JP5641299B2 - Motor control device and vehicle steering device - Google Patents

Description

  The present invention relates to a motor control device for driving a brushless motor and a vehicle steering device using the motor control device. The brushless motor can be used, for example, as a drive source for a vehicle steering apparatus. An example of a vehicle steering device is an electric power steering device.

  A motor control device for driving and controlling a brushless motor is generally configured to control the supply of motor current in accordance with the output of a rotation angle sensor for detecting the rotation angle of the rotor. As the rotation angle sensor, a resolver that outputs a sine wave signal and a cosine wave signal corresponding to the rotor rotation angle (electrical angle) is generally used. However, the resolver is expensive, has a large number of wires, and has a large installation space. Therefore, there exists a subject that the cost reduction and size reduction of an apparatus provided with the brushless motor are inhibited.

  Therefore, a sensorless driving method for driving a brushless motor without using a rotation angle sensor has been proposed. The sensorless driving method is a method for estimating the phase of the magnetic pole (electrical angle of the rotor) by estimating the induced voltage accompanying the rotation of the rotor. Since the phase of the magnetic pole cannot be estimated when the rotor is stopped and when rotating at a very low speed, the phase of the magnetic pole is estimated by another method. Specifically, a sensing signal is injected into the stator, and a motor response to the sensing signal is detected. Based on this motor response, the rotor rotational position is estimated.

JP 2007-267549 Gazette

  The above sensorless driving method estimates the rotational position of the rotor using an induced voltage or a sensing signal, and controls the motor based on the rotational position obtained by the estimation. However, this drive system is not suitable for any use. For example, a brushless motor used as a drive source of an electric power steering apparatus or other vehicle steering apparatus that applies a steering assist force to a steering mechanism of a vehicle. A method for applying to control has not been established yet. Therefore, realization of sensorless control by another method is desired.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a motor control device that can control a motor by a new control method that does not use a rotation angle sensor, and a vehicle steering device that includes such a motor control device. .

The invention of claim 1, wherein for achieving the above object, a rotor (50), a motor controller for controlling the motor (3) provided with a facing stator (55) to the rotor (5) A current driving means (31-36B) for driving the motor with an axis current value (I _γ ^* ) of a rotating coordinate system in accordance with a control angle (θ _C ) which is a control rotation angle, and the control angle An addition angle calculation means (22, 23) for calculating an addition angle (α) to be added, and an addition angle calculated by the addition angle calculation means for each predetermined calculation cycle is added to the previous value of the control angle. Control angle calculation means (26) for determining the current value of the control angle, and induced voltage square value calculation means (28,) for estimating the induced voltage of the motor and calculating the square value (Σ) of the estimated induced voltage. 37) and the induced voltage square value calculation means A motor control device including correction means ( 38, 39, 41, 43, 44, 60 to 64, 70, 71) for correcting the addition angle based on the calculated induced voltage square value. The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later. The same applies hereinafter.

  According to this configuration, the axis current value (hereinafter referred to as “virtual axis”) of the rotational coordinate system (γδ coordinate system, hereinafter referred to as “virtual rotational coordinate system”, which is referred to as “virtual axis”) according to the control angle. While the motor is driven by the "shaft current value"), the control angle is updated by adding the addition angle every calculation cycle. Thus, the necessary torque can be generated by driving the motor with the virtual axis current value while updating the control angle, that is, while updating the coordinate axis (virtual axis) of the virtual rotation coordinate system. Thus, an appropriate torque can be generated from the motor without using a rotation angle sensor. That is, an appropriate torque is generated by introducing a deviation amount (load angle) between the coordinate axis of the rotating coordinate system (dq coordinate system) and the virtual axis according to the magnetic pole direction of the rotor to an appropriate value.

Furthermore, in the present invention, the induced voltage of the motor is estimated, and the addition angle is corrected based on the square value (induced voltage square value). The square value of the induced voltage reflects the rotational state of the motor (particularly the magnitude of the rotor angular velocity). Therefore, by using the square value of the motor induced voltage, it is possible to appropriately correct the addition angle according to the rotation state of the motor, and thereby to more appropriately control the motor.

In particular, in a motor used in a vehicle steering apparatus, the rotor angular velocity and the generated torque change remarkably. Therefore, by correcting the addition angle based on the square value of the induced voltage, it is possible to appropriately control the motor as the drive source of the vehicle steering apparatus, and to improve the steering feeling .

The invention according to claim 2 further includes addition angle limiting means (24) for limiting the addition angle calculated by the addition angle calculation means with a predetermined limit value, wherein the correction means is the induced voltage square value calculation means. 2. The motor control according to claim 1 , wherein the addition angle is substantially corrected by changing the limit value in the addition angle limiting means according to the square value of the induced voltage calculated by Device.

By adding an appropriate limit to the addition angle, it is possible to suppress an excessive addition angle from being added to the control angle as compared to the actual rotation of the rotor. Thereby, a motor can be controlled appropriately. Further, in the present invention, the limit value is changed based on the induced voltage square value. As described above, the induced voltage square value corresponds to the rotor angular velocity. Further, since the addition angle is a change amount of the control angle during the control cycle, it corresponds to the angular velocity of the rotating coordinate system. Therefore, by correcting the limit value according to the induced voltage square value, the addition angle can be limited according to the rotor angular velocity. This makes it possible to perform more appropriate motor control.
The limit value is preferably determined in a range equal to or less than an upper limit value determined by the following equation, for example. However, the “maximum rotor angular velocity” in the following equation is the maximum value of the rotor angular velocity in electrical angle.
Upper limit value = Maximum rotor angular speed x Calculation cycle
For example, when the rotation of the motor is transmitted to the steering shaft of the vehicle steering device via a speed reduction mechanism with a predetermined reduction ratio, the maximum rotor angular velocity is the maximum steering angular velocity (maximum rotational angular velocity of the steering shaft) × deceleration It is given as ratio x number of pole pairs. The “number of pole pairs” is the number of magnetic pole pairs (pairs of N poles and S poles) that the rotor has.

According to a third aspect of the invention, the correction means corrects the addition angle by multiplying the addition angle after being limited by the addition angle limiting means by a gain corresponding to the square value of the induced voltage. It is a motor control device of Claim 2 containing .
In this configuration, the addition angle can be limited according to the rotor angular velocity by correcting the limit value according to the square value of the induced voltage. Furthermore, the addition angle can be corrected according to the rotor angular velocity by multiplying the addition angle after being limited by the addition angle limiting means by a gain corresponding to the square value of the induced voltage. Therefore, more appropriate motor control becomes possible.

The correction means may be configured to correct the addition angle by multiplying the addition angle calculated by the addition angle calculation means by a gain corresponding to the square value of the induced voltage. and it has a motor control device according to claim 1. In this configuration, the addition angle is corrected by multiplying the addition angle by a gain corresponding to the induced voltage square value. Therefore, the control angle of the current control cycle obtained by adding the addition angle of the current control cycle to the control angle of the previous control cycle is substantially corrected according to the square value of the induced voltage. Since the induced voltage square value has a value corresponding to the rotor angular velocity, the control angle can be corrected according to the rotor angular velocity. Thereby, the control angle can be appropriately corrected according to the rotor angular velocity.
Specifically, the addition angle may be multiplied by a gain that decreases as the induced voltage square value decreases. As a result, the absolute value of the addition angle is suppressed in a low speed region where the rotor angular speed is low, so that the motor torque applied to the drive target is reduced. For example, when controlling a motor that applies a steering assist force to a steering mechanism of a vehicle, a steering assist force (assist torque) at the initial operation of an operation member such as a steering wheel is suppressed. Thereby, when the steering wheel or the like is started, a good feeling of response can be obtained.
Conversely, a gain having a characteristic that becomes smaller as the induced voltage square value is larger may be multiplied by the addition angle. Accordingly, the addition angle is suppressed in the high speed region where the rotor angular velocity is large, and thus the motor torque applied to the drive target is reduced. For example, when controlling a motor that applies a steering assist force to the steering mechanism of the vehicle, the steering assist force is suppressed as the operation speed of an operation member such as a steering wheel increases. Thereby, what is called damping control can be performed and a feeling of wobbling can be suppressed.

According to a fifth aspect of the present invention, the correction means sets an interval time according to the square value of the induced voltage, and executes correction processing for reducing and correcting the addition angle for a predetermined time each time the interval time elapses. it is configured, a motor control device according to claim 1.
The addition angle reduction correction may be performed by correcting the addition angle by multiplying the addition angle by a reduction gain (G _α : 0 or more and less than 1). The interval time may be set longer as the induced voltage square value is larger. As a result, the smaller the induced voltage square value, the greater the influence of the reduction gain. Therefore, when the rotor angular speed is small, the motor torque can be reduced. For example, when the motor torque and the torque other than the motor torque (external input torque) are opposed to the load torque to be driven by the motor, the burden due to the external input torque is reduced by reducing the motor torque. growing. Therefore, the external input torque can be increased when the rotor angular speed is low. For example, when controlling a motor that applies a steering assist force to a steering mechanism of a vehicle, a steering assist force (assist torque) at the initial operation of an operation member such as a steering wheel is suppressed. Thereby, when the steering wheel or the like is started, a good feeling of response can be obtained. That is, it is possible to realize an appropriate response feeling according to the speed of the steering operation.

According to a sixth aspect of the present invention, the correction means is configured to change the limit value to a first limit value when the induced voltage square value is equal to or greater than a first predetermined value (C _th1 ). The motor control device according to 2 or 3 .

According to a seventh aspect of the present invention, the correction means changes the limit value to the first limit value when a state where the induced voltage square value is equal to or greater than a first predetermined value (C _th1 ) continues for a predetermined time or longer. The motor control device according to claim 2 , wherein the motor control device is configured as follows.

Invention 請 Motomeko 8 wherein, said correction means changes the induced voltage square value and the second predetermined value smaller than the first predetermined value (C _th2) and falls below the limit value to the second limit value It is a motor control apparatus of Claim 6 or 7 comprised as follows .

The invention according to claim 9 includes a rotor (50) and a stator (55) facing the rotor, and controls a motor (3) for applying a driving force to the steering mechanism (2) of the vehicle. Current control means (31-36B) for driving the motor with an axial current value (I _γ ^* ) of a rotating coordinate system according to a control angle (θ _C ) which is a control rotation angle. ), And control angle calculation means (26) for obtaining the current value of the control angle by adding the addition angle (α) to the previous value of the control angle for each predetermined calculation cycle, and for steering the vehicle Steering torque detection means (1) for detecting steering torque applied to the operating member (10) to be operated, instruction steering torque setting means (21) for setting instruction steering torque that is an instruction value of steering torque, Detected by the steering torque detecting means Using the detected steering torque and the command steering torque set by the command steering torque setting unit, the angle calculation means (22, 23) for calculating the addition angle, and the induced voltage of the motor is estimated and estimated Induced voltage square value calculation means (28, 37) for calculating the square value (Σ) of the induced voltage, and when the induced voltage square value is equal to or greater than a predetermined value (L _th ), the rotor angular displacement of the electric motor is A corresponding damping torque command value is generated, and the command steering torque is corrected by adding the damping torque command value to the command steering torque set by the command steering torque setting means. And a first correction means (60, 61, 62, 63) for correcting, and when the induced voltage square value is less than a predetermined value, an addition angle corresponding to the induced voltage square value It generates in, by multiplying the addition angle gain for the addition angle, and a second correction means for correcting (44,60,64) the addition angle, a motor control device.
With this configuration, the addition angle can be corrected in two types according to the magnitude of the induced voltage square value. Since the induced voltage square value corresponds to the rotor angular speed, the addition angle is corrected by selecting the appropriate mode according to the rotor angular speed by changing the correction mode of the added angle according to the magnitude of the induced voltage square value. it can. Thereby, more appropriate motor control becomes possible.
For example, when the induced voltage square value is sufficiently large, a highly accurate rotor angular displacement can be calculated from the estimated induced voltage. Therefore, the addition angle can be appropriately corrected by using the rotor angular displacement. On the other hand, when the induced voltage square value is small, the accuracy of the rotor angular displacement obtained using the estimated induced voltage is low. In such a case, the addition angle can be corrected by multiplying the addition angle gain corresponding to the square value of the induced voltage.

The invention according to claim 10 includes a rotor (50) and a stator (55) facing the rotor, and controls a motor (3) for applying a driving force to the steering mechanism (2) of the vehicle. Motor control device (5), which is a control angle (θ _C ) Axis current value (I _γ ^* ) And current angle control means (26 to 36B) for driving the motor, and control angle calculation means (26) for obtaining the current value of the control angle by adding the addition angle to the previous value of the control angle at every predetermined calculation cycle. ), A steering torque detecting means (1) for detecting a steering torque, which is applied to the operation member (10) operated for steering the vehicle, and an instruction steering torque which is an instruction value of the steering torque. Addition for calculating the addition angle using the instruction steering torque setting means (21) to be set, the detected steering torque detected by the steering torque detection means, and the instruction steering torque set by the instruction steering torque setting means An angle calculating means (22, 23), an induced voltage square value calculating means (28, 37) for estimating the induced voltage of the motor and calculating a square value (Σ) of the estimated induced voltage; The holding steering state determining means determines whether Luke (27), the absolute value of the predetermined torque threshold value of the steering torque (E _th1 ) And the square of the induced voltage is a predetermined value (F _th And a correction means (44) for reducing and correcting the addition angle when the steering state determination means determines that the steering state is maintained when the following state continues for a predetermined time or more. The motor control device.
In this configuration, the displacement of the steering mechanism is suppressed by the motor torque at the time of steering to hold the operation member such as the steering wheel, so that the driver's steering burden can be reduced.

