JP4650110B2 - Electric motor control device - Google Patents

Description

  The present invention relates to a motor control device, and more particularly to a technique for suppressing a delay in compensation in non-interference control.

  In current control by dq axis vector conversion of a synchronous motor, non-interference control that cancels mutual interference components according to the d axis current value and the q axis current value is used as means for improving current response performance. Regarding the calculation of the mutual interference component in the non-interference control, the mutual interference component was previously calculated from the d-axis current value and the q-axis current value that have been generated, whereas the conventional example described in Patent Document 1 below. Describes a technique for stabilizing the operation of the non-interference control unit by calculating from the d-axis current command value and the q-axis current command value.

JP 2004-40861 A

As described above, in the conventional technique, the calculation of the mutual interference component is mainly performed by the d-axis current value Id and the q-axis current value Iq or the d-axis current command value Id ^* and the q-axis current command value Iq ^* and the d-axis inductance Ld. And the q-axis inductance Lq. If there is a deviation in the mutual interference component calculation result, the integral term of the proportional-integral control unit provided before or after the non-interference control unit. It was configured to compensate for the misalignment. For this reason, a deviation occurs in the calculation result of the mutual interference component, and when the deviation is mainly compensated by the integral term of the proportional integral control unit, the torque command value fluctuates sharply, and the q-axis current value Iq steeply changes accordingly. When it changes, the mutual interference component fluctuates proportionally, but the term compensated by the integral term of the proportional integral control does not respond immediately, and there is a problem that the current response is deteriorated.
That is, when the q-axis inductance Lq is a constant value, the error of the mutual interference component between the actual q-axis inductance Lq and the q-axis inductance Lq used for the calculation is compensated by the integral term of the proportional integral control. However, when the q-axis current value Iq changes in accordance with the change of the torque command value, the mutual interference component proportional to the q-axis current value Iq also changes, but the integral term of the proportional integral control that compensates for the error is Since there is a delay in the integral calculation, there is a problem that the response delay becomes large.
The present invention has been made to solve the above-described problems, and an electric motor control device capable of preventing deterioration of current response performance even when the q-axis current value or the q-axis current command value fluctuates sharply. The purpose is to provide.

  In order to achieve the above object, in the present invention, the value of the q-axis inductance Lq used for the calculation of the q-axis interference component for compensating the d-axis voltage command value by non-interference control is set as the q-axis current value or the q-axis current value. Correction means for correcting based on the command value and the d-axis integral term output in proportional integral control is provided.

  When the d-axis integral term output Sd, the d-axis current value Id, the q-axis current value Iq, the motor winding resistance value Ra, and the motor angular velocity ω are calculated, the correction means performs the following equation (1). A correction amount α is calculated, and a value obtained by adding the correction amount α to the q-axis inductance Lq is defined as a corrected q-axis inductance Lq ′.

α = (Sd−Id × Ra) / (Iq × ω) (Equation 1)
Lq ′ = Lq + α

In the present invention, in non-interference control, the value of the q-axis inductance Lq, which is the basis of the q-axis interference component for correcting the d-axis voltage command value, is expressed as d-axis integral term output Sd, d-axis current value Id, q-axis current. Since the correction is always performed based on the correction amount α calculated based on the value Iq and the motor angular velocity ω, and the configuration is not such that the deviation of the interference component is steadily compensated by the integral term of the proportional integral control, the torque command value T ^* Even when the q-axis current command value fluctuates sharply at the time of sudden change, there is an effect that deterioration of current response performance is suppressed.

FIG. 1 shows a current feedback control block diagram by vector control of a three-phase synchronous motor to which the present invention is applied.
In FIG. 1, a torque command value calculation unit 1 provided outside determines a torque command value T ^* from an accelerator opening or the like.
The angle detector 10 (resolver, encoder, etc.) detects the rotation angle θ (rotation phase: electrical angle) of the armature of the electric motor 9, and the rotation speed calculation unit 11 differentiates the rotation angle θ to thereby rotate the rotation speed of the electric motor 9. ω (armature angular velocity: electrical angle) is calculated.
The current command value calculation unit 2 calculates a d-axis current command value Id ^* and a q-axis current command value Iq ^* from the torque command value T ^* and the rotation speed ω. In the following, when both are expressed together, they may be displayed as dq-axis current command values Id ^* and Iq ^* .

