JP4539065B2 - Motor control method and motor control apparatus - Google Patents

Description

  The present invention relates to a technique for controlling a motor, and in particular, introduces a coordinate system that rotates with the rotation of a rotor of the motor, and supplies the current to be supplied to the motor to the d axis in the direction of the magnetic pole of the rotor and to this electrically. The present invention relates to a technique for obtaining a command value of the current in the case where it is regarded as a component about an orthogonal q axis.

  2. Description of the Related Art Conventionally, a method for controlling driving of a motor by dividing a current to be supplied to a motor into the above-described d-axis component (so-called d-axis current) and q-axis component (so-called q-axis current) is known. At this time, command values for the d-axis current and the q-axis current are respectively generated using the position angle indicating the position of the rotor of the motor as an angle, the speed of the rotor, and its command value. The rotor position angle is detected by, for example, a current actually supplied to the motor.

A method for determining the phase angle command value β ^* corresponding to the ratio between the d-axis current command value i _d ^* and the q-axis current command value i _q ^* is described in Non-Patent Document 1, for example. Are introduced in Non-Patent Document 2, for example.

Shigeo Morimoto, Yoji Takeshi, Yoji Takeda, Tagao Hirata, “PM motor equipment constants and output range”, IEEJ Transactions Volume 110, No.11, 1171 to 1176 (Heisei 2) Chen Zhen, Ikuo Hamada, Shinji Michiki, Okuma Tsukasa “Sensorless position estimation method and stability of salient pole type brushless DC motor”, 1998 IEEJ National Conference on Industrial Applications, No. 59, 1998, 179-182

  From the above, it is necessary to accurately detect the current in order to accurately estimate the position angle of the rotor. However, in the prior art, the smaller the motor torque, the smaller the current applied to the motor to control the rotation of the motor. Therefore, in view of the fact that there are errors and variations in the current sensor that measures the current, and that the specifications of the motor vary with respect to its rated value, it is possible to accurately estimate the rotor position angle. The smaller the torque, the more difficult it is. If the estimation error of the position angle becomes large, there arises a problem that the rotation control of the motor becomes unstable and becomes cheap.

  Therefore, an object of the present invention is to provide a technique for stabilizing the rotation control of the motor by reducing the estimation error of the position angle even when the motor torque is small.

The motor control method according to the present invention includes: (a) coordinates that rotate with the rotation of the rotor based on the rotational speed (ω) of the rotor of the motor (5) and its command value (ω ^* ). A first current command value ( _id1 ^* ) which is a current command value in the magnetic pole direction of the rotor in the system, and a second current command which is a current command value in a direction electrically orthogonal to the magnetic pole direction. Generating a value (i _q1 ^* ), (b) updating the first current command value or / and the second current command value, (c) after step (b), Supplying a current (i _x ) for controlling the rotation of the motor based on the first current command value, the second current command value, and the position (θ) of the rotor.

In the first aspect, in the step (b), the first current command value obtained from the step (a) is a first limit value ( _id0 ^* ; √ (I ₀ ² -i _q1 ^{*). 2} )), when the second current command value is left as it is, the first current command value is updated to be decreased, and the first current command value is less than or equal to the first limit value. And

The second aspect is a motor control method according to the first aspect, wherein the first limit value ( _id0 ^* ) is a constant value.

The third aspect is a motor control method according to the first aspect, wherein the first limit value is a square of the second current command value (i _q1 ^* ) and a second limit value (I _0). ² ) The value obtained by multiplying the square root of the difference from (1) by (-1).

In the fourth aspect, in step (b), the sum of the square of the first current command value and the square of the second current command value obtained from step (a) is a predetermined minimum value. When the sum is less than (I ₀ ² ), the fluctuation of the motor torque (τ) determined based on the first current command value and the second current command value is kept within an allowable range. The first current command value or / and the second current command value that are equal to or greater than the predetermined minimum value are updated.

