Aiming at the permanent magnet DC linear motor with distorted opposite potential, this paper proposes a position sensorless commutation control method based on the principle of the zero-crossing point of the line back EMF. The qualitative analysis of the waveform and the quantitative derivation of the series theory formula prove that the zero point of the line back EMF is still consistent with the actual electronic commutation point of the system even when the opposite potential is distorted. In order to avoid the missed detection of the zero point of the line back EMF, a commutation control method based on the S function is further constructed. The simulation results prove that the method meets the system requirements.

Sensorless Control，Permanent Magnet DC Linear Motor，Line Back EMF