Torque ripple minimization in PM synchronous motor using iterative learning control

Permanent magnet synchronous motor (PMSM) drives are increasingly used in high-performance motion control applications where smooth torