JP5412391B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus.

  As this type of technology, the technology described in Patent Document 1 below is disclosed. This publication discloses a motor control device including a non-interference control unit having a transfer function that cancels interference generated in a d-axis control system and a q-axis control system of a motor. In this motor control device, in order to suppress the occurrence of vibrations when non-interference control is performed, the gain of non-interference control is reduced in the vicinity of the vibration frequency of the rotor angular velocity of the motor.

JP 2009-106015 A

However, in the above-described prior art, even in a high rotation region where high responsiveness is required, adjustment is performed to reduce the gain of non-interference control, so that the effect of improving current responsiveness, which is a feature of non-interference control, is achieved. There was a possibility that it could not be obtained sufficiently.
The present invention has been made paying attention to the above problems, and its object is to provide an electric power steering device capable of ensuring current responsiveness while suppressing vibration due to non-interference control. is there.

In order to achieve the above object, in the present invention, when performing non-interference control that cancels the mutual interference component between the d-axis command voltage and the q-axis command voltage, when the angular velocity of the rotor is equal to or less than a predetermined value, the angular velocity of the rotor small so the determining the corrected angular velocity, when the angular velocity of the rotor is greater than a predetermined value, together with the corrected angular velocity is smaller than the angular velocity of the rotor, substantially matches the rate of change of the correction angular velocity is an angular velocity rate of change of the rotor The correction angular velocity is determined so as to be.

  According to the present invention, high responsiveness can be ensured when the angular velocity of the rotor is greater than a predetermined value, and vibration due to non-interference control can be suppressed when the angular velocity of the rotor is equal to or less than a predetermined value.

1 is an overall configuration diagram of an electric power steering apparatus according to Embodiment 1. FIG. 2 is a partial cross-sectional view of a resolver according to Embodiment 1. FIG. FIG. 3 is a control block diagram of a controller according to the first embodiment. FIG. 3 is a control block diagram of a non-interference control unit according to the first embodiment. It is a graph which shows the relationship between the motor rotation speed of Example 1, and the rotation speed fluctuation frequency of an electric motor, and the natural frequency area | region of a vehicle. It is a graph which shows the relationship between the motor rotation speed of Example 1, and correction | amendment angular velocity. 4 is a graph showing motor rotation speeds before and after conversion to a corrected angular velocity according to the first embodiment. It is a graph which shows the motor rotational speed before converting into the correction | amendment angular velocity of Example 1, the motor rotational speed (omega) in a prior art, and the motor rotational speed (omega) in Example 1. FIG. 6 is a time chart of q-axis current when the motor rotation speed of Example 1 is controlled to be constant. 6 is a time chart of the q-axis current when the motor rotation speed of Example 1 is changed.

[Example 1]
[overall structure]
FIG. 1 is an overall configuration diagram of the electric power steering apparatus 1.
The electric power steering apparatus 1 includes a steering wheel 2 to which a steering operation by a driver is input, a steering shaft 22 connected to the steering wheel 2, a pinion 5 that rotates integrally with the steering shaft 22, and a pinion that meshes with the pinion 5 A rack 4 that converts the rotational motion of 5 into a linear motion and a tie rod 25 that transmits the motion of the rack 4 to the steered wheels 3 are provided.
The pinion 5 is provided with a worm wheel 23 that rotates integrally with the pinion 5. A worm shaft 24 is engaged with the worm wheel 23. The worm shaft 24 is provided with an electric motor 8 for applying a steering assist force. The electric motor 8 includes a rotor 6 that rotates integrally with the worm shaft 24, and a stator 7 that is provided on the outer periphery of the rotor 6. The electric motor 8 is controlled by the controller 26.
A resolver 20 is provided on the worm shaft 24. FIG. 2 is a partial cross-sectional view of the resolver 20. The resolver 20 includes a rotor 21 that rotates integrally with the worm shaft 24, and a stator 33 provided on the outer periphery of the rotor 21. In the first embodiment, the number of reactance changes (number of pole pairs, shaft angle multiplier) of the rotor 21 is set to 4. The stator 33 is composed of teeth 28 arranged in the circumferential direction on the side facing the rotor 21. A coil 29 is wound around the teeth 28, and a set of four teeth 28 is formed.

