JP2006254618A - Motor control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control apparatus capable of properly protecting a motor from overheat, by limiting a motor current command value according to the revolution state of the motor. <P>SOLUTION: This apparatus is provided with a PWM inverter 3 that drives a three-phase brushless motor 1, a position sensor 2 that detects the magnetic pole position of the rotor of the motor 1, a current detector 4 that detects motor drive currents Iu, Iv, Iw that are inputted from the PWM inverter 3 into the motor 1, a current command value calculator 5 that generates the motor current values Id*, Iq* of the motor 1, and a microcontroller 6 that controls the PWM inverter 3 using the motor current command values Id*, Iq*. The microcontroller 6 calculates the motor current limit values Idr, Iqr that limit the motor current command values Id*, Iq* based on the rotation speed of the motor 1 calculated by the magnetic pole position, and the motor drive currents Iu, Iv, Iw. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor control device that limits a motor current command value such as a brushless motor.

  A conventional motor control device includes a drive circuit that drives a multiphase motor and a microcontroller that controls the drive circuit. The microcontroller limits the motor current according to an integrated value of a predetermined function of the phase current. (For example, refer to Patent Document 1).

JP 2002-238293 A

  Since the conventional motor control device does not consider the rotation state of the motor, if the motor is energized while the motor is stopped, the current of a specific motor phase will increase, compared to other motor phases. There was a problem that a specific motor phase was overheated.

  Also, if the motor is energized while the motor is rotating, the microcontroller will limit the motor current and the motor current will be excessively limited even though the heat is in each phase. There was also a problem.

  An object of the present invention is to solve the above-described problems, and an object of the present invention is to appropriately protect the motor from overheating by limiting the motor current command value according to the rotational state of the motor. It is an object of the present invention to provide a motor control device that can do the above.

  A motor control device according to the present invention detects an inverter device that drives a multiphase motor, position detection means that detects a magnetic pole position of a rotor of the multiphase motor, and a motor drive current input from the inverter device to the multiphase motor. Drive current detection means, a current command value calculation means for generating a motor current command value for the multiphase motor, and a motor control means for controlling the inverter device using the motor current command value. A motor current limit value that limits the motor current command value is calculated based on the rotational speed of the multiphase motor calculated from the position and the motor drive current.

  According to the motor control device of the present invention, the motor current command value can be limited in accordance with the rotation state of the motor, so that the motor can be appropriately overheat protected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding members and parts will be described with the same reference numerals.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a motor control device according to Embodiment 1 of the present invention together with peripheral devices.
In FIG. 1, this motor control device is connected to a three-phase brushless motor 1 (hereinafter abbreviated as “motor 1”) which is a multiphase motor.

  The motor control device includes a position sensor (position detection means) 2 that detects the magnetic pole position of the rotor of the motor 1, a PWM inverter (inverter device) 3 that drives the motor 1, and 3 that is input from the PWM inverter 3 to the motor 1. Motor current command of motor 1 based on current detector (drive current detection means) 4 for detecting motor drive currents Iu, Iv, Iw of the phase, and torque command value T * and magnetic flux command value F * given from the outside PWM using current command value calculation unit 5 that generates d-axis (magnetic flux axis) command current Id * and q-axis (torque axis) command current Iq *, and motor current command values (Id *, Iq *). And a microcontroller 6 (motor control means) for controlling the inverter 3.

  The microcontroller 6 limits the motor current command values (Id *, Iq *) to prevent overheating, and the A / D converters 8u, 8v for converting the output of the current detector 4 into digital values. (Hereinafter collectively referred to as “A / D converter 8”), the output of the A / D converter 8 is converted from a three-phase AC coordinate into a dq coordinate consisting of a d axis and a q axis orthogonal to the d axis. Subtractors 18d, 18q (hereinafter referred to as "subtractor 18") that output the difference between the output of the phase-dq coordinate converter 9, the output of the motor current limiter 14 (described later) and the output of the three-phase-dq coordinate converter 9. General control), current control units 10d and 10q (hereinafter collectively referred to as "current control unit 10") that perform feedback control on the dq coordinate based on the output of the subtractor 18, and the output of the current control unit 10 as dq Dq-3 phase transformation to convert from coordinates to 3 phase AC coordinate 11, and a motor rotational speed calculating section 12 for calculating a rotational speed R1 of the motor 1 from the magnetic pole position of the rotor.

