JP4687104B2 - Control device and method for permanent magnet type rotary motor - Google Patents

Description

  The present invention relates to a control device and method for a permanent magnet type rotary electric motor, and more particularly to torque correction for correcting the influence of magnet temperature on torque.

  In a rotary motor having a permanent magnet in the rotor (hereinafter abbreviated as “PM motor”), it has been found that the magnetic flux density of the permanent magnet changes due to the temperature change of the permanent magnet. In actual PM motors, the torque also fluctuates due to the change in magnetic density. Therefore, the output torque fluctuates even with the same torque command, and depending on the situation, there has been a problem of control failure due to output decrease or voltage increase. Further, when obtaining a reference current map in order to make the conditions the same, it takes a lot of man-hours to keep the temperature condition of each part of the motor constant.

  In order to explain the influence of the temperature change of the motor on the torque, FIG. 1 shows a graph for explaining the relationship between the temperature of each element of the rotary electric motor (motor) and the actual torque value. As shown in the figure, the motor coil temperature and the magnet temperature increase with time with respect to the rotational speed of 4000 rpm-150 Nm and the torque command value, and the actual torque value decreases accordingly. Observed. In this case, it can be seen that the torque error increases as the temperature of the constituent elements of the motor increases, and is finally reduced by 3.5% and saturated.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 2000-224812 (refer to Patent Document 1) attempts to suppress the torque fluctuation of the motor by measuring or estimating the magnetic flux density. The change measurement method and estimation method are unclear, and the problem remains that the error becomes very large due to the estimation accuracy of the magnet. In addition, this conventional technique proposes to increase or decrease the d-axis current to make the torque constant, but since voltage monitoring and control are not performed, unstable control when the current value is increased or decreased, In the worst case, inefficient control is expected to result in control failure.
Furthermore, in Japanese Patent Laid-Open No. 7-212915 (refer to Patent Document 2) of the prior art, an attempt is made to correct the magnet temperature by measuring the induced voltage, but the actual induced voltage is actually measured during operation. It is impossible to do so, and it will be necessary to measure current, voltage and stator temperature.
JP 2000-224812 (paragraph 0008, FIG. 1) Japanese Patent Laid-Open No. 7-212915 (paragraphs 0016-0020, FIG. 1)

  An object of the present invention is to provide a control device that corrects a torque error associated with a temperature change of an element of a permanent magnet motor without measuring the temperature with a temperature sensor or the like.

In order to solve the above-mentioned problems, a control device for a permanent magnet type rotary electric motor according to the first invention is provided:
Position detection means (circuit) for detecting the motor phase of the rotary motor;
Based on the motor rotational speed obtained from the detected motor phase and the given torque command value, each current command is referred to by referring to a torque current conversion map showing the relationship between the torque value, the motor rotational speed and the current value prepared in advance. Torque calculation means (circuit) for obtaining a value;
Conversion means for converting each current command value into each voltage command value (for example, a PI-type control circuit);
Based on the given torque command value, each voltage value read with reference to the torque voltage conversion map showing the relationship between the torque value, the rotational speed and the voltage value acquired simultaneously with the torque current conversion map, and the rotation obtains the voltage values applied to the motor, wherein the voltage values to be applied to the rotary electric machine, taking the difference between the voltage values, wherein the read, at least one correction value of the respective current based on these Correction control means (circuit) for obtaining
With

Further, the control device for the permanent magnet type rotary electric motor according to the second invention is:
The correction control means obtains a correction value of only the q-axis current among the currents, that is, obtains only a correction value (Δq) of a current of a component contributing to torque (ie, q-axis current). .

A control device for a permanent magnet type rotary electric motor according to a third invention is:
Map rewriting means (circuit) for rewriting (updating) the torque current conversion map based on at least one correction value obtained by the correction control means;
It is characterized by comprising.