[Controller control block]
FIG. 3 is a control block diagram of the controller 26. The controller 26 includes a motor rotation angle detection unit 32, a motor rotation number calculation unit 9, a current detection unit 10, a three-phase / two-phase conversion unit 11, a command current calculation unit 12, a PI control unit 13, a non-interference control unit 14, and a correction. It has a d-axis command voltage calculation circuit 17, a corrected q-axis command voltage calculation circuit 18, a two-phase / three-phase conversion unit 30 , and an inverter 31.
The motor rotation angle detector 32 analyzes the signal from the resolver 20 and detects the motor rotation angle θ. This motor rotation angle θ indicates the rotation angle of the rotor 6 of the electric motor 8. The motor rotation number calculation unit 9 calculates the motor rotation number ω by differentiating the motor rotation angle θ with respect to time. The motor rotation speed ω indicates the rotation speed of the rotor 6 of the electric motor 8. Current detection unit 10 detects actual currents (U-phase actual measurement current Iu, V-phase actual measurement current Iv, and W-phase actual measurement current Iw) flowing from inverter 31 to electric motor 8. The three-phase / two-phase converter 11 receives the three-phase actual currents Iu, Iv, Iw and the motor rotation angle, and converts them into dq-axis two-phase currents (d-axis current Id, q-axis current Iq).

The command current calculation unit 12 inputs the command torque T * and the motor rotation speed ω, and calculates the d-axis command current Id * and the q-axis command current Iq *. The PI control unit 13 determines the d-axis command voltage Vd * for performing PI control based on the deviation between the d-axis command current Id * and the d-axis current Id and the deviation between the q-axis command current Iq * and the q-axis current Iq. And q-axis command voltage Vq *.
The non-interference control unit 14 receives the d-axis command current Id *, the q-axis command current Iq *, and the motor rotation speed ω, and receives the d-axis non-interference correction value Vd * a, which is the non-interference control correction value, The interference correction value Vq * a is calculated. The non-interference control unit 14 will be described in detail later.
The corrected d-axis command voltage calculation circuit 17 calculates a corrected d-axis command voltage Vd ** obtained by correcting the d-axis command voltage Vd * based on the d-axis non-interference correction value Vd * a. The corrected q-axis command voltage calculation circuit 18 calculates a corrected q-axis command voltage Vq ** obtained by correcting the q-axis command voltage Vq * based on the q-axis non-interference correction value Vq * a.
The two-phase / three-phase converter 30 inputs a two-phase corrected d-axis command voltage Vd **, a corrected q-axis command voltage Vq **, and a motor rotation angle θ, and outputs a three-phase command voltage (U-phase command Voltage Vu *, V-phase command voltage Vv *, and W-phase command voltage Vw *).
The inverter 31 supplies a drive current to the electric motor 8 based on the three-phase command voltage.

[Control block of non-interference control unit]
FIG. 4 is a control block diagram of the non-interference control unit 14. The non-interference control unit 14 includes a d-axis non-interference correction value calculation unit 15, a q-axis non-interference correction value calculation unit 16, and a motor rotation speed conversion unit 19.
The motor rotation speed conversion unit 19 converts the motor rotation speed ω into a corrected angular velocity ω ′. The correction angular velocity ω ′ is a value used in place of the motor rotation speed ω when obtaining a q-axis non-interference correction value Vq * a described later. Briefly describing the correction angular velocity ω ′, the correction angular velocity ω ′ is set smaller than the motor rotational speed ω so that the non-interference control does not operate when the electric motor 8 is rotating at low speed, and the electric motor 8 is rotated at high speed. In some cases, the displacement amount of the correction angular velocity ω ′ is set to be close to the displacement amount of the motor rotational speed ω so that non-interference control acts. Specifically, the corrected angular velocity ω ′ can be obtained by the following equation (1).

ここでω0[rpm]は、車両の固有振動数f0[Hz]とレゾルバ20の回転子21のリアクタンス変化数（極対数、軸倍角）Reにより次の式(2)により求められる。

このω0[rpm]は、モータ回転数ωのときに発生するトルク変動による振動の周波数が、車両の固有振動数f0よりも大きくなる値である。またω1[rpm]は、モータ回転数ωがω1のときに電動モータ8が車体と共振せず、かつ、干渉電圧により電流制御応答性が大きく低下しないような回転数に設定している。
d軸非干渉補正値演算部15はq軸電流指令値Iq*とモータ回転数ωを入力して、d軸非干渉補正値Vd*aを演算する。d軸非干渉補正値Vd*aは次の式(3)により求めることができる。

ここでLqは、電動モータ8のq軸インダクタンスを示す。

Here, ω0 [rpm] is obtained by the following equation (2) from the natural frequency f0 [Hz] of the vehicle and the number of reactance changes (number of pole pairs, shaft angle multiplier) Re of the rotor 21 of the resolver 20.

This ω0 [rpm] is a value at which the frequency of vibration due to torque fluctuations generated at the motor rotational speed ω is greater than the natural frequency f0 of the vehicle. Further, ω1 [rpm] is set to a rotational speed at which the electric motor 8 does not resonate with the vehicle body when the motor rotational speed ω is ω1 and the current control response is not greatly reduced by the interference voltage.
The d-axis non-interference correction value calculation unit 15 receives the q-axis current command value Iq * and the motor rotation speed ω, and calculates the d-axis non-interference correction value Vd * a. The d-axis non-interference correction value Vd * a can be obtained by the following equation (3).

Here, Lq represents the q-axis inductance of the electric motor 8.

ここでLdは、電動モータ8のd軸インダクタンス、Φは電動モータの鎖交磁束を示す。
式(3)、式(4)に示すように、補正角速度ω'は誘起電圧を非干渉化している式(4)の右辺第2項にだけ適用している。 The q-axis non-interference correction value calculation unit 16 inputs the d-axis current command value Id *, the motor rotation speed ω, and the correction angular velocity ω ′, and calculates the q-axis non-interference correction value Vq * a. The q-axis non-interference correction value Vq * a can be obtained by the following equation (4).

Here, Ld represents the d-axis inductance of the electric motor 8, and Φ represents the interlinkage magnetic flux of the electric motor.
As shown in the equations (3) and (4), the corrected angular velocity ω ′ is applied only to the second term on the right side of the equation (4) in which the induced voltage is made non-interfering.

[Action]
FIG. 5 is a graph showing the relationship between the motor rotational speed ω and the rotational speed fluctuation frequency of the electric motor 8, and the natural frequency region of the vehicle. As shown in FIG. 5, when the motor rotational speed ω is in the range of approximately 200 [rpm] to 600 [rpm], the rotational speed fluctuation frequency coincides with the vicinity of 30 [Hz] which is the natural frequency region of the vehicle. Further, when the motor rotational speed is in the range of 2700 [rpm] to 3200 [rpm], the rotational speed fluctuation frequency coincides with the vicinity of 200 [Hz] which is the natural frequency region of the vehicle.
Although the current response can be improved by correcting the command voltage by non-interference control, the torque fluctuation of the electric motor 8 is more likely to occur than when the command voltage is not corrected by non-interference control. Therefore, conventionally, the gain of the motor rotational speed used for non-interference control is reduced in the vicinity where the natural frequency of the vehicle coincides with the rotational speed fluctuation frequency. As a result, the correction amount of the command current by the non-interference control is reduced to suppress the torque fluctuation, and the resonance with the vehicle is avoided (hereinafter referred to as the prior art).

However, in the high rotation region (region B), since the rotation is high, the effect of the decrease in current responsiveness is significant unless non-interference control is performed, so that sufficient current responsiveness could not be secured with the conventional technology. . On the other hand, in the low rotation region (region A), since the rotation is slow in the first place, there is little influence of the current response reduction without performing non-interference control.
The relationship between the motor rotation speed and the rotation speed fluctuation frequency is as described above. The vibration in the low rotation region is mainly caused by non-interference control, but the vibration in the high rotation region is mainly caused by field-weakening control other than torque fluctuation and an error of the current detection unit 10. That is, even if the non-interference control is not performed in the high rotation region, the vibration cannot be sufficiently suppressed.

