A Random-Based High-Frequency Square Wave Injection Sensorless Control System with Reduced Acoustic Noise and Electromagnetic Interference

Aiming at the acoustic noise and electromagnetic interference (EMI) caused by high-frequency square wave injection (HFSWI) in the position sensorless control system of interior permanent magnet synchronous motor (IPMSM), a new high-frequency injection scheme based on random algorithm is proposed and implemented in the paper. Compared with the conventional scheme, the key is to employ a no-periodic modulation on the injected signal to broaden the spectrum of current. With the adoption of the random HFSWI, harmonic peaks can be reduced, therefore the acoustic noise and EMI caused by HFSWI can be effectively solved. Based on the principle of random HFSWI scheme, two different random algorithms are considered and compared in the paper. Markov chain-based HFSWI scheme can reduce the harmonic peak by at least 12dB. Both computer simulation and experimental results verify that the proposed strategy exhibits good capability in harmonic suppression and retain the accuracy of estimated angle.