On the other hand, the current sensor 12 detects the u-phase current Iu, the v-phase current Iv, and the w-phase current Iw flowing in the u, v, and w phases of the electric motor 9, and the d-axis current is detected by the three-phase to two-phase conversion unit 4 therefrom. A value Id and a q-axis current value Iq are calculated.
Current PI control unit 3, the above-described d-q axis current command value ^Id *, Iq ^* and the d-q axis current value Id, each of the deviation between ^{Iq (Id * -Id, Iq *} -Iq) asking, By performing proportional-integral control on them, the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* are calculated.

The non-interference control unit 5 removes the d-q axis mutual interference component from the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* , and the d-axis voltage command value Vd ^* ′ after removing the interference component. Q-axis voltage command value Vq ^* ′ is calculated.

The q-axis interference component is basically “q-axis interference component = Lq × Iq × ω”, but in the configuration of the conventional example, an error between the actual q-axis inductance Lq and the q-axis inductance Lq used in the calculation is calculated. Since compensation is performed using the integral term output Sd of the proportional integral control, “q-axis interference component = Lq × Iq × ω + Sd”. That is, during steady state, the error of the mutual interference component is compensated by the integral term of proportional integral control. However, when the q-axis current value Iq changes according to the change of the torque command value, the q-axis inductance Lq proportional to the q-axis current value Iq also changes, but the integral term Sd of proportional integral control that compensates for the error. Has a problem that the response is delayed because of the delay of the integral operation.
Therefore, the present invention is configured to always correct Lq itself by calculating the error of the q-axis inductance Lq based on the integral term output Sd and the q-axis current value Iq (or q-axis current command value). (Details will be described later).

In the above configuration, the current PI control unit 3 is provided before the non-interference control unit 5. However, the current PI control unit 3 may be provided after the non-interference control unit 5. In other words, the proportional-integral control may be performed on the result of performing non-interference control on the dq-axis current command values Id ^* and Iq ^* from the current command value calculation unit 2.

The d-axis voltage command value Vd ^* ′ and q-axis voltage command value Vq ^* ′ after the interference component removal is converted into three-phase voltage command values Vu ^* , Vv ^* , Vw ^* by the two-phase / three-phase converter 6. The PWM control unit 7 converts the signal into a PWM signal.
The inverter 8 is controlled by this PWM signal, and the electric motor 9 is driven by converting the power of a DC power source (not shown) into three-phase AC power.
The above process is repeated to perform vector control by current feedback of the motor.

FIG. 2 is a basic block diagram of current PI control unit 3 in FIG.
In the current PI control unit 3 of FIG. 2, PI (proportional integration) calculation is performed for each of the dq axes as follows.
First, for the d-axis, a current deviation (Id ^* −Id) is calculated by subtracting the d-axis current value Id from the d-axis current command value Id ^* , and this is multiplied by the proportional gain Kpd and the current deviation ( Id ^* −Id) multiplied by integral gain Kid and integrated (1 / s) is added to obtain d-axis voltage command value Vd ^* .
Similarly for the q-axis, the current deviation (Iq ^* −Iq) is calculated by subtracting the q-axis current value Iq from the q-axis current command value Iq ^*, and the current deviation (Iq ^* −Iq) multiplied by the proportional gain Kpq. Iq ^* −Iq) multiplied by integral gain Kiq and integrated (1 / s) is added to obtain q-axis voltage command value Vq ^* .

FIG. 3 is a basic block diagram of the non-interference control unit 5 in FIG.
The non-interference control unit 5 performs the removal of the dq axis mutual interference components as follows.
First, for the d-axis, the q-axis current value Iq is multiplied by the q-axis inductance Lq of the electric motor 9 (a predetermined value is set as a basic value), and further multiplied by the rotational angular velocity (rotational velocity) ω of the electric motor. calculating a q-axis interference component, the q-axis interference component is added to the d-axis voltage command value Vd ^*, and calculates a d-axis voltage command value Vd after the interference component removal * ^'. That is, Vd ^* ′ = Vd ^* + (Lq × Iq × ω).

For the q-axis, the d-axis interference component is calculated by adding the magnetic flux φa of the motor to the value obtained by multiplying the d-axis current value Id by the d-axis inductance Ld of the motor, and further multiplying the rotation speed ω of the motor. By subtracting the d-axis interference component from the q-axis voltage command value Vq ^* , the q-axis voltage command value Vq ^* ′ after removing the interference component is calculated. That is, Vq ^* ′ = Vq ^* − [(Ld × Id) + φa] × ω.
In the present invention, the error between the calculation q-axis inductance Lq used for non-interference calculation and the actual q-axis inductance Lq is always calculated based on the integral term output Sd and the q-axis current value Iq (or q-axis current command value). A non-interference term correction calculation unit 13 for correction is provided.

