JP2011097810A - Motor control device and vehicle steering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control device for controlling a motor by a new control system that does not use a rotational angle sensor. <P>SOLUTION: A motor control stop/restart timing detecting part 41 detects a timing when motor control is to be stopped, and a timing when motor control is to be restarted after motor control is stopped. A motor control stop processing part 43 gradually decreases an indicated current value I<SB>γ</SB><SP>*</SP>to a predetermined value or lower after gradually decreasing a limit value ω<SB>max</SB>down to zero when a motor control stop timing is detected by the motor control stop/restart timing detecting part 41. A motor control restart processing part 44 gradually increases the limit value ω<SB>max</SB>to a predetermined value or higher after gradually increasing the indicated current value I<SB>γ</SB><SP>*</SP>to a predetermined value or higher in the state of the limit value ω<SB>max</SB>being fixed to zero when a motor control restart timing is detected by the motor control stop/restart timing detecting part 41. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a motor control apparatus for driving a brushless motor and a vehicle steering apparatus including the motor control 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 induced voltage 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.

Japanese Patent Laid-Open No. 10-243699

  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 the motor control device.

In order to achieve the above object, the invention according to claim 1 is a motor control device (5) for controlling a motor (3) including a rotor (50) and a stator (55) facing the rotor. A current driving means (30 to 36) for driving the motor with an axis current value (I _γ ^* ) of a rotating coordinate system according to 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 to be added, and a control angle by adding the addition angle calculated by the addition angle calculation means to the previous value of the control angle every predetermined calculation cycle. Control angle calculating means (26) for obtaining the current value of the current value, addition angle limiting means (24) for limiting the absolute value of the addition angle to a limit value or less, and when the motor control is stopped, the limit value is reduced to zero. After gradually decreasing, the motor drive value (I _γ ^* ) Is a motor control device including stop processing means (43, 46) for gradually decreasing the value to a predetermined value or less. In addition, although the alphanumeric characters in parentheses represent corresponding components in the embodiments described later, of course, the scope of the present invention is not limited to the embodiments. The same applies hereinafter.

  According to this configuration, the axis current value (hereinafter “virtual axis”) of the rotating coordinate system (γδ coordinate system, hereinafter referred to as “virtual rotating coordinate system”, the coordinate axis of this virtual rotating coordinate system being 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.

  In the present invention, there is provided addition angle limiting means for limiting the absolute value of the addition angle to be equal to or less than the limit value. When stopping the motor control, after the limit value is gradually reduced to zero, it is gradually reduced until the motor drive value becomes a predetermined value or less. According to this configuration, when stopping the motor control, the motor drive value is not changed instantaneously to a predetermined value or less, but is gradually decreased until the motor drive value becomes a predetermined value or less. It can be stopped smoothly. When stopping the motor control, after the limit value is gradually decreased to zero, the motor drive value is gradually decreased to a predetermined value or less, so that the control angle of the motor is fixed so as not to change. The driving value is gradually decreased until the driving value becomes a predetermined value or less. For this reason, when the driving value of the motor is gradually reduced to a predetermined value or less, it is possible to suppress an undesired fluctuation in the control angle.

  According to a second aspect of the present invention, when the motor control is resumed, the drive value of the motor is gradually increased to a predetermined value or more in a state where the limit value is fixed to zero, and then the limit value is increased to a predetermined value or more. The motor control device according to claim 1, further comprising restart processing means that gradually increases until In this invention, when resuming the motor control, with the limit value fixed at zero, the motor drive value is gradually increased until it reaches a predetermined value or higher, and then gradually increased until the limit value reaches a predetermined value or higher. .

  According to this configuration, when the motor control is resumed, the motor drive value is not instantaneously changed to a predetermined value, but is gradually increased until the motor drive value becomes a predetermined value or more. Can be resumed. When resuming motor control, the limit value is fixed to zero, the motor drive value is gradually increased to a predetermined value or higher, and then the limit value is gradually increased to the predetermined value. In a fixed state, the motor drive value is gradually increased until it reaches a predetermined value or more. For this reason, when the driving value of the motor is gradually increased to a predetermined value or more, it is possible to suppress an undesired fluctuation in the control angle. Then, after the drive value of the motor becomes equal to or greater than the predetermined value, the limit value is gradually increased until the limit value becomes equal to or greater than the predetermined value, so that the motor control can be resumed smoothly.