The fifth and sixth aspects are the motor control method according to the fourth aspect, wherein the step (b) is (b-1) the first current command value obtained from the step (a). _Obtaining a reference value (τ ₁ ) of the torque based on (i _d1 ^* ) and the second current command value (i _q1 ^* ); (b-2) the second current command value (i _updating the first current command value by multiplying the square root of the square of _qJ ^* ) from the predetermined minimum value by (-1) ( _{id (J + 1)} ^* ); (B-3) After updating based on the first current command value ( _{id (J + 1)} ^* ) and the second current command value (i _qJ ^* ) after the step (b-2) It obtains the torque _{(τ (J + 1))} , updating the second current command value when the said torque exceeds the allowable range with respect to the reference value _{(i q (J + 1)} *) to And a step. Then, the steps (b-2) and (b-3) are repeatedly executed until the torque obtained in the step (b-3) falls within the allowable range.

In the fifth aspect, the second inductance is a component in a direction electrically orthogonal to the magnetic pole direction rather than the first inductance component (L _d ) that is the magnetic pole direction component of the rotor inductance. This is a control method when the component (L _q ) is large. In the step (b-3), when the updated torque (τ _{(J + 1)} ) is larger than the allowable range for the reference value, Decreases the second current command value, and when the torque is smaller than the allowable range, increases the second current command value to update each (i _{q (J + 1)} ^* ) To do.

In the sixth aspect, the second inductance is a component in a direction electrically orthogonal to the magnetic pole direction rather than the first inductance component (L _d ) which is the magnetic pole direction component of the inductance of the rotor. This is a control method when the component (L _q ) is small. In the step (b-3), when the updated torque (τ _{(J + 1)} ) exceeds the permissible range with respect to the reference value, Increases the second current command value, and when the torque is smaller than the allowable range, decreases the second current command value and updates each (i _{q (J + 1)} ^* ) To do.

The motor control device according to the present invention is based on the rotational speed (ω) of the rotor of the motor (5) and its command value (ω ^* ), and the coordinate system rotates with the rotation of the rotor. A first current command value (i _d1 ^* ) that is a current command value for the magnetic pole direction of the rotor and a second current command value (i that is a current command value for a direction that is electrically orthogonal to the magnetic pole direction). _q1 ^* ) is obtained from the speed control unit (1), the current limit value (2) for updating the first current command value or / and the second current command value, and the current limit unit. said first current command value and the second current command value, and the current for controlling the rotation of the motor based on the position of the rotor (theta) (i _x) current controller supplies (3) With.

In the first mode, in the current limiting unit (2), the first current command value obtained from the speed control unit (1) is a first limiting value ( _id0 ^* ; √ (I ₀ ² -I _q1 ^{* 2} )) is larger than the first current command value by updating the first current command value while keeping the second current command value as it is. Or less.

The second aspect is the motor control device according to the first aspect, wherein the first limit value ( _id0 ^* ) is a constant value.

The third aspect is a motor control device according to the first aspect, wherein the first limit value is a square of the second current command value (i _q1 ^* ) and a second limit value (I _0). ² ) The value obtained by multiplying the square root of the difference from (1) by (-1).

In the fourth aspect, in the current limiting unit (2), the sum of the square of the first current command value and the square of the second current command value obtained from the speed control unit (1) is calculated. When the motor current (τ) is smaller than a predetermined minimum value (I ₀ ² ), the fluctuation of the motor torque (τ) determined based on the first current command value and the second current command value is kept within an allowable range. The first current command value and / or the second current command value at which the sum is equal to or greater than the predetermined minimum value are updated.

The fifth and sixth aspects are the motor control device according to the fourth aspect, wherein the current limiter (2) is (i) the first current obtained from the speed controller (1). A first step of obtaining a reference value (τ ₁ ) of the torque based on a command value ( _{id 1} ^* ) and the second current command value (i _q1 ^* ); and (ii) the second current command The first current command value is updated by multiplying the square root of the value (i _qJ ^* ) by the square root of the value obtained by subtracting from the predetermined minimum value ( _{id (J + 1)} ^* ). A second step, and (iii) after the second step, based on the first current command value ( _{id (J + 1)} ^* ) and the second current command value (i _qJ ^* ). The updated torque (τ _{(J + 1)} ) is obtained, and when the torque exceeds the allowable range with respect to the reference value, the second current command value is updated (i _{q (J + 1)} ^* 3rd step. Then, the second step and the third step are repeatedly executed until the torque obtained in the third step falls within the allowable range.

