Design and Comparative Analysis of Discrete-Time Current Control Algorithms for Permanent Magnet Synchronous Machines

PMSM drives are favorable for applications with high demands on the dynamic behavior due to their advantageous torque density. To make optimal use of the PM material, a highly dynamic control of the stator currents is decisive. Therefore different discrete-time current control algorithms for PMSM drives have been developed, including current state-space and current vector controllers. Nevertheless, classical discrete-time PI controllers with decoupling networks are still frequently applied for control of industrial and electric vehicle drives due to their simple design and high robustness against parameter deviations. In this paper, three different methods for discrete-time current control of a PMSM are compared and tested practically (PI controller, current vector controller and current state-space controller). All controllers performed satisfactorily and robustly against parameter deviations, though their dynamic performance did not meet theoretical expectations. Hence, in the paper a modified discrete-time model for PMSM with pulse-width modulated stator voltages and symmetrical current sensing is introduced. This model leads to the derivation of a new current vector controller with "true" deadbeat behaviour, which almost meets the theoretically expected control performance.