The invention according to claim 3 includes a motor (3) that applies a driving force to the steering mechanism (2) of the vehicle, and a motor control device according to claim 1 or 2 that controls the motor. It is.
According to this configuration, it is possible to realize a vehicle steering apparatus that can smoothly stop and smoothly resume control of a motor that applies driving force to the steering mechanism of the vehicle. Thereby, the uncomfortable feeling accompanying stop / resumption of motor control can be suppressed.

The motor control device includes a torque detection means (1) for detecting a torque (T) other than the motor torque applied to a drive target driven by the motor, and an instruction torque (T ^* ) to be applied to the drive target ^. : Command torque setting means (21) for setting torque command value other than motor torque). In this case, for example, the addition angle calculation means operates to calculate the addition angle so that the torque detected by the torque detection means matches the indicated torque. Thereby, the motor torque is controlled (feedback control) so 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.

  The motor control device further includes a current detection means (13) for detecting a current flowing in the stator winding of the motor, and the current driving means generates an instruction current that generates a current value to be passed through the virtual axis as an instruction current value. An instruction to be applied to the stator winding of the motor according to the generating means (30), the detected current value detected by the current detecting means, the indicated current value generated by the indicated current generating means, and the control angle Instruction voltage generating means (31 to 34, 36) for generating a voltage may be included.

In this case, the driving value of the motor may be, for example, an instruction current value generated by the instruction current generation unit or an instruction voltage value generated by the instruction voltage generation unit. The command current generating unit may generate a command current value based on the torque detected by the torque detection unit, for example.
In a vehicle steering device (for example, an electric power steering device) in which an operation member and a steering mechanism are mechanically coupled, the driving force of a motor is applied to the steering mechanism as an assist torque (steering assist force). A value obtained by subtracting the assist torque from the motor load (load torque) is the steering torque that the driver should apply to the operation member.

  If the motor drive value (for example, current instruction value) is simply decreased when stopping the motor control, the assist torque required for the motor load cannot be output during the gradual decrease of the motor drive value. As a result, when the steering torque exceeds the detection range of the torque detection means, there is a risk that torque feedback control will not operate normally. Therefore, when the motor control is stopped, if the limit value is gradually decreased to zero and then the motor drive value is gradually decreased to a predetermined value or less, the motor is fixed so that the control angle does not change. The drive value is gradually decreased until it becomes equal to or less than a predetermined value. As a result, the motor can be smoothly stopped by limiting the control angle. Therefore, after that, when the driving value of the motor is gradually decreased to a predetermined value or less, it is possible to suppress a sense of incongruity caused by the torque feedback control becoming abnormal. That is, even when the torque feedback control becomes abnormal due to a shortage of the drive value, the addition angle is fixed to zero, so that it is not affected by the abnormal torque feedback control.

  On the other hand, when the motor control value is resumed, if the motor drive value (for example, current instruction value) is gradually increased from zero to a predetermined value or more, the assist torque required for the motor drive value with respect to the motor load. Until the value reaches the value at which the torque can be generated, the steering torque may exceed the detection range of the torque detection means, and the torque feedback control may not operate normally. Therefore, when the motor control is resumed, the drive value of the motor is gradually increased to a predetermined value or more with the limit value fixed at zero. As a result, the control angle does not change until the drive value becomes sufficiently large. Therefore, even if the torque feedback control is not normal, an undesirable behavior does not appear in the motor. Thereby, motor control can be restarted smoothly.

  The motor may provide a driving force to the steering mechanism (2) of the vehicle. In this case, the torque detection means may detect a steering torque applied to the operation member (10) operated for steering the vehicle. 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 or the vehicle steering device further includes steering angle detection means (4) for detecting a steering angle of the operation member, and the command torque setting means is a steering angle detected by the steering angle detection means. It is preferable that the command steering torque is set according to the above. 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.