The overheat protection unit 7 generates motor current command values (Id *, Iq *) based on the motor rotation speed R1 output from the motor rotation speed calculation unit 12 and the motor drive current output from the three-phase-dq coordinate conversion unit 9. The motor current limit value calculation unit 13 that calculates the motor current limit value that limits the motor current limit value), and the motor current command value (Id *, Iq *) based on the motor current limit value output by the motor current limit value calculation unit 13 Motor current limiting units 14d and 14q for limiting (hereinafter collectively referred to as “motor current limiting unit 14”) are provided.
Here, the 3-phase-dq coordinate conversion unit 9, the current control unit 10, the dq-3 phase coordinate conversion unit 11, the motor rotation speed calculation unit 12, the motor current limit value calculation unit 13, and the motor current limit unit 14 Built in the controller 6 as software.

FIG. 2 is a flowchart showing the operation of the software program built in the microcontroller 6 of FIG. This program is called periodically and repeatedly.
The operation of the motor control device having the above configuration will be described below with reference to FIG.
First, the magnetic pole position of the rotor of the motor 1 is detected every predetermined time by the position sensor 2, and the difference calculation between the magnetic pole position detected by the motor rotation speed calculation unit 12 and the previously detected magnetic pole position is performed, and the motor rotation speed R1 Is calculated and output (step S21).

  The current detector 4 detects the u-phase drive current Iu and the v-phase drive current Iv out of the three-phase motor drive currents input from the PWM inverter 3 to the motor 1, and the w-phase drive current Iw is the next. The three-phase motor drive currents Iu, Iv, and Iw are calculated by the equation (1) (step S22).

    Iw = −Iu−Iv (1)

The three-phase motor drive currents Iu, Iv, and Iw are converted into digital signals by the A / D converter 8 and then converted to the dq coordinates by the three-phase-dq coordinate conversion unit 9, and the d-axis drive currents shown in FIG. (D-axis component current) Id and q-axis drive current (q-axis component current) Iq are output (step S23).
In the motor current limit value calculation unit 13, the d-axis drive current Id and the q-axis drive current Iq are vector-synthesized by the following equation (2) to obtain a combined drive current (synthesized current) Is (step S24).

  Here, when the combined drive current Is is constant, a circle with a constant radius indicated by a broken line in FIG. 3 can be expressed as a motor current limit value. This indicates that the result of combining the three-phase motor drive currents Iu, Iv, and Iw is a constant current value. The combined drive current Is is not affected by the magnetic pole position of the rotor of the motor 1, that is, the phase angle θ1 formed by the q axis and the combined drive current Is (hereinafter abbreviated as “current phase angle θ1”), The current value energized to the motor 1 can be represented.

Similarly, the motor current limit value calculation unit 13 obtains a motor current limit value for limiting the motor current command value (Id *, Iq *) from the combined drive current Is and the motor rotation speed R1. The d-axis current limit value Idr and the q-axis current limit value Iqr are output (step S25).
In the motor current limiting unit 14, the d-axis command current Id * and the q-axis command current Iq * are limited to be equal to or less than the d-axis current limit value Idr and the q-axis current limit value Iqr, respectively, and the d-axis limited current Idr * And q-axis-limited current Iqr * are output (step S26, step S27).

The subtractor 18 outputs the difference between the d-axis limited current Idr * and the d-axis drive current Id, and the q-axis limited current Iqr * and the q-axis drive current Iq, and the current control unit 10 outputs the difference between the subtracter 18 and the output. Based on this, feedback control is performed (step S28, step S29).
In the dq-3 phase coordinate conversion unit 11, the output of the current control unit 10 is converted from the dq coordinate to the three-phase AC coordinate and output to the PWM inverter 3 (step S30). The motor 1 is driven by the output of the PWM inverter 3.