In the fifth aspect, the second inductance is a component in a direction electrically orthogonal to the magnetic pole direction rather than the first inductance component (L _d ) that is the magnetic pole direction component of the rotor inductance. In the case where the component (L _q ) is large, in the third step, if the updated torque (τ _{(J + 1)} ) is larger than the allowable range for the reference value, the second current When the command value is decreased and the torque is smaller than the allowable range, the second current command value is increased and updated (i _{q (J + 1)} ^* ).

In the sixth aspect, the second inductance is a component in a direction electrically orthogonal to the magnetic pole direction rather than the first inductance component (L _d ) which is the magnetic pole direction component of the inductance of the rotor. In the case where the component (L _q ) is small, in the third step, if the updated torque (τ _{(J + 1)} ) is large beyond the allowable range for the reference value, the second current When the command value is increased and the torque is smaller than the allowable range, the second current command value is decreased and updated (i _{q (J + 1)} ^* ).

  According to the first and fourth aspects of the motor control method according to the present invention and the first and fourth aspects of the motor control apparatus according to the present invention, the motor can be rotated even when the motor torque is small. The current applied to the motor to be controlled can be increased, and therefore the position of the rotor can be accurately estimated. This leads to stable rotation control of the motor. In particular, in the third aspect of the motor control method according to the present invention and the third aspect of the motor control apparatus according to the present invention, torque fluctuations can be reduced.

  According to the third aspect of the motor control method according to the present invention and the third aspect of the motor control device according to the present invention, the first aspect of the motor control method and the motor control according to the present invention The effect of the first aspect of the device can be easily obtained.

  According to the third aspect of the motor control method of the present invention and the third aspect of the motor control apparatus of the present invention, the efficiency is not significantly reduced even when the second current command value is large. .

  According to the fifth and sixth aspects of the motor control method according to the present invention and the fifth and sixth aspects of the motor control apparatus according to the present invention, the torque fluctuation is reduced in the saliency motor. Can do.

  FIG. 1 is a block diagram illustrating a configuration to which a motor control technique according to the present invention can be applied. The configuration includes a speed control unit 1, a current limiting unit 2, a current control unit 3, a position detection unit 4, and a motor 5, and can be grasped as a motor control device except for the motor 5. In addition, the motor control method can be implemented in this configuration.

The speed controller 1 determines the d-axis current command value i _d1 ^* and the q-axis current command value i _q1 ^* based on the rotational speed (here, angular speed) ω of the rotor of the motor 5 and its command value ω ^*. Is generated.

When the d-axis current command value i _d1 ^* (<0) obtained from the speed control unit 1 is larger than a certain limit value (<0) (that is, the d-axis current command value i _d1 ^* When the absolute value is smaller than the absolute value of the limit value), the d-axis current command value i _d1 ^* is decreased (that is, the absolute value is increased) while keeping the q-axis current command value i _q1 ^* as it is. Update. Thereby, the d-axis current command value is set to be equal to or less than the above limit value. Alternatively, the sum of the square of the d-axis current command value i _d1 ^{* and} the square of the q-axis current command value i _q1 ^* is increased while keeping the torque fluctuation within a predetermined allowable range. Details of these methods will be described later. The current limiting unit 2 outputs the updated d-axis current command value i _de ^* and q-axis current command value i _qe ^* . However, in the former method, the q-axis current command value i _qe ^* coincides with the q-axis current command value i _q1 ^* before being updated (that is, obtained from the speed control unit 1).

The current control unit 3 controls the rotation of the motor 5 based on the d-axis current command value i _de ^* and the q-axis current command value i _qe ^* obtained from the current limiting unit 2 and the rotor position angle θ. Supply _x .

The position detector 4 detects the position angle θ based on the current i _x and the voltage v _x supplied to the motor 5 and also obtains the rotational angular velocity ω.

The current i _x and the voltage v _x are a general term for the U-phase current i _u , the V-phase current i _v , and the W-phase current i _w , for example, if the motor 5 is a U-phase, V-phase, and W-phase motor. And U-phase voltage v _u , V-phase voltage v _v , and W-phase voltage v _w , respectively.

  The circuit equation of the brushless DC motor is expressed by equation (1) in a rotating coordinate system composed of a d-axis and a q-axis.

