JP5376213B2 - Motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a motor by a new control method which does not use a rotation angle sensor. <P>SOLUTION: The motor is driven at a &gamma;-axis current I<SB>&gamma;</SB>of a &gamma;&delta;-coordinate system which is a virtual rotating coordinate system. The &gamma;&delta;-coordinate system follows a control angle &theta;<SB>C</SB>which is a rotation angle on control. An assist torque T<SB>A</SB>is generated according to a load angle &theta;<SB>L</SB>which is a difference between the control angle &theta;<SB>C</SB>and a rotor angle &theta;<SB>M</SB>. Alternatively, a steering torque T is fed back, and an addition angle &alpha; is generated so that the steering torque T approximates a command steering torque T<SP>*</SP>. A present value &theta;<SB>C</SB>(n) of the control angle &theta;<SB>C</SB>is obtained by adding the angle &alpha; to a previous value &theta;<SB>C</SB>(n-1) of the control angle &theta;<SB>C</SB>. An angle speed operation unit 27 obtains a rotation angle speed &omega; on the basis of an interval between zero-cross points of a three-phase detection current I<SB>UVW</SB>. A correction unit 28 makes correction to the rotation angle speed &omega; according to a change of the command steering torque T<SP>*</SP>. An angle speed adaptation control unit 29 changes a gain of a PI control unit 33 on the basis of the rotation angle speed &omega;. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a motor control device for driving a brushless motor. 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 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.

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 application. For example, this drive system is used to control a brushless motor used as a drive source of an electric power steering device that applies a steering assist force to a steering mechanism of a vehicle. The method 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 apparatus that can control a motor by a new control method that does not use a rotation angle sensor.

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 (31-36) for performing current feedback control to drive the motor with an axial current value of a rotating coordinate system in accordance with a control angle (θ _C ) which is a control rotation angle; and the motor An instruction torque setting means (21) for setting an instruction torque as an instruction value of a torque other than the motor torque to be applied to the drive object driven by the motor, and for detecting a torque other than the motor torque acting on the drive object Torque detection means (1), a torque deviation which is a deviation between the instruction torque set by the instruction torque setting means and the detection torque detected by the torque detection means And an addition angle calculation means (22, 23) for calculating an addition angle (α) to be added to the control angle by performing a proportional integral calculation on the torque deviation, and for each predetermined calculation cycle, The control angle calculation means (26) for calculating 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, and the motor current waveform of the motor or applied to the motor The angular velocity calculating means (27) for calculating the rotational angular speed of the motor from the interval of the zero cross points of the motor voltage waveform, and the difference between the control angle calculated by the control angle calculating means and the rotational angle (θ _M ) of the rotor in accordance with a change of the change and the command torque that correlates the load angle (theta _L) represented, and correcting means (28) for correcting the rotational angular velocities calculated by the angular velocity calculating means, before Serial saw including a changing means for changing the motor control mode (29) in accordance with the rotational angular velocity corrected by the correcting means, change of the motor control mode is the change in the gain of the current feedback control, or the control angle and A load angle adjusting method for controlling the motor by adjusting the load angle by using the shaft current value, and a rotation angle of the rotor is estimated based on an induced voltage estimated based on the motor current and the motor voltage. , it switched including the induced voltage estimation method for performing energization control to the motor based on the rotation angle which is the estimated, a motor control device. 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 “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. When the shaft current value is constant, the torque generated from the motor has a value corresponding to the load angle represented by the difference between the control angle and the rotor rotation angle. The addition angle may be determined according to, for example, a torque that should be generated by the motor or a torque other than the motor torque that should be applied to an object driven by the motor.

Furthermore, in the present invention, the rotational angular velocity of the motor is calculated based on the interval between the zero cross points of the motor current waveform or the motor voltage waveform. Therefore, control using the rotational angular velocity of the motor can be added.
Furthermore, the rotation angular velocity calculated according to the interval between the zero cross points is corrected according to the change in the load angle. If the load angle is stable, the relationship between the rotor rotation angle and the control angle is stable. Therefore, the rotation angular velocity calculated based on the motor current (stator current) or the phase of the motor voltage is a reasonable value. Take. On the other hand, when the load angle changes, the relationship between the rotor rotation angle and the control angle changes. Therefore, an error between the rotational angular velocity calculated based on the motor current or motor voltage phase of the load angle and the actual rotational angular velocity of the rotor increases. Therefore, in the present invention, the rotational angular velocity is corrected according to the change in the load angle. Thereby, a reasonable rotational angular velocity can be obtained.