Next, the operation of the motor control device in step S25 will be described in detail.
The motor current limit value calculating unit 13 uses the motor rotation speed R1 and the combined drive current Is to gradually reduce or gradually increase the maximum current allowed for the motor 1 based on the characteristic (predetermined function) shown in FIG. A current limit value changing speed Vm is calculated. Subsequently, the motor current limit value change speed Vm is integrated, and motor current limit values (Idr, Iqr) are calculated. The motor current limit values (Idr, Iqr) limit the motor current command values (Id *, Iq *) on the dq coordinates.

Here, the motor current limit value calculation unit 13 determines that the motor 1 is rotating when the motor rotation speed R1 is equal to or higher than a predetermined rotation speed ξ that is arbitrarily set. The motor current limit values (Idr, Iqr) are calculated using the speed Vm (see FIG. 4).
In addition, the motor current limit value calculation unit 13 determines that the motor 1 is stopped when the motor rotation speed R1 is equal to or less than a predetermined rotation speed ξ that is arbitrarily set, and the solid line motor current limit value change speed. The motor current limit values (Idr, Iqr) are calculated using Vm (see FIG. 4).

  Therefore, since the gradient when gradually decreasing the maximum current allowed for the motor 1 can be switched according to the motor rotation speed R1, the gradient of gradual decrease can be made smaller when the motor 1 is rotating than when the motor 1 is stopped. Can do.

  When the motor current limit values (Idr, Iqr) are gradually increased, the motor current limit values (Idr, Iqr) are determined by the heat dissipation characteristics of the microcontroller 6 or the motor 1 regardless of whether the motor 1 is rotating or stopped. 1 is set as the same parameter when rotating and stopping.

  The motor current limit values (Idr, Iqr) are decomposed into the d-axis current limit value Idr and the q-axis current limit value Iqr so that the current phase angle θ1 (see FIG. 3) is constant, and are supplied to the motor current limiter 14. Is output. The d-axis current limit value Idr and the q-axis current limit value Iqr are, for example, as shown in FIG. 5 when the motor rotates and stops.

According to the motor control device according to the first embodiment of the present invention, the motor current limit values (Idr, Iqr) can be calculated according to the motor rotation speed R1, so that the motor 1 can be appropriately overheat protected. it can.
Further, since the motor current limit values (Idr, Iqr) are calculated according to the combined drive current Is, it is possible to cope with heat concentration on a specific motor phase when the motor 1 is stopped, and to generate heat when the motor 1 rotates. It is possible to cope with the situation where is averaged.

The motor current limit values (Idr, Iqr) calculated by the motor current limit value calculation unit 13 limit the motor current command values (Id *, Iq *) on the dq coordinates, and are three-phase AC coordinates. Since the motor current command values (Id *, Iq *) are limited before the coordinate conversion is performed, the current can be gradually reduced without losing the current balance of each motor phase depending on the rotation state of the motor 1.
Further, since the motor current limit values (Idr, Iqr) are calculated using the combined drive current Is, there is no need to calculate the motor current limit values (Idr, Iqr) for each phase current, and the calculation process is simplified. Therefore, the processing load of the motor current limit value calculation unit 13 can be reduced.

  Further, since the motor current limit values (Idr, Iqr) are calculated so as to maintain the current phase angle θ1, the motor current command values (Id *, Iq *) are decreased while gradually decreasing the motor rotation speed R1 and the torque in a balanced manner. Can be limited.

  In the first embodiment, the motor current limit value calculation unit 13 calculates the motor current limit values (Idr, Iqr) using the combined drive current Is. However, the power function of the combined drive current Is ( The motor current limit values (Idr, Iqr) may be calculated using a predetermined function. Since the loss of the motor 1 or the PWM inverter 3 is almost proportional to the 1st to 2nd power of the motor drive current, more appropriate overheat protection can be performed.

  Here, as the power function, for example, there are those shown in the following equations (3) to (5).

f1 (i) = i ^3/2 (3)
f2 (i) = i ² (4)
f3 (i) = i ^3/2 + a (5)

Note that f1, f2, and f3 are power functions, i is a motor current, and a is an arbitrary constant.
At this time, when the power function of the combined drive current Is is expressed by Expression (2), Expression (4) can be expressed by the following Expression (6).

f2 (Is) = Id ² + Iq ² (6)

  By using Expression (6), the calculation expression can be simplified, and the processing load of the motor current limit value calculation unit 13 can be reduced.