However, the d-axis component (so-called d-axis voltage) v _d and q-axis component (so-called q-axis voltage v _q ) of the voltage applied to the motor, and the d-axis component (so-called d-axis current) i _d and q of the current applied to the motor. Axial component (so-called q-axis current i _q ), d-axis direction inductance component (so-called d-axis inductance) L _d , q-axis direction inductance component (so-called q-axis inductance) L _q , armature resistance R, main rotor the introduction of the magnetic flux ψ _a. However, when there is no saliency, the d-axis inductance L _d and the q-axis inductance L _q are equal.

FIG. 2 is a vector diagram showing the relationship between the various quantities in a rotating coordinate system composed of d-axis and q-axis. Here, ψ ₀ is a combined magnetic flux of the magnetic flux due to the armature reaction and the main magnetic flux ψ _a . I _a and V _a are absolute values of current and voltage, respectively, and β = tan ⁻¹ (−i _d / i _q ).

  The torque τ is obtained by the equation (2).

First embodiment.
As understood from the equation (2), the torque τ greatly depends on the q-axis current i _q . In particular, when there is no saliency, it is determined only by the q-axis current i _q and the main magnetic flux ψ _a and does not depend on the d-axis current i _d . Therefore, the efficiency although reduced, without hardly varying the torque τ by increasing the d-axis current i _d, it is possible to increase the absolute value I _a current. Even if the torque τ of the motor 5 is small, the current applied to the motor to control the rotation of the motor 5 can be increased, and therefore the rotational position angle θ can be easily estimated accurately. This leads to stable rotation control of the motor 5.

FIG. 3 is a vector diagram showing the operation of the current limiting unit 2 in the present embodiment. The d-axis current command value i _d1 ^* obtained from the speed control unit 1 is larger than the limit value i _d0 ^* (the absolute value of the d-axis current command value i _d1 ^* is smaller than the absolute value of the limit value i _d0 ^* ). In this case, while maintaining the q-axis current command value i _q1 ^* , the d-axis current command value i _d1 ^* is decreased (that is, the absolute value of the d-axis current command value i _d1 ^* is increased) and updated. Here updated d-axis current command value i _de ^* is equal to the limit value i _d0 ^* but the limit value i _d0 ^* smaller than (i.e. d-axis current command value i _de ^* absolute value limit value i greater than the absolute value of _d0 ^* ).

The limit value i _d0 ^* can be obtained experimentally so that the rotational position angle θ is stably estimated. For example, it can be set based on variations in current sensors, load fluctuations, and minimum drive frequency.

With this control, there is a possibility that the command value β ^* of the phase angle varies and the rotational angular velocity ω varies, but the variation can be eliminated by the operation of the speed control unit 1.

Second embodiment.
In the first embodiment, since the d-axis current command value i _de ^* is set to the minimum value i _d0 ^* or more without depending on the q-axis current command value i _q1 ^* , the control can be easily performed. When the q-axis current command value i _q1 ^* is large, the reduction in efficiency becomes significant. Therefore, in the present embodiment, the minimum value i _d0 ^* is a function of the q-axis current command value i _q1 ^* . Specifically, the updated d-axis current command value i _de ^* is obtained by equation (3). Here, I ₀ ² is a constant.

Of course, even if a value smaller than the value on the right side of Expression (3) is taken (that is, the absolute value of the d-axis current command value i _de ^* is larger than (I ₀ ² −i _q1 ^{* 2} ) ^1/2 ) Good.

FIG. 4 is a vector diagram showing the operation of the current limiting unit 2 in the present embodiment. According to Equation (3), the end point of the updated current vector is placed on the lowest current value circle represented as a circle with a radius | I ₀ |.

As described above, in the present embodiment, the updated d-axis current command value i _de ^* is obtained by decreasing the d-axis current command value i _d1 ^* while setting the absolute value I _a of the current to be greater than or equal to | I ₀ |. Even when the current command value i _q1 ^* is large, the reduction in efficiency does not become remarkable, and even if the torque τ of the motor 5 is small, the current supplied to the motor is increased to control the rotation of the motor 5, and thus the rotation is performed. The position angle θ is easily estimated accurately.

