JP4771384B2 - Induction motor control device - Google Patents

Description

  The present invention relates to a control device that controls an induction motor that does not include a speed sensor according to an input speed command value while referring to a primary current of the induction motor.

  Conventionally, various types of motor control devices have been used depending on the type of motor to be controlled. For example, as a conventional control device that performs vector control of an induction motor that does not include a speed sensor, the one shown in FIG.

The control device 100 performs vector control of the induction motor 20 according to the input speed command value ω _r ^* while referring to the primary currents I _{U, V, W} of the induction motor 20.
In this control device 100, the speed control unit 2 includes a field current command value I _d ^* and a torque current such that the deviation between the speed command value ω _r ^* and the actual rotational speed ω _r obtained by calculation becomes zero. The command value I _q ^* is obtained. The three-phase to two-phase converter 6 obtains the actual torque current I _q from the detected primary currents I _{U, V, W.} The frequency control unit 7 obtains the primary angular frequency ω ₁ such that the deviation between the torque current command value I _q ^* obtained in the B part and the actual torque current I _q becomes zero.

ここで、Ｒ₁、Ｌ₁、Ｌ₂、Ｌ_Mはそれぞれ誘導電動機２０の一次抵抗、一次インダクタンス、二次インダクタンス、相互インダクタンスである。 Further, the voltage calculation unit 11 calculates the d-axis voltage command value V by the following formula based on the field current command value I _d ^* , the torque current command value I _q ^* , the primary angular frequency ω ₁ and the constants of the induction motor 20. _{Determine d} ^* and q-axis voltage command value _Vq ^* .

Here, R ₁ , L ₁ , L ₂ , and L _M are the primary resistance, primary inductance, secondary inductance, and mutual inductance, respectively, of the induction motor 20.

The two-phase / three-phase converter 4 converts the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* into three phases and outputs primary voltage command values V _{U, V, W.} The inverter 5 drives the induction motor 20 based on the primary voltage command values V _{U, V, W.}

"Basics and Applications of AC Motor Variable Speed Drive", IEEJ Technical Class / Terminology Organizing Investigation Committee, 28 October 1998, p. 93 (Fig. 4.16)

As described above, the conventional control device 100 performs feedback control via the primary angular frequency ω ₁ . However, since the primary angular frequency ω ₁ generally fluctuates only slowly with respect to sudden fluctuations in the load of the induction motor 20, the control device 100 has poor responsiveness to fluctuations in the load. For this reason, in the conventional control device 100, the inverter 5 and the induction are in the period until the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* are updated according to the latest state of the induction motor 20. There was a case where overcurrent continued to flow through the electric motor 20 and these were damaged.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for an induction motor that has good responsiveness and a relatively simple configuration.

  In order to solve the above problems, a control device according to the present invention is a control device that controls an induction motor that does not include a speed sensor in accordance with an input speed command value while referring to a primary current of the induction motor. The d-axis voltage command is such that the deviation between the torque current command value and the actual torque current obtained from the primary current and the deviation between the magnetizing current command value and the actual magnetizing current obtained from the primary current are zero. A current control unit that calculates a value and a q-axis voltage command value, a current predicted value calculation unit that calculates a torque current predicted value based on the d-axis voltage command value and the q-axis voltage command value, and the torque current predicted value; A frequency control unit for obtaining a primary angular frequency such that a deviation from the actual torque current is zero; a rotational speed of the induction motor obtained by adding a slip angular frequency to the primary angular frequency, and the speed command value; As deviation becomes 0, and a speed control section for determining at least the torque current command value.

（ただし、Ｒ₁、Ｌ₁、Ｌ₂、Ｌ_Mはそれぞれ前記誘導電動機の一次抵抗、一次インダクタンス、二次インダクタンス、相互インダクタンス、ω₁は前記一次角周波数、Ｖ_d ^*は前記ｄ軸電圧指令値、Ｖ_q ^*は前記ｑ軸電圧指令値である） In the control device, the predicted torque current value (I _q ^** ) is preferably calculated by the following equation.

(However, the primary resistance _{R 1, L 1, L 2} , L M respectively the induction motor, the primary inductance, secondary inductance, mutual inductance, omega ₁ is the primary angular frequency, V _d ^* is the d-axis voltage command Value, V _q ^* is the q-axis voltage command value)

  According to the present invention, it is possible to provide a control device for an induction motor that has good responsiveness and a relatively simple configuration.

It is a block diagram of a control device concerning the present invention. It is a block diagram of the conventional control apparatus.

  Hereinafter, a preferred embodiment of a control device for an induction motor according to the present invention will be described with reference to FIG.

The control device 1 according to the present invention performs vector control of the induction motor 20 according to the input speed command value ω _r ^* while referring to the primary currents I _{U, V, W} of the induction motor 20.
The speed control unit 2 sets the field current command value I _d ^* and the torque current command value I _q ^* so that the deviation between the speed command value ω _r ^* and the actual rotational speed ω _r obtained by calculation becomes zero. Obtained by PI control. The current control unit 3 determines the d-axis voltage command value V so that the deviation between the field current command value I _d ^* and the actual field current I _d obtained from the primary currents I _{U, V, W} is zero. _d ^* and a q-axis voltage command value V _q ^* such that a deviation between the torque current command value I _q ^* and the actual torque current I _q is zero are obtained by PI control.

そして、インバータ５は、この一次電圧指令値Ｖ_U,V,Wに基づいて誘導電動機２０を駆動する。 The two-phase to three-phase conversion unit 4 converts the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* into three phases using the following equation, and converts the primary voltage command values V _{U, V, and W} into Output. In the following equation, θ ₁ is a magnetic flux angle obtained by time integration of the primary angular frequency ω ₁ by the integrating unit 8.