(Example)
FIG. 4 is a block diagram showing an embodiment of the current PI control unit provided with the non-interference term correction calculation unit 13.
In FIG. 4, the portions of Kpd, KId, 1 / s and the portions of Kpq, KIq, 1 / s correspond to the current PI control unit 3 shown in FIG. That is, in FIG. 4, the d-axis side and the q-axis side in the current PI control unit 3 of FIG. 2 are displayed separately in two vertically, and a non-interference term correction calculation unit 13 is provided between them. ing.
As in the current PI control unit 3 described with reference to FIG. 2, the basic control performs PI calculation for each dq axis and outputs a d-axis voltage command value Vd ^* and a q-axis voltage command value Vq ^* .

The non-interference term correction calculation unit 13 receives the d-axis current deviation (Id ^* −Id) calculated by subtracting the d-axis current value Id from the d-axis current command value Id ^* as a d-axis state determination unit 14. For example, “the fluctuation of the d-axis current command value Id ^* is within 10 A within 10 ms” and “the d-axis current deviation is within 10% of the d-axis current command value Id ^* continues for 10 ms or more. In other words, the calculation command signal Sc1 is output when the d-axis current command value fluctuation is small and the current deviation is small. The correction amount α is calculated at the timing of the calculation command signal Sc1.

The correction amount calculation unit 15 receives the calculation command signal Sc1, the d-axis integral term output Sd, the d-axis current value Id, the q-axis current value Iq, and the motor angular velocity ω (rotation speed: electrical angle), and the calculation command signal Sc1 When the correction amount is issued, the correction amount α is calculated by the following equation (Equation 5) (= Equation 1). Note that Id × Ra is a d-axis control voltage.
α = (Sd−Id × Ra) / (Iq × ω) (Equation 5)
Here, Ra is a motor winding resistance value and is a constant.

Alternatively, as shown in the following formula (6) (= formula 2), the d-axis current value Id and the q-axis current value Iq are replaced with a d-axis current command value Id ^* and a q-axis current command value Iq ^* ,
α = (Sd−Id ^* × Ra) / (Iq ^* × ω) (Expression 6)
It is good.

Since the values of Id × Ra and Id ^* × Ra are significantly smaller than the d-axis integral term output Sd, in the above formulas (5) and (6), Id × Ra and Id ^* × Ra Is omitted, and it can be used even if some errors occur even if it is expressed by the following equation (equation 7) (= equation 3) and equation (8) (= equation 4).
α = Sd / (Iq × ω) (Expression 7)
α = Sd / (Iq ^* × ω) (Equation 8)
Next, the filter processing unit 16 calculates the non-interference correction value X by performing, for example, a low-pass filter process on the correction amount α calculated as described above.

FIG. 5 is a block diagram showing an embodiment of the non-interference control unit 5 to which non-interference term correction is added. The basic operation in FIG. 5 is the same as that in FIG. 3, but in FIG. 5, the q-axis current value Iq is multiplied by the q-axis inductance Lq of the electric motor 9, and further multiplied by the rotational speed ω of the electric motor. When calculating the interference component, the Lq correction unit 17 corrects Lq with a non-interference correction value X (output of the filter processing unit 16 in FIG. 4) instead of the q-axis inductance Lq (basic value). (Lq ′ = Lq + X) is used. The correction amount α may be used as it is instead of the non-interference correction value X obtained by filtering the correction amount α.
Therefore, the d-axis voltage command value Vd ^* ′ after non-interference control is
Vd ^* ′ = Vd ^* + (Lq ′ × Iq × ω) = Vd ^* + [(Lq + X) × Iq × ω].

  As described above, when the q-axis current command value and the q-axis current value are stable, the correction amount is based on the d-axis integral term output Sd, the d-axis current value Id, the q-axis current value Iq, and the motor angular velocity ω. By calculating α (non-interference correction value X) and always correcting the value of the q-axis inductance Lq with this value, the current response performance can be kept good.

FIG. 6 is a diagram showing a simulation result when the torque command value T ^* is changed stepwise from 0 Nm to 100 Nm (STEP command 0 → 100 Nm) when the present invention as described above is applied.

In FIG. 6, the solid line indicates the characteristic when the non-interference term of the present invention is corrected, the broken line indicates the characteristic when the correction is not performed, and the torque command value T ^* suddenly changes stepwise at time 1.00 sec. The case where the command values of Id and Iq change suddenly as shown by the alternate long and short dash line is shown.