The radius | I ₀ | of the minimum current value circle can also be obtained experimentally so that the rotational position angle θ is stably estimated. For example, it can be set based on variations in current sensors, load fluctuations, and minimum drive frequency. Similarly to the first embodiment, there is a possibility that the rotational angular velocity ω may fluctuate due to the fluctuation of the command value β ^* of the phase angle in the control, but the fluctuation can be eliminated by the operation of the speed controller 1. it can.

Third embodiment.
As described in the first embodiment, the formula (2) is a torque τ Without saliency as shown in not dependent on the d-axis current i _d. However, if there is saliency, the torque τ is affected by the d-axis current i _d . Therefore, a method will be described in which, when there is saliency, the variation in torque τ can be further reduced as compared with the first and second embodiments.

In the present embodiment, the sum of the square of the q-axis current command value i _q1 ^* obtained from the speed control unit 1 and the square of the d-axis current command value i _d1 ^* is smaller than a predetermined minimum value I ₀ ² In addition, the q-axis current command value i _q1 ^* or / and the d-axis current command value i _d1 ^* are updated to obtain the q-axis current command value i _qe ^* and the d-axis current command value i _de ^* . The sum of the square of the q-axis current command value i _qe ^{* and} the square of the d-axis current command value i _de ^* is not less than a predetermined minimum value I ₀ ² , and the q-axis current command value i _qe ^* and the d-axis current command The variation of the torque τ determined based on the value i _de ^* is kept within an allowable range.

The magnitude of the predetermined minimum value I ₀ ² can be determined experimentally. Further, it may be set depending on the rotational angular velocity ω. For example, the minimum value I ₀ ² may be decreased as the rotational angular velocity ω increases. This is because although the motor voltage increases as the rotational angular velocity ω increases, disturbances such as sensor noise often do not depend on the rotational angular velocity ω.

Specifically, the following steps are executed. First, the case of L _d <L _q (reverse saliency) will be described as an example. FIG. 5 is a graph showing how the q-axis current command value and the d-axis current command value are updated. The horizontal axis represents the q-axis current command value i _q ^* and the vertical axis represents the torque τ. Yes. As a motor having reverse saliency, a brushless DC motor that employs an embedded magnet type rotor can be cited as an example.

As a first step, a q-axis current command value i _q1 ^* and a d-axis current command value i _d1 ^* are used to obtain a reference value τ ₁ of torque τ based on equation (2). At this time, the expression (2) is expressed as a straight line having _a slope k ₁ (= ψ _a + (L _d −L _q ) i _d1 ^* ), and the reference value τ ₁ is a case where the q-axis current command value is i _q1 ^*. Are expressed as τ coordinates of points on the straight line.

As a second step, the d-axis current command value i _{d (J +} is calculated based on the equation (4) using the q-axis current command value i _qJ ^* (J = 1, 2, 3...) And the minimum value I ₀ ^2. ₁₎ ^{Find *} . That is, the d-axis current command value i _{d (J + 1)} ^* is obtained by multiplying the square root of the value obtained by subtracting the square of the q-axis current command value i _qJ ^* from the minimum value I ₀ ² by (−1).

As a third step, torque τ _{(J + 1)} is obtained based on equation (2) using d-axis current command value i _{d (J + 1)} ^* and q-axis current command value i _qJ ^* . At this time, the expression (2) is expressed as a straight line having _a slope k _{J + 1} (= ψ _a + (L _d −L _q ) i _{d (J + 1)} ^* ), and the torque τ _{(J + 1)} is expressed as a q-axis current. It is expressed as the τ coordinate of a point on the straight line when the command value is i _qJ ^* .

In the third step, when the torque τ _{(J + 1)} is larger than the allowable range ε ₁ (> 0) with respect to the reference value τ ₁ (τ ₁ + ε ₁ <τ _{(J + 1)} ). When the q-axis current command value is small and the torque τ _{(J + 1)} is smaller than the allowable range ε ₂ (> 0) with respect to the reference value τ ₁ (τ _{(J + 1)} <τ ₁ −ε _{In 2} ), the q-axis current command value is increased and updated respectively to obtain the q-axis current command value i _{q (J + 1)} ^* .

The torque tau in a third step _{(J + 1)} is the allowable range epsilon ₁ or less with respect to the reference value tau _1, and tolerance epsilon ₂ or more _{(τ 1 -ε 2 ≦ τ (} J + 1) ≦ τ The second step and the third step are repeated until ₁ + ε ₁ ).

