Redundant control of IPMSM at zero low speed based on high frequency signal injection

A new method for position sensorless control with randomly injected high-frequency square wave signal injection is investigated in order to reduce the noise impact attached to the conventional high-frequency signal injection method as software redundancy in practical applications of electric vehicles. The method improves the spectral concentration problem caused by the traditional fixed switching probability method by varying the switching probability in real time, and then eliminates the use of low-pass filters in the traditional method by means of an improved filter-free signal separation strategy that takes into account the sampling delay, increasing the control bandwidth of the system while reducing the estimated rotor position error. Simulation results show that the proposed method has both good noise reduction performance and observation accuracy.