Sensorless control of permanent magnet external rotor hoist under time-varying load

To address the problems of low system reliability and high maintenance costs caused by reliance on mechanical position sensors in permanent magnet external rotor hoists, a sensorless control strategy integrating multibody dynamics modeling for permanent magnet external rotor hoists under time-varying load was proposed. First, a mathematical model of the permanent magnet external rotor hoist was established, and the pulsating high-frequency signal injection method was theoretically analyzed. Second, a phase-locked loop position observer was used to dynamically track the rotor position, and a sensorless control system was constructed. Then, a multibody dynamics model of the hoist was established using RecurDyn software, including the elastic deformation of the wire rope and the drum winding effect, to accurately characterize the time-varying characteristics of the system load. Finally, an electromechanical coupling co-simulation model based on Matlab/Simulink and RecurDyn was established, and the proposed sensorless control system was experimentally verified using a physical verification platform. The results showed that under the time-varying load torque condition of the hoist, the proposed sensorless control strategy controlled the speed tracking error within ±0.2 r/min and the rotor position observation error below 0.01 rad. It showed good rotor position tracking accuracy and speed tracking performance throughout the entire operating cycle of the permanent magnet external rotor hoist.