1 is a block diagram for explaining an electrical configuration of an electric power steering apparatus to which a motor control device according to an embodiment of the present invention is applied. FIG. 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 | indication 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 a motor control stop / restart timing detection part. It is a flowchart for demonstrating the function of a motor control stop process part. It is a flowchart which shows the detailed procedure of a motor control stop process. It is a flowchart for demonstrating the function of a motor control restart process part. It is a flowchart which shows the detailed procedure of a motor control restart process. It is a flowchart which shows the other operation example of a motor control stop / restart timing detection part. It is a block diagram for demonstrating the electric constitution of the electric power steering apparatus which concerns on other embodiment of this invention. It is a flowchart for demonstrating the function of a motor control stop timing detection part. It is a flowchart for demonstrating the function of a motor control stop process part.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
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 angle calculation unit. 26, an indicated current value generation unit 30, an indicated current value change unit 31, a current deviation calculation unit 32, a PI control unit 33, a γδ / UVW conversion unit 34, a PWM (Pulse Width Modulation) control unit 35, , A UVW / γδ conversion unit 36, a motor control stop / restart timing detection unit 41, and a motor control stop / restart processing unit 42 are included.

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.

Steering torque limiter 20, the output of the torque sensor 1 _{T S} a predetermined upper saturation value _{+ T max (+ T max>} 0. For example + T _max = 7Nm) and lower saturation value -T _max (-T _max <0. For example -T _max = −7 Nm). Specifically, the steering torque limiter 20, as shown in FIG. 5, between the upper saturation value + T _max and the lower limit saturation value -T _max, directly outputs the detected steering torque T _S of the torque sensor 1. Also, the steering torque limiter 20, the detected steering torque T _S of the torque sensor 1 is equal upper saturation value + T _max above, outputs the upper saturation value + T _max. Then, the steering torque limiter 20, the detected steering torque T _S of 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.

The addition angle limiter 24 is addition angle control 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). Using the limit value ω _max , the upper limit value UL and the lower limit value LL of the addition angle α can be expressed by the following equations (2) and (3), respectively.

UL = + ω _max (2)
LL = −ω _max (3)
The limit value ω _max is normally set to a predetermined reference value Ω (hereinafter referred to as a limit reference value; for example, Ω = 45 degrees). The limit value ω _max is gradually decreased or gradually increased in the motor control stop process and restart process, as will be described later. For example, the limit reference value Ω is determined based on the maximum steering angular velocity. 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 the maximum steering angular speed, the reduction ratio of the speed reduction mechanism 7, the rotor 50, as shown in the following equation (4). Given by the product of the 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 50 has.
Maximum rotor angular speed = Maximum steering angular speed x Reduction ratio x Number of pole pairs (4)
The maximum electrical angle change amount (rotor angle change amount maximum value) of the rotor 50 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 (5). 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 computation cycle (5)
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 maximum value of the rotor angle change may be set as the limit reference value Ω.
The addition angle α after the limit processing by the addition angle limiter 24 is added to the previous value θ _C (n−1) (n is the number of the current calculation cycle) of the control angle θ _C in the adder 26A of the control angle calculation unit 26. (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 limiter 24 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) that is the control angle θ _C in the current calculation cycle is obtained.
The command current value generation unit 30 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 30 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 30 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 command current value changing unit 31 is provided to change the two-phase command current value I ′ _γδ ^* generated by the command current value generating unit 30. The command current value changing unit 31 is controlled by the motor control stop / restart processing unit 42. The command current value changing unit 31 normally outputs the two-phase command current value I ′ _γδ ^* generated by the command current value generating unit 30 as it is. The γ-axis command current value and the δ-axis command current value output from the command current value changing unit 31 are represented by I _γ ^* and I _δ ^* . These are collectively referred to as “two-phase command current value I _γδ ^* ”.

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 ^* output from the command current value change 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 UVW / γδ conversion unit 36 to the deviation calculation unit 32.
The UVW / γδ conversion unit 36 converts the three-phase detection current I _UVW (U-phase detection current I _U , V-phase detection current I _V and W-phase detection current I _W ) of the UVW coordinate system detected by the current detection unit 13 to γδ. Two-phase detection currents I _γ and I _{δ in the} coordinate system (hereinafter collectively referred to as “two-phase detection currents I _γδ ”). These are supplied to the current deviation calculation unit 32. For the coordinate conversion in the UVW / γδ conversion unit 36, 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 / UVW conversion unit 34.
The γδ / UVW conversion unit 34 generates a three-phase instruction voltage V _UVW ^* by performing a coordinate conversion operation on the two-phase instruction voltage V _γδ ^* . 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 30.
The motor control stop / restart timing detection unit 41 detects a timing at which the motor control should be stopped (motor control stop timing) and a timing at which the motor control should be restarted after stopping the motor control (motor control restart timing). The specific operation of the motor control stop / restart timing detection unit 41 will be described later.

