A Sensorless Control Strategy for Permanent Magnet Synchronous Motor at Low Switching Frequency

The high-frequency (HF) square-wave voltage injection method can be used in permanent magnet synchronous motor (PMSM) drive systems. However, when the switching frequency is too low, will also decrease, which reduce update of HF response current, making it difficult to extract position quadrature signal and affecting accuracy estimation control performance. This paper proposes a for extracting signals based on sampling rate transformation, processing strategy Cascade Integrator Comb (CIC) interpolation filtering, solve problem waveform distortion caused by low extracted signal. increase pulse width modulation (PWM) interpolating thereby reducing harmonic content improving estimation. precision. In addition, PWM estimated rotational speed information are compensate delay inverter update, effectively improves Finally, effectiveness proposed verified simulation.