Robust Adaptive Current Control of a 1.2 MW Direct-Drive PMSM for Traction Drives based on Internal Model Control with Disturbance Observer

In order to improve the efficiency of electric locomotive, the MW-level direct-drive permanent magnet synchronous motor (DD-PMSM) is used to replace the original traction motor and gearbox in electric locomotive. However, the DD-PMSM parameters will change with the operating conditions during the operation of the electric locomotive, and the absence of the gear box in direct drives increases the sensitivity of the control performance to uncertainties in the drive system. In order to solve the problems, a novel robust adaptive (RA) current control of MW-level DD-PMSM for traction drives base on internal model control with disturbance observer (IMCDO) is proposed in this paper. IMCDO is simply designed as the estimated uncertainty function, and a simple control law is derived based on Lyapunov function to guarantee the system stability and improve the anti-disturbance performance. Then, in order to adjust the internal model disturbance observer properly, the observer gain selection criteria is given by using the stability analysis based on discrete Lyapunov function. The proposed method in the paper is verified on a 1.2 MW DD-PMSM and the comparative experiments demonstrate the validity and effectiveness of the proposed method.