  The motor control stop / restart processing unit 42 includes a motor control stop processing unit 43 and a motor control restart processing unit 44. In response to the detection of the motor control stop timing by the motor control stop / restart timing detection unit 41, the motor control stop processing unit 43 performs a process for stopping the motor control. In response to the detection of the motor control restart timing by the motor control stop / restart timing detection unit 41, the motor control restart processing unit 44 performs a process for restarting the motor control. Specific operations of the motor control stop processing unit 43 and the motor control restart processing unit 44 will be described later.

FIG. 3 is a control block diagram of the electric power steering apparatus. However, for the sake of simplicity, the function of the addition angle limiter 24 is 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.
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 with the upper limit value UL (step S1), and when the addition angle α exceeds the upper limit value UL (step 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 is equal to or smaller than the upper limit value UL (step S1: NO), the addition angle limiter 24 further compares the addition angle α with the lower limit value LL (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.

The addition angle α obtained or lower than the lower limit LL or the upper limit UL by the PI control unit 23: if (step S3 NO), the addition angle α is used as is added to the control angle theta _C.
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. 8 is a flowchart for explaining the operation of the motor control stop / restart timing detection unit 41. The process shown in FIG. 8 is executed every calculation cycle. The motor control stop / restart timing detection unit 41 is a timing at which the motor control should be stopped when the absolute value of the detected steering torque T _S (output value of the torque sensor) is a predetermined value or more continues for a predetermined time or longer ( Motor control stop timing). Further, the motor control stop and resumption timing detection unit 41, when the motor control is stopped, when the absolute value of the detected steering torque T _S is the state of less than the predetermined value continues for a predetermined time or more, resumed motor control It is determined that it should be the timing (motor control restart timing).

  The motor control stop / restart timing detection unit 41 determines whether or not the control stop flag F is set (step S11). The control stop flag F is a flag for storing that the motor control is in a stop state. If the motor control is in a stop state, it is set (F = 1), and if the motor control is not in a stop state. Reset (F = 0). Note that the initial value of the control stop flag F is zero.

If the control stop flag F is not set (step S11: NO), that is, when the motor control is being executed, the timing detection unit 41 sets the second count value K2 to 0 (step S12). , the absolute value of the detected steering torque _{T S} is determined whether or not a predetermined value _{T th} or more (step S13). The predetermined value T _th is set to the same value as the saturation value T _max described above, for example. If the absolute value is less than the predetermined value _{T th} of the detected steering torque _{T S} (step S13: NO), the timing detection unit 41, the detected steering torque _{T S} is determined that not saturated, the first count value K1 After setting to 0 (step S14), the processing in the current calculation cycle is terminated. Note that the initial values of the first count value K1 and the second count value K2 are zero.

On the other hand, when the absolute value of the detected steering torque T _S is determined to be the predetermined value T _th or more (Step S13: YES), the timing detection unit 41, determines that the detected steering torque T _S is saturated Then, the first count value K1 is incremented by 1 (step S15). Then, the timing detection unit 41 determines whether or not the first count value K1 is greater than or equal to a predetermined value Na (step S16). If the first count value K1 is less than the predetermined value Na (Step S16: NO), the timing detection unit 41 determines that the state where the detected steering torque T _S is saturated does not continue for a predetermined time or more Then, the processing in the current calculation cycle is finished.

In step S16, when the first count value K1 is determined to be equal to or greater than the predetermined value Na, the timing detection unit 41, a state where the detected steering torque T _S is saturated has continued for a predetermined time or more The stop timing detection flag Fa is set (Fa = 1), and the stop process initial flag Fas is set (Fas = 1) (step S17). Then, the processing in the current calculation cycle is finished.

In step S11, if the control stop flag F is set (step S11: YES), that is, if the motor control is stopped, the timing detection unit 41 sets the first count value K1. After setting to 0 (step S18), it is determined whether or not the absolute value of the detected steering torque T _S is less than a predetermined value T _th (step S19). If the absolute value of the detected steering torque _{T S} is equal to the predetermined value _{T th} or more (step S19: NO), the timing detection unit 41 determines that the detected steering torque _{T S} is saturated, the second count value K2 After setting to 0 (step S20), the processing in the current calculation cycle is terminated.