The motor control device according to any one of claims 1 to 8 includes a torque detection means (1) for detecting a torque (T) other than the motor torque, which is applied to the drive target (2) driven by the motor. Instruction torque setting means (21) for setting instruction torque (T ^* : instruction value of torque other than motor torque) to be applied to the drive target may be further provided .
The addition angle calculation means, for example, is the detected torque detected by the torque detecting means (detected steering torque by the motor controller according to claim 9 or 10, wherein is detected by the steering torque detection means. Hereinafter the same.) The instruction The motor operates to calculate an addition angle so as to coincide with the torque (the command steering torque set by the command steering torque setting means in the motor control device according to claim 9 or 10; the same applies hereinafter) . As a result, the motor torque is controlled such that a torque (torque other than the motor torque) corresponding to the command torque is applied to the drive target. The motor torque corresponds to a load angle that is a deviation amount between the coordinate axis of the rotating coordinate system (dq coordinate system) according to the magnetic pole direction of the rotor and the virtual axis. The load angle is represented by the difference between the control angle and the rotor angle. Control of the motor torque is achieved by adjusting the load angle, and this adjustment of the load angle is achieved by controlling the addition angle.

On the other hand, the command torque and the detected torque are compared, and the addition angle is increased or decreased according to the comparison result. Thereby, for example, when an addition angle that does not match the magnitude relationship between the command torque and the detected torque is calculated, such an addition angle can be corrected to an appropriate value.
The motor control device estimates an induced voltage of the motor, and based on the estimated induced voltage, angular displacement calculating means (30) for calculating the angular displacement of the rotor per rotor cycle (equivalent value of the rotor angular velocity). Further, it may be included. In this case, the correction means includes addition angle correction means (41) for correcting the addition angle so as to be a value within a predetermined range determined based on the angular displacement calculated by the angular displacement calculation means. May be.

  The control angle changes by the addition angle between calculation cycles. That is, the change in the control angle per calculation cycle is equal to the addition angle. When the addition angle is larger than the angular displacement of the rotor per calculation cycle, the load angle increases. Therefore, when there is a positive correlation between the load angle and the motor torque, the motor torque increases as the load angle increases. Further, when there is a negative correlation between the load angle and the motor torque, the motor torque decreases as the load angle increases. Thus, there is a correlation between the load angle and the motor torque.

  When a certain torque is to be applied to the drive target as a whole (for example, when the insufficient torque is compensated for by the motor torque), the torque other than the motor torque applied to the drive target decreases as the motor torque increases. Therefore, the detected torque is reduced. On the other hand, if the motor torque decreases, the torque other than the motor torque applied to the drive target increases, so the detected torque increases. Therefore, if the magnitude relationship between the command torque and the detected torque and the magnitude relationship between the rotor angular displacement per calculation cycle and the addition angle are appropriate, the detected torque can be brought close to the command torque. Therefore, the addition angle correction means corrects the addition angle so that the detected torque becomes a value within a predetermined range determined based on the angular displacement of the rotor according to the comparison result with the command torque.

  More specifically, when there is a positive correlation between the load angle and the motor torque, the addition angle correction means calculates the addition angle by the angular displacement calculation means when the detected torque is larger than the command torque. When the detected torque is smaller than the indicated torque, the added angle is preferably corrected to a value equal to or smaller than the angular displacement calculated by the angular displacement calculating means.

  When there is a positive correlation between the load angle and the motor torque, if the detected torque is greater than the command torque, the detected torque is converted to the command torque if the addition angle is greater than the rotor angular displacement per calculation cycle. You can get closer. Therefore, the addition angle correction means corrects the addition angle to a value greater than or equal to the rotor angular displacement per calculation cycle when the detected torque is larger than the command torque and the addition angle is smaller than the rotor angular displacement per calculation cycle. . When the detected torque is smaller than the command torque, the detected torque can be brought close to the command torque if the addition angle is smaller than the rotor angular displacement per calculation cycle. Therefore, the addition angle correction means corrects the addition angle to a value less than or equal to the rotor angular displacement per calculation cycle when the detected torque is smaller than the command torque and the addition angle is larger than the rotor angular displacement per calculation cycle. .

In this way, since the addition angle can be corrected to an appropriate value in accordance with the magnitude relationship between the detected torque and the command torque, it is possible to perform appropriate control so that the detected torque approaches the command torque. .
Also, when there is a positive correlation between the load angle and the motor torque, when the detected torque is larger than the command torque and the added angle is excessively larger than the rotor angular displacement per calculation cycle, the added angle is set to an appropriate value. It takes time to converge. Further, when the detected torque is smaller than the command torque, if the added angle is excessively smaller than the rotor angular displacement per calculation cycle, it takes time to converge the added angle to an appropriate value. Therefore, when the detected torque is greater than the command torque, the addition angle correction means reduces the addition angle to a value that is equal to or less than a value that is larger than the angular displacement calculated by the angular displacement calculation means by a predetermined change limit value. When the detected torque is smaller than the command torque, it is preferable that the added angle is corrected to a value equal to or greater than a value smaller than the angular displacement calculated by the angular displacement calculating means by a predetermined change limit value. As a result, the addition angle easily converges to an appropriate value, so that the control can be stabilized and the return to the normal state can be effectively promoted even when a control abnormality occurs. In particular, if both the lower limit and the upper limit of the addition angle are determined according to the angular displacement per calculation cycle, more appropriate control can be realized.

  On the other hand, when there is a negative correlation between the load angle and the motor torque, the addition angle correction means calculates the angular displacement calculated by the angular displacement calculation means when the detected torque is smaller than the command torque. When the detected torque is larger than the command torque, the added angle is preferably corrected to a value equal to or smaller than the angular displacement calculated by the angular displacement calculating means.

  When there is a negative correlation between the load angle and the motor torque, when the detected torque is smaller than the command torque, the detected torque is brought closer to the command torque if the addition angle is larger than the rotor angular displacement per calculation cycle. be able to. Therefore, the addition angle correction means corrects the addition angle to a value greater than or equal to the rotor angular displacement per calculation cycle when the detected torque is smaller than the command torque and the addition angle is smaller than the rotor angular displacement per calculation cycle. . Further, when the detected torque is larger than the command torque, the detected torque can be brought close to the command torque if the addition angle is smaller than the rotor angular displacement per calculation cycle. Therefore, the addition angle correction means corrects the addition angle to a value equal to or less than the rotor angular displacement per calculation period when the detected torque is larger than the command torque and the addition angle is larger than the rotor angular displacement per calculation period. .

In this way, since the addition angle can be corrected to an appropriate value in accordance with the magnitude relationship between the detected torque and the command torque, it is possible to perform appropriate control so that the detected torque approaches the command torque. .
Also, when there is a negative correlation between the load angle and the motor torque, when the detected torque is smaller than the command torque and the added angle is excessively larger than the rotor angular displacement per calculation cycle, the added angle is set to an appropriate value. It takes time to converge. Further, when the detected torque is larger than the command torque, if the addition angle is excessively smaller than the rotor angular displacement per calculation cycle, it takes time to converge the addition angle to an appropriate value. Therefore, when the detected torque is smaller than the command torque, the addition angle correction means reduces the addition angle to a value equal to or smaller than a value larger than the angular displacement calculated by the angular displacement calculation means by a predetermined change limit value. When the detected torque is larger than the command torque, it is preferable that the added angle is corrected to a value equal to or larger than a value smaller than the angular displacement calculated by the angular displacement calculating means by a predetermined change limit value. As a result, the addition angle easily converges to an appropriate value, so that the control can be stabilized and the return to the normal state can be effectively promoted even when a control abnormality occurs. In particular, more appropriate control can be realized by determining both the lower limit and the upper limit of the addition angle according to the angular displacement per calculation cycle.

The addition angle calculation means may include feedback control means (22, 23) for calculating the addition angle so that the detected torque approaches the command torque.
Claim 1 1 the described invention, a motor (3) for applying a driving force to the vehicle steering mechanism (2), for controlling the motor, the motor according to any one of claims 1-10 It is a steering device for vehicles including a control device (5). According to this configuration, the addition angle for motor control can be appropriately corrected according to the square value of the induced voltage, so that the steering performance of the vehicle steering apparatus can be improved.

  In this case, the torque detection means may detect a steering torque (an example of an external input torque other than the motor torque) applied to the operation member (10) operated for steering the vehicle. Good. The command torque setting means may set command steering torque as a target value of steering torque. The addition angle calculation means may calculate the addition angle in accordance with a deviation between the instruction steering torque set by the instruction torque setting means and the steering torque detected by the torque detection means. .

  According to this configuration, the command steering torque is set, and the addition angle is calculated according to the deviation between the command steering torque and the steering torque (detected value). Thus, the addition angle is determined so that the steering torque becomes the command steering torque, and the control angle corresponding to the addition angle is determined. Therefore, by appropriately determining the instruction steering torque, it is possible to generate an appropriate driving force from the motor and apply it to the steering mechanism. That is, the deviation (load angle) between the coordinate axis of the rotating coordinate system (dq coordinate system) and the virtual axis according to the magnetic pole direction of the rotor is led to a value corresponding to the command steering torque. As a result, an appropriate torque is generated from the motor, and a driving force according to the driver's steering intention can be applied to the steering mechanism.

  The motor control device further includes a steering angle detection means (4) for detecting a steering angle of the operation member, and the instruction torque setting means is an instruction steering torque according to a steering angle detected by the steering angle detection means. Is preferably set. According to this configuration, since the instruction steering torque is set according to the steering angle of the operation member, an appropriate torque according to the steering angle can be generated from the motor, and the steering torque applied to the operation member by the driver can be increased. The value can be derived according to the steering angle. Thereby, a favorable steering feeling can be obtained.

  The command torque setting means may set the command steering torque according to the vehicle speed detected by the vehicle speed detection means (6) for detecting the vehicle speed of the vehicle. According to this configuration, since the command steering torque is set according to the vehicle speed, so-called vehicle speed sensitive control can be performed. As a result, a good steering feeling can be realized. For example, an excellent steering feeling can be obtained by setting the command steering torque to be smaller as the vehicle speed is higher, that is, at higher speeds.

It is a block diagram for demonstrating the electric constitution of the electric power steering apparatus to which the motor control apparatus which concerns on 1st Embodiment of this invention is applied. It is an illustration figure for demonstrating the structure of a motor. It is a control block diagram of the electric power steering device. It is a figure which shows the example of a characteristic of the instruction | indication steering torque with respect to a steering angle. It is a figure for demonstrating the effect | action of a steering torque limiter. It is a figure which shows the example of a setting of (gamma) axis instruction | command electric current value. It is a flowchart for demonstrating the effect | action of an addition angle limiter. It is a flowchart for demonstrating the function of an addition angle guard. It is a flowchart for demonstrating the function of an addition angle guard. It is a flowchart for demonstrating the effect | action of a correction control part. It is a flowchart for demonstrating the other example of an operation | movement of a correction control part. It is a block diagram for demonstrating the structure of an induced voltage estimation part. 11A is a diagram illustrating a characteristic example of the addition angle gain, and FIG. 11B is a diagram illustrating another characteristic example of the addition angle gain. It is a flowchart for demonstrating the function of a torque setting part at the time of a failure. It is a flowchart for demonstrating addition angle correction | amendment at the time of control failure. It is a flowchart for demonstrating the specific example of a steering hold determination process. It is a block diagram which shows the structure of the electric power steering apparatus provided with the motor control apparatus which concerns on 2nd Embodiment of this invention. FIG. 16A is a characteristic diagram for explaining a setting example of a damping torque instruction value, and FIG. 16B is a diagram showing a characteristic example of the addition angle gain. It is a flowchart for demonstrating the function of a damping control part. It is a figure which shows the example of the time change of the gradual increase / decrease gain, the corrected damping torque instruction value, and the corrected addition angle gain. It is a block diagram for demonstrating the structure of the vehicle steering device with which the motor control apparatus which concerns on 3rd Embodiment of this invention was applied. It is a flowchart for demonstrating operation | movement of an addition angle gain production | generation part, an integral term setting part, etc. It is a figure which shows an example of the time change of an addition angle | corner. It is a characteristic view which shows the example of a setting of the interval time according to the induced voltage square sum.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[First Embodiment]
FIG. 1 is a block diagram for explaining an electrical configuration of an electric power steering device (an example of a vehicle steering device) to which a motor control device according to a first embodiment of the present invention is applied. This electric power steering apparatus includes a torque sensor 1 for detecting a steering torque T applied to a steering wheel 10 as an operation member for steering the vehicle, and a steering assist force via a speed reduction mechanism 7 to the steering mechanism 2 of the vehicle. The motor 3 (brushless motor) that gives the power, the steering angle sensor 4 that detects the steering angle that is the rotation angle of the steering wheel 10, the motor control device 5 that drives and controls the motor 3, and the electric power steering device are mounted. And a vehicle speed sensor 6 for detecting the speed of the vehicle.

The motor control device 5 drives the motor 3 according to the steering torque detected by the torque sensor 1, the steering angle detected by the steering angle sensor 4, and the vehicle speed detected by the vehicle speed sensor 6, thereby responding to the steering situation and the vehicle speed. Realize appropriate steering assistance.
In this embodiment, the motor 3 is a three-phase brushless motor. As schematically shown in FIG. 2, the rotor 50 as a field and a U-phase, V arranged in a stator 55 facing the rotor 50, V Phase and W phase stator windings 51, 52, 53. The motor 3 may be of an inner rotor type in which a stator is disposed facing the outside of the rotor, or may be of an outer rotor type in which a stator is disposed facing the inside of a cylindrical rotor.