  Further, by performing polynomial approximation or broken line approximation on the above power function, the amount of calculation can be further reduced, and the processing load on the motor current limit value calculation unit 13 can be reduced. Also, the amount of calculation can be reduced by making a table of some or all of the above calculations and referring to the table.

  In the first embodiment, the combined drive current Is is obtained from the d-axis drive current Id and the q-axis drive current Iq. However, the present invention is not limited to this. In general, in the control of the motor 1, the d-axis drive current Id, which is a magnetic flux axis, is usually used as a flux weakening control, but is often smaller than the q-axis drive current Iq, which is a torque axis. Therefore, when the d-axis drive current Id is sufficiently smaller than the q-axis drive current Iq, the amount of calculation can be further reduced by simplifying the combined drive current Is as shown in the following equation (7). The processing load of the motor current limit value calculation unit 13 can be reduced.

  Is = Id + Iq (7)

Further, when the motor 1 is efficiently controlled, the d-axis drive current Id is normally controlled to zero. In this case, since the d-axis drive current Id is 0, the combined drive current Is may be regarded as the q-axis drive current Iq.
In motor control in which the q-axis drive current Iq hardly flows, the combined drive current Is may be regarded as the d-axis drive current Id.
Alternatively, the maximum value of the d-axis drive current Id and the q-axis drive current Iq may be selected as the combined drive current Is.
Also in the above case, the calculation amount can be further reduced, and the processing load of the motor current limit value calculation unit 13 can be reduced.

  In the first embodiment, the motor current limit values (Idr, Iqr) are obtained using the combined drive current Is. However, the motor current limit values (Idr, qqr) are calculated using the d-axis drive current Id and the q-axis drive current Iq. Idr, Iqr) may be obtained.

  In the first embodiment, the combined drive current Is is obtained from the d-axis drive current Id and the q-axis drive current Iq, but the absolute values of the d-axis drive current Id and the q-axis drive current Iq are time-smoothed. In order to achieve this, the combined drive current Is may be obtained after the d-axis drive current Id and the q-axis drive current Iq are added for an arbitrary predetermined time at an arbitrary predetermined period, respectively.

  In the first embodiment, the motor current limit values (Idr, Iqr) are calculated using the d-axis drive current Id and the q-axis drive current Iq. However, as shown in FIG. The motor current limit values (Idr, Iqr) may be calculated using the axis component current) Id * and the q-axis command current (q-axis component current) Iq *. In this case, the present invention can also be applied to a motor control device that does not include a detection circuit for each phase current, such as open loop control.

  In the first embodiment, the three-phase brushless motor 1 has been described as a multiphase motor. However, the present invention is not limited to this, and the same effect can be obtained if a multiphase motor such as an induction motor is used. Can be played.

In the first embodiment, the motor current limit value is decomposed into the d-axis current limit value Idr and the q-axis current limit value Iqr so that the current phase angle θ1 is constant, but the current phase angle θ1 is changed. Also good.
In this case, a method of preferentially flowing the d-axis current and a method of preferentially flowing the q-axis current while limiting the combined command current of the d-axis command current Id * and the q-axis command current Iq * to a predetermined value or less. You could think so. As shown in the first embodiment, when the three-phase brushless motor 1 is controlled, a field weakening effect can be obtained by flowing the d-axis drive current Id in the negative direction. Accordingly, when the d-axis drive current Id is preferentially passed, the motor 1 can be driven with priority on the rotation speed.
If the field is constant, the q-axis drive current Iq is proportional to the output torque. Therefore, when the q-axis drive current Iq is preferentially flowed, the motor 1 can be driven with priority given to the torque.

  The above method can also be applied to the case where the magnetic flux is controlled by the excitation current, such as an induction motor. In the first embodiment, the method of controlling the three-phase brushless motor 1 on the dq coordinate has been described. However, when the induction motor is controlled on the γδ coordinate, the number of γ-axis rotor flux linkages and the δ-axis fixed are shown. The child current may be gradually decreased uniformly.