FIG. 5 illustrates the case where the torque τ ₂ obtained by executing the second step first is larger than the reference value τ ₁ beyond the allowable range ε ₁ . In this case, the q-axis current command value i _q1 ^* is updated to a smaller q-axis current command value i _q2 ^* by the third step. Then, the d-axis current command value i _d3 ^* is obtained by the equation (4), and the torque τ ₃ corresponding to the q-axis current command value i _q2 ^* is obtained on the straight line having the slope k ₃ . Here, a case where the torque τ ₃ is smaller than the reference value τ ₁ is illustrated. If τ ₃ <τ ₁ −ε ₂ , the q-axis current command value i _q2 ^* is updated to a larger q-axis current command value i _q3 ^* . If τ ₁ −ε ₂ ≦ τ ₃ , i _de ^* = i _d3 ^* , i _qe ^* = i _q2 ^* .

In the case of L _d > L _q (saliency), the direction of increase / decrease when updating the q-axis current command value is opposite to that in the case of reverse saliency. That is, in the third step, when the torque τ _{(J + 1)} is larger than the allowable range ε ₁ (> 0) with respect to the reference value τ ₁ (τ ₁ + ε ₁ <τ _{(J + 1)} ). Increases the q-axis current command value, and conversely when the torque τ _{(J + 1)} is smaller than the allowable range ε ₂ (> 0) with respect to the reference value τ ₁ (τ _{(J + 1)} <τ ₁ −ε _{In 2} ), the q-axis current command value is decreased and updated to obtain the q-axis current command value i _{q (J + 1)} ^* .

FIG. 6 is a graph illustrating the effect of the first embodiment. It is a simulation result in the case of driving a brushless DC motor rated at 100 kg / cm class with a small load of −5 to 15 kg / cm. The horizontal axis represents time, and the vertical axis represents rotational angular velocity ω, torque τ, and estimated angular error θ _e .

  The figure (a) shows the case where there is no error in the current sensor, the voltage sensor, and the motor equipment constant, and the figures (b) and (c) both show an error of about several percent in the current sensor, the voltage sensor, and the motor equipment constant. Indicates the case. FIGS. 7A and 7B show the case where the d-axis current command value is not updated, and FIG. 10C shows the case where the d-axis current command value is updated according to the first embodiment.

When there is no error, the estimated angle error θ _e is substantially zero even if the d-axis current command value is not updated ((a) in the figure). However, if there is an error, unless the d-axis current command value is updated, the estimated angle error θ _e is greatly disturbed in the region where the torque τ is low, and reaches about −20 degrees ((b) in the figure). On the other hand, when the d-axis current command value is updated even if there is an error, the estimated angle error θ _e is not zero due to the error, but the estimated angle error θ _e is hardly disturbed even in a region where the torque τ is low. It is stable at a small value of about several degrees ((c) in the figure).

In view of FIG. 6C, in the third embodiment, when the estimated angle error θ _e is greatly disturbed, the predetermined minimum value I ₀ ² may be increased. For example, when a high frequency component (for example, a frequency component more than three times the rotational angular frequency) is detected in the estimated angle error θ _e , the predetermined minimum value I ₀ ² is increased. For such control, it is desirable that the rotation angle θ is given not only to the current control unit 3 from the position detection unit 4 but also to the current limiting unit 2. Such a deformation is indicated by a dashed arrow in FIG.

It is a block diagram which illustrates the control technology of the motor concerning the present invention. It is a vector diagram which shows the relationship of the various quantities in a d-axis-q-axis rotation coordinate system. It is a vector diagram which shows the operation | movement in the 1st Embodiment of this invention. It is a vector diagram which shows the operation | movement in the 2nd Embodiment of this invention. It is a graph which shows the operation | movement in the 3rd Embodiment of this invention. It is a graph which shows the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Speed control part 2 Current limiting part 3 Current control part 4 Position detection part 1 Motor

Claims (12)