As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium storing the program substantially corresponding to these, and the scope of the present invention. It should be understood that these are also included.
For example, when the control device for a permanent magnet type rotary electric motor according to the first invention is realized as a method, the control method for the permanent magnet type rotary electric motor is:
Based on the motor rotation speed and the given torque command value, the torque current conversion map showing the relationship between the torque value, the motor rotation speed and the current value prepared in advance is used to calculate each current command value using the calculation means. The required torque calculation step;
A conversion step of converting each current command value into each voltage command value using the computing means;
Based on the given torque command value using the arithmetic means, it is read with reference to the torque voltage conversion map showing the relationship between the torque value, the rotational speed and the voltage value acquired simultaneously with the torque current conversion map. The respective voltage values and the respective voltage values applied to the rotary motor are obtained, the difference between the respective voltage values applied to the rotary motor and the read voltage values is taken, and the currents are determined based on these differences. A correction control step for obtaining at least one correction value of
It is characterized by including.

  In the first invention, having a torque-current conversion map, and having the voltage conversion map at the time of acquisition of the conversion map, torque correction can be performed only by detecting the voltage difference when the motor temperature changes. That is, according to the first invention, torque correction can be performed only by detecting a voltage difference when the temperature of the motor changes without using a temperature measuring means. In other words, the present invention is a control method that enables temperature correction in a pseudo manner without measuring the temperature of the motor. Therefore, a temperature measuring device (such as a thermistor or a thermocouple) for measuring the coil temperature of the motor is used. It is unnecessary.

  According to the second invention, when the above control is performed, the torque correction control can be performed by correcting only the q-axis current contributing to the torque. Therefore, it is not necessary to use a complicated calculation formula, and torque correction control can be performed with a simple calculation formula. That is, voltage control logic can be provided in addition to the above correction control, and voltage adjustment can be performed by complementing only the d-axis current. As a result, it is possible to perform highly efficient control and to avoid control failure and the like.

According to the third aspect of the invention, the control logic can be simplified by rewriting and learning the torque current conversion map with the value corrected in this control, and high response control is possible.
By applying this control, the efficiency of the experiment can be improved because it is not necessary to consider the current map acquisition condition as a reference.

（ここで、P：極対数、φａ：磁石による磁束、ｄ軸電流ｉｄ：ｉａ・sinβ、ｑ軸電流ｉｑ：ｉａ・cosβ、β：磁石位置と電流ベクトルの角度、Lｄ：ｄ軸インダクタンス、Lｑ：ｑ軸インダクタンス）
と表わせる。
一方、ｄ軸電圧ｖdおよびｑ軸電圧Ｖｑはそれぞれ
ｖd＝R・ｉｄ+ω・Lｄ・ｉｑ
ｖｑ＝R・ｉｄ+（ω・φａ−Lｄ・ｉｄ）
であり、Ld，Lｑの温度変化は小さいことから無視でき、
トルク誤差ΔＴは

と表せる。
っまり、常にトルク誤差ΔTを0にしようとすると、ｉｑ＝Δｖｑ／ΔＲとなるように制御することで成立する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the outline of the principle of the present invention will be described. The torque T of the PM motor is

(Where P: number of pole pairs, φa: magnetic flux by magnet, d-axis current id: ia · sinβ, q-axis current iq: ia · cosβ, β: angle of magnet position and current vector, Ld: d-axis inductance, Lq : Q-axis inductance)
It can be expressed as
On the other hand, the d-axis voltage vd and the q-axis voltage Vq are vd = R · id + ω · Ld · iq, respectively.
vq = R · id + (ω · φa-Ld · id)
Since the temperature change of Ld and Lq is small, it can be ignored.
Torque error ΔT is

It can be expressed.
In other words, if the torque error ΔT is always set to 0, it is established by controlling so that iq = Δvq / ΔR.

この場合、求めたこのトルク誤差ΔＴをトルク値に直接フィードバックしてトルクを補正する。 When ω = 0, vd = R · id
Because it can be expressed as vq = R · id

In this case, the obtained torque error ΔT is directly fed back to the torque value to correct the torque.

  In the control according to the present invention, the voltage map is acquired at the same time as the reference torque-current conversion map (torque-to-current conversion map) is acquired, and is owned for control. FIG. 2 is a schematic diagram showing an image of a torque current conversion map and a torque voltage conversion map. As shown in the figure, current and voltage values are defined for various combinations of torque values and motor rotation values.

  An example of a torque current conversion map is shown as a table below.