  More specifically, when the load angle tends to increase, the control angle changes faster than the rotor rotation angle, so the rotation angular velocity calculated based on the phase of the motor current or motor voltage may be corrected to decrease. . On the other hand, when the load angle tends to decrease, the change in the control angle is slower than the rotor rotation angle. Therefore, the rotation angular velocity calculated based on the phase of the motor current or motor voltage may be increased and corrected.

  The load angle corresponds to the torque that should be generated by the motor. That is, when the torque to be generated by the motor tends to increase, the load angle also tends to increase, and when the torque to be generated by the motor tends to decrease, the load angle also tends to decrease. Therefore, when the torque to be generated by the motor tends to increase, the rotational angular velocity is corrected to decrease. When the torque to be generated by the motor tends to decrease, the rotational angular velocity is corrected to increase.

The present invention acts on driven by the motor, generates an instruction value of the torque other than the motor torque (instruction torque), Ru configuration der that calculates the addition angle based on the instruction torque. In this case, the rotational angular velocity can be corrected according to the correlation between the instruction torque and the torque that should be generated by the motor. In other words, if there is a positive correlation between the command torque and the torque that should be generated by the motor, the rotation angular velocity is corrected to decrease when the command torque tends to increase, and the rotation angular velocity is corrected to increase when the command torque tends to decrease. Good. On the other hand, if there is a negative correlation between the command torque and the torque that should be generated by the motor, the rotation angular velocity is corrected to increase when the command torque is increasing, and the rotation angular velocity is corrected to decrease when the command torque is decreasing. That's fine. As a result, when the load angle tends to increase, the rotational angular velocity is corrected to decrease, and when the load angle tends to decrease, the rotational angular velocity is corrected to increase. In other words, by utilizing the fact that there is a correlation between the change in load angle and the change in command torque, the rotation angular speed can be corrected according to the change in load angle by correcting the rotation angular speed according to the change in command torque. Become.

More specifically, the motor control device includes an instruction torque setting means (21) for setting an instruction torque other than the motor torque to be applied to the drive target of the motor, and a function other than the motor torque that is applied to the drive object. torque torque detecting means (1) for detecting (detected torque) and the including. In this case, the addition angle calculation means constitutes a feedback control means (22, 23) for calculating the addition angle so that the detected torque approaches the command torque.

Changing the motor control mode in accordance with the motor rotational angular velocity (rotational angular velocity corrected by the correcting means), specifically, changing the control gain for the axis current value control (current feedback control) in response to the rotational angular velocity Control may be performed. Also, for example, in the low speed region where the rotational angular velocity is low, the low speed region control (load angle adjustment method) using the control angle and the shaft current value is executed, and in the high speed region where the rotational angular velocity is high, another high speed region control is performed. When executed, the rotational angular velocity may be used to switch between these controls. Specifically, the high-speed control is based on estimating the rotor rotation angle based on the estimated value of the motor induced voltage, and performing energization control on the motor using the estimated rotor rotation angle (the induced voltage estimation method). ) Ru der.

As described in claim 2, the motor may provide a driving force to the steering mechanism (2) of the vehicle. In this case, the torque detection means detects the steering torque applied to the operation member (10) that is operated to steer the vehicle. The command torque setting means sets command steering torque (command torque) based on the steering angle of the operation member . The addition angle calculation means, you calculates the addition angle based on the deviation between the steering torque detected by the command steering torque and the torque detection means is set by the command steering torque setting unit.

  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 steering torque setting means indicates instruction steering according to a steering angle detected by the steering angle detection means. The torque 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 steering torque setting unit may set the command steering torque according to the vehicle speed detected by the vehicle speed detection unit (6) that detects 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.
The invention according to claim 3 is the motor control device according to claim 2, wherein the instruction torque setting means sets the instruction steering torque based on a vehicle speed of the vehicle and a steering angle of the operation member. .
The invention according to claim 4 is the motor control device according to any one of claims 1 to 3, which can control the motor without using a rotation angle sensor.

