Square Wave Control System for Dual-sided Long-stator Permanent Magnet Synchronous Linear Motors with Sensorless Control

In the case of UAV ejection, a linear brushless DC motor offers the advantages of simple control and high reliability. This paper focuses on the research of a dual-sided permanent magnet synchronous linear motor (DLPMSLM). To address the reliability and cost issues associated with using position sensors along the entire travel distance of the motor, a control scheme is proposed that combines Hall start-up with medium-high speed control based on virtual Hall and line back-electromotive force for sensorless control. Considering the delay caused by the digital filter, this paper designs a compensation commutation strategy. Simulation results demonstrate that the control strategy based on line back-electromotive force allows for accurate determination of the commutation timing and enables position control within the entire speed range of a long-travel brushless DC motor. This approach helps reduce the errors that are typically encountered during the commutation process with traditional back-electromotive force methods.