The inverter 5 drives the induction motor 20 based on the primary voltage command values V _{U, V, W.}

The three-phase to two-phase converter 6 refers to the primary currents I _{U, V, W} (three-phase) flowing from the inverter 5 toward the induction motor 20, and calculates the actual field current I _d and torque current according to the following equations: _Iq is obtained.

As described above, the field current I _d and the torque current I _q are used in the current control unit 3 when obtaining the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* .
That is, in the control device 1 according to the present invention, the field current I _d and the torque current I _q are directly fed back, and the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* corresponding to the feedback result are obtained. Desired. Therefore, according to the present invention, it is possible to realize a control device having better responsiveness than the conventional one that performs feedback via the primary angular frequency ω ₁ .

By the way, in the control apparatus 1 which concerns on this invention, (1) Formula used by the conventional current calculating part 11 (refer FIG. 2) is not used in the current control part 3. FIG. Accordingly, the relationship of the equation (1) between the field current command value I _d ^* and the torque current command value I _q ^* and the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* is _{maintained as} it is. Is not established, and the induction motor 20 cannot be vector controlled.

上記（６）式は、（１）式で用いられている行列の逆行列を用いている。したがって、ｄ軸電圧指令値Ｖ_d ^*及びｑ軸電圧指令値Ｖ_q ^*と、この式で得られる界磁電流予測値Ｉ_d ^**及びトルク電流予測値Ｉ_q ^**との間には、（１）式の関係が成立することになる。 Therefore, the control device 1 according to the present invention, based on the primary angular frequency ω ₁ , the d-axis voltage command value V _d ^*, and the q-axis voltage command value V _q ^* , the torque current I _q (= A predicted current value calculation unit 10 for ^{obtaining a} predicted torque current value I _q ^** ) is provided. The predicted torque current value I _q ^** is obtained by the following equation.

The above equation (6) uses an inverse matrix of the matrix used in equation (1). Therefore, between the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* and the predicted field current value I _d ^** and the predicted torque current value I _q ^** obtained by this equation, The relationship of equation (1) is established.

The predicted torque current value I _q ^** can be obtained by referring to the primary voltage of the induction motor 20 instead of the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* . In this case, the calculation for ^{obtaining the} predicted torque current value I _q ^** becomes more complicated than the calculation of the above equation (6). Therefore, from the viewpoint of simplifying the configuration, the predicted torque current value I _q ^** is based on the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* as shown in the equation (6). Is desirable.

The frequency control unit 7 obtains the primary angular frequency ω ₁ such that the deviation between the torque current predicted value I _q ^** obtained in the A part and the actual torque current I _q becomes zero. Thereafter, the primary angular frequency ω ₁ becomes the actual rotational speed ω _{r of the} induction motor 20 by adding the slip angular frequency ω _sl output from the slip angular frequency calculation unit 9. Then, the speed control unit 2 obtains a field current command value I _d ^* and a torque current command value I _q ^* such that the deviation between the rotational speed ω _r and the speed command value ω _r ^* is zero.

After all, according to the control device of the present invention, the field current I _d and the torque current I _q are directly fed back, and the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* corresponding to the results are obtained. As a result, the responsiveness can be improved as compared with the conventional control device that performs feedback via the primary angular frequency ω ₁ .
Further, according to the control device of the present invention, the torque current predicted value I _q ^** is obtained using the equation (6), and the deviation between the torque current predicted value I _q ^** and the actual torque current I _q is calculated. By obtaining the primary angular frequency ω ₁ that becomes 0, the relationship of the expression (1) can be maintained with a relatively simple configuration.

As mentioned above, although preferable embodiment of the control apparatus which concerns on this invention has been described, this invention is not limited to the said structure.
For example, the field current command value I _d ^* is not determined by the speed control unit 2 by PI control, but can be a predetermined constant. The field current command value I _d ^* and the torque current command value I _q ^* can also be obtained based on the required torque corresponding to the actual rotational speed ω _r .
In addition, the control in the speed control unit 2, the current control unit 3, and the frequency control unit 7 is not limited to PI control, and may be other control methods such as PID control.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 Speed control part 3 Current control part 4 Two-phase / three-phase conversion part 5 Inverter 6 Three-phase / two-phase conversion part 7 Frequency control part 8 Integration part 9 Slip angle frequency calculation part 10 Current prediction value calculation part 20 Induction Electric motor

Claims (2)

In accordance with an input speed command value, a control device that controls an induction motor that does not include a speed sensor while referring to a primary current of the induction motor,
A d-axis voltage command value such that a deviation between the torque current command value and the actual torque current obtained from the primary current, and a deviation between the magnetizing current command value and the actual magnetization current obtained from the primary current are zero, and a current control unit for obtaining a q-axis voltage command value;
A predicted current value calculation unit for obtaining a predicted torque current value based on the d-axis voltage command value and the q-axis voltage command value;
A frequency control unit for obtaining a primary angular frequency such that a deviation between the predicted torque current value and the actual torque current is zero;
A speed control unit that determines at least the torque current command value so that a deviation between the rotation speed of the induction motor and the speed command value obtained by adding a slip angular frequency to the primary angular frequency is zero;
A control device comprising: The control device according to claim 1, wherein the predicted torque current value (I _q ^** ) is calculated by the following equation.

(However, the primary resistance _{R 1, L 1, L 2} , L M respectively the induction motor, the primary inductance, secondary inductance, mutual inductance, omega ₁ is the primary angular frequency, V _d ^* is the d-axis voltage command Value, V _q ^* is the q-axis voltage command value)

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