Therefore, in the electric power steering apparatus 1 of the first embodiment, the motor angular velocity ω used for non-interference control is converted into a corrected angular velocity ω ′ for use. The corrected angular velocity ω ′ is set using the equation (1).
FIG. 6 is a graph showing the relationship between the motor rotational speed ω and the corrected angular velocity ω ′.
As shown in FIG. 6, the corrected angular velocity ω ′ is set to zero in a range where the vehicle resonates due to vibration by non-interference control (predetermined value ω0 or less). Thereby, resonance with the vehicle can be suppressed.
Further, in the range where the vehicle resonates due to the field weakening control or the vibration due to the error of the current detection unit 10 (greater than the predetermined value ω1), the change rate of the correction angular velocity ω ′ is made to coincide with the change rate of the motor rotational speed ω. . As a result, it is possible to ensure current responsiveness in a high rotation region such as when the steering wheel 2 is steered rapidly.

FIG. 7 is a graph showing the motor rotational speed ω before and after converting the motor rotational speed ω used in the non-interference control into the corrected angular velocity ω ′. As shown in FIG. 7, fluctuations in the rotational speed of the motor rotational speed ω converted to the corrected angular velocity ω ′ are suppressed in the low rotational speed region.
FIG. 8 is a graph showing the motor rotational speed ω before the motor rotational speed ω used in the non-interference control is converted into the corrected angular velocity ω ′, the motor rotational speed ω in the prior art, and the motor rotational speed ω in the first embodiment. is there. In the prior art, the rotational speed fluctuation is suppressed as compared with that before the conversion, but in the first embodiment, the rotational speed fluctuation is further suppressed particularly in the low rotational speed region.
FIG. 9 is a time chart of the q-axis command current Iq * and the prior art and the q-axis current Iq of Example 1 when the motor rotation speed ω is controlled to 2000 [rpm]. FIG. 10 is a time chart of the q-axis command current Iq * and the prior art and the q-axis current Iq of the first embodiment when the motor rotation speed ω is controlled from 2000 [rpm] to 1000 [rpm]. Note that 1000 [rpm] and 2000 [rpm] are equal to or higher than the predetermined value ω1 and belong to the high rotation region.

When the rotational speed is controlled to be constant, as shown in FIG. 9, the q-axis current Iq according to the first embodiment and the prior art follows the q-axis command current Id * in the same manner. On the other hand, when the number of revolutions is changed, as shown in FIG. 10, the q-axis current Iq of the prior art is more delayed than the q-axis current Iq of the first embodiment with respect to the q-axis command current Id *. End up.
In summary, in the conventional technology in the low rotation region, the current response is high, and the generation of vibrations and noise due to fluctuations in the rotational speed is suppressed. In the prior art, even if the correction amount of the non-interference control with respect to the command voltage is reduced in the low rotation region, that is, even if interference occurs, the decrease in current response is small because of the low rotation. Further, in the vicinity where the natural frequency of the vehicle coincides with the rotation speed fluctuation frequency, the correction amount of the non-interference control with respect to the command voltage is reduced, so that the rotation speed fluctuation is small and generation of vibration and sound can be suppressed. .

In Example 1, in the low rotation region, the current response is high, and the generation of vibration and sound due to fluctuations in the rotation speed is suppressed. In the first embodiment, even if the correction amount of non-interference control with respect to the command voltage is reduced in the low rotation region, the current response is hardly reduced because of the low rotation. In addition, since the correction amount for non-interference control with respect to the command voltage is reduced throughout the low-speed region, fluctuations in the rotational speed are small, and generation of vibration and sound can be suppressed.
Moreover, in the high speed region, in the conventional technology, although the generation of vibration and sound due to fluctuations in the rotational speed is suppressed, the current response is low. In the prior art, even in the high speed region, the correction amount of the non-interference control for the command voltage is reduced near the point where the natural frequency of the vehicle and the rotational speed fluctuation frequency coincide with each other. It is large and steerability is also deteriorated. On the other hand, in the vicinity where the natural frequency of the vehicle coincides with the rotational frequency fluctuation frequency, the correction amount of the non-interference control with respect to the command voltage is reduced, so that the rotational frequency variation is small and generation of vibration and sound can be suppressed. .
In Example 1, in the high rotation region, the current response is high, and the increase in the generation of vibration and sound due to fluctuations in the rotation speed is suppressed. In Example 1, since the correction amount of non-interference control with respect to the command voltage is increased in the high rotation region, the current response is improved. On the other hand, by performing non-interference control, the generation of vibration and sound due to non-interference control cannot be reduced, but the cause of the generation of vibration and sound in the high rotation range is due to field weakening and current detection unit 10 errors. Since the main thing is, even if non-interference control is performed, it hardly affects the increase in vibration and sound.