On the other hand, when it is determined that the absolute value of the detected steering torque T _S is less than the predetermined value T _th (step S19: YES), the timing detection unit 41 determines that the detected steering torque T _S is not saturated. Then, the second count value K2 is incremented by 1 (step S21). Then, the timing detection unit 41 determines whether or not the second count value K2 is greater than or equal to a predetermined value Nb (step S22). If the second count value K2 is less than the predetermined value Nb (step S22: NO), the timing detection unit 41 determines that the state where the detected steering torque T _S is not saturated is not continued for a predetermined time or more Then, the processing in the current calculation cycle is finished.

In the step S22, if the second count value K2 is determined to be equal to or greater than the predetermined value Nb, the timing detection unit 41, a state where the detected steering torque T _S is not saturated has continued for a predetermined time or more And the restart timing detection flag Fb is set (Fb = 1), and the restart process initial flag Fbs is set (Fbs = 1) (step S23). Then, the processing in the current calculation cycle is finished.

  FIG. 9 is a flowchart for explaining the operation of the motor control stop processing unit 43. The motor control stop processing unit 43 determines whether or not the stop timing detection flag Fa is set (step S31). If the stop timing detection flag Fa is not set (step S31: NO), the motor control stop processing unit 43 ends the current process without performing the process for stopping the motor control.

  On the other hand, if the stop timing detection flag Fa is set (step S31: YES), the motor control stop processing unit 43 performs a process for stopping the motor control (hereinafter referred to as "motor control stop process") ( Step S32). Details of the motor control stop process will be described later. When the motor control stop process ends, the motor control stop processing unit 43 sets the control stop flag F (F = 1) (step S33). And this process is complete | finished.

  FIG. 10 is a flowchart showing a detailed procedure of the motor control stop process in step S32 of FIG. The motor control stop processing unit 43 determines whether or not the stop processing initial flag Fas is set (Fas = 1) (step S41). The stop process initial flag Fas is set immediately after the motor control stop process is started (see step S17 in FIG. 8).

If the stop process initial flag Fas is set (step S41: YES), the motor control stop processing unit 43 uses the current γ-axis command current value I _γ ^* (n) output from the command current value changing unit 31. The γ-axis command current value I ′ _γ ^* generated by the command current value generation unit 30 is set (step S42). Further, the motor control stop processing unit 43 sets the current limit value ω _max (n) set in the addition angle limiter 24 to the limit reference value Ω (step S43), and then resets the stop process initial flag Fas (Fas = 0) (step S44). Then, the process proceeds to step S51.

In step S51, the motor control stop processing unit 43 uses the current γ-axis command current value I _γ ^* (n) output from the command current value change unit 31 as the previous γ-axis command current value I _γ ^* (n− Remember as 1). Further, the motor control stop processing unit 43 stores the current limit value ω _max (n) set in the addition angle limiter 24 as the previous limit value ω _max (n−1) (step S52). Then, the process returns to step S41.

If the stop process initial flag Fas is reset (Fas = 0) in step S41 (step S41: NO), the motor control stop processing unit 43 determines that the previous limit value ω _max (n−1) is It is determined whether or not the value is equal to or greater than a predetermined value A (step S45). This predetermined value A is set to about 0 to 1 degree, for example. When the previous limit value ω _max (n−1) is equal to or greater than the predetermined value A (step S45: YES), the motor control stop processing unit 43 determines whether or not the predetermined limit value ω _max (n−1) The value obtained by subtracting the gradual decrease amount Δωa is set in the addition angle limiter 24 as the current limit value ω _max (n) (step S46). Then, the process proceeds to step S51.

If it is determined in step S45 that the previous limit value ω _max (n−1) is less than the predetermined value A (step S45: NO), the motor control stop processing unit 43 determines that the current limit value ω _max (n) is set to 0 (step S47). Then, the motor control stop processing unit 43 determines whether or not the previous γ-axis command current value I _γ ^* (n−1) is larger than the predetermined value B (step S48). This predetermined value B is set to 0, for example.

When the previous γ-axis command current value I _γ ^* (n−1) is larger than the predetermined value B (step S48: YES), the motor control stop processing unit 43 causes the previous γ-axis command current value I _γ ^*. A value obtained by subtracting a predetermined gradual decrease amount ΔIa from (n−1) is set as the current γ-axis command current value I _γ ^* (n) output from the command current value changing unit 31 (step S49). However, when the value obtained by subtracting the predetermined gradual decrease ΔIa from the previous γ-axis command current value I _γ ^* (n−1) is smaller than 0, the current γ-axis command current value I _γ ^* (n) is 0. Set to When the process of step S49 ends, the process proceeds to step S51.