1 is a block diagram for explaining an electrical configuration of an electric power steering device 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 which shows the example of a setting of (gamma) axis instruction | indication electric current value. It is a block diagram which shows the structural example of an angular velocity calculating part. It is a wave form diagram for demonstrating the space | interval of the zero crossing point of a three-phase detection electric current. It is a figure for demonstrating the pulsation of a detection steering torque. It is a figure for demonstrating the function of a correction | amendment 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 an 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 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, a control angle calculation unit 26, and an angular velocity calculation unit. 27, a correction unit 28, an angular velocity adaptive control unit 29, a command current value generation unit 31, a current deviation calculation unit 32, a PI control unit 33, a γδ / UVW conversion unit 34, and a PWM (Pulse Width Modulation). A control unit 35 and a UVW / γδ conversion unit 36 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, for example, 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 The instruction steering torque T ^* is set to a negative value (torque in the left direction) when the value is negative (a state in which steering is performed 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 torque deviation calculation unit 22 is a commanded steering torque T ^* set by the commanded steering torque setting unit 21 and a steering torque T detected by the torque sensor 1 (hereinafter referred to as “detected steering torque T” for distinction). Deviation (torque deviation) ΔT. 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.

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 a predetermined limit value ω _max (ω _max > 0, for example, ω _max = 45 degrees). The predetermined limit value ω _max is determined based on, for example, 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, and the rotor 50 as shown in the following equation (2). 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 (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 maximum value of the rotor angle change may be set to the limit value 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 (4) and (5), respectively.

UL = + ω _max (4)
LL = −ω _max (5)
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), which is the control angle θ _C in the current calculation cycle, is obtained.
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 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 31.
The angular velocity calculator 27 calculates the rotational angular velocity ω of the rotor 50 based on the motor current detected by the current detector 13. In this embodiment, the angular velocity calculator 27 calculates the rotational angular velocity ω based on the three-phase detection current I _UVW . However, the angular velocity calculation unit 27 may calculate the rotation angular velocity ω based on the two-phase detection current I _γδ generated by the UVW / γδ conversion unit 36.

The correcting unit 28 corrects the rotational angular velocity ω obtained by the angular velocity calculating unit 27. More specifically, the correction unit 28 performs a correction corresponding to the change in the load angle theta _L with respect to the rotational angular velocity omega. Load angle theta _L, as described above, the difference between the control angle theta _C and the rotor angle theta _M, corresponds to the torque motor 3 to be generated (assist torque). In this embodiment, the command steering torque T ^* takes a larger value as the steering angle increases. Moreover, since the torque (load torque) input from the road surface to the steering mechanism 2 increases as the steering angle increases, the torque (assist torque) to be generated by the motor 3 also increases. That is, there is a positive correlation between the command steering torque T ^* and the torque that should be generated by the motor 3. Therefore, if the increase is the command steering torque T ^*, the load angle theta _L is also increasing, the command steering torque T ^* is also the load angle theta _L if decreasing a decreasing trend. Therefore, in this embodiment, the correction unit 28 performs a correction with respect to the rotation angular velocity ω in response to the change of the command steering torque T ^*, thereby, in effect, in accordance with a change in the load angle theta _L Correction is performed on the rotational angular velocity ω.

  The angular velocity adaptive control unit 29 changes the control mode according to the rotational angular velocity ω corrected by the correction unit 28. In this embodiment, the angular velocity adaptive control unit 29 changes the control gain of the PI control unit 33 (current feedback control gain). For example, the angular velocity adaptive control unit 29 may lower the control gain as the absolute value of the rotational angular velocity ω increases.

However, changing the control mode is not limited to the change of the current feedback control gain, a motor control for adjusting the load angle theta _L (load angle adjusting method), or may be a switching between motor control of the other aspects . As motor control other than the load angle adjustment method, for example, an induced voltage of the motor 3 is estimated based on the motor current and the motor voltage, and the rotation angle of the rotor 50 is estimated based on the estimated induced voltage. An induced voltage estimation method that performs energization control to the motor 3 based on the rotation angle that has been made can be mentioned.

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. 6 is a block diagram illustrating a configuration example of the angular velocity calculation unit 27. The angular velocity calculation unit 27 includes a zero-cross point detection unit 41, a dead zone setting unit 42, a zero-cross point interval calculation unit 43, a division unit 44, a convergence determination unit 45, and a pulsation determination unit 46.