In the current map as described above in the present invention, the temporal influence does not usually need to be considered. For this reason, the actual torque value is determined according to the conditions when the current map is acquired. In order to match the actual torque, it is necessary to make the conditions constant, but it takes time and is practically impossible. Instead of matching the above map acquisition conditions, it is possible to measure the temperature at the time of map acquisition and match the torque by actually comparing the temperature at the time of driving the motor, but a thermistor or the like is required.
Therefore, in the present invention, the voltage at the time of map acquisition is dealt with by detecting the voltage at the time of map acquisition and the voltage at the time of actual motor drive. That is, the time element is substituted by detecting the voltage of the motor.

FIG. 3 is a control block diagram for explaining an example of the motor control device according to the present invention. As shown in the figure, the motor control device according to the present invention includes a torque calculation unit 10, a PI (proportional integration) control unit 12, a two-phase / three-phase conversion unit 14, a power supply 16, an IGBT (inverter) 18, and a motor (rotary motor). 20, a position sensor 22, a terminal voltage temperature correction control unit 24, a three-phase / two-phase conversion unit 26, an ω calculation / Θ calculation unit 28 and a torque temperature correction control unit 30.
In the motor control, the position sensor 22 (resolver or encoder) of the motor 20 detects the position of the rotor, calculates the rotation speed, and gives the obtained resolver signal or encoder signal to the ω calculation / Θ calculation unit 28. The ω calculation / Θ calculation unit 28 calculates the electrical angular velocity ω and the electrical angle Θ based on the given signal, and the electrical angular velocity ω is output to the torque calculation unit 10 and the electrical angle Θ is input to the 2-phase / 3-phase conversion unit 14. give. The three-phase / two-phase conversion unit 26 converts the three-phase current into two phases and supplies it to the PI control unit 12.

FIG. 4 is a flowchart illustrating an example of torque correction control processing in the control device of FIG. FIG. 5 is a flowchart illustrating an example of voltage correction control processing in the control device of FIG. By referring to a torque current conversion map prepared in advance, the torque calculation unit 10 draws the current from the motor rotation speed at that time and maps the torque command value to the torque command value T * given from the outside. Is converted into a current command value.
The current command values (id ^* , iq ^* ) are converted into voltage command values (vd ^* , vq ^* ) by the PI (proportional integration) control unit 12. At this time, the torque temperature correction control unit 30 reads the voltage values vd and vq applied to the motor 20.
Also, refer to the reference torque voltage conversion map, read vd * and vq * at the time of vd and vq standard torque, and finally calculate d-axis voltage correction value Δvd and q-axis voltage correction value Δvq with the following formulas (Step S10).
Δvd = vd ^* −vd
Δvq = vq ^* −vq

したがって、サーミスタ等の温度計測装置を用いてモータの巻き線抵抗の温度を計測することなく、抵抗の温度変化を計算して補正抵抗値ΔＲを求めることが可能となる。 Next, the resistance value is calculated. In general, the resistance is calculated by measuring the coil temperature and multiplying the resistance value at normal temperature by a coefficient. However, in the present invention, only the change in voltage is expressed by the following equation. The resistance change is calculated by using this, and the resistance value is calculated by correcting with the obtained resistance change (step S14).

Therefore, it is possible to calculate the resistance resistance change ΔR by calculating the temperature change of the resistance without measuring the temperature of the winding resistance of the motor using a temperature measuring device such as a thermistor.

としてΔｉｑをｑ軸電流への補正値とする（ステップS18）。ここでモータの磁石温度変化の時定数は数分以上あるため、急激には変化しない。また、演算量は少ないほど良いため、本補正値を常に電流フィードバックロジックで計算するのではなく、次回以降のループではトルク電流変換マップ自体を書き換える（ステップS20）ことで他への制御遅れ等の影響を最小限にするための機構を設けることが好適である。電圧補正制御を行うステップS22の詳細は、図５の各処理に示す通りである。
また、角速度ω＝0時には、

である。 Further, the amount of change in current value is calculated using this resistance change (step S16).

Δiq is a correction value for the q-axis current (step S18). Here, since the time constant of the magnet temperature change of the motor is several minutes or more, it does not change abruptly. In addition, since the smaller the amount of calculation, the better. This correction value is not always calculated by the current feedback logic, but the torque current conversion map itself is rewritten in the subsequent loop (step S20), so that the control delay to others is reduced. It is preferable to provide a mechanism for minimizing the influence. The details of step S22 for performing voltage correction control are as shown in each process of FIG.
When the angular velocity ω = 0,

It is.