If it is determined in step S48 that the previous γ-axis command current value I _γ ^* (n-1) is equal to or less than the predetermined value B (step S48: NO), the motor control stop processing unit 43 After the stop timing detection flag Fa is reset (Fa = 0) (step S50), the motor control stop process is terminated.
That is, when the motor control stop process is started, first, the current γ-axis command current value I _γ ^* (n) is set to the command current value I _γ ^* generated by the command current value generation unit 30, and The current limit value ω _max (n) is set to the limit reference value Ω (see steps S42 and S43). Thereafter, only the limit value ω _max (n) is gradually reduced (see steps S45 and S46). When the limit value ω _max (n) is less than the predetermined value A, the limit value ω _max (n) is set to 0 (see steps S45 and 47). After the limit value ω _max (n) is set to 0, the γ-axis command current value I _γ ^* (n) is gradually decreased (see steps S48 and S49). When the γ-axis command current value I _γ ^* (n) becomes equal to or less than the predetermined value B, the stop timing detection flag Fa is reset, and the motor control stop process ends (see steps S48 and S50).

When motor control is stopped, if the γ-axis command current value I _γ ^* (n) is simply decreased gradually, the assist torque required for the motor load is output while the command current value I _γ ^* (n) is gradually decreased. In some cases, the value detected by the torque sensor 1 exceeds a reliable range, and torque feedback control does not operate normally.
Therefore, as in the above-described embodiment, when the motor control is stopped, the limit value ω _max (n) is gradually decreased to 0, and then the command current value I _γ ^* (n) is gradually decreased to a predetermined value B or less. As a result, the command current value I _γ ^* (n) is gradually decreased until the control angle θ _C is fixed so as not to change until the command current value I _γ ^* (n) becomes equal to or less than the predetermined value B. Thus, it is possible to stop the motor 3 smoothly by the limitation of the control angle theta _C. When the control angle θ _C is fixed, the motor 3 is in a locked state. Thereafter, when the command current value I _γ ^* (n) is gradually decreased to a predetermined value B or less, torque feedback control is performed. Even if it does not operate normally, the behavior of the motor 3 is not affected.

  FIG. 11 is a flowchart for explaining the operation of the motor control restart processing unit 44. The motor control restart processing unit 44 determines whether or not the restart timing detection flag Fb is set (step S61). If the restart timing detection flag Fb is not set (step S61: NO), the motor control restart processing unit 44 ends the current process without performing the process for restarting the motor control.

  On the other hand, if the resumption timing detection flag Fb is set (step S61: YES), the motor control resumption processing unit 44 performs a process for resuming the motor control (hereinafter referred to as “motor control resumption process”) ( Step S62). Details of the motor control restart process will be described later. When the motor control restart process ends, the motor control restart processing unit 44 resets the control stop flag F (step S63). And this process is complete | finished.

  FIG. 12 is a flowchart showing a detailed procedure of the motor control restart process in step S62 of FIG. The motor control restart processing unit 44 determines whether or not the restart processing initial flag Fbs is set (Fbs = 1) (step S71). The restart process initial flag Fbs is set immediately after the start of the motor control restart process (see step S23 in FIG. 8).

If the resumption process initial flag Fbs is set (step S71: YES), the motor control resumption processing unit 44 uses the current γ-axis instruction current value I _γ ^* (n) output from the instruction current value changing unit 31. , 0 is set (step S72). Further, the motor control restart processing unit 44 sets the current limit value ω _max (n) set in the addition angle limiter 24 to 0 (step S73), and then resets the restart processing initial flag Fbs (Fbs = 0). (Step S74). Then, the process proceeds to step S81.

In step S81, the motor control restart processing unit 44 uses the current γ-axis command current value I _γ ^* (n) output from the command current value change unit 31 as the previous γ-axis command current value I _γ ^* (n− Remember as 1). In addition, the motor control restart processing unit 44 stores the current limit value ω _max (n) set in the addition angle limiter 24 as the previous limit value ω _max (n−1) (step S82). Then, the process returns to step S71.