Three-phase fixed coordinates (UVW coordinate system) are defined in which the U, V, and W axes are taken in the direction of the stator windings 51, 52, and 53 of each phase. Also, a two-phase rotational coordinate system (dq coordinate system) in which the d axis (magnetic pole axis) is taken in the magnetic pole direction of the rotor 50 and the q axis (torque axis) is taken in the direction perpendicular to the d axis in the rotation plane of the rotor 50. The actual rotating coordinate system) is defined. The dq coordinate system is a rotating coordinate system that rotates with the rotor 50. In the dq coordinate system, since only the q-axis current contributes to the torque generation of the rotor 50, the d-axis current may be set to zero and the q-axis current may be controlled according to the desired torque. A rotation angle (rotor angle) θ _M of the rotor 50 is a rotation angle of the d-axis with respect to the U-axis. dq coordinate system is an actual rotating coordinate system that rotates in accordance with the rotor angle theta _M. With the use of the rotor angle theta _M, coordinate conversion may be made between the UVW coordinate system and the dq coordinate system.

On the other hand, in this embodiment, a control angle θ _C representing a control rotation angle is introduced. The control angle θ _C is a virtual rotation angle with respect to the U axis. A virtual axis corresponding to the control angle θ _C is a γ-axis, and an axis advanced by 90 ° with respect to the γ-axis is a δ-axis, and a virtual two-phase rotational coordinate system (γδ coordinate system, virtual rotational coordinate system) is defined. Define. When the control angle θ _C is equal to the rotor angle θ _M , the γδ coordinate system, which is a virtual rotation coordinate system, matches the dq coordinate system, which is an actual rotation coordinate system. That is, the γ-axis as the virtual axis matches the d-axis as the real axis, and the δ-axis as the virtual axis matches the q-axis as the real axis. γδ coordinate system is an imaginary rotating coordinate system that rotates in accordance with the control angle theta _C. Coordinate conversion between the UVW coordinate system and the γδ coordinate system can be performed using the control angle θ _C.

A difference between the control angle θ _C and the rotor angle θ _M is defined as a load angle θ _L (= θ _C −θ _M ).
When the γ-axis current I _γ is supplied to the motor 3 according to the control angle θ _C, the q-axis component of the γ-axis current I _γ (orthographic projection onto the q-axis) contributes to the q-axis current I _q that contributes to the torque generation of the rotor 50. Become. That is, the relationship of the following formula (1) is established between the γ-axis current I _γ and the q-axis current I _q .
I _q = I _γ · sin θ _L (1)
Refer to FIG. 1 again. The motor control device 5 detects a current flowing in a microcomputer 11, a drive circuit (inverter circuit) 12 that is controlled by the microcomputer 11 and supplies electric power to the motor 3, and a stator winding of each phase of the motor 3. And a current detection unit 13.

The current detection unit 13 uses phase currents I _U , I _V , I _W (hereinafter, collectively referred to as “three-phase detection current I _UVW ”) flowing through the stator windings 51, 52, 53 of each phase of the motor 3. To detect. These are current values in the coordinate axis directions in the UVW coordinate system.
The microcomputer 11 includes a CPU and a memory (such as a ROM and a RAM), and functions as a plurality of function processing units by executing a predetermined program. The plurality of function processing units include a steering torque limiter 20, an instruction steering torque setting unit 21, a torque deviation calculation unit 22, a PI (proportional integration) control unit 23, an addition angle limiter 24, and a control failure monitoring unit. 25, a control angle calculation unit 26, a steering determination unit 27, an induced voltage estimation unit 28, a rotation angle estimation unit 29, a rotor angular displacement calculation unit 30, a command current value generation unit 31, and a current deviation calculation Unit 32, PI control unit 33, γδ / αβ conversion unit 34A, αβ / UVW conversion unit 34B, PWM (Pulse Width Modulation) control unit 35, UVW / αβ conversion unit 36A, and αβ / γδ conversion unit 36B, induced voltage sum of squares calculation unit 37, correction control unit 38, gain generation unit 39, torque deviation monitoring unit 40, addition angle guard 41, failure detection unit 42, gain multiplication unit 43, and addition And a corner correction unit 44. .

The command steering torque setting unit 21 sets the command steering torque T ^* based on the steering angle detected by the steering angle sensor 4 and the vehicle speed detected by the vehicle speed sensor 6. For example, as shown in FIG. 4, when the steering angle is a positive value (a state of steering to the right), the command steering torque T ^* is set to a positive value (torque to the right), and the steering angle is negative. The instruction steering torque T ^* is set to a negative value (torque in the left direction) when the value is in the state (steered in the left direction). Then, the command steering torque T ^* is set so that the absolute value of the steering angle increases as the absolute value of the steering angle increases (in a non-linear manner in the example of FIG. 4). However, the command steering torque T ^* is set within a predetermined upper limit value (positive value, for example, +6 Nm) and lower limit value (negative value, for example, −6 Nm). Further, the command steering torque T ^* is set such that the absolute value thereof decreases as the vehicle speed increases. That is, vehicle speed sensitive control is performed.

The command steering torque setting unit 21 has a fault torque setting unit 21A that sets the command steering torque T ^* when the steering angle sensor 4 is faulty. The failure time torque setting unit 21A gives a plus sign “+” or a minus sign “−” to a predetermined command torque absolute value T ₀ (> 0, for example, T ₀ = 2Nm), thereby giving a command steering torque. Set T ^* (= + T ₀ or -T ₀ ). Which sign is given is determined based on the rotor angular displacement Δθ calculated by the rotor angular displacement calculating unit 30 or the steering torque T detected by the torque sensor 1. The command steering torque T ^* determined in this way is used when the steering angle sensor 4 fails.

The presence or absence of a failure in the steering angle sensor 4 is detected by the failure detection unit 42. For example, the failure detection unit 42 is configured to monitor a signal appearing on the signal line of the steering angle sensor 4 and detect a disconnection failure, a short-circuit failure, or other failure of the steering angle sensor 4. When the failure detection unit 42 detects a failure of the steering angle sensor 4, the failure detection unit 42 notifies the instruction steering torque setting unit 21 of the occurrence of the failure. When the occurrence of the failure is notified, the command steering torque setting unit 21 outputs the command steering torque T ^* set by the fault torque setting unit 21A.

The steering torque limiter 20 outputs the output of the torque sensor 1 to a predetermined upper limit saturation value + T _max (+ T _max > 0. For example, + T _max = 7 Nm) and a lower limit saturation value −T _max (−T _max <0. For example, −T _max = -7 Nm). Specifically, as shown in FIG. 5, the steering torque limiter 20 outputs the detected steering torque T of the torque sensor 1 as it is between the upper limit saturation value + T _max and the lower limit saturation value −T _max . Further, the steering torque limiter 20 outputs the upper limit saturation value + T _max when the detected steering torque T of the torque sensor 1 is equal to or higher than the upper limit saturation value + T _max . Then, the steering torque limiter 20, the detected steering torque T from the torque sensor 1 is equal to or lower than the lower saturation value -T _max, and outputs the lower saturation value -T _max. The saturation values + T _max and −T _max define the boundary of the region (reliable region) where the output signal of the torque sensor 1 is stable. That is, the output signal of the torque sensor 1 is unstable in a section exceeding the upper limit saturation value T _max and a section lower than the lower limit saturation value −T _max and does not correspond to the actual steering torque. In other words, the saturation values + T _max and −T _max are determined according to the output characteristics of the torque sensor 1.

The torque deviation calculation unit 22 is detected by the command steering torque T ^* set by the command steering torque setting unit 21 and the steering torque T detected by the torque sensor 1 and subjected to the limiting process by the steering torque limiter 20 (hereinafter, for distinction). A deviation (torque deviation) ΔT (= T ^* −T) from “detected steering torque T” is obtained. The PI control unit 23 performs a PI calculation on the torque deviation ΔT. That is, the torque deviation calculation unit 22 and the PI control unit 23 constitute torque feedback control means for guiding the detected steering torque T to the command steering torque T ^* . The PI control unit 23 calculates the addition angle α for the control angle θ _C by performing PI calculation for the torque deviation ΔT. Therefore, the torque feedback control means constitutes an addition angle calculation means for calculating the addition angle α.

More specifically, the PI control unit 23 includes a proportional element 23a, an integral element 23b, and an adder 23c. However, _{K P} is a proportional gain, _{K I} is an integral gain, 1 / s is an integration operator. The proportional element (proportional calculation value) of the proportional integral calculation is obtained by the proportional element 23a, and the integral term (integral calculation value) of the proportional integral calculation is obtained by the integral element 23b. These calculation results (proportional term and integral term) are added by the adder 23c, whereby the addition angle α is obtained.

The addition angle limiter 24 is addition angle limiting means for limiting the addition angle α obtained by the PI control unit 23. More specifically, the addition angle limiter 24 limits the addition angle α to a value between a predetermined upper limit value UL (positive value) and a lower limit value LL (negative value). The upper limit value UL and the lower limit value LL are determined based on the limit value ω _max (ω _max > 0). In this embodiment, the limit value ω _max is set to two types of the first limit value ω _max1 and the second limit value ω _max2 (ω _max1 > ω _max2 > 0) by the correction control unit 38. It has become. Both of the limit values ω _max1 and ω _max2 are set to an upper limit value or less determined based on the maximum steering angular velocity, for example. The maximum steering angular velocity is a maximum value that can be assumed as the steering angular velocity of the steering wheel 10 and is, for example, about 800 deg / sec.

The change speed of the electrical angle of the rotor 50 at the maximum steering angular speed (the angular speed at the electrical angle. The maximum rotor angular speed) is expressed by the following formula (2): the maximum steering angular speed, the reduction ratio of the speed reduction mechanism 7, the rotor 5
It is given as the product of the number of pole pairs of zero. The number of pole pairs is the number of magnetic pole pairs (pairs of N poles and S poles) that the rotor 50 has.
Maximum rotor angular speed = Maximum steering angular speed x Reduction ratio x Number of pole pairs (2)
The maximum value of the electrical angle change amount of the rotor 50 (the maximum value of the rotor angle change amount) during the calculation (control cycle) of the control angle θ _C is a value obtained by multiplying the maximum rotor angular velocity by the calculation cycle as shown in the following equation (3). It becomes.

Maximum value of rotor angle change = Maximum rotor angular speed x Calculation cycle
= Maximum steering angular velocity x reduction ratio x number of pole pairs x calculation cycle (3)
The rotor angle variation maximum value is the maximum variation of the control angle theta _C that is permitted within one calculation cycle. Therefore, the rotor angle change maximum value may be set as the upper limit value of the limit value ω _max . Using the limit value ω _max (ω _max = ω _max1 or ω _max = ω _max2 ) determined below this upper limit value, the upper limit value UL and the lower limit value LL of the addition angle α are expressed by the following equations (4) and (5), respectively. Can be expressed as

UL = + ω _max (4)
LL = −ω _max (5)
The addition angle α after the limit processing by the addition angle limiter 24 is multiplied by the addition angle gain G _α in the gain multiplication unit 43, and further, the addition angle correction unit 44 corrects it when necessary. In the adder 26A of the control angle calculation unit 26, the addition angle α output from the addition angle correction unit 44 becomes the previous value θ _C (n−1) (n is the number of the current calculation cycle) of the control angle θ _C. It is added (Z- ¹ represents the previous value of the signal). However, the initial value of the control angle θ _C is a predetermined value (for example, zero).

The control angle calculation unit 26 includes an adder 26A that adds the addition angle α given from the addition angle correction unit 44 to the previous value θ _C (n−1) of the control angle θ _C. That is, the control angle calculation unit 26 calculates the control angle θ _C every predetermined calculation cycle. Then, the control angle θ _C in the previous calculation cycle is set as the previous value θ _C (n−1), and the current value θ _C (n), which is the control angle θ _C in the current calculation cycle, is obtained.
The control failure monitoring unit 25 determines that a control failure has occurred when a state occurs in which the control angle θ _C does not converge. For example, the control failure monitoring unit 25 determines that a control failure has occurred when a state where the absolute value of the steering torque T output from the torque sensor 1 is equal to or greater than a predetermined threshold (for example, 7 Nm) continues for a predetermined time. There may be. This situation, for example, have insufficient current supplied to the motor 3, in any of the control angle theta _C, occurs when it is not possible to achieve the command steering torque T ^*. Further, the control failure monitoring unit 25 monitors the addition angle α generated from the addition angle limiter 24, and an addition angle threshold (for example, a limit value ω) whose absolute value of the addition angle α is smaller than the limit value ω _{max. It} may be monitored whether or not the _maximum value of 80% is reached. In this case, for example, the control failure monitoring unit 25 determines that a control failure has occurred when the addition angle absolute value | α | is equal to or greater than the addition angle threshold for a predetermined time. This situation, for example, have insufficient current supplied to the motor 3, in any of the control angle theta _C, occurs when it is not possible to achieve the command steering torque T ^*. When the control failure monitoring unit 25 determines that a control failure has occurred in this manner, the control failure monitoring unit 25 notifies the addition angle correction unit 44 of this.

The induced voltage estimation unit 28 estimates an induced voltage generated by the rotation of the motor 3. Then, the rotational angle estimation unit 29, based on the induced voltage estimated by the induced voltage estimation unit 28, and thereby calculates the estimated value of the rotation angle of the rotor 50 (the estimated rotation angle) theta _E. Specific examples of the induced voltage estimation unit 28 and the rotation angle estimation unit 29 will be described later.
The rotor angular displacement calculation unit 30, by determining the amount of change in the estimated rotational angle theta _E between calculation cycle to obtain the angular displacement Δθ of the rotor 50 in the calculation cycle (a value corresponding to the rotor angular speed).

