Vector control-based prediction method for uncontrollability of electric current of induction machine
A technology of induction motor and prediction method, which is applied in the direction of controlling generators, vector control systems, and controlling electromechanical brakes, etc. It can solve the problems that the current regulator is difficult to meet the design requirements, damage the power device and motor, and the current is out of control, etc., to achieve shortening prediction time, reduce misoperation, and improve reliability
Inactive Publication Date: 2013-04-17
HUAZHONG UNIV OF SCI & TECH
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[0004] The induction motor vector control system includes two current regulators, namely the q-axis current regulator and the d-axis current regulator. Due to the cross-coupling between the d / q-axis currents, the bandwidth of the conventional PI regulator will increase with the current frequency And when the motor speed is high, the d / q axis current regulator is more likely to be saturated due to the continuous increase of the counter electromotive force. Therefore, the current regulator may be difficult to meet the design requirements, resulting in current runaway or even damage Power Units and Motors
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[0027] In the vector control system, the voltage and current under the d / q axis satisfy the following relationship:
[0028] V ds = i ds R s -i qs σL s ω e (1)
[0029] V qs = i qs R s + i ds L s ω e (2)
[0030] where: R s : stator phase resistance; L s : stator inductance; σ: total leakage inductance; i ds : d-axis current; i qs ;q-axis current; V ds : d-axis voltage; V qs : q-axis voltage; ω e : Synchronous angular velocity.
[0031] Equations (1) and (2) show that there is cross-coupling between the d / q axis current and voltage. Therefore, it is difficult for PI regulators 1 and 2 used in conventional vector control to guarantee the design bandwidth, and its bandwidth decreases with the increase of current frequency. decrease, and referring to formula (2), since the counter electromotive force increases with the increase of frequency, the current regulators 1 and 2 are more likely to be saturated, so that the current regulation ability of the curr...
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The invention discloses a vector control-based prediction method for the uncontrollability of an electric current of an induction machine. The method specifically comprises the following steps of: repeatedly adopting two-phase electric current within a single PWM (pulse-width modulation) period, and decoupling a d / q axis to obtain electric current ids and iqs under the d / q axis; computing deviation delta ids and delta iqs between the ids, the iqs and the set value of the d / q axis electric current; computing the allowed change range delta i'ds and delta i'qs of the d / q axis electric current under the current voltage margin according to a motor electric parameter and a motor model; and comparing the delta ids and the delta i'ds as well as the delta iqs and the delta i'qs, and comparing the electric current uncontrollability threshold value delta d with the electric current uncontrollability threshold value delta q of the d / q axis electric current to predict whether the electric current is uncontrollable or not. According to the method, the saturation degree of the electric current adjuster, the voltage use margin and the electrical characteristics of the motor are comprehensively considered, and the prediction method for the possible uncontrollability of the electric current is given, so that the running reliability of the motor and a driving device can be obviously improved, and the damage of a power device or the motor caused by overcurrent can be avoided.
Description
technical field [0001] The invention belongs to the technical field of AC induction motors and their control, and in particular relates to a method for predicting the out-of-control induction motor current under the condition of vector control. Background technique [0002] AC motor frequency conversion speed regulation methods mainly include open-loop V / f speed regulation and closed-loop speed regulation. Closed-loop speed regulation is also called vector control method, which specifically includes indirect rotor field orientation, direct rotor field orientation, and direct stator field orientation. Among them, the indirect rotor field orientation is widely used because it needs less hardware and has high control performance. [0003] The principle of indirect rotor field-oriented vector control of induction motors is as follows: the rotating coordinate system is established on the direction of the rotor magnetic field, and through this coordinate, the stator current is dec...
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Inventor 刘洋
Owner HUAZHONG UNIV OF SCI & TECH