that the motor rotation angle θ is zero. The failure may be detected based on the angle difference Δθ between the detected rotation angle θd and the actual rotation angle θa.

DESCRIPTION OF SYMBOLS 10 ... Control apparatus, 20 ... Target electric current calculation part, 30 ... Control part, 31 ... Motor drive control part, 35 ... Motor rotation angle calculation part, 36 ... Rotation angle correction part, 70 ... Resolver failure detection part, 100 ... Electric power Steering device 109 ... Torque sensor 110 ... Electric motor 120 ... Resolver

Claims (8)

A three-phase brushless electric motor having a resolver;
Calculation means for calculating a rotation angle of the electric motor based on an output value from the resolver;
A torque sensor for detecting the steering torque of the steering wheel;
Energizing means for energizing a predetermined direct current between two specific phases of the electric motor;
Correction means for correcting the rotation angle calculated by the calculation means based on the difference between the rotation angle calculated by the calculation means when the energization means supplies the predetermined direct current, and a predetermined angle;
Control means for controlling the driving of the electric motor based on the corrected rotation angle corrected by the correction means;
An electric power steering apparatus comprising: 2. The electric power steering apparatus according to claim 1, wherein the energization unit energizes the predetermined DC current when the steering torque detected by the torque sensor is equal to or less than a predetermined steering torque. 3. The electric power according to claim 1, wherein the electric motor is set to have the predetermined angle when the predetermined DC current is applied between the two specific phases. Steering device. A resolver failure detection device for detecting a failure of a resolver provided in a three-phase brushless electric motor,
Calculation means for calculating a rotation angle of the electric motor based on an output value from the resolver;
Energizing means for energizing a predetermined direct current between two specific phases of the electric motor;
Detecting means for detecting a failure of the resolver based on a difference between a rotation angle calculated by the calculating means when the energizing means energizes the predetermined direct current and a predetermined angle;
A resolver failure detection apparatus comprising: The resolver failure detection according to claim 4, wherein the detection unit determines that the resolver has failed when a difference between a rotation angle calculated by the calculation unit and a predetermined angle is larger than a reference angle. apparatus. The resolver failure according to claim 4 or 5, wherein the energization means energizes the predetermined DC current when a steering torque detected by a torque sensor is equal to or less than a predetermined steering torque. Detection device. A resolver failure detection method for detecting a failure of a resolver provided in a three-phase brushless electric motor,
When the difference between the rotation angle of the electric motor calculated based on the output value from the resolver and a predetermined angle when a predetermined direct current is applied between two specific phases of the electric motor is larger than a reference angle And a resolver failure detection method characterized by determining that the resolver is malfunctioning. 8. The resolver failure detection method according to claim 7, wherein the predetermined direct current is applied when the steering torque detected by the torque sensor is equal to or less than a predetermined steering torque.

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