Further, the corrected angular velocity ω ′ from the predetermined value ω0 to the predetermined value ω1 is smoothly connected. A large change in the change rate (inclination change) of the corrected angular velocity ω ′ may cause torque fluctuation of the electric motor 8. By smoothly connecting the corrected angular velocity ω ′ from the predetermined value ω0 to the predetermined value ω1, torque fluctuation can be suppressed.
Further, the predetermined value ω 0 is set to a value at which the frequency of vibration due to torque fluctuation generated at the motor rotation speed ω is higher than the natural frequency f 0 of the vehicle. Thereby, resonance with the vehicle due to vibration caused mainly by non-interference control can be suppressed.
Further, the predetermined value ω0 is obtained from the equation (2). The vibration frequency of the motor rotation speed ω is caused by the structural error of the resolver 27. For example, when the rotor 21 reactance change number Re of the resolver 27 is 4, rotation fourth-order vibration is generated. Therefore, a value obtained by dividing the natural frequency f0 of the vehicle by the reactance change number Re is a value corresponding to the fourth-order frequency. Furthermore, by multiplying this value by 60, the frequency per minute can be obtained and compared with the motor rotation speed ω [rpm] in the same row. Thereby, resonance with the vehicle due to vibration caused mainly by non-interference control can be suppressed.

[effect]
(1) An electric power steering apparatus 1 mounted on a vehicle, which includes a rack 4 and a pinion 5 that transmit a steering operation of a steering wheel 2 to a steered wheel 3, a rotor 6 and a stator 7, and the pinion 5 An electric motor 8 that transmits steering assist force, a motor rotation speed calculation unit 9 that calculates the motor rotation speed ω (angular velocity of the rotor 6), and current detection that detects actual currents Iu, Iv, and Iw that flow through the electric motor 8. Part 10 and a three-phase / calculation of the d-axis current Id that is the d-axis component of the actual currents Iu, Iv, and Iw and the q-axis current Iq that is the q-axis component of the actual current based on the actual currents Iu, Iv, and Iw Based on the two-phase converter 11, the motor rotational speed ω and the torque command value T *, the d-axis command current Id * that is the d-axis command current and the q-axis command current Iq * that is the q-axis command current are Command current calculation unit 12 to calculate, d-axis command voltage Vd * and q-axis which are d-axis command voltage based on deviation of d-axis command current Id * and d-axis current Id PI controller 13 that calculates q-axis command voltage Vq *, which is the q-axis command voltage based on the deviation between command current Iq * and q-axis current Iq, and d-axis command voltage Vd * and q-axis command voltage Vq * A non-interference control unit 14 that performs non-interference control that cancels the mutual interference components, and a d-axis command voltage that is provided in the non-interference control unit 14 and based on the motor rotation speed ω, the q-axis inductance Lq, and the q-axis command current Iq * A d-axis non-interference correction value calculator 15 for calculating a d-axis non-interference correction value Vd * a, which is a non-interference control correction value for Vd *, and a non-interference controller 14 are provided. Q-axis that calculates q-axis non-interference correction value Vq * a that is non-interference control correction value of q-axis command voltage Vq * based on inductance Ld, d-axis command current Id *, and linkage flux Φ of electric motor 8 Non-interference correction value calculation unit 16 and corrected d-axis command voltage calculation that calculates a corrected d-axis command voltage Vd ** that is a voltage obtained by correcting the d-axis command voltage Vd * based on the d-axis non-interference correction value Vd * a Times 17 and the corrected q-axis command voltage calculation circuit 18 for calculating the corrected q-axis command voltage Vq **, which is a voltage obtained by correcting the q-axis command voltage Vq * based on the q-axis non-interference correction value Vq * a, and the non-interference An arithmetic circuit provided in the control unit 14 for calculating a correction angular velocity ω ′ that is a correction value of the motor rotational speed ω in the d-axis non-interference correction value Vd * a and the q-axis non-interference correction value Vq * a, When the rotational speed ω is equal to or smaller than the predetermined value ω0, the correction angular velocity ω ′ is determined so that the influence of the motor rotational speed ω on the q-axis non-interference correction value Vd * a is reduced, and the motor rotational speed ω is determined from the predetermined value ω1. A motor rotation speed conversion unit 19 that determines the correction angular velocity ω ′ so that the change rate of the motor rotation speed ω in the q-axis non-interference correction value Vq * a is substantially equal to the change rate of the motor rotation speed ω. It was.
When the motor rotation speed ω, which is the sudden steering region, is larger than the predetermined value ω1, the correction angular velocity ω ′ is determined so that the correction amount of the non-interference control with respect to the command voltage is increased, so that high steering responsiveness can be obtained. On the other hand, when the motor rotation speed ω, which is a steering region where high steering responsiveness is not required, is equal to or less than the predetermined value ω0, the correction angular velocity ω ′ is determined so that the correction amount of the non-interference control with respect to the command voltage is small. Vibration caused by interference control can be suppressed.