The command current value generation unit 31 generates a current value to be passed through the coordinate axis (virtual axis) of the γδ coordinate system, which is a virtual rotation coordinate system corresponding to the control angle θ _C that is a control rotation angle, as the command current value. Is. Specifically, a γ-axis command current value I _γ ^* and a δ-axis command current value I _δ ^* (hereinafter referred to as “two-phase command current value I _γδ ^* ”) are generated. The command current value generation unit 31 sets the γ-axis command current value I _γ ^* to a significant value, and sets the δ-axis command current value I _δ ^* to zero. More specifically, the command current value generation unit 31 sets the γ-axis command current value I _γ ^* based on the detected steering torque T detected by the torque sensor 1.

A setting example of the γ-axis command current value I _γ ^* with respect to the detected steering torque T is shown in FIG. A dead zone NR is set in a region where the detected steering torque T is near zero. The γ-axis command current value I _γ ^* rises steeply in a region outside the dead zone NR, and is set to be a substantially constant value above a predetermined torque. Thereby, when the driver is not operating the steering wheel 10, the energization to the motor 3 is stopped, and unnecessary power consumption is suppressed.

The current deviation calculation unit 32 includes a deviation I _γ ^* −I _γ of the γ-axis detection current I _γ with respect to the γ-axis command current value I _γ ^* generated by the command current value generation unit 31 and a δ-axis command current value I _δ ^*. A deviation I _δ ^* −I _δ of the δ-axis detection current I _δ with respect to (= 0) is calculated. The γ-axis detection current I _γ and the δ-axis detection current I _δ are supplied from the αβ / γδ conversion unit 36B to the deviation calculation unit 32.

The UVW / αβ conversion unit 36A outputs the three-phase detection current I _UVW (the U-phase detection current I _U , the V-phase detection current I _V and the W-phase detection current I _W ) of the UVW coordinate system detected by the current detection unit 13. The two-phase detection currents I _α and I _β (hereinafter collectively referred to as “two-phase detection current I _αβ ”) in the αβ coordinate system which is a phase-fixed coordinate system are converted. As shown in FIG. 2, the αβ coordinate system defines the α axis and the β axis (in the example of FIG. 2, coaxial with the U axis) orthogonal to the rotation axis of the rotor 50 with the rotation center of the rotor 50 as the origin. It is a fixed coordinate system. The αβ / γδ converter 36B converts the two-phase detection current I _αβ into two-phase detection currents I _γ and I _δ (hereinafter collectively referred to as “two-phase detection current I _γδ ”) in the γδ coordinate system. These are supplied to the current deviation calculation unit 32. For the coordinate conversion in the αβ / γδ conversion unit 36B, the control angle θ _C calculated by the control angle calculation unit 26 is used.

The PI control unit 33 performs a PI calculation on the current deviation calculated by the current deviation calculation unit 32 to thereby provide a two-phase command voltage V _γδ ^* (γ-axis command voltage V _γ ^* and δ-axis command to be applied to the motor 3. Voltage V _δ ^* ). This two-phase command voltage V _γδ ^* is _supplied to the γδ / αβ conversion unit 34A.
The γδ / αβ converter 34A converts the two-phase command voltage V _γδ ^* into a two-phase command voltage V _αβ ^* in the αβ coordinate system. For this coordinate conversion, the control angle θ _C calculated by the control angle calculation unit 26 is used. The two-phase command voltage V _αβ ^* is composed of an α-axis command voltage V _α ^* and a β-axis command voltage V _β ^* . The αβ / UVW conversion unit 34B generates a three-phase instruction voltage V _UVW ^* by performing a coordinate conversion operation on the two-phase instruction voltage V _αβ ^* . The three-phase command voltage V _UVW ^* includes a U-phase command voltage V _U ^* , a V-phase command voltage V _V ^*, and a W-phase command voltage V _W ^* . The three-phase instruction voltage V _UVW ^* is given to the PWM control unit 35.

The PWM control unit 35 includes a U-phase PWM control signal, a V-phase PWM control signal, and a W-phase PWM having a duty corresponding to the U-phase instruction voltage V _U ^* , the V-phase instruction voltage V _V ^*, and the W-phase instruction voltage V _W ^* , respectively. A control signal is generated and supplied to the drive circuit 12.
The drive circuit 12 includes a three-phase inverter circuit corresponding to the U phase, the V phase, and the W phase. The power elements constituting the inverter circuit are controlled by a PWM control signal supplied from the PWM control unit 35, so that a voltage corresponding to the three-phase instruction voltage V _UVW ^* becomes a stator winding 51, 52 for each phase of the motor 3. , 53 is applied.

The current deviation calculation unit 32 and the PI control unit 33 constitute a current feedback control unit. By the function of this current feedback control means, the motor current flowing through the motor 3 is controlled so as to approach the two-phase command current value I _γδ ^* set by the command current value generation unit 31.
The induced voltage sum-of-squares calculation unit 37 obtains the sum of squares of the estimated induced voltage obtained by the induced voltage estimation unit 28. The induced voltage estimation unit 28 calculates, for example, an α-axis estimated induced voltage E ^ _α and a β-axis estimated induced voltage E ^ _β . In this case, the induced voltage square sum calculation unit 37 calculates the induced voltage square sum Σ = E ^ _α ² + E ^ _β ² (≧ 0).

The steering holding determination unit 27 determines whether or not the vehicle is in the steering holding state based on the induced voltage square sum Σ calculated by the induced voltage square sum calculation unit 37. The steered state is a steered state in which the driver holds the steering wheel 10 in a state of hardly rotating. The steering holding determination unit 27 gives the addition angle correction unit 44 the determination result as to whether or not the steering holding state is established.
The addition angle correction unit 44 has a function of correcting the addition angle α when the control failure monitoring unit 25 is notified of the occurrence of a control failure. Specifically, the addition angle correction unit 44 adds a positive sign “+” or a negative sign “−” to a predetermined basic value B (0 <B <ω _max ), or adds zero to the addition angle α. Set as. The addition angle correction unit 44 sets the addition angle α to zero when the steering determination unit 27 determines that the steering state is maintained. When the steering angle is not maintained, the addition angle correction unit 44 sets the addition angle target value α ^* by adding a sign corresponding to the steering torque T to the basic value B, and toward the addition angle target value α ^* . Thus, the addition angle α is gradually changed. When the control failure has not occurred, the addition angle α generated by the gain multiplication unit 43 is directly supplied to the control angle calculation unit 26 without being corrected by the addition angle correction unit 44.

The correction control unit 38 determines whether or not to perform the processing by the addition angle guard 41 based on the induced voltage square sum Σ, and further switches the limit value ω _max in the addition angle limiter 24.
The torque deviation monitoring unit 40 determines the magnitude relationship between the command steering torque T ^* and the detected steering torque T by monitoring the sign of the torque deviation ΔT calculated by the torque deviation calculation unit 22. The determination result is given to the addition angle guard 41.

The addition angle guard 41 is for performing an addition angle guard process on the addition angle α generated by the PI control unit 23. In the addition angle guard process, when the addition angle α generated by the PI control unit 23 conflicts with the magnitude relationship between the command steering torque T ^* and the detected steering torque T, the addition angle α is set so as to eliminate this contradiction. Is a process of correcting the above. More specifically, the addition angle guard 41 corrects the addition angle α based on the rotor angular displacement Δθ obtained by the rotor angular displacement calculation unit 30 when necessary. Since the rotor angular displacement Δθ corresponds to the rotor angular velocity, the process by the addition angle guard 41 is nothing but the process of correcting the addition angle α according to the rotor angular velocity.

The gain generation unit 39 generates an addition angle gain G _α corresponding to the induced voltage square sum Σ. The addition angle gain _Gα is multiplied by the addition angle α output from the addition angle limiter 24 in the gain multiplier 43. The addition angle α after multiplication or the addition angle α generated by the addition angle correction unit 44 is given to the control angle calculation unit 26.
FIG. 3 is a control block diagram of the electric power steering apparatus. However, in order to simplify the description, the functions of the addition angle guard 41, the addition angle limiter 24, the gain multiplication unit 43, and the addition angle correction unit 44 are omitted.

Command steering torque T ^* and the deviation (torque deviation) of the detected steering torque T PI control for the [Delta] T (K _P is a proportionality coefficient, K _I is an integration coefficient, 1 / s is an integration operator.) By the addition angle α Is generated. It is obtained by adding the addition the addition angle alpha control angle theta previous value of _{C θ C (n-1)} , the current value of the control angle _{θ C θ C (n) =} θ C (n-1) + α is Desired. At this time, the deviation between the control angle θ _C and the actual rotor angle θ _M of the rotor 50 is the load angle θ _L = θ _C −θ _M.

Accordingly, when the γ-axis current I _γ is supplied according to the γ-axis command current value I _γ ^* to the γ-axis (virtual axis) of the γδ coordinate system (virtual rotation coordinate system) according to the control angle θ _C , the q-axis current I _q = I _γ sinθ _L This q-axis current I _q contributes to the torque generated by the rotor 50. That is, the value obtained by multiplying the torque constant _{K T} of the motor 3 to the q-axis current _{I q (= I γ sinθ L} ) is, as the assist torque _{T A (= K T · I} γ sinθ L), via a speed reduction mechanism 7 And transmitted to the steering mechanism 2. _A value obtained by subtracting the assist torque TA from the load torque _TL from the steering mechanism 2 is the steering torque T that the driver should apply to the steering wheel 10. As the steering torque T is fed back, the system operates so as to guide the steering torque T to the command steering torque T ^* . That is, in order to make the detected steering torque T coincide with the command steering torque T ^* , the addition angle α is obtained, and the control angle θ _C is controlled accordingly.

In this way, while a current is passed through the γ axis, which is a virtual axis for control, the control angle θ _C is updated with the addition angle α obtained according to the deviation ΔT between the command steering torque T ^* and the detected steering torque T. by going, the load angle theta _L is changed, the torque corresponding to the load angle theta _L is adapted to generate from the motor 3. As a result, a torque corresponding to the command steering torque T ^* set based on the steering angle and the vehicle speed can be generated from the motor 3, so that an appropriate steering assist force corresponding to the steering angle and the vehicle speed can be applied to the steering mechanism 2. Can be given. That is, the steering assist control is executed such that the steering torque increases as the absolute value of the steering angle increases, and the steering torque decreases as the vehicle speed increases.

In this way, an electric power steering apparatus that can appropriately control the motor 3 without using a rotation angle sensor and perform appropriate steering assistance can be realized. Thereby, a structure can be simplified and cost reduction can be aimed at.
In this embodiment, as the load angle theta _L is adjusted in a region having a load angle theta _L and the motor torque (assist torque) Tadashi Toga correlation, the addition angle α is controlled. Specifically, since the q-axis current I _q = I _γ sinθ _L , the addition angle α is controlled so that −90 ° ≦ θ _L ≦ 90 °. Of course, as the load angle theta _L in a region where the load angle theta _L and the motor torque (assist torque) has a negative correlation is adjusted, it is also possible to control the addition angle alpha. In this case, the addition angle α is controlled so that 90 ° ≦ θ _L ≦ 270 °. When the gain of the PI control unit 23 is positive, control is performed in a positive correlation region, and when the gain of the PI control unit 23 is negative, control is performed in a negative correlation region.

FIG. 7 is a flowchart for explaining the operation of the addition angle limiter 24. The addition angle limiter 24 compares the addition angle α obtained by the PI control unit 23 and corrected by the addition angle guard 41 with the upper limit value UL (step S1), and when the addition angle α exceeds the upper limit value UL (step S1). In S1: YES, the upper limit value UL is substituted for the addition angle α (step S2). Therefore, the upper limit value UL (= + ω _max ) is added to the control angle θ _C.

If the addition angle α obtained by the PI control unit 23 and corrected by the addition angle guard 41 is equal to or smaller than the upper limit value UL (step S1: NO), the addition angle limiter 24 further sets the addition angle α as the lower limit value LL. Compare (step S3). If the addition angle α is less than the lower limit value (step S3: YES), the lower limit value LL is substituted for the addition angle α (step S4). Therefore, the lower limit LL (= −ω _max ) is added to the control angle θ _C.

Corrected addition angle α is less than the lower limit LL or the upper limit UL by the addition angle guard 41 obtained by the PI control unit 23: if (step S3 NO), the addition of the addition angle α is directly to the control angle theta _C Used for.
In this way, the addition angle α can be limited between the upper limit value UL and the lower limit value LL, so that the control can be stabilized. More specifically, even if a control unstable state (a state where the assist force is unstable) occurs when the current is insufficient or the control is started, the transition from this state to the stable control state can be promoted.

FIG. 8A is a flowchart for explaining the addition angle guard process. However, as the load angle theta _L and the motor torque (assist torque) load angle theta _L in the area having a positive correlation transgressions are adjusted, the addition angle α is processing example is shown if you controlled.
The torque deviation monitoring unit 40 monitors the sign of the torque deviation ΔT calculated by the torque deviation calculation unit 22, and provides the addition angle guard 41 with information regarding the magnitude relationship between the command steering torque T ^* and the detected steering torque T. .

