Direct-torque control of the brushless double-fed machines based on sliding-mode variable structure control strategy
无刷双馈电机滑模变结构直接转矩控制

A novel sliding-mode variable structure(SMVS) control strategy is proposed to reduce the ripples of flux and torque of brushless double-fed machines(BDFM) based on direct torque control system(DTC). In order to ensure the constant switching frequency for the inverter, two hysteresis regulators in the conventional DTC system are substituted by the SMVS controllers of flux and torque, and the space voltage vector pulse-width-modulation is used in the output of the voltage vector switches. The SMVS controllers are designed with the method of exponential approach law, and the Lyapunov stability theory is utilized to solve for the control law of the SMVS controllers. The simulation model of DTC is established in MATLAB/Simulink environment. The simulation results show that this new control method effectively reduces the torque ipples and improves the waveforms of the stator flux and current. The inherent advantage of the fast dynamic-response of the torque in DTC is reserved. The stability and robust performance of the system is enhanced.