(2) The predetermined values ω0 and ω1 are values corresponding to the natural frequency of the vehicle.
When the vibration frequency of the electric motor 8 matches the natural frequency of the vehicle, resonance occurs, and this resonance may cause a feeling of steering discomfort and noise. When non-interference control is performed, the vibration of the electric motor 8 increases, and this phenomenon appears more prominently. Therefore, the amount of non-interference control correction for the command voltage is reduced in the region where the natural frequency of the vehicle exists, and non-interference control is performed in the region exceeding the natural frequency of the vehicle, resulting in non-interference control. Resonance between the natural frequency of the vehicle and the vibration frequency of the electric motor 8 can be suppressed.
(3) The motor rotation number calculation unit 9 is calculated based on the output value of the resolver 20 that detects the angle of the rotor 6, and the resolver 20 has the same number of reluctance changes as the number of pole pairs of the electric motor 8. The predetermined value ω0 is set based on a value obtained by dividing the natural frequency of the vehicle by the number of pole pairs.
The motor rotational speed ω is obtained from the angle of the rotor 6 detected by the resolver 27. The vibration frequency of the motor rotation speed ω is caused by the structural error of the rotor 21 of the resolver 27. By setting the predetermined value ω0 based on the rotor 21 of the resolver 27, ω0 can be set to a frequency exceeding the natural frequency of the vehicle. For this reason, the correction amount of non-interference control for the command voltage is reduced in the region where the natural frequency of the vehicle exists, and non-interference control is performed in the region exceeding the natural frequency of the vehicle, resulting in non-interference control. Resonance between the natural frequency of the vehicle and the vibration frequency of the electric motor 8 can be suppressed.

[Other Examples]
As described above, the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment. It is included in the present invention.
For example, the electric power steering apparatus 1 according to the first embodiment is a pinion assist type that applies a steering assist force from the electric motor 8 to the pinion 5, but a column assist type that applies a steering assist force to the steering shaft 22. A rack assist type that applies a steering assist force may be used.
In the electric power steering apparatus 1 of the first embodiment, the reactance change number Re of the rotor 21 of the resolver 27 is set to 4, but the reactance change number Re may be other numbers.

Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.
(A) In the electric power steering apparatus according to claim 1,
The electric power steering apparatus according to claim 1, wherein the correction angular velocity calculation circuit determines the correction angular velocity so that the correction angular velocity is substantially zero when the angular velocity of the rotor is equal to or less than the predetermined value.
In the region where the natural frequency of the vehicle exists, vibration due to non-interference control can be reduced.