When the detected steering torque T is greater than the command steering torque T ^* (step S11: YES), the addition angle guard 41 has the addition angle α obtained by the PI control unit 23 obtained by the rotor angular displacement calculation unit 30. It is determined whether it is smaller than the rotor angular displacement Δθ per calculation cycle (step S12). If this determination is affirmed, the addition angle guard 41 substitutes the rotor angular displacement Δθ for the addition angle α (step S13). That is, the addition angle α is corrected to the rotor angular displacement Δθ. If the addition angle α is greater than or equal to the rotor angular displacement Δθ (step S12: NO), the addition angle guard 41 further sets the addition angle α to a predetermined change limit value A (A> 0 from the rotor angular displacement Δθ. For example, A large value (Δθ + A) by A = 7 deg is compared (step S14). When the addition angle α is larger than the value (Δθ + A) (step S14: YES), the addition angle guard 41 substitutes the value (Δθ + A) for the addition angle α (step S15). If the addition angle α is equal to or smaller than the value (Δθ + A) (step S14: NO), the addition angle α is not corrected.

On the other hand, when the detected steering torque T is smaller than the command steering torque T ^* (step S11: NO, step S16: YES), the addition angle guard 41 has the addition angle α obtained by the PI control unit 23 so that the rotor angular displacement Δθ. It is judged whether it is larger than (step S17). If this determination is affirmative, the addition angle guard 41 substitutes the rotor angular displacement Δθ for the addition angle α (step S13), and corrects the addition angle α to the rotor angular displacement Δθ. If the addition angle α is equal to or smaller than the rotor angular displacement Δθ (step S17: NO), the addition angle guard 41 further reduces the addition angle α by a value (Δθ−A) smaller than the rotor angular displacement Δθ by the change limit value A. ) (Step S18). When the addition angle α is smaller than the value (Δθ−A) (step S18: YES), the addition angle guard 41 substitutes the value (Δθ−A) for the addition angle α (step S19). If the addition angle α is equal to or greater than the value (Δθ−A) (step S18: NO), the addition angle α is not corrected.

Further, when the detected steering torque T is equal to the command steering torque T ^* (determinations in steps S11 and S16 are both negative), the addition angle α is not corrected.
The addition angle α is the amount of change in the control angle θ _C during the calculation cycle, and is equal to the angular displacement (corresponding to the rotor angular velocity) per calculation cycle of the γδ coordinate axis. Therefore, the addition angle α is greater if the load angle theta _L is larger than the rotor angular displacement Δθ in the calculation cycle, the addition angle α is the load angle theta _L is smaller than the rotor angular displacement Δθ is reduced. When there is a positive correlation to the load angle theta _L and the motor torque (assist torque), the motor torque becomes larger the larger the load angle theta _L is smaller motor torque becomes smaller load angle theta _L is Become.

On the other hand, the case where the detected steering torque T is larger than the command steering torque T ^* is a state where the motor torque (assist torque) is insufficient. Therefore, in order to increase the motor torque by increasing the load angle theta _L. That is, if the addition angle α is equal to or greater than the rotor angular displacement Δθ, the detected steering torque T can be brought close to the command steering torque T ^* . Therefore, in this embodiment, when the detected steering torque T is larger than the command steering torque T ^* by the processing of steps S11 to S13 in FIG. 8A, the addition angle guard processing is performed to limit the addition angle α to the rotor angular displacement Δθ or more. Is done. In other words, even if the detected steering torque T is larger than the command steering torque T ^* , if the addition angle α is less than the rotor angular displacement Δθ, it does not match the purpose of the control and a contradiction occurs. For example, such a situation may occur depending on the responsiveness of the PI control unit 23. In such a case, the addition angle α is corrected to a value equal to or larger than the rotor angular displacement Δθ (in this embodiment, a value equal to the rotor angular displacement Δθ). Of course, the addition angle α may be corrected to a value larger than the rotor angular displacement Δθ (for example, a value larger by a predetermined value (a value smaller than the change limit value A)).

Similarly, when the detected steering torque T is smaller than the instruction steering torque T ^* , the motor torque (assist torque) is excessive. Therefore, in order to reduce the motor torque, it is sufficient to reduce the load angle theta _L. That is, if the addition angle α is equal to or less than the rotor angular displacement Δθ, the detected steering torque T can be brought close to the command steering torque T ^* . Therefore, in this embodiment, when the detected steering torque T is smaller than the command steering torque T ^* by the processing in steps S16, S17, and S13 in FIG. 8A, the addition angle that limits the addition angle α to the rotor angular displacement Δθ or less. Guard processing is performed. In other words, even if the detected steering torque T is smaller than the command steering torque T ^* , if the addition angle α exceeds the rotor angular displacement Δθ, it does not match the purpose of the control and a contradiction occurs. For example, such a situation may occur depending on the responsiveness of the PI control unit 23. In such a case, the addition angle α is corrected to a value equal to or smaller than the rotor angular displacement Δθ (a value equal to the rotor angular displacement Δθ in this embodiment). Of course, the addition angle α may be corrected to a value smaller than the rotor angular displacement Δθ (for example, a value smaller by a predetermined value (a value smaller than the change limit value A)).

Furthermore, in this embodiment, when the detected steering torque T is larger than the command steering torque T ^* (step S11: YES), when the addition angle α is larger than the value obtained by adding the change limit value A to the rotor angular displacement Δθ. (Step S12: NO, Step S14: YES), the addition angle α is corrected to Δθ + A (Step S15). This is because if the addition angle α is excessively larger than the rotor angular displacement Δθ per calculation cycle, it takes time to converge the addition angle α to an appropriate value. When the detected torque T is smaller than the command torque T ^* (step S16: YES), when the addition angle α is smaller than the value obtained by subtracting the change limit value A from the rotor angular displacement Δθ (step S17: NO: Step S18: YES), the addition angle α is corrected to Δθ−A (Step S19). This is because if the addition angle α is excessively smaller than the rotor angular displacement Δθ per calculation cycle, it takes time to converge the addition angle to an appropriate value. By performing such correction, the addition angle α easily converges to an appropriate value, so that the control can be stabilized and the return to the normal state can be effectively promoted even when a control abnormality occurs. Can do.

8A, when the detected steering torque T is larger than the command steering torque T ^* , the addition angle α is limited to the range of Δθ + A ≧ α ≧ Δθ, and the detected steering torque T is changed to the command steering torque T. When smaller than ^* , the addition angle α is limited to a range of Δθ ≧ α ≧ Δθ−A. In this way, the addition angle α can take a reasonable value according to the rotor angular displacement Δθ.

As the load angle theta _L and the motor torque and (assist torque) is the load angle theta _L in the area having a negative correlation is adjusted, the example of the addition angle guard process when the addition angle α is controlled in FIG. 8B Show. In FIG. 8B, steps in which the same processing as that shown in FIG. 8A is performed are denoted by the same reference numerals as in FIG. 8A.
In the process shown in FIG. 8B, the process according to the magnitude relationship between the detected steering torque T and the command steering torque T ^* is opposite to the process in FIG. 8A. That is, when the detected steering torque T is smaller than the command steering torque T ^* (step S11A: YES), the addition angle guard 41 determines whether the addition angle α is smaller than the rotor angular displacement Δθ (step S12). . If this determination is affirmed, the addition angle guard 41 substitutes the rotor angular displacement Δθ for the addition angle α (step S13). That is, the addition angle α is corrected to the rotor angular displacement Δθ. If the addition angle α is greater than or equal to the rotor angular displacement Δθ (step S12: NO), the addition angle guard 41 further compares the addition angle α with a value (Δθ + A) that is larger than the rotor angular displacement by the change limit value A. (Step S14). When the addition angle α is larger than the value (Δθ + A) (step S14: YES), the addition angle guard 41 substitutes the value (Δθ + A) for the addition angle α (step S15). If the addition angle α is equal to or smaller than the value (Δθ + A) (step S14: NO), the addition angle α is not corrected.

On the other hand, when the detected steering torque T is larger than the command steering torque T ^* (step S11A: NO, step S16A: YES), the addition angle guard 41 determines whether or not the addition angle α is larger than the rotor angular displacement Δθ. (Step S17). If this determination is affirmative, the addition angle guard 41 substitutes the rotor angular displacement Δθ for the addition angle α (step S13), and corrects the addition angle α to the rotor angular displacement Δθ. If the addition angle α is equal to or smaller than the rotor angular displacement Δθ (step S17: NO), the addition angle guard 41 further reduces the addition angle α by a value (Δθ−A) smaller than the rotor angular displacement Δθ by the change limit value A. ) (Step S18). When the addition angle α is smaller than the value (Δθ−A) (step S18: YES), the addition angle guard 41 substitutes the value (Δθ−A) for the addition angle α (step S19). If the addition angle α is equal to or greater than the value (Δθ−A) (step S18: NO), the addition angle α is not corrected.

Further, when the detected steering torque T is equal to the command steering torque T ^* (the determinations in steps S11A and S16A are both negative), the addition angle α is not corrected.
If there is a negative correlation to the load angle theta _L and the motor torque (assist torque), the motor torque is decreased the greater the load angle theta _L is the load angle theta _L is familiar motor torque increases if smaller.

On the other hand, when the detected steering torque T is smaller than the command steering torque T ^* , the motor torque (assist torque) is excessive. Therefore, in order to reduce the motor torque by increasing the load angle theta _L. That is, if the addition angle α is equal to or greater than the rotor angular displacement Δθ, the detected steering torque T can be brought close to the command steering torque T ^* . Therefore, in this embodiment, when the detected steering torque T is smaller than the command steering torque T ^* by the processing in steps S11A to S13 in FIG. 8B, the addition angle guard processing is performed to limit the addition angle α to the rotor angular displacement Δθ or more. Is done. In other words, although the detected steering torque T is smaller than the command steering torque T ^* , if the addition angle α is less than the rotor angular displacement Δθ, it does not match the purpose of the control and a contradiction occurs. In such a case, the addition angle α is corrected to a value equal to or larger than the rotor angular displacement Δθ (in this embodiment, a value equal to the rotor angular displacement Δθ). Of course, the addition angle α may be corrected to a value larger than the rotor angular displacement Δθ (for example, a value larger by a predetermined value (a value smaller than the change limit value A)).

Similarly, when the detected steering torque T is larger than the command steering torque T ^* , the motor torque (assist torque) is insufficient. Therefore, in order to increase the motor torque, it is sufficient to reduce the load angle theta _L. That is, if the addition angle α is equal to or less than the rotor angular displacement Δθ, the detected steering torque T can be brought close to the command steering torque T ^* . Therefore, in this embodiment, when the detected steering torque T is larger than the command steering torque T ^* by the processing of steps S16A, S17, and S13 in FIG. 8B, the addition angle α is limited to the rotor angular displacement Δθ or less. Guard processing is performed. In other words, even if the detected steering torque T is larger than the command steering torque T ^* , if the addition angle α exceeds the rotor angular displacement Δθ, it does not match the purpose of the control and a contradiction occurs. In such a case, the addition angle α is corrected to a value equal to or smaller than the rotor angular displacement Δθ (a value equal to the rotor angular displacement Δθ in this embodiment). Of course, the addition angle α may be corrected to a value smaller than the rotor angular displacement Δθ (for example, a value smaller by a predetermined value (a value smaller than the change limit value A)).

8B, when the detected steering torque T is smaller than the command steering torque T ^* (step S11A: YES), the addition angle α is larger than the value obtained by adding the change limit value A to the rotor angular displacement Δθ. (Step S12: NO, step S14: YES), the addition angle α is corrected to Δθ + A (step S15). This is because if the addition angle α is excessively larger than the rotor angular displacement Δθ per calculation cycle, it takes time to converge the addition angle α to an appropriate value. When the detected torque T is larger than the command torque T ^* (step S16A: YES), when the addition angle α is smaller than the value obtained by subtracting the change limit value A from the rotor angular displacement Δθ (step S17: NO: Step S18: YES), the addition angle α is corrected to Δθ−A (Step S19). This is because if the addition angle α is excessively smaller than the rotor angular displacement Δθ per calculation cycle, it takes time to converge the addition angle to an appropriate value. By performing such correction, the addition angle α easily converges to an appropriate value, so that the control can be stabilized and the return to the normal state can be effectively promoted even when a control abnormality occurs. Can do.

By performing such processing, when the detected steering torque T is smaller than the commanded steering torque T ^* , the addition angle α is limited to the range of Δθ + A ≧ α ≧ Δθ, and the detected steering torque T becomes the commanded steering torque T ^*. Is larger than that, the addition angle α is limited to a range of Δθ ≧ α ≧ Δθ−A. In this way, the addition angle α can take a reasonable value according to the rotor angular displacement Δθ.

FIG. 9A is a flowchart for explaining the operation of the correction control unit 38 and the like. The correction control unit 38 acquires the induced voltage square sum Σ (= E ^ _α ² + E ^ _β ² ) calculated by the induced voltage square sum calculating unit 37 (step S21), and corrects the induced voltage square sum Σ. It is compared with a threshold value C _th1 (for example, C _th1 = 30) (step S22).
When the induced voltage square sum Σ is equal to or greater than the correction execution threshold C _th1 (step S22: YES), the correction execution flag is set to “ON” (step S23), and the limit value ω _{max is set} to the first limit value ω _max1 (for example, ω _max1 = 35 degrees) (step S24). Using this limit value ω _max (= ω _max1 ), a limit process (see FIG. 7) by the addition angle limiter 24 is executed (step S25). Further, since the correction execution flag is “ON” (step S26: YES), the addition angle guard process (see FIGS. 8A and 8B) by the addition angle guard 41 is executed (step S27).