In the first embodiment, whether or not the motor 1 is rotating is determined using a predetermined rotation speed ξ of the motor 1 that is arbitrarily set as a threshold value, and the parameter of the motor current limit value changing speed Vm is switched. However, of course, it is not limited to this.
For example, the motor current limit value calculation unit 13 may be configured as shown in FIG. In FIG. 7, a motor current limit value calculation unit 13 outputs a rotation coefficient table 13a that outputs a rotation coefficient Kr that is 1 or less in accordance with the motor rotation speed R1, and changes in the motor current limit value in accordance with the combined drive current Is. A motor current limit value change speed table 13b for outputting the speed Vm ′ and a multiplier 13c for multiplying the rotation coefficient Kr and the motor current limit value change speed Vm ′ are included.

The rotation coefficient Kr output from the rotation coefficient table 13a and the motor current limit value change speed Vm ′ output from the motor current limit value change speed table 13b are multiplied by the multiplier 13c to obtain a motor current limit value change speed. Output as Vm.
Thereby, the motor current limit values (Idr, Iqr) corresponding to the motor rotation speed R1 can be obtained more finely.

  Further, as shown in FIG. 8, a product obtained by multiplying the combined drive current Is by the rotation coefficient Kr output from the rotation coefficient table 13a may be input to the motor current limit value changing speed table 13b. In this case, the same effect as described above can be obtained.

Embodiment 2. FIG.
In the first embodiment, the current control unit 10 performs feedback control of the limited current on the dq coordinate, but may perform feedback control on the three-phase AC coordinate. Further, in order to obtain the motor rotation speed, the motor rotation speed is calculated using the magnetic pole position of the rotor detected by the position sensor 2, but the motor rotation speed may be estimated from the motor terminal voltage and the motor drive current. .

FIG. 9 is a block diagram showing a motor control apparatus according to Embodiment 2 of the present invention.
In FIG. 9, the motor control device applies a motor current command value (Id *, Iq *) to the motor 1 from the dq-3 phase coordinate conversion unit 15 that converts the dq coordinate to the three-phase AC coordinate, and the PWM inverter 3. And a terminal voltage detecting unit (terminal voltage detecting means) 16 for detecting the motor terminal voltage.
Further, the motor rotation speed calculation unit 12 shown in FIG. 1 is omitted, and a motor rotation speed estimation calculation unit 17 that estimates the motor rotation speed from the motor terminal voltage and the motor drive current is provided. Further, the dq-3 phase coordinate conversion unit 11 shown in FIG. 1 is omitted, and an adder 19 is provided in the output part of the current control means 10, and other configurations are the same as those in the first embodiment. The description is omitted. The program installed in the microcontroller 6B is the same as that shown in the first embodiment, and a description thereof will be omitted.

The operation of the motor control device having the above configuration will be described below. Note that the description of the same operation as in the first embodiment is omitted.
First, the motor drive currents Iu, Iv, Iw for three phases output from the current detector 4 are converted into digital signals by the A / D converter 8 and then input to the motor rotation speed estimation calculation unit 17. .
Further, the three-phase motor terminal voltages Vu, Vv, and Vw detected by the terminal voltage detection unit 16 are input to the motor rotation speed estimation calculation unit 17.

  Here, the model of the three-phase permanent magnet synchronous motor can be generally expressed as the following equation (8).

  Ω is the motor rotation speed, θ2 is the motor angle based on the u phase, R is the armature resistance, L is the self-inductance of the armature winding, M is the mutual inductance of the armature winding, and Φ is the flux linkage , P is the differential operator (d / dt).

  Here, when the motor 1 is driven, there is a motor angle where Iv = −Iw. At this time, the u-phase terminal voltage can be expressed by the following equation (9).

    Vu = −ωΦsin (θ2) (9)

At this time, θ2 becomes a predetermined value because the motor angle is a predetermined angle, R, L, and Φ are determined by the characteristics of the motor 1, and Vu and Iu are detected.
Therefore, when Iv = −Iw, the motor rotation speed ω can be calculated.
Further, the rotational speed ω can be similarly determined when Iu = −Iw and when Iu = −Iv.