(B) In the electric power steering apparatus according to claim 1,
In the correction angular velocity calculation circuit, a ratio of the correction angular velocity to the angular velocity of the rotor is gradually increased from a region where the angular velocity of the rotor is equal to or less than the predetermined value to a region where the angular velocity of the rotor is larger than the predetermined value. An electric power steering apparatus characterized in that the correction angular velocity is determined so as to change periodically.
If there is an inflection point in the relationship between the corrected angular velocity and the angular velocity of the rotor, there is a risk of torque fluctuation of the electric motor in the vicinity of a predetermined value for the angular velocity of the rotor. Thus, by determining the corrected angular velocity so that the corrected angular velocities around the predetermined value are smoothly connected, torque fluctuation of the electric motor can be suppressed.

1 Electric power steering device
2 Steering wheel
3 Steering wheel
4 racks
5 Pinion
6 Rotor
7 Stator
8 Electric motor
9 Motor speed calculator
10 Current detector
11 Two-phase converter
12 Command current calculator
13 Control unit
14 Non-interference controller
15 d-axis non-interference correction value calculator
16 q-axis non-interference correction value calculator
17 d-axis command voltage calculation circuit
18 q-axis command voltage calculation circuit
19 Motor speed converter
20 Resolver
21 Rotor

Claims (3)

An electric power steering device mounted on a vehicle,
A steering mechanism that transmits the steering operation of the steering wheel to the steered wheels;
An electric motor comprising a rotor and a stator and transmitting a steering assist force to the steering mechanism;
Angular velocity detection means for detecting or estimating the angular velocity of the rotor;
A current detection circuit for detecting an actual current flowing through the electric motor;
Based on the real current, a d-axis current that is a d-axis component that is a rotational coordinate axis synchronized with rotation of the rotor of the real current and a q-axis that is a q-axis component orthogonal to the d-axis of the real current D-axis q-axis current calculation circuit for calculating current,
A command current calculation circuit that calculates a d-axis command current that is a command current of the d-axis and a q-axis command current that is a command current of the q-axis;
Based on the deviation between the d-axis command current and the d-axis current, the d-axis command voltage, which is the d-axis command voltage, and the q-axis command voltage based on the deviation between the q-axis command current and the q-axis current. q A command voltage calculation circuit that calculates the axis command voltage,
A non-interference control unit that performs non-interference control to cancel a mutual interference component between the d-axis command voltage and the q-axis command voltage;
Provided in the non-interference control unit, calculates a d-axis non-interference correction value that is a non-interference control correction value of the d-axis command voltage based on the angular velocity of the rotor, the q-axis inductance, and the q-axis command current D-axis non-interference correction value calculation unit
Based on the angular velocity of the rotor, the d-axis inductance, the d-axis command current, and the linkage flux of the electric motor, the non-interference control correction value of the q-axis command voltage is provided in the non-interference control unit. A q-axis non-interference correction value calculator for calculating a certain q-axis non-interference correction value;
A corrected d-axis command voltage calculation circuit that calculates a corrected d-axis command voltage that is a voltage obtained by correcting the d-axis command voltage based on the d-axis non-interference correction value;
A corrected q-axis command voltage calculation circuit that calculates a corrected q-axis command voltage that is a voltage obtained by correcting the q-axis command voltage based on the q-axis non-interference correction value;
Wherein provided on the decoupling control unit, an arithmetic circuit for calculating a corrected angular velocity which is a correction value of the angular velocity of the rotor before Symbol q-axis non-interacting correction value, when the angular velocity of the rotor is less than a predetermined value the determining the corrected angular velocity so as to be smaller than the rotor angular velocity, when the angular velocity of the rotor is greater than the predetermined value, together with the corrected angular velocity is smaller than the angular speed of the rotor, the corrected angular velocity and corrected angular velocity calculating circuit rate of change to determine the corrected angular velocity so as to substantially coincide with the angular velocity change rate of the rotor,
An electric power steering apparatus comprising: The electric power steering apparatus according to claim 1, wherein
The electric power steering apparatus according to claim 1, wherein the predetermined value is a value corresponding to a natural frequency of the vehicle. The electric power steering apparatus according to claim 1, wherein
The angular velocity detection means is calculated based on an output value of a resolver that detects an angle of the rotor,
The resolver includes a rotor having a reluctance change equal to the number of pole pairs of the electric motor,
The electric power steering apparatus, wherein the predetermined value is set based on a value obtained by dividing a natural frequency of a vehicle by the number of pole pairs.

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