(A) Based on the rotational speed (ω) of the rotor of the motor (5) and its command value (ω ^* ), the magnetic pole direction of the rotor in the coordinate system that rotates with the rotation of the rotor. A first current command value (i _d1 ^* ) that is a current command value and a second current command value (i _q1 ^* ) that is a current command value in a direction electrically orthogonal to the magnetic pole direction are generated. Steps,
(B) the step wherein the first current command value obtained from (a) a first limit value; if _{^{(i d0 * √ (I 0}} 2 -i q1 * 2)) is greater than the first Performing an update to decrease the first current command value while keeping the current command value of 2, and setting the first current command value to be equal to or less than the first limit value;
(C) after said step (b), the first current command value and the second current command value and the current to control the rotation of the motor based on the position (theta) of the rotor (i _x) A method for controlling a motor. The motor control method according to claim 1, wherein the first limit value ( _id0 ^* ) is a constant value. The first limit value is a value obtained by multiplying the square root of the difference between the square of the second current command value (i _q1 ^* ) and the second limit value (I ₀ ² ) by (−1). Item 5. A motor control method according to Item 1. (A) Based on the rotational speed (ω) of the rotor of the motor (5) and its command value (ω ^* ), the magnetic pole direction of the rotor in the coordinate system that rotates with the rotation of the rotor. A first current command value (i _d1 ^* ) that is a current command value and a second current command value (i _q1 ^* ) that is a current command value in a direction electrically orthogonal to the magnetic pole direction are generated. Steps,
(B) When the sum of the square of the first current command value obtained from step (a) and the square of the second current command value is smaller than a predetermined minimum value (I ₀ ² ), While the fluctuation of the torque (τ) of the motor determined based on the first current command value and the second current command value is kept within an allowable range, the sum is not less than the predetermined minimum value. Updating the current command value or / and the second current command value;
(C) After the step (b), supplying a current for controlling the rotation of the motor based on the first current command value, the second current command value, and the position (θ) of the rotor. A method for controlling a motor comprising: The motor has a second inductance component (L _q ) which is a component in a direction electrically orthogonal to the magnetic pole direction, rather than a first inductance component (L _d ) which is the magnetic pole direction component of the inductance of the rotor. ,
The step (b) is based on (b-1) the first current command value (i _d1 ^* ) and the second current command value (i _q1 ^* ) obtained from the step (a). Obtaining a reference value of torque (τ ₁ );
(B-2) The first current command value is updated by multiplying the square root of the value obtained by subtracting the square of the second current command value (i _qJ ^* ) from the predetermined minimum value by (−1). Step ( _{id (J + 1)} ^* )
(B-3) After updating based on the first current command value ( _{id (J + 1)} ^* ) and the second current command value (i _qJ ^* ) after the step (b-2) The torque (τ _{(J + 1)} ) is calculated, and if the torque is larger than the allowable range for the reference value, the second current command value is decreased and the torque exceeds the allowable range. The second current command value is increased and updated (i _{q (J + 1)} ^* ) respectively.
The motor control method according to claim 4, wherein the steps (b-2) and (b-3) are repeatedly executed until the torque obtained in the step (b-3) falls within the allowable range. . The motor has a second inductance component (L _q ) that is a component in a direction electrically orthogonal to the magnetic pole direction smaller than a first inductance component (L _d ) that is the magnetic pole direction component of the inductance of the rotor. ,
The step (b) is based on (b-1) the first current command value (i _d1 ^* ) and the second current command value (i _q1 ^* ) obtained from the step (a). Obtaining a reference value of torque (τ ₁ );
(B-2) The first current command value is updated by multiplying the square root of the value obtained by subtracting the square of the second current command value (i _qJ ^* ) from the predetermined minimum value by (−1). Step ( _{id (J + 1)} ^* )
(B-3) After updating based on the first current command value ( _{id (J + 1)} ^* ) and the second current command value (i _qJ ^* ) after the step (b-2) The torque (τ _{(J + 1)} ) is calculated, and if the torque is larger than the allowable range for the reference value, the second current command value is increased, and the torque exceeds the allowable range. The second current command value is reduced and updated (i _{q (J + 1)} ^* ) respectively.
The motor control method according to claim 4, wherein the steps (b-2) and (b-3) are repeatedly executed until the torque obtained in the step (b-3) falls within the allowable range. . Based on the rotational speed (ω) of the rotor of the motor (5) and its command value (ω ^* ), the current command value for the magnetic pole direction of the rotor in the coordinate system that rotates as the rotor rotates. the first current command value is (i _d1 ^*) and the second current command value is a current command value for the magnetic pole direction and electrically orthogonal directions (i _q1 ^*) and a speed control unit for generating a (1) and
