Control method of brushless doubly-fed induction motor under unbalanced power grid

Abstract

The invention discloses a control method of a brushless doubly-fed induction motor under an unbalanced power grid. The control method comprises the steps of (1) collecting three-phase voltage and current of a power-side stator and three-phase current of a control-side stator under a static coordinate system; (2) obtaining the flux linkage amplitude, the phase angle, the frequency and the flux linkage of the power-side stator; (3) dividing voltage, current and flux linkage vectors into positive and negative sequence components; (4) calculating a flux linkage angle of the power-side stator; (5)establishing a two-phase synchronous rotating coordinate system, and converting the negative-sequence component into a positive-sequence reference coordinate for control; (6) solving expressions of the electromagnetic torque, the reactive power and the control-side stator current; (7) obtaining a q-axis instruction signal of the contro-side stator current; (8) obtaining a d-axis instruction signalof the control-side stator current; (9) obtaining a dq-axis voltage component given value of the control-side stator voltage under a two-phase rotating coordinate system; and (10) applying the outputvoltage of the converter to the motor control side stator. The method is low in parameter dependence and simple in algorithm.

Description

technical field [0001] The invention relates to motor control, in particular to a control method for a brushless double-fed induction motor under an unbalanced power grid. Background technique [0002] As a new type of motor in recent years, brushless double-fed induction motor inherits the advantages of cage-type, wound-type induction motor and electric excitation synchronous motor, and can realize various operation modes such as self-starting, asynchronous, synchronous and double-fed. Good starting characteristics and running performance. Compared with ordinary double-fed induction motors of mainstream motors, brushless double-fed induction motors do not have brushes and slip rings, which greatly reduces system costs, improves system stability, and saves maintenance costs. It has become the direction of the future motor drive field. However, due to the special structure of the brushless double-fed induction motor, it has two stators and one rotor winding, and the rotating...

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Problems solved by technology

[0004] At present, most of the vector control for brushless doubly-fed induction motors is based on rotor field orientation and integrated flux orientation, but this control scheme has dq axis current coupling phenomenon, which cannot realize the complete decoupling of system active power and reactive power; and In the vector control based on the magnetic field on the power side, the three-loop control strategy with the speed loop as the outer loop and the stator current on the power side and the stator current on the control side as the inner loop can realize decoupling control, but the number of controllers increases, and the feedforward term The calculation is complex and highly dependent on the motor parameters; moreover, the application of brushless doubly-fed induction motors is becoming more and more widespread, not only limited to normal working conditions, but also the control scheme for unbalanced power grids is also the focus of consideration, but At present, the control of brushless doubly-fed induction motors in the unbalanced power grid is less, and most of them use dual PWM inverters to control brushless doubly-fed induction motors. The algorithm of using dual PWM inverters to control brushless doubly-fed induction motors is complex and the amount of calculation is large. Large, large dependence on parameters

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