On the other hand, when the induced voltage square sum Σ is less than the correction execution threshold value C _th1 (step S22: NO), the correction control unit 38 further converts the induced voltage square sum Σ into a corrected non-execution threshold value C _th2 (<C _th1 . , C _th2 = 15) (step S28). When the induced voltage square sum Σ is equal to or less than the correction non-execution threshold C _th2 , the correction execution flag is set to “off” (step S29), and the limit value ω _{max is set} to the second limit value ω _max2 (<ω _max1 . For example, ω _max2. = 17 degrees) (step S30). Using this limit value ω _max (= ω _max2 ), a limit process (see FIG. 7) by the addition angle limiter 24 is executed (step S25). In this case, since the correction execution flag is “OFF” (step S26: NO), the addition angle guard process by the addition angle guard 41 is omitted.

When the induced voltage square sum Σ is smaller than the correction execution threshold C _{th1 and} larger than the correction non-execution threshold C _th2 (step S28: NO), the correction execution flag is held at the value (ON or OFF) at that time. The limit value ω _{max is} also held at that value. Therefore, the addition angle limiter process (step S25) according to the limit value ω _max is executed, and whether or not the addition angle guard process (step S27) is performed is determined according to the value of the correction execution flag (step S27). S26).

Thus, in this embodiment, when the induced voltage square sum Σ becomes equal to or greater than the correction execution threshold C _th1 , the correction execution flag is turned on, and the limit value ω _max is set to the relatively large first limit value ω _max1 . On the other hand, when the induced voltage square sum Σ becomes equal to or less than the correction non-execution threshold C _th2 , the correction execution flag is turned off, and the limit value ω _max is set to a relatively small second limit value ω _max2 . When the induced voltage square sum Σ is relatively large and therefore the rotor angular velocity is relatively high, the reliability of the rotor angular displacement Δθ (the value corresponding to the rotor angular velocity) is high. Therefore, while increasing the limit value ω _max to allow a large addition angle α, the addition angle α is corrected based on the rotor angular displacement Δθ (the rotor angular velocity equivalent value) by the guard process by the addition angle guard 41. In addition, when the induced voltage square sum Σ is relatively small and therefore the rotor angular velocity is low, the reliability of the rotor angular displacement Δθ is low. Therefore, the addition angle guard processing by the addition angle guard 41 is invalidated while the addition angle α is limited by reducing the limit value ω _max .

If the limit value ω _max for the addition angle α is set to be large, the amount of change in the control angle θ _C during the control cycle increases, so that the control angle θ _C is less likely to converge to an appropriate value corresponding to the torque deviation ΔT. Control breakdown tends to occur. Therefore, in this case, the addition angle α is suppressed to an appropriate range corresponding to the rotor angular displacement Δθ by intervening the addition angle guard process by the addition angle guard 41. Thereby, control failure can be suppressed. At the time of low speed rotation where the limit value ω _max for the addition angle α is set to be small, the amount of change in the control angle θ _C is small, so that it is easy to guide the control angle θ _C to an appropriate value corresponding to the torque deviation ΔT. Therefore, control failure is unlikely to occur. Thus, according to this embodiment, control failure can be suppressed or prevented, so that excellent steering feeling can be realized.

In addition, since two types of threshold values C _th1 and C _th2 for switching on / off of the correction execution flag and limit value ω _max are used to provide hysteresis for switching, the control mode is frequently switched. There is no change. Thereby, since stabilization of control can be aimed at, a much better steering feeling can be realized.
FIG. 9B is a flowchart for explaining another example of the operation of the correction control unit 38 and the like. In FIG. 9B, steps in which processing similar to that in each step shown in FIG. 9A is performed are denoted by the same reference numerals as in FIG. 9A.

In the process shown in FIG. 9B, the process in step S22A is different from the process in step S22 in FIG. 9A. In step S21, the correction control unit 38 obtains the induced voltage square sum Σ (= E ^ _α ² + E ^ _β ² ) calculated by the induced voltage square sum calculation unit 37. In step S22A, the correction control unit 38 determines whether or not the state where the induced voltage square sum Σ acquired in step S21 is equal to or greater than the correction execution threshold C _th1 (for example, C _th1 = 30) continues for a predetermined time Ta or more. Determine.

As described above, the rotational angle estimation unit 29, based on the induced voltage estimated by the induced voltage estimation unit 28 calculates the estimated value of the rotation angle of the rotor 50 (the estimated rotation angle) theta _E. The rotor angular displacement calculation unit 30, by determining the amount of change in the estimated rotational angle theta _E between calculation cycle to obtain the angular displacement Δθ of the rotor 50 in the calculation cycle (a value corresponding to the rotor angular speed). The predetermined time Ta has two operation interval of the estimated rotational angle theta _E used to calculate the angular displacement Δθ of the rotor 50 (the rotor angular velocity equivalent value) (in this embodiment, the calculation cycle of the estimated rotational angle theta _E) The above time is set. In this embodiment, the predetermined time Ta is set to a time corresponding to the calculation period of the estimated rotational angle theta _E.

If it is determined in step S22A that the state where the induced voltage square sum Σ is equal to or greater than the correction execution threshold C _th1 continues for a predetermined time Ta or longer (step S22A: YES), the process proceeds to step S23. On the other hand, when it is determined that the state where the induced voltage square sum Σ is not more than the correction execution threshold C _th1 has not continued for the predetermined time Ta or more (step S22A: NO), the process proceeds to step S28.

That is, in the process of FIG. 9B, when the state where the induced voltage square sum Σ is equal to or greater than the correction execution threshold C _th1 continues for a predetermined time Ta or more, the reliability of the rotor angular displacement Δθ (the rotor angular velocity equivalent value) is high. It is determined. Therefore, while increasing the limit value ω _max to allow a large addition angle α, the addition angle α is corrected based on the rotor angular displacement Δθ (the rotor angular velocity equivalent value) by the guard process by the addition angle guard 41.

On the other hand, it is determined that the reliability of the rotor angular displacement Δθ is low when the state where the induced voltage square sum Σ is not longer than the correction execution threshold C _th1 does not continue for the predetermined time Ta or longer. Therefore, the addition angle guard processing by the addition angle guard 41 is invalidated while the addition angle α is limited by reducing the limit value ω _max .
FIG. 10 is a block diagram for explaining the configuration of the induced voltage estimation unit 28. The induced voltage estimation unit 28 estimates the induced voltage of the motor 3 based on the two-phase detection current I _αβ and the two-phase command voltage V _αβ ^* . More specifically, the induced voltage estimation unit 28 has a form as a disturbance observer that estimates the induced voltage of the motor 3 as a disturbance based on a motor model that is a mathematical model of the motor 3. The motor model can be expressed as, for example, (R + pL) ⁻¹ . Here, R is an armature winding resistance, L is an αβ axis inductance, and p is a differential operator. It can be considered that the two-phase command voltage V _αβ ^* and the induced voltage E _αβ (α-axis induced voltage E _α and β-axis induced voltage E _β ) are applied to the motor 3.

The induced voltage estimation unit 28 receives the two-phase detection current I _αβ as an input and estimates a motor voltage, which is an inverse motor model (inverse model of the motor model) 65, a motor voltage estimated by the inverse motor model 65, and a two-phase indication voltage A voltage deviation calculation unit 66 for _obtaining a deviation from V _αβ ^* may be used. The voltage deviation calculator 66 obtains a disturbance with respect to the two-phase indication voltage V _αβ ^* . As is apparent from FIG. 10, this disturbance is an estimated value E ^ _αβ (α-axis induced voltage corresponding to the induced voltage E _αβ. The estimated value E ^ _α and the β-axis induced voltage estimated value E ^ _β (hereinafter collectively referred to as “estimated induced voltage E ^ _αβ ”) The reverse motor model 65 is represented by R + pL, for example.

The induced voltage E _αβ can be expressed by the following equation (6). However, _KE is an induced voltage constant, θ _M is a rotor angle, and ω is a rotor angular velocity.

Therefore, if the estimated induced voltage E ^ _.alpha..beta is obtained, according to the following equation (7), is obtained estimated rotational angle theta _E. This calculation is performed by the rotation angle estimation unit 29.

The induced voltage sum of squares calculation unit 37 calculates the induced voltage square sum Σ by performing the calculation of the following equation (8) based on the estimated induced voltage.
Σ = E ^ _α ² + E ^ _β ² ...... (8)
FIG. 11A is a diagram illustrating a characteristic example of the addition angle gain generated by the gain generation unit 39. The gain generation unit 39 generates an addition angle gain G _α that is 0 or more and 1 or less. In the example of FIG. 11A, the addition angle gain _Gα is set according to a characteristic that monotonously increases as the induced voltage square sum Σ increases. More specifically, in the low value range where the induced voltage square sum Σ is from 0 to a predetermined value, the addition angle gain G _α is a relatively small constant value less than 1. Further, in the range where the induced voltage square sum Σ is greater than or equal to the predetermined value, the addition angle gain G _α is set according to a characteristic that increases monotonously (in the example of FIG. 11A) from the constant value to 1.

Thus the addition angle gain G _alpha which is set, in the gain multiplication unit 43, is multiplied by the addition angle alpha (addition angle after the addition angle limiter processing and the addition angle guard process). Accordingly, the absolute value of the addition angle α is suppressed as the induced voltage square sum Σ is smaller and therefore the rotor angular velocity is smaller. As a result, when the steering wheel 10 is started to be turned, the generated torque (assist torque) of the motor 3 can be suppressed, so that a good feeling of response can be given to the driver.

11B is a diagram showing another example of the characteristic of the addition angle gain G _alpha gain generating unit 39 generates. In the example of FIG. 11B, the addition angle gain _Gα is set according to a characteristic that monotonously decreases as the induced voltage square sum Σ increases. More specifically, the addition angle gain _Gα is set to 1 in the low value region where the induced voltage square sum Σ is from 0 to a predetermined value. Furthermore, in the range where the induced voltage square sum Σ is equal to or greater than the predetermined value, the addition angle gain G _α is set according to a characteristic that decreases from 1 to monotonously (linear in the example of FIG. 11B).

Thus the addition angle gain G _alpha which is set, in the gain multiplication unit 43, is multiplied by the addition angle alpha (addition angle after the addition angle limiter processing and the addition angle guard process). As a result, the induced voltage square sum Σ is large, and therefore the absolute value of the addition angle α is suppressed as the rotor angular velocity is larger. As a result, the motor torque (assist torque) can be suppressed as the rotor angular speed increases, so that damping control for suppressing inertial rotation and the like of the motor 3 can be performed. Thereby, since a feeling of wobbling can be suppressed, an excellent steering feeling can be realized.

FIG. 12 is a flowchart for explaining the function of the failure time torque setting unit 21A. The fault torque setting unit 21A obtains the induced voltage square sum Σ from the induced voltage square sum computing unit 37 (step S31), and uses the induced voltage square sum Σ as a predetermined threshold D _th (for example, D _th = 30). Compare (step S32). If the induced voltage square sum Σ is larger than the threshold value D _th (step S32: NO), and therefore the accuracy of the rotor angular displacement Δθ (rotor angular velocity equivalent value) calculated by the rotor angular displacement calculating unit 30 is sufficiently high, a failure occurs. The hour torque setting unit 21A determines the steering direction based on the sign of the rotor angular displacement Δθ (step S33).

On the other hand, when the induced voltage square sum Σ is equal to or less than the threshold value D _th (step S32: YES), therefore, when the accuracy of the rotor angular displacement is low, the steering direction cannot be appropriately determined based on the rotor angular displacement Δθ. Therefore, the failure torque setting unit 21A controls (turns on) the command current value I _γδ ^* for a fixed time (for example, 0.05 seconds) for a fixed time (for example, 0.1 seconds). / OFF control) is executed (step S34). On the other hand, the failure time torque setting unit 21A acquires the steering torque T when the command current value I _γδ ^* is turned off (set to zero), and based on the sign of the acquired steering torque T, the steering direction Is determined (step S35).

Thus, when the steering direction is determined based on the rotor angular displacement Δθ or the steering torque T (steps S33, S35), the failure torque setting unit 21A adds a plus sign “2” to the predetermined target absolute value T ₀ (for example, 2 Nm). An instruction steering torque T ^* is generated with “+” or a minus sign “−” (step S36). That is, when the command steering torque T ^* is generated based on the rotor angular displacement Δθ, the same sign as the rotor angular displacement Δθ is attached to the target absolute value T ₀ and the command steering torque T ^* (= + T ₀ or −T ₀ ). Is generated. Similarly, when the command steering torque T ^* is generated based on the steering torque T, the same sign as the detected steering torque T is attached to the target absolute value T ₀ and the command steering torque T ^* (= + T ₀ or −T ₀ ) is generated. When the failure detection unit 42 detects a failure of the steering angle sensor 4, the command steering torque T ^* generated in this way is given to the torque deviation calculation unit 22.

Instead of the on / off control in step S34, a process of periodically reducing the motor torque by multiplying the command current value I _γδ ^* by a gain (for example, 0.5) less than 1 may be performed. Further, the command current value I _γδ ^* may be gradually decreased. In any case, since the motor torque (assist torque) is temporarily reduced, the steering torque T detected by the torque sensor 1 clearly represents the direction of the steering torque applied to the steering wheel 10 by the driver. It will be. Therefore, by using the steering torque T when the motor torque is temporarily reduced, it is possible to generate an appropriate instruction steering torque T ^* according to the steering direction. Of course, besides reducing the command current value I _γδ ^* , the motor torque (assist torque) may be reduced by temporarily reducing the command voltage value V _αβ ^* , for example.