The zero cross point detector 41 detects a zero cross point of the three-phase detection current I _UVW . More specifically, the zero cross point of the U phase detection current I _U , the zero cross point of the V phase detection current _IV , and the zero cross point of the W phase detection current I _W are detected. The zero cross point is a point where the positive / negative of the current value is reversed. As shown in FIG. 7, the zero-cross point of the three-phase detection current I _UVW appears every π / 3 (rad) in the rotor rotation angle (electrical angle).

The dead zone setting unit 42 executes dead zone processing for invalidating the detection of the zero cross point for a certain time (for example, 600 μsec) after the zero cross point detection unit 41 detects the zero cross point. Thereby, when noise is mixed in the vicinity of the zero cross point, an error in estimation of the rotational angular velocity due to the noise is suppressed.
The zero cross point interval calculation unit 43 calculates a time interval (zero cross point interval) t between the zero cross points after the dead zone processing. As described above, this time interval corresponds to π / 3 in the rotor rotation angle. Therefore, the division unit 44 divides π / 3 by the zero cross point interval t. Thereby, the rotational angular velocity ω = π / 3t is obtained. The rotation direction can be obtained based on the detection order of the zero-cross point of the UVW phase.

The zero-cross point detection unit 41 detects zero-cross points of the two-phase detection currents I _α and I _β obtained by converting the three-phase detection current I _UVW into a two-phase fixed coordinate system (αβ coordinate system). Also good. In this case, since the time interval t between the zero cross points corresponds to π / 2 (rad), the division unit 44 obtains the rotational angular velocity ω = π / 2t. The direction of rotation can be determined by observing the sign of the other current at the zero cross point of one current.

  The convergence determination unit 45 and the pulsation determination unit 46 constitute a probability information generation unit 47 that generates information (accuracy information) indicating the probability of the rotational angular velocity ω. The accuracy information generated by the accuracy information generation unit 47 is given to the angular velocity adaptive control unit 29. The angular velocity adaptive control unit 29 interrupts the control according to the rotation angular velocity ω, when the accuracy information indicating that the probability of the rotation angular velocity ω is low is given. When accuracy information indicating that the probability of the rotational angular velocity ω is not low is given, the angular velocity adaptive control unit 29 executes (restarts) control according to the rotational angular velocity ω.

The convergence determination unit 45 generates accuracy information indicating that the probability of the rotational angular velocity ω is reduced when the detected steering torque T does not converge to the command steering torque T ^* for a certain time (for example, 100 msec) or longer. In addition, the pulsation determining unit 46 generates accuracy information indicating that the probability of the rotational angular velocity ω is reduced when the detected steering torque T has pulsation.
As shown in FIG. 8, the pulsation means a state in which the detected steering torque T changes periodically with time and is not stable. Such pulsation is different from the angular velocity of the N pole generated to the rotational angular velocity and the stator 55 side of the rotor 50, therefore occurs when the load angle theta _L is constantly changing. Therefore, when the detected steering torque T has a pulsation, the reliability of the rotational angular velocity ω estimated based on the motor current is low. Accordingly, when the pulsation of the detected steering torque T is detected, the pulsation determining unit 46 generates accuracy information indicating that the probability of the rotational angular velocity ω is low.

FIG. 9 is a diagram for explaining the function of the correction unit 28. When the torque motor 3 is generated (assist torque) is stable, the load angle theta _L is stable. At this time, since the change speeds of the control angle θ _C and the rotor angle θ _M are substantially equal, the time change of the control angle θ _C , that is, the time change of the motor current accurately corresponds to the time change of the rotor angle θ _M. Therefore, an appropriate rotational angular velocity ω can be obtained based on the time change of the motor current. In contrast, when the torque motor 3 is generated varies, since the load angle theta _L is changed, the change rate of change speed and the rotor angle theta _M of the control angle theta _C is not equal. Therefore, the correction unit 28 corrects the rotational angular velocity ω to decrease when the load angle θ _L increases, that is, when the motor-generated torque increases. The correction unit 28, when the load angle theta _L is decreased, i.e., at the time of reduction of the motor torque increases correcting a rotational angular velocity omega. Thus, the rotational angular velocity omega can be corrected in accordance with a change in the load angle theta _L, it is possible to obtain a more reasonable rotational angular velocity omega.