In step S71, when the restart process initial flag Fbs is reset (Fbs = 0) (step S71: NO), the motor control restart processor 44 determines that the previous γ-axis command current value I _γ ^* (n It is determined whether (-1) is less than a predetermined value C (step S75). This predetermined value C is set to the rated current value of the motor 3, for example. When the previous γ-axis command current value I _γ ^* (n−1) is less than the predetermined value C (step S75: YES), the motor control restart processing unit 44 sets the previous γ-axis command current value I _γ ^*. A value obtained by adding a predetermined incremental amount ΔIb to (n−1) is set as the current γ-axis command current value I _γ ^* (n) output from the command current value changing unit 31 (step S76). Further, the current limit value ω _max (n) is set to 0 (step S77). Then, the process proceeds to step S81.

If it is determined in step S75 that the previous γ-axis command current value I _γ ^* (n-1) is equal to or greater than the predetermined value C (step S75: NO), the motor control restart processing unit 44 It is determined whether or not the limit value ω _max (n−1) is less than a predetermined value D (step S78). The predetermined value D is set to, for example, about 14 to 17 degrees. When the previous limit value ω _max (n−1) is less than the predetermined value D (step S78: YES), the motor control restart processing unit 44 sets the predetermined limit value ω _max (n−1) to a predetermined value. A value obtained by adding the incremental amount Δωb is set in the addition angle limiter 24 as the current limit value ω _max (n) (step S79). Then, the process proceeds to step S81.

When it is determined in step S78 that the previous limit value ω _max (n−1) is equal to or greater than the predetermined value D (step S78: NO), the motor control restart processing unit 44 determines the restart timing detection flag Fb. Is reset (Fb = 0) (step S80), the motor control restart process is terminated.
That is, when the motor control restart process is started, first, the current γ-axis command current value I _γ ^* (n) is set to 0, and the current limit value ω _max (n) is set to 0. (See steps S72 and S73). Thereafter, only the γ-axis command current value I _γ ^* (n) is gradually increased (see steps S75 and S76). When the γ-axis command current value I _γ ^* (n) becomes equal to or greater than the predetermined value C, the limit value ω _max (n) is gradually increased (see steps S78 and S79). When the limit value ω _max (n) becomes equal to or greater than the predetermined value D, the restart timing detection flag Fb is reset, and the motor control restart process ends (see steps S78 and S80).

When resuming motor control, if the γ-axis command current value I _γ ^* (n) is gradually increased from 0 to a predetermined value or more, the command current value I _γ ^* (n) is required for the motor load. Until the value corresponding to the assist torque is reached, the value detected by the torque sensor 1 may exceed a reliable range, and torque feedback control may not operate normally.
Therefore, as in the above embodiment, when the motor control is resumed, the command current value I _γ ^* (n) is gradually increased to a predetermined value C or more with the limit value ω _max (n) fixed at 0. Then, the command current value I _γ ^* (n) is gradually increased until the control angle θ _C is fixed so as not to change until the command current value I _γ ^* (n) becomes equal to or greater than the predetermined value C. When the control angle θ _C is fixed, the motor 3 is in a locked state. _Therefore , when the command current value I _γ ^* (n) is gradually increased to a predetermined value C or more, the torque feedback control operates normally. Even if not, the behavior of the motor 3 is not affected. In this way, after the command current value I _γ ^* (n) is gradually increased to the predetermined value C or more, the limit value ω _max (n) is gradually increased to the predetermined value D or more, so that the motor control is smoothly performed. Can be resumed.

  FIG. 13 is a flowchart illustrating another operation example of the motor control stop / restart timing detection unit 41. In this operation example, the motor control stop / restart timing detection unit 41 determines that it is time to stop the motor control when the vehicle is stopped. In addition, when the motor control is stopped, the motor control stop / restart timing detection unit 41 determines that it is time to restart the motor control when the vehicle changes from the stop state to the travel state. Whether the vehicle has stopped or whether the vehicle has changed from a stopped state to a traveling state is determined based on a vehicle speed detected by the vehicle speed sensor 6 (hereinafter referred to as “detected speed V”).

The motor control stop / restart timing detection unit 41 determines whether or not the control stop flag F is set (step S91). If the control stop flag F is not set (step S91: NO), that is, when the motor control is being executed, the timing detector 41 determines whether or not the detected speed V is less than a predetermined value V _thL. A determination is made (step S92). This predetermined value T _thL is set to a value close to 0, for example. If the detected speed V is equal to or higher than the predetermined value V _thL (step S92: NO), the timing detection unit 41 determines that the vehicle is not stopped, and ends the processing in the current calculation cycle.