FIG. 13 is a flowchart for explaining the functions of the control failure monitoring unit 25, the steering determination unit 27, and the addition angle correction unit 44. For example, the control failure monitoring unit 25 has a steering torque absolute value | T | exceeding a first torque threshold value E _th1 (for example, E _th1 = 7 Nm), and the induced voltage square sum Σ is a predetermined threshold value F _th ( For example, if the state of F _th = 15) or less continues for a certain time (for example, 0.03 seconds) or longer, it is determined that a control failure has occurred (step S41). The case where the state where the steering torque absolute value | T | exceeds the first torque threshold value E _th1 continues is a case where the shortage state of the motor torque (assist torque) continues. For example, there is a case where the current value is insufficient and the control angle θ _C cannot be converged to a value that generates an appropriate assist torque. However, even in such a case, if the induced voltage square sum Σ is sufficiently large and therefore the reliability of the rotor angular displacement Δθ (the value corresponding to the rotor angular velocity) is sufficient, the addition angle guard 41 performs the addition angle guard process. The addition angle α can be kept in an appropriate range. Therefore, the control failure monitoring unit 25 determines whether or not a control failure has occurred by determining both the condition relating to the steering torque absolute value | T | and the condition relating to the induced voltage square sum Σ.

When the condition of step S41 is satisfied, the control failure monitoring unit 25 sets the failure detection flag to the on state (step S42). On the other hand, the control failure monitoring unit 25 determines that the steering torque absolute value | T | is equal to the second torque threshold value E _th2 (<E _th1 . _{On the} condition that it is less than ( _th2 = 6Nm) (step S43: YES), the failure detection flag is turned off (step S44).

When the failure detection flag is off (step S45: NO), the addition angle correction unit 44 does not perform the following processing and supplies the addition angle α from the gain multiplication unit 43 to the control angle calculation unit 26 as it is. When the failure detection flag is on (step S45: YES), the addition angle correction unit 44 acquires the determination result of the steering determination unit 27 and determines whether or not the steering state is maintained (step S46). When in the steered state (step S46: NO), the addition angle correction unit 44 corrects the addition angle α to 0 (step S47). As a result, the control angle θ _C does not change, and the motor 3 generates torque that suppresses rotor rotation. Thereby, even if it is a control failure state, a driver | operator's steering maintenance can be assisted and a driver | operator's steering burden can be eased. Further, since the control angle theta _C the torque is generated by the motor 3 so as not to change, it is possible to suppress the generation of unpleasant vibrations. If a significant (non-zero) addition angle α is set at the time of steering, the motor 3 generates a torque for assisting the steering and a torque in a direction opposite to the torque for the steering. In such a case, vibration may occur. Such vibration can be suppressed or prevented by setting the addition angle α to zero during steering.

When not in the steering holding state (step S46: YES), the addition angle correction unit 44 determines whether the steering torque T is positive or negative (step S48). When the steering torque T is zero or a positive value (step S48: YES), the addition angle correction unit 44 adds a positive sign to the predetermined basic value B (> 0, for example, B = 5 degrees) (that is, B = 5 degrees). The basic value B is used as it is), and the addition angle target value α ^* (= + B) is set (step S49). When the steering torque T is a negative value (step S47: NO), the addition angle correction unit 44 attaches a negative sign to the basic value B and sets the addition angle target value α ^* (= −B). (Step S50). Then, the addition angle correction unit 44 gradually increases or decreases the addition angle α so that the current addition angle α gradually approaches the addition angle target value α ^* (step S51). Thus, even when the control fails, the addition angle α can be set according to the direction of the steering torque T, so that appropriate steering assistance can be continued.

The basic value B used when setting the addition angle target value α ^* does not have to be a constant value, and may be a variable that is variably set according to the value of the induced voltage square sum Σ, for example. For example, a map of the basic value B for the induced voltage square sum Σ may be created, and the basic value may be variably set according to this map. This process can be used in place of the processes in steps S45 to S51 in FIG. For example, the basic value B may be variably set according to a characteristic that increases as the induced voltage square sum Σ increases.

FIG. 14 is a flowchart for explaining a specific example of the steering determination process by the steering determination unit 27. The steering determination unit 27 turns the steering determination flag on when it determines that it is in the steering state, and sets the steering determination flag off when it determines that it is not in the steering state. The addition angle correction unit 44 determines whether or not the steering holding state is on the basis of whether the steering holding determination flag is on or off.
The steerage determination unit 27 determines whether or not the steerage determination flag is in an off state and the induced voltage square sum Σ is smaller than a threshold value G _th (> 0, eg, G _th = 10) (step S61). If this determination is positive, the steering determination unit 27 determines whether or not the counter C1 is larger than the threshold value H _th (step S62). The counter C1 is a counter for measuring the duration time for which the condition of step S61 is established. The threshold value H _th may be a value corresponding to about 0.1 seconds in terms of time, for example. When the value of the counter C1 is equal to or less than the threshold value H _th (step S62: NO), the steering keeping determination unit 27 increments the counter C1 (step S63). When the value of the counter C1 exceeds the threshold value H _th (step S62: YES), the steering determination unit 27 turns the steering determination flag on (step S64). In this way, when the induced voltage square sum Σ is small and therefore the state where the rotor angular speed is low continues, it is determined that the steering is held and the steering determination flag is turned on.

Next, the steering retention determination unit 27 clears the counter C2 (step S65). The counter C2 is a counter for measuring the duration time of the steering determination flag off condition (step S66) described below.
If it is determined in step S61 that the steering determination flag is on or the induced voltage square sum Σ is greater than or equal to the threshold value G _th , the processes in steps S62 to S65 are omitted.

The steerage determination unit 27 further determines whether or not the steerage determination flag off condition is satisfied (step S66). Specifically, it is determined whether the steering torque absolute value | T | is larger than a threshold value J _th (for example, J _th = 7 Nm) and the steering determination flag is in an on state. If an affirmative determination is made (step S66: YES), maintenance determination unit 27, the counter C2 is determined whether greater than the threshold value K _th (step S67). The threshold value K _th may be a value corresponding to about 0.03 seconds in terms of time, for example. When the value of the counter C2 is equal to or smaller than the threshold K _th (Step S67: NO), maintenance determination unit 27 increments the counter C2 (step S68). When the value of the counter C2 exceeds the threshold value K _th (Step S67: YES), maintenance determination unit 27 may be turned off maintenance determination flag (step S69). In this way, when the steering determination flag is turned on and the steering torque absolute value | T | continues to be large, it is determined that the driver has a steering intention and is not in the steering holding state. The steering retention determination flag is turned off. Thereafter, the counter C1 is cleared (step S70).

[Second Embodiment]
FIG. 15 is a block diagram showing a configuration of an electric power steering device including a motor control device according to the second embodiment of the present invention. In FIG. 15, the same reference numerals are given to the corresponding parts of the respective parts shown in FIG. 1, and differences from the first embodiment will be mainly described below. In the second embodiment, the microcomputer 11 includes a damping control unit 60, a damping torque generation unit 61, a torque instruction value addition unit 62, a gain multiplication unit 63, and a gain correction unit 64 as function processing units. have.

The damping torque generation unit 61 generates a damping torque instruction value for damping control. The damping torque instruction value is multiplied by the gain in the gain multiplication section 63 and then given to the torque instruction value adding section 62. The torque command value adding unit 62 adds the damping torque command value after the gain multiplication to the command steering torque set by the command steering torque setting unit 21. The addition result is supplied to the torque deviation calculation unit 22 as the command steering torque T ^* corrected for damping control.

The damping control unit 60 sets a gradually increasing / gradually decreasing gain ξ (0 ≦ ξ ≦ 1) to the gain multiplying unit 63 and gives the gradually increasing / gradually decreasing gain ξ to the gain correcting unit 64. The gain multiplication unit 63 multiplies the damping torque instruction value by a gradual increase / decrease gain ξ. The gain correction unit 64 applies correction corresponding to the gradual increase / decrease gain ξ to the addition angle gain G _α generated by the gain generation unit 39. Specifically, for example, the corrected addition angle gain G _α ′ is represented by G _α ′ = ξ + G _α (1−ξ). The corrected addition angle gain G _α ′ is multiplied by the addition angle α in the gain multiplier 43. The damping control unit 60 switches between two types of damping control modes based on the induced voltage square sum Σ. A 1st aspect is an aspect which performs the damping control based on the damping torque instruction | indication value which the damping torque production | generation part 61 produces | generates. The second mode is a mode for performing the damping control using the addition angle gain G _alpha gain generating unit 39 generates. The damping control unit 60 gradually changes the damping control mode between the first and second modes by gradually changing the gradual increase / decrease gain ξ.

FIG. 16A is a characteristic diagram for explaining a setting example of a damping torque instruction value generated by the damping torque generation unit 61. The damping torque generation unit 61 may have, for example, a map form in which a damping torque instruction value for the rotor angular displacement Δθ (rotor angular velocity equivalent value) is set. In the example of FIG. 16A, when the rotor angular displacement Δθ is zero, the damping torque instruction value is zero. In the positive region of the rotor angular displacement Δθ, the damping torque instruction value is a positive value, and the rotor angular displacement Δθ is negative. In this area, the damping torque instruction value is a negative value. Further, as the absolute value of the rotor angular displacement Δθ increases, the absolute value of the damping torque instruction value increases monotonously. Thereby, the absolute value of the damping torque instruction value increases as the operation speed of the steering wheel 10 increases. Since such a damping torque command value is added to the command steering torque set by the command steering torque setting unit 21, the absolute value of the command steering torque T ^* increases as the absolute value of the rotor angular displacement Δθ increases. Thereby, motor torque (assist torque) is reduced and damping control is realized.

FIG. 16B is a diagram illustrating a characteristic example of the addition angle gain G _α generated by the gain generation unit 39. In the example of FIG. 16B, the addition angle gain _Gα is set according to a characteristic that monotonously decreases as the induced voltage square sum Σ increases. More specifically, the addition angle gain is set to 1 in the low value region where the induced voltage square sum Σ is from 0 to a predetermined value. Further, in the range where the induced voltage square sum Σ is greater than or equal to the predetermined value, the addition angle gain is set according to a characteristic that decreases from 1 to monotonously (linear in the example of FIG. 16B).

Thus the addition angle gain G _alpha which is set is multiplied by the addition angle alpha (addition angle after the addition angle limiter processing and the addition angle guard process). As a result, the induced voltage square sum Σ is large, and therefore the absolute value of the addition angle α is suppressed as the rotor angular velocity is larger. Thereby, since the motor torque can be suppressed as the rotor angular speed is higher, the damping control for suppressing the inertial rotation or the like of the motor 3 can be performed. Thereby, since a feeling of wobbling can be suppressed, an excellent steering feeling can be realized.

FIG. 17 is a flowchart for explaining the operation of the damping control unit 60. The damping control unit 60 acquires the induced voltage square sum Σ calculated by the induced voltage square sum calculation unit 37 (step S81) and compares it with a threshold value L _th (> 0, for example, L _th = 30) (step S82).
When the induced voltage square sum Σ is equal to or greater than the threshold value L _th (step S82: YES), and therefore the reliability of the rotor angular displacement Δθ (the rotor angular velocity equivalent value) is sufficient, the damping control unit 60 generates the damping torque. The damping control using the unit 61 (the first mode) is validated, and the damping control (the second mode) by the gain generation unit 39 is invalidated. Specifically, the damping torque generation unit 61 generates a damping torque instruction value corresponding to the rotor angular displacement Δθ (step S83), and the damping control unit 60 sets the target value of the gradually increasing / gradually decreasing gain ξ to 1 (step S84). ). The gradually increasing / decreasing gain ξ is multiplied by the damping torque instruction value in the gain multiplier 63. As described above, the addition angle gain G _α ′ corrected by the gain correction unit 64 is G _α ′ = ξ + G _α (1−ξ). When ξ = 1, the damping torque instruction value generated by the damping torque generation unit 61 is completely valid, and G _α ′ = ξ = 1. Therefore, the addition angle gain G _α generated by the gain generation unit 39 is It becomes completely invalid.

On the other hand, when the induced voltage square sum Σ is less than the threshold value L _th (step S82: NO), and therefore the reliability of the rotor angular displacement Δθ (the rotor angular velocity equivalent value) is insufficient, the damping control unit 60 The damping control (the first mode) using the damping torque generation unit 61 is invalidated, and the damping control (the second mode) performed by the gain generation unit 39 is enabled. Specifically, the gain generation unit 39 generates the addition angle gain G _α corresponding to the induced voltage square sum Σ (step S85), and the damping control unit 60 sets the target value of the gradually increasing / gradually decreasing gain ξ to 0 ( Step S86). When ξ = 0, the damping torque instruction value generated by the damping torque generation unit 61 is completely invalid. Further, since the gain correction unit addition angle corrected by 64 gain _{G α '= ξ + G α} (1-ξ) = G α, the addition angle gain G _alpha to gain generator 39 generates becomes fully effective.

When the target value of the gradual increase / gradual decrease gain ξ is thus set (steps S84 and S86), the damping control unit 60 executes a low-pass filter (LPF) process on the gradual increase / gradual decrease gain ξ (step S87). The low-pass filter process is a process of gradually changing (gradually increasing or decreasing) the gradual increase / decrease gain ξ toward a target value with a certain time constant. As a result, the final gradual increase / decrease gain ξ is determined between 0 and 1. The gradual increase, gradual decrease gain xi] is given to the gain multiplication unit 63 and the gain correction unit 64, using the incremental-decreasing gain xi], the correction is applied to the damping torque command value and the addition angle gain G _alpha (step S88 ).