Wherein said obtained from the speed controller first current command value is a first limit value; if _{^{(i d0 * √ (I 0}} 2 -i q1 * 2)) is greater than said second current command A current limiting unit (2) that updates the first current command value to decrease while keeping the value as it is, and sets the first current command value to be equal to or less than the first limit value;
The current the resulting from the restriction portion first current command value and the second current command value, and supplying a current (i _x) for controlling the rotation of the motor based on the position of the rotor (theta) And a current control unit (3) for controlling the motor. The motor control device according to claim 7, wherein the first limit value ( _id0 ^* ) is a constant value. The first limit value is a value obtained by multiplying the square root of the difference between the square of the second current command value (i _q1 ^* ) and the second limit value (I ₀ ² ) by (−1). Item 8. The motor control device according to Item 7. Based on the rotational speed (ω) of the rotor of the motor (5) and its command value (ω ^* ), the current command value for the magnetic pole direction of the rotor in the coordinate system that rotates as the rotor rotates. the first current command value is (i _d1 ^*) and the second current command value is a current command value for the magnetic pole direction and electrically orthogonal directions (i _q1 ^*) and a speed control unit for generating a (1) and
When the sum of the square of the first current command value obtained from the speed control unit and the square of the second current command value is smaller than a predetermined minimum value (I ₀ ² ), the first The first current command value at which the sum is equal to or greater than the predetermined minimum value while keeping fluctuations in the motor torque (τ) determined based on the current command value and the second current command value within an allowable range. Or / and a current limiting unit (2) for updating the second current command value;
A current control unit that supplies a current for controlling rotation of the motor based on the first current command value and the second current command value obtained from the current limiting unit, and the position (θ) of the rotor. And a motor control device. The motor has a second inductance component (L _q ) which is a component in a direction electrically orthogonal to the magnetic pole direction, rather than a first inductance component (L _d ) which is the magnetic pole direction component of the inductance of the rotor. ,
The current limiting unit (2) is based on (i) the first current command value (i _d1 ^* ) and the second current command value (i _q1 ^* ) obtained from the speed control unit (1). A first step of obtaining a reference value (τ ₁ ) of the torque,
(Ii) The first current command value is updated by multiplying the square root of the value obtained by subtracting the square of the second current command value (i _qJ ^* ) from the predetermined minimum value by (−1). i _{d (J + 1)} ^* ) second step;
(Iii) After the second step, based on the first current command value ( _{id (J + 1)} ^* ) and the second current command value (i _qJ ^* ), the updated torque ( τ _{(J + 1)} ), and when the torque is larger than the allowable range for the reference value, the second current command value is decreased, and when the torque is smaller than the allowable range, _Includes a third step of increasing the second current command value and updating (i _{q (J + 1)} ^* ) respectively,
The motor control device according to claim 10, wherein the second step and the third step are repeatedly executed until the torque obtained in the third step falls within the allowable range. The motor has a second inductance component (L _q ) that is a component in a direction electrically orthogonal to the magnetic pole direction smaller than a first inductance component (L _d ) that is the magnetic pole direction component of the inductance of the rotor. ,
The current limiting unit (2) is based on (i) the first current command value (i _d1 ^* ) and the second current command value (i _q1 ^* ) obtained from the speed control unit (1). A first step of obtaining a reference value (τ ₁ ) of the torque,
(Ii) The first current command value is updated by multiplying the square root of the value obtained by subtracting the square of the second current command value (i _qJ ^* ) from the predetermined minimum value by (−1). i _{d (J + 1)} ^* ) second step;
(Iii) After the second step, based on the first current command value ( _{id (J + 1)} ^* ) and the second current command value (i _qJ ^* ), the updated torque ( τ _{(J + 1)} ) is obtained, and when the torque is larger than the allowable range with respect to the reference value, the second current command value is increased, and when the torque is smaller than the allowable range, _Includes a third step of reducing the second current command value and updating (i _{q (J + 1)} ^* ) respectively.
The motor control device according to claim 10, wherein the second step and the third step are repeatedly executed until the torque obtained in the third step falls within the allowable range.

Images