On the other hand, if the detection speed V is less than the predetermined value V _thL , the timing detection unit 41 determines that the vehicle has stopped, sets the stop timing detection flag Fa (Fa = 1), and stops the process first flag. Fas is set (Fas = 1) (step S93). Then, the processing in the current calculation cycle is finished.
In step S91, if the control stop flag F is set (step S91: YES), that is, if the motor control is in a stopped state, the timing detection unit 41 sets the detected speed V to a predetermined value. It is determined whether or not V _thH or more (step S94). The predetermined value T _thH is set to a value slightly larger than the predetermined value V _thL . If the detected speed V is less than the predetermined value V _thH (step S94: NO), the timing detection unit 41 determines that the vehicle is not in a traveling state, and ends the processing in the current calculation cycle.

On the other hand, when it is determined that the detected speed V is equal to or higher than the predetermined value V _thH (step S94: YES), the timing detection unit 41 determines that the vehicle is in the traveling state and sets the restart timing detection flag Fb. (Fb = 1) and the restart process initial flag Fbs is set (Fbs = 1) (step S95). Then, the processing in the current calculation cycle is finished.
FIG. 14 is a block diagram for illustrating a configuration of an electric power steering apparatus according to the second embodiment of the present invention. In FIG. 14, parts corresponding to those shown in FIG. 1 are given the same reference numerals.

In this embodiment, the motor control stop / restart timing detection unit 41 and the motor control stop / restart processing unit 42 are not provided. In this embodiment, a motor control stop timing detection unit 45 and a motor control stop processing unit 46 are provided as function processing units of the microcomputer 11.
FIG. 15 is a flowchart for explaining the operation of the motor control stop timing detection unit 45. The process of FIG. 15 is executed for each calculation cycle. When the motor control stop timing detection unit 45 detects a component failure (step S101: YES), the motor control stop timing detection unit 45 sets a stop timing detection flag Fa (Fa = 1) and sets a stop process initial flag Fas (Fas = 1). (Step S102). The failure of the component includes, for example, a failure of the torque sensor 1, a failure of the current detection unit 13, a disconnection of the motor wire, and the like.

  FIG. 16 is a flowchart for explaining the operation of the motor control stop processing unit 46. The motor control stop processing unit 46 determines whether or not the stop timing detection flag Fa is set (Fa = 1) (step S111). When the stop timing detection flag Fa is reset (Fa = 0) (step S111: NO), the motor control stop processing unit 46 performs the current process without performing the process for stopping the motor control. finish. On the other hand, when the stop timing detection flag Fa is set (Fa = 1) (step S111: YES), the motor control stop processing unit 46 performs a motor control stop process (step S112). When the motor control stop process ends, the current process ends.

The motor control stop process executed in step S112 is the same as the motor control stop process executed in step S32 of FIG. That is, the motor control stop process executed in step S112 is the same as the motor control stop process described with reference to FIG.
As mentioned above, although several embodiment of this invention was described, this invention can also be implemented with another form. For example, in the above-described embodiment, the motor control stop processing units 43 and 46 and the motor control restart processing unit 44 gradually decrease or gradually increase the command current value I _γδ ^* as the drive value of the motor 3, but the command current value I _{the ??} ^* instead the command voltage V _{the ??} ^*, may be a V _UVW ^* so as to gradually decrease or gradually increased as the drive value of the motor 3.

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. The sensorless control may be performed. 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 the rotation angle sensor is used, the command current value generation unit 30 may generate the δ-axis command current value I _δ ^* according to a 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, 50 ... Rotor, 51, 52, 53 ... Stator winding, 55 ... Stator

Claims (3)

A motor control device for controlling a motor including 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;
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;
Addition angle limiting means for limiting the absolute value of the addition angle to a limit value or less;
A motor control device, comprising: stop processing means for gradually decreasing the limit value to zero when the motor control is stopped, and then gradually decreasing the drive value of the motor to a predetermined value or less.   When resuming motor control, restart processing means for gradually increasing the drive value of the motor to a predetermined value or more and then gradually increasing the limit value to a predetermined value or more with the limit value fixed at zero The motor control device according to claim 1, further comprising: A motor for applying a driving force to the steering mechanism of the vehicle;
A vehicle steering apparatus, comprising: the motor control apparatus according to claim 1, which controls the motor.

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