FIG. 18 is a diagram illustrating an example of temporal changes of the gradually increasing / decreasing gain, the corrected damping torque instruction value, and the corrected addition angle gain G _α ′. At time t1, when the induced voltage square sum Σ switches from a state below the threshold value L _{th to} a state larger than the threshold value L _th , the gradually increasing / gradually decreasing gain ξ gradually increases from 0 and increases to 1. At time t2, when the induced voltage square sum Σ switches from a state where the induced voltage square sum Σ is larger than the threshold value L _th to a state where the induced voltage is less than the threshold value L _th , the gradually increasing / gradually decreasing gain ξ gradually decreases from 1 and decreases to 0. Accordingly, the damping torque instruction value multiplied by the gradually increasing / gradually decreasing gain ξ gradually increases from 0 to the value generated by the damping torque generating unit 61 during the period from time t1, and during the period from time t2. The torque generator 61 gradually decreases from the value generated by the torque generator 61 to zero. Further, the corrected addition angle gain G _α ′ gradually decreases from 1 to the uncorrected addition angle gain G _α during the period from time t1. The corrected addition angle gain G _α ′ gradually increases from the uncorrected addition angle gain G _α to 1 during the period from time t2.

Thus, according to this embodiment, when the induced voltage square sum Σ is large and therefore the reliability of the rotor angular displacement Δθ (the rotor angular velocity equivalent value) is high, the damping torque instruction determined based on the rotor angular displacement Δθ. Damping control is performed using the value. On the other hand, when the induced voltage square sum Σ is small and therefore the reliability of the rotor angular displacement Δθ is low, damping control is executed using the addition angle gain G _α determined based on the induced voltage square sum Σ. Thereby, appropriate damping control can be performed according to the rotor angular velocity.

Moreover, it is possible by changing the increasing-decreasing gain ξ progressively, causing a damping control using the damping torque command value, the switching of the damping control using the addition angle gain G _alpha incrementally . Thereby, since the sudden change of motor torque (assist torque) can be suppressed, the uncomfortable feeling accompanying the change of the aspect of damping control can be relieved.

Although not shown in FIG. 15, the second embodiment may include the failure detection unit 42 and the failure torque setting unit 21 </ b> A as in the case of the first embodiment.
[Third Embodiment]
FIG. 19 is a block diagram for explaining a configuration of a vehicle steering apparatus to which a motor control device according to a third embodiment of the present invention is applied. In FIG. 19, parts corresponding to the respective parts shown in FIG. 1 are given the same reference numerals, and the differences from the first embodiment will be mainly described below.

In this embodiment, as a function processing unit of the microcomputer 11, an addition angle gain generation unit 70 that generates an addition angle gain G _α that is multiplied by the addition angle _α, and an integration term setting that changes the value of the integration term in the PI control unit 23. Part 71 is provided. However, any one of these may be provided.
The addition angle gain generation unit 70 is a constant addition angle gain G _α (0 <G _α <0) over a predetermined execution time (for example, 0.005 seconds) with an interval time variably set according to the induced voltage square sum Σ. 1. For example, G _α = 0.9) is given to the gain multiplier 43. Further, the integral term setting unit 71 changes the previous value of the integral term in the PI control unit 23 during the execution time. More specifically, a value obtained by multiplying the previous integral term value by the addition angle gain _Gα is set as a new previous integral term value. The interval time is preferably set in the range of 0.001 second to 1 second, for example. However, the multiplication of the addition angle gain G _alpha in multiplier 43, and the change of the integral term immediately preceding value of the integral term setting unit 71, either one may if performed.

FIG. 20 is a flowchart for explaining operations of the addition angle gain generation unit 70, the integral term setting unit 71, and the like. The addition angle gain generation unit 70 sets an interval time corresponding to the induced voltage square sum Σ calculated by the induced voltage square sum calculation unit 37 (step S91). Then, the addition angle gain generation unit 70 determines whether the value of the counter that measures the passage of time is equal to or less than the execution time (step S92). If the value of the counter is less than the execution time (step S92: YES), the addition angle gain generator 70 generates a constant addition angle gain G _alpha less than 1. The addition angle gain _Gα is multiplied by the addition angle α in the gain multiplier 43 (step S93). Substituted instead of multiplying the addition angle gain G _alpha addition angle alpha, the integral term setting unit 71, as the integral term previous value, the value obtained by multiplying the addition angle gain G _alpha to the integral term obtained in the calculation of the previous control cycle You may do (step S94). Thereafter, the counter is incremented (step S95), and the processing of the current cycle is finished.

  On the other hand, when the measured value of the counter exceeds the execution time (step S92: NO), the addition angle gain generation unit 70 further determines whether the measured value of the counter is less than or equal to the sum of the interval time and the execution time. Judgment is made (step S96). If this determination is affirmed (step S96: YES), the counter is incremented (step S95), and the processing of this cycle is finished. When the measured value of the counter exceeds the sum of the interval time and the execution time (step S96: NO), the counter is reset to 0 (step S97), and the processing of this cycle is finished.

FIG. 21 is a diagram for explaining a specific operation example, and shows an example of a time change of the addition angle α supplied to the control angle calculation unit 26. During a period corresponding to the “execution time”, the addition angle α is multiplied by an addition gain G _α less than 1, or the integral term in the PI control unit 23 is multiplied by an addition angle gain G _α less than 1. It is done. The period not corresponding to the “execution time” is a period corresponding to the “interval time”. This period, the correction of the addition angle alpha or the integral term by the addition angle gain G _alpha not performed, the addition angle alpha is maintained at a relatively large value. In this way, the motor torque (assist torque) is reduced and corrected by the correction of the addition angle α being reduced by the intermittent correction processing for each interval time.

  FIG. 22 is a characteristic diagram showing an example of setting the interval time according to the induced voltage square sum Σ. In this example, the interval time monotonously increases as the induced voltage square sum Σ increases. As a result, the faster the rotational angular velocity of the steering wheel 10, the longer the interval time, and the motor torque (assist torque) is corrected to be reduced. Thereby, what is called damping control is implement | achieved and wobbling feeling can be reduced. When the induced voltage square sum Σ is zero, the interval time may be a positive value or zero.

FIG. 22 shows an example in which the interval time is continuously changed according to the induced voltage square sum Σ. For example, when the induced voltage square sum Σ is equal to or less than a predetermined threshold, the first interval time is set. Thus, the addition angle α may be substantially reduced and corrected. In this case, when the induced voltage square sum Σ is larger than the threshold value, a second interval time longer than the first interval time may be set or the interval time may not be set. Thus, when the induced voltage square sum Σ is larger than the threshold value, the addition angle α having a large absolute value is used for the calculation of the control angle θ _C.

As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form. For example, in the above-described embodiment, the square sum Σ of the α-axis induced voltage estimated value E ^ _α and the β-axis induced voltage estimated value E ^ _β is used. For example, the d-axis induced voltage estimated value and the q-axis induced voltage The sum of squares of estimated values may be used, or the sum of squares of estimated γ-axis induced voltage and estimated δ-axis voltage may be used. Further, instead of using the induced voltage square sum as it is, the square root of the induced voltage square sum may be used.

In the above-described embodiment, the detection current and the instruction voltage are used for estimating the induced voltage. However, the instruction current may be used instead of the detection current, or the detection voltage is used instead of the instruction voltage. May be.
In the above-described embodiment, the addition angle α is corrected based on not only the rotor angular displacement Δθ but also the torque deviation ΔT. However, the correction of the addition angle α based on the torque deviation ΔT may be omitted. Specifically, the addition angle guard 41 may limit the addition angle α to a range of Δθ−A ≦ α ≦ Δθ + A using the rotor angular displacement Δθ.

In the above-described embodiment, the configuration in which the motor 3 is driven exclusively by sensorless control without the rotation angle sensor has been described. However, the rotation angle sensor such as a resolver is provided, and when the rotation angle sensor fails, as described above. It is good also as a structure which performs a sensorless control. Thereby, since the drive of the motor 3 can be continued even when the rotation angle sensor fails, the steering assist can be continued.
In this case, when using the rotation angle sensor, the command current value generation unit 31 may generate the δ-axis command current value I _δ ^* according to the predetermined assist characteristic according to the steering torque and the vehicle speed.

  Further, in the above-described embodiment, the example in which the present invention is applied to the electric power steering apparatus has been described. However, the present invention is not limited to the motor control for the electric pump type hydraulic power steering apparatus or the power steering apparatus. It can be used for control of a brushless motor provided in a steer-by-wire (SBW) system, a variable gear ratio (VGR) steering system and other vehicle steering devices. Of course, the motor control device of the present invention can be applied not only to the vehicle steering device but also to control a motor for other purposes.

  In addition, various design changes can be made within the scope of matters described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Torque sensor, 3 ... Motor, 5 ... Motor control apparatus, 11 ... Microcomputer, 26 ... Control angle calculating part, 43 ... Gain multiplication part, 44 ... Addition angle correction part, 50 ... Rotor, 51, 52, 53 ... Stator winding, 55 ... stator, 62 ... torque command value addition unit, 63 ... gain multiplication unit, 64 ... gain correction unit

Claims (11)

A rotor, a motor control device for control the motor having a stator that faces the rotor,
Current driving means for driving the motor with an axial current value of a rotating coordinate system according to a control angle that is a control rotation angle;
An addition angle calculation means for calculating an addition angle to be added to the control angle;
Control angle calculation means for obtaining the current value of the control angle by adding the addition angle calculated by the addition angle calculation means to the previous value of the control angle for each predetermined calculation cycle;
An induced voltage square value calculation means for estimating an induced voltage of the motor and calculating a square value of the estimated induced voltage;
And a correction unit that corrects the addition angle based on an induced voltage square value calculated by the induced voltage square value calculation unit. An addition angle limiting means for limiting the addition angle calculated by the addition angle calculation means with a predetermined limit value;
The correction means substantially corrects the addition angle by changing the limit value in the addition angle limiting means according to the induced voltage square value calculated by the induced voltage square value calculation means. The motor control device according to claim 1, which is configured . The motor according to claim 2 , wherein the correction unit includes a unit that corrects the addition angle by multiplying the addition angle after being limited by the addition angle limitation unit by a gain according to the square value of the induced voltage. Control device. It said correcting means, by multiplying the gain in accordance with the induced voltage squared value for the addition angle that is calculated by the addition angle calculation unit, the addition angle is configured to correct the, according to claim 1, wherein Motor control device. The correction means is configured to set an interval time according to the square value of the induced voltage and to execute a correction process for reducing and correcting the addition angle for a predetermined time each time the interval time elapses. The motor control device according to 1 . 4. The motor control device according to claim 2 , wherein the correction unit is configured to change the limit value to a first limit value when the induced voltage square value becomes equal to or greater than a first predetermined value . 5. Wherein the correction means, the induced voltage squared value is configured at or above the first predetermined value changes the limit value when the predetermined time or longer in the first limit value, according to claim 2 or 3, wherein Motor control device. Wherein the correction means, the induced voltage squared value is configured to change the limit value and equal to or less than a second predetermined value smaller than the first predetermined value to the second limit value, according to claim 6 or 7, wherein Motor control device. A motor control device for controlling a motor for providing a driving force to a steering mechanism of a vehicle, comprising a rotor and a stator facing the rotor,
Current driving means for driving the motor with an axial current value of a rotating coordinate system according to a control angle that is a control rotation angle;
Control angle calculation means for obtaining the current value of the control angle by adding the addition angle to the previous value of the control angle for each predetermined calculation cycle;
Steering torque detection means for detecting steering torque applied to an operating member operated for steering the vehicle;
Command steering torque setting means for setting command steering torque which is a command value of steering torque;
An addition angle calculation means for calculating the addition angle using a detected steering torque detected by the steering torque detection means and an instruction steering torque set by the instruction steering torque setting means;
An induced voltage square value calculation means for estimating an induced voltage of the motor and calculating a square value of the estimated induced voltage;
When the induced voltage square value is equal to or greater than a predetermined value, a damping torque command value corresponding to the rotor angular displacement of the electric motor is generated, and the damping torque command value is set to the command steering torque set by the command steering torque setting means. A first correction means for substantially correcting the addition angle by correcting the command steering torque by adding;
When the induced voltage square value is less than a predetermined value, a second correction unit corrects the addition angle by generating an addition angle gain corresponding to the induced voltage square value and multiplying the addition angle gain by the addition angle gain. And a motor control device. A motor control device for controlling a motor for providing a driving force to a steering mechanism of a vehicle, comprising a rotor and a stator facing the rotor,
Current driving means for driving the motor with an axial current value of a rotating coordinate system according to a control angle that is a control rotation angle;
Control angle calculation means for obtaining the current value of the control angle by adding the addition angle to the previous value of the control angle for each predetermined calculation cycle;
Steering torque detection means for detecting steering torque applied to an operating member operated for steering the vehicle;
Command steering torque setting means for setting command steering torque which is a command value of steering torque;
An addition angle calculation means for calculating the addition angle using a detected steering torque detected by the steering torque detection means and an instruction steering torque set by the instruction steering torque setting means;
An induced voltage square value calculation means for estimating an induced voltage of the motor and calculating a square value of the estimated induced voltage ;
A steered state judging means for judging whether or not the steered state,
When the absolute value of the steering torque exceeds a predetermined torque threshold and the state where the induced voltage square value is equal to or less than a predetermined value continues for a predetermined time or longer, the steered state determination means causes the And a correction unit that reduces and corrects the addition angle when determined to be present . A motor for applying a driving force to the steering mechanism of the vehicle;
A vehicle steering apparatus including the motor control apparatus according to claim 1 for controlling the motor.

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