Multi-closed loops strategy combined with torque correction for high precision tracking system

High precision tracking system has strict rapidity and smooth requirements of speed and torque. For the system is a direct drive structure, it is more sensitive to torque disturbances. Traditional current closed loop cannot suppress torque ripples caused by flux distortion of the motor. Torque closed loop´s bandwidth is restricted and cannot provide fast torque response. Aimed at a high precision tracking system driven by a permanent magnet synchronous motor, multi-closed loops strategy combined with torque correction is proposed: Based on current closed loop and speed closed loop, torque coefficient is estimated by torque estimator, and used to correct current expectation. Simulation results show that the proposed control can provide high bandwidth torque response, suppress torque ripples caused by motor´s flux harmonics, and has strong robustness to variances of motor parameters.