A Hybrid Starting Method Based on Improved Sliding-Mode Control for Permanent Synchronous Motor

Starting permanent synchronous motor(PMSM) is a difficulty of sensor-loss control. When speed is low, common sensor-less control modes are not applicable. I/F mode is implemented. To deal with the problem of susceptible to load torque mutations, an optimized I/F mode is mentioned in this paper. Until the speed rises to a certain value, the sliding mode observer(SMO) manner is implemented, because it is insensitive to motor parameters accuracy. However, the general SMO has chattering phenomenon and poor speed convergence ability. In this case, an optimized SMO mode based on variable exponential approach law and sigmoid function is illustrated. By applying the hybrid control mode, PMSM can start smoothly in the whole speed area and chattering is suppressed. Simulation is carried out according to this control mode.