In this embodiment, the correction unit 28 corrects the rotational angular velocity ω according to the command steering torque T ^* . This is because the change of the command steering torque T ^* corresponds to the change in the load angle theta _L. For example, if there is a positive correlation to the command steering torque T ^* and the assist torque T _{A (see} FIG. 3), the command steering torque T ^* is greater as the load angle theta _L increases. Therefore, when the command steering torque T ^* is increasing, the load angle theta _L is increasing may be reduced correcting a rotational angular velocity omega. Further, when the command steering torque T ^* is decreasing, the load angle theta _L is decreasing may be increased correcting a rotational angular velocity omega. Further, when there is a negative correlation between the command steering torque T ^* and the assist torque T _A is the command steering torque T ^* is greater as the load angle theta _L decreases. In this case, when the command steering torque T ^* is increasing, the load angle theta _L is decreasing may be increased correcting a rotational angular velocity omega. Further, when the command steering torque T ^* is decreasing, the load angle theta _L is increasing may be reduced correcting a rotational angular velocity omega. Similar correction can be performed using the detected steering torque T instead of the command steering torque T ^* . The degree of correction of the rotational angular velocity ω may be obtained in advance by experiments.

As described above, according to this embodiment, the rotation angular velocity ω is obtained based on the zero cross point of the motor detection current, and a correction corresponding to the change in the load angle θ _L is performed on the rotation angular velocity ω. The angular velocity ω can be calculated. Therefore, control using this rotational angular velocity ω can be performed appropriately. Further, when the convergence of the detected steering torque T to the command steering torque T ^* is poor, or when the detected steering torque T has a pulsation, it is assumed that the rotational angular velocity ω is less likely and the rotational angular velocity ω Control based on is interrupted. Thereby, undesired control based on the uncertain rotational angular velocity ω can be avoided.

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 rotational angular velocity ω is obtained based on the zero cross point of the motor current, but the instruction voltage (three-phase instruction voltage V _UVW ^* or instruction voltage in the two-phase fixed coordinate system. The rotational angular velocity ω may be obtained based on the zero cross point of the motor voltage.

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.
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, 4 ... Steering angle sensor, 5 ... Motor control apparatus, 11 ... Microcomputer, 26 ... Control angle calculating part, 50 ... Rotor, 51, 52, 52 ... Stator winding, 55 ... Stator

Claims (4)

A motor control device for controlling a motor including a rotor and a stator facing the rotor,
Current driving means for performing current feedback control to drive the motor with an axial current value of a rotating coordinate system according to a control angle that is a control rotation angle;
An instruction torque setting means for setting an instruction torque as an instruction value of a torque other than the motor torque to be applied to a drive target driven by the motor;
Torque detecting means for detecting torque other than motor torque acting on the drive target;
A torque deviation, which is a deviation between the instruction torque set by the instruction torque setting means and the detection torque detected by the torque detection means, is calculated, and is added to the control angle by performing a proportional integral calculation on the torque deviation. An addition angle calculation means for calculating an addition angle to be calculated;
Control angle calculation means for calculating 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;
Angular velocity calculating means for calculating the rotational angular velocity of the motor from the interval of zero cross points of the motor current waveform of the motor or the motor voltage waveform applied to the motor;
The rotation calculated by the angular velocity calculation means according to the change in the indicated torque correlated with the change in the load angle represented by the difference between the control angle calculated by the control angle calculation means and the rotation angle of the rotor. Correction means for correcting the angular velocity ;
See containing and changing means for changing the motor control mode depending on the rotational angular velocity corrected by the correcting means,
The change of the motor control mode is
Changing the gain of the current feedback control, or
A load angle adjustment method for controlling the motor by adjusting the load angle by using the control angle and the shaft current value, and rotation of the rotor based on an induced voltage estimated based on the motor current and the motor voltage estimating a corner, it switched including the induced voltage estimation method for performing energization control of the on the basis of the rotation angle which is the estimated motor, the motor controller.   The motor gives a driving force to the steering mechanism of the vehicle,
  The torque detection means detects a steering torque applied to an operation member operated for steering the vehicle,
  The motor control device according to claim 1, wherein the command torque setting unit is configured to set the command torque based on a steering angle of the operation member.   The motor control device according to claim 2, wherein the command torque setting unit is configured to set a command steering torque based on a vehicle speed of the vehicle and a steering angle of the operation member.   The motor control device according to claim 1, wherein the motor can be controlled without using a rotation angle sensor.

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