  The motor current limit value calculation unit 13 uses the d-axis drive current Id, the q-axis drive current Iq, and the motor rotation speed ω calculated by the motor rotation speed estimation calculation unit 17, and the method described in the first embodiment. The motor current limit values (Idr, Iqr) are obtained by the same method.

  Further, the d-axis command current Id * and the q-axis command current Iq * are converted into the u-phase command current Iu * and the v-phase command current Iv * on the three-phase AC coordinates by the dq-3 phase coordinate conversion unit 15. .

  The motor current limit values (Idr, Iqr) calculated by the motor current limit value calculation unit 13 limit the peak value of the three-phase alternating current. Therefore, the motor current limiter 14 limits the peak values of the u-phase command current Iu * and the v-phase command current Iv * to be less than or equal to the motor current limit value, and after the u-phase control current Iur * and the v-phase control Output as current Ivr *.

  The subtractor 18 outputs a difference between the u-phase controlled current Iur * and the u-phase driving current Iu, and the v-phase controlled current Ivr * and the v-phase driving current Iv. Based on this, feedback control is performed. As for the output of the current control unit 10, the w-phase current is obtained by the adder 19 and input to the PWM inverter 3. The motor 1 is driven by the output of the PWM inverter 3.

  According to the motor control device according to the second embodiment of the present invention, the motor current command value (Iu *, Iv *) can be limited on the three-phase AC coordinate according to the motor rotational speed ω. The motor 1 can be protected from overheating.

In the second embodiment, the motor rotation speed ω is estimated from the motor terminal voltages Vu, Vv, Vw on the three-phase AC coordinates and the motor drive currents Iu, Iv, Iw, but the motor terminal voltage Vd on the dq coordinates is used. , Vq and motor drive currents Iu, Iv, Iw may be estimated.
When the motor terminal voltages Vu, Vv, Vw and the motor driving currents Iu, Iv, Iw, which are three-phase AC coordinates, are coordinate-converted to the dq coordinates, which are orthogonal coordinate systems, the model of the three-phase permanent magnet synchronous motor is generally Can be described as the following equation (10).

Note that Φf is the flux linkage on the dq coordinate.
Here, when Id = 0, the q-axis terminal voltage can be expressed by the following equation (11).

    Vq = (R + pL) Iq + ωΦf (11)

  At this time, R, L, and Φf are determined by motor characteristics, and Vq and Iq can be calculated by dq coordinate transformation. Therefore, the motor rotation speed ω can be obtained.

  When the motor control device of the second embodiment is used for an electric power steering device, the rotation speed of the motor is estimated by substituting a sensor for detecting the steering wheel angle or a snake angle sensor for detecting the horn angle of the steering wheel. Also good.

Embodiment 3 FIG.
In the first and second embodiments, the motor current limit values (Idr, Iqr) are calculated using the d-axis drive current Id and the q-axis drive current Iq. However, the threshold value for overheat protection determination and the d-axis drive current are calculated. The motor current limit values (Idr, Iqr) may be calculated based on the deviation between Id and the q-axis drive current Iq.

FIG. 10 is a block diagram showing a motor control apparatus according to Embodiment 3 of the present invention.
In FIG. 10, the microcontroller 6C is given a threshold value for determining an overheat protection that is arbitrarily set. Further, the microcontroller 6C has subtractors 20d and 20q (hereinafter collectively referred to as “subtractor 20”) that output the difference between the d-axis drive current Id and the q-axis drive current Iq and the overheat protection determination threshold value. is doing.
Other configurations are the same as those of the first embodiment, and the description thereof is omitted. The program installed in the microcontroller 6C is the same as that shown in the first embodiment, and a description thereof will be omitted.

The operation of the motor control device having the above configuration will be described below. Note that the description of the same operation as in the first embodiment is omitted.
The d-axis drive current Id and the q-axis drive current Iq output from the dq-3 phase coordinate conversion unit 15 are respectively compared with the overheat protection determination threshold value by the subtractor 20 to obtain a deviation. The maximum value of each deviation is output as the motor current limit value change speed, for example, according to the same characteristics as in FIG. At this time, the horizontal axis shown in FIG. 4 is replaced with the above deviation from the combined drive current. Subsequently, the motor current limit values (Idr, Iqr) are calculated by integrating the motor current limit value change speed.