と表せることから、
ΔＴ＝P・ｉq²・Ｌd
として計算する（ステップS28）。
このトルク補正値をトルク指令値に加えて補正したトルク
T＝T^＊＋ΔT
を計算する（ステップS30）。
に基づき、トルク電流変換マップを参照して、トルク指令を電流指令へと変更することで対応する。 When the motor speed is 0 (step S2), the motor constant Ld and the q-axis current Iq actually applied to the motor 20 are read (steps S24 and S26). Therefore, the torque correction value is

Because it can be expressed as
ΔT = P ・ iq ²・ Ld
(Step S28).
Torque corrected by adding this torque correction value to the torque command value
T = T ^* + ΔT
Is calculated (step S30).
Based on the above, the torque current conversion map is referred to and the torque command is changed to the current command.

となるように電流を補完することで電圧を一定に保つことが可能となる。
または、この場合、△idは一定値にすることも可能である。 In addition, during voltage control, when the current value shown above is corrected, the voltage may exceed the battery voltage limit. At this time,

It is possible to keep the voltage constant by complementing the current so that
In this case, Δid can be a constant value.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention.

It is a graph explaining the relationship between the temperature of each element of a rotary electric motor (motor), and an actual torque value. It is a schematic diagram showing the image of a torque current conversion map and a torque voltage conversion map. It is a control block diagram explaining an example of the motor control apparatus by this invention. It is a flowchart explaining an example of the process of torque correction control in the control apparatus of FIG. It is a flowchart explaining an example of the process of the voltage correction control in the control apparatus of FIG.

Explanation of symbols

10 Torque calculator
12 PI (proportional integral) controller
14 2-phase / 3-phase converter
16 Power supply
18 IGBT (Inverter)
20 Motor (Rotary motor)
22 Position sensor
24 terminal voltage temperature compensation controller
26 3-phase / 2-phase converter
28 ω operation / Θ operation unit
30 Torque temperature compensation controller

Claims (4)

A control device for a permanent magnet type rotary electric motor,
Torque calculation means for obtaining each current command value by referring to a torque current conversion map showing a relationship between a torque value, a motor rotation number and a current value prepared in advance based on the motor rotation number and a given torque command value;
Conversion means for converting each current command value into each voltage command value;
Based on the given torque command value, each voltage value read with reference to the torque voltage conversion map showing the relationship between the torque value, the rotational speed and the voltage value acquired simultaneously with the torque current conversion map, and the rotation obtains the voltage values applied to the motor, wherein the voltage values to be applied to the rotary electric machine, taking the difference between the voltage values, wherein the read, at least one correction value of the respective current based on these Correction control means for obtaining
A control device for a permanent magnet type rotary electric motor. In the control device for the permanent magnet type rotary electric motor according to claim 1,
The correction control means obtains a correction value of only the q-axis current among the currents;
A control device for a permanent magnet type rotary electric motor. In the control apparatus of the permanent magnet type rotary electric motor according to claim 1 or 2,
Map rewriting means for rewriting the torque current conversion map based on at least one correction value obtained by the correction control means;
A control device for a permanent magnet type rotary electric motor, comprising: A method for controlling a permanent magnet type rotary electric motor,
Based on the motor rotation speed and the given torque command value, the torque current conversion map showing the relationship between the torque value, the motor rotation speed and the current value prepared in advance is used to calculate each current command value using the calculation means. The required torque calculation step;
A conversion step of converting each current command value into each voltage command value using the computing means;
Based on the given torque command value using the arithmetic means, it is read with reference to the torque voltage conversion map showing the relationship between the torque value, the rotational speed and the voltage value acquired simultaneously with the torque current conversion map. The respective voltage values and the respective voltage values applied to the rotary motor are obtained, the difference between the respective voltage values applied to the rotary motor and the read voltage values is taken, and the currents are determined based on these differences. A correction control step for obtaining at least one correction value of
A control method of a permanent magnet type rotary electric motor including

Images