  As shown in FIG. 6, due to the correction, the value at the time of application indicated by the solid line is faster in rising and convergence than the value at the time of non-application indicated by the broken line, and the response of the d-axis current Id is also non-adaptive. Compared with adaptation, it is improved.

As described above, in the present invention, in the non-interference control, the value of the q-axis inductance Lq serving as the basis of the q-axis interference component for correcting the d-axis voltage command value is set as the d-axis integral term output Sd and the d-axis current value Id. , The correction is always made on the basis of the correction amount α calculated based on the q-axis current value Iq and the motor angular velocity ω, and is not configured to steadily compensate for the deviation of the interference component with the integral term of the proportional integral control. Even if the q-axis current command value fluctuates sharply when the command value T ^* changes suddenly, there is an effect that the current response performance is prevented from deteriorating.

The block diagram of the current feedback control by vector control of the three-phase synchronous motor to which this invention is applied. FIG. 2 is a basic block diagram of a current PI control unit 3 in FIG. 1. The basic block diagram of the non-interference control part 5 in FIG. The block diagram which shows the Example of the electric current PI control part which provided the non-interference term correction | amendment calculating part. The block diagram which shows the Example of the non-interference control part 5 which performs non-interference term correction. The figure which shows the simulation result at the time of changing torque command value T ^* in step shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Torque command value calculation part 2 ... Current command value calculation part 3 ... Current PI control part 4 ... Three phase two phase conversion part 5 ... Non-interference control part 6 ... Two phase three phase conversion part 7 ... PWM control part 8 ... Inverter DESCRIPTION OF SYMBOLS 9 ... Electric motor 10 ... Angle detector 11 ... Rotation speed calculation part 12 ... Current sensor 13 ... Non-interference term correction calculating part 14 ... d-axis state determination part 15 ... Correction amount calculating part 16 ... Filter processing part 17 ... Lq correction part

Claims (5)

The d-axis current command value and the q-axis current command value are obtained from the torque command value and the rotation speed of the motor, and the respective deviations of the d-axis current command value, the q-axis current command value, the d-axis current value, and the q-axis current value are obtained. Is applied with proportional-integral control to calculate a d-axis voltage command value and a q-axis voltage command value, and performs non-interference control for canceling a mutual interference component between the d-axis current value and the q-axis current value. The voltage command value and the q-axis voltage command value are converted into a three-phase voltage command value by two-phase and three-phase conversion, and the inverter is controlled by a PWM signal obtained by PWM-converting the three-phase voltage command value, whereby three-phase AC power is supplied to the motor. In a control device for an electric motor that supplies and drives
The value of the q-axis inductance Lq used for the calculation of the q-axis interference component for compensating the d-axis voltage command value by non-interference control is the q-axis current value or the q-axis current command value and the d-axis integral in the proportional integral control. A control device for an electric motor, comprising correction means for correcting based on a term output. When the d-axis integral term output Sd, the d-axis current value Id, the q-axis current value Iq, the motor winding resistance value Ra, and the motor angular velocity ω are used as the correction means, the correction amount is calculated by the following equation (1). The motor control apparatus according to claim 1, wherein α is calculated, and a value obtained by adding the correction amount α to the q-axis inductance Lq is defined as a corrected q-axis inductance Lq ′.
α = (Sd−Id × Ra) / (Iq × ω) (Equation 1)
Lq ′ = Lq + α The correction amount α is calculated by the following equation (Equation 2) in which the d-axis current value Id or the q-axis current value Iq according to claim 2 is replaced with a d-axis current command value Id ^* or a q-axis current command value Iq ^* , respectively. The motor control device according to claim 1, wherein the motor control device is calculated.
α = (Sd−Id ^* × Ra) / (Iq ^* × ω) (Equation 2) The correction amount α is calculated by the following equation (3) or equation (4) in which Id × Ra in the equation (2) or Id ^* × Ra in the equation (3) is omitted. The motor control device according to claim 1, wherein the motor control device is calculated.
α = Sd / (Iq × ω) (Equation 3)
α = Sd / (Iq ^* × ω) (Expression 4) The deviation (Id ^* −Id) between the d-axis current command value Id ^* and the d-axis current value Id is detected, the fluctuation of the d-axis current command value Id ^* is smaller than a predetermined value, and the deviation value 5. The motor control device according to claim 1, wherein the correction amount α is calculated when the value is smaller than a predetermined value. 6.

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