  According to the motor control device of the third embodiment of the present invention, the motor current limit values (Idr, Iqr) are based on the deviation between the overheat protection determination threshold value and the d-axis drive current Id and the q-axis drive current Iq. ), The motor current command value (Id *, Iq *) can be limited early when the motor drive current is large and late when the motor drive current is small, and more practical overheat protection can be applied. Can do.

  For example, if a current value at which the motor 1 can be continuously operated (hereinafter referred to as “continuous rated current”) is set as the threshold value for determining the overheat protection, the motor 1 or the PWM inverter 3 can be used for a short time. A large current can be applied for a short time according to the rating, and the motor current can be smoothly converged to the continuous rated current according to the operating conditions.

In the third embodiment, the maximum current is gradually decreased or increased based on the deviation between the coordinate-converted current, that is, the combined drive current Is and the predetermined overheat protection determination threshold. The maximum current may be gradually decreased or gradually increased based on the integrated value of the deviation between the power function and a predetermined overheat protection determination threshold value.
Since the loss of the motor 1 or the PWM inverter 3 is almost proportional to the 1st to 2nd power of the motor drive current, more appropriate overheat protection can be performed by this method.

  Further, the same effect can be obtained even if the maximum current is gradually reduced or gradually increased based on the power function of the deviation between the combined drive current Is and the predetermined overheat protection determination threshold value shown in the first embodiment. it can.

It is a block diagram which shows the motor control apparatus which concerns on Embodiment 1 of this invention with a peripheral device. It is a flowchart which shows the operation | movement of the program of the software built in the microcontroller of FIG. It is explanatory drawing which shows the motor current limiting value of the motor control apparatus which concerns on Embodiment 1 of this invention. It is a characteristic view which shows the synthetic | combination drive current vs. motor current limiting value change speed of the motor control apparatus which concerns on Embodiment 1 of this invention at the time of rotation of a motor, and a stop. It is explanatory drawing which shows the d-axis current limiting value and q-axis current limiting value of the motor control apparatus which concerns on Embodiment 1 of this invention at the time of rotation of a motor, and a stop. It is another block diagram which shows the motor control apparatus which concerns on Embodiment 1 of this invention with a peripheral device. It is explanatory drawing which shows the method of calculating | requiring a motor current limiting value change speed using the rotational speed of the motor of the motor control apparatus which concerns on Embodiment 1 of this invention. It is another explanatory drawing which shows the method of calculating | requiring a motor current limiting value change speed using the rotational speed of the motor of the motor control apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the motor control apparatus which concerns on Embodiment 2 of this invention with a peripheral device. It is a block diagram which shows the motor control apparatus which concerns on Embodiment 3 of this invention with a peripheral device.

Explanation of symbols

  1 3-phase brushless motor, 2 position sensor, 3 PWM inverter, 4 current detector, 5 current command value calculation unit, 6 microcontroller, 7 overheat protection unit, 8 A / D converter, 9 3-phase-dq coordinate conversion unit DESCRIPTION OF SYMBOLS 10 Current control part, 11 dq-3 phase coordinate conversion part, 12 Motor rotation speed calculation part, 13 Motor current limit value calculation part, 14 Motor current limit part, 15 dq-3 phase coordinate conversion part, 16 Terminal voltage detection part , 17 Motor rotation speed estimation calculation unit, 18 subtractor, 19 adder, 20 subtractor, Id d-axis drive current, Iq q-axis drive current, Id * d-axis command current, Iq * q-axis command current, Idr d-axis Motor current limit value, Iqr q-axis motor current limit value, Idr * q-axis limited current, Iqr * q-axis limited current.

Claims (18)

An inverter device for driving a multiphase motor;
Position detecting means for detecting the magnetic pole position of the rotor of the multiphase motor;
Drive current detection means for detecting a motor drive current input from the inverter device to the multiphase motor;
Current command value calculation means for generating a motor current command value of the multiphase motor;
Motor control means for controlling the inverter device using the motor current command value,
The motor control means calculates a motor current limit value for limiting the motor current command value based on the rotation speed of the multiphase motor calculated from the magnetic pole position and the motor drive current. Motor control device. An inverter device for driving a multiphase motor;
Terminal voltage detection means for detecting a terminal voltage applied to the multiphase motor from the inverter device;
Drive current detection means for detecting a motor drive current input from the inverter device to the multiphase motor;
Current command value calculation means for generating a motor current command value of the multiphase motor;
Motor control means for controlling the inverter device using the motor current command value,
The motor control means calculates a motor current limit value for limiting the motor current command value based on the rotation speed of the multiphase motor calculated from the terminal voltage and the motor drive current and the motor drive current. A motor control device. An inverter device for driving a multiphase motor;
Position detecting means for detecting the magnetic pole position of the rotor of the multiphase motor;
Current command value calculation means for generating a motor current command value of the multiphase motor;
Motor control means for controlling the inverter device using the motor current command value,
The motor control means calculates a motor current limit value for limiting the motor current command value based on the rotation speed of the multiphase motor calculated from the magnetic pole position and the motor current command value. A motor control device. An inverter device for driving a multiphase motor;
Terminal voltage detection means for detecting a terminal voltage applied to the multiphase motor from the inverter device;
Drive current detection means for detecting a motor drive current input from the inverter device to the multiphase motor;
Current command value calculation means for generating a motor current command value of the multiphase motor;
Motor control means for controlling the inverter device using the motor current command value,
The motor control means sets a motor current limit value for limiting the motor current command value based on the rotation speed of the multiphase motor calculated from the terminal voltage and the motor drive current and the motor current command value. A motor control device characterized by computing.   5. The motor control unit according to claim 1, wherein the motor control unit calculates the motor current limit value according to an integrated value of a predetermined function of the motor drive current or the motor current command value. The motor control device according to item 1.   The said motor control means judges the presence or absence of rotation of the said multiphase motor from the said rotational speed, and calculates the said motor current limit value, The any one of Claim 1-5 characterized by the above-mentioned. The motor control apparatus described.   7. The motor control unit according to claim 5, wherein the motor control unit obtains an integrated value after multiplying a value obtained by the predetermined function by a coefficient of 1 or less corresponding to the rotation speed. The motor control device according to item.   The motor control apparatus according to claim 5, wherein the predetermined function is a power function.   The motor control means performs coordinate conversion of the motor drive current or the motor current command value into a d-axis (magnetic flux axis) component current and a q-axis (torque axis) component current orthogonal to the d-axis component current. The motor control device according to any one of claims 1 to 8, wherein a motor current limit value is calculated.   The motor control device according to claim 9, wherein the motor control unit calculates the motor current limit value by using any one of the d-axis component current and the q-axis component current.   The motor control device according to claim 9, wherein the motor control unit calculates the motor current limit value using a combined current obtained by combining the d-axis component current and the q-axis component current.   11. The motor control unit according to claim 9, wherein the motor control unit calculates the motor current limit value using a current having a large amount of conduction among the d-axis component current and the q-axis component current. Motor control device.   The motor control means calculates the motor current limit value using a deviation between a threshold value for overheat protection determination and the d-axis component current and the q-axis component current. Motor control device.   The motor control means performs coordinate conversion of the motor current command value into a d-axis command current and a q-axis command current orthogonal to the d-axis command current, and based on the motor current limit value, the d-axis command current The motor control device according to any one of claims 1 to 13, wherein at least one of the q-axis command current is limited.   The motor control according to claim 14, wherein the motor control means maintains an angle formed by the q-axis command current and a combined command current obtained by combining the d-axis command current and the q-axis command current. apparatus.   The motor control means performs coordinate conversion of the motor current command value into a d-axis command current and a q-axis command current orthogonal to the d-axis command current, and based on the motor current limit value, the d-axis command current 14. The motor control device according to claim 1, wherein a combined command current obtained by combining the q-axis command current and the q-axis command current is limited.   The said motor control means controls the said synthetic | combination command current so that either the said d-axis command current or the said q-axis command current may be prioritized based on the said motor current limiting value. The motor control apparatus described. The said motor control means restrict | limits the peak value of the phase current of the said motor current command value based on the said motor current limit value, The any one of Claim 1-13 characterized by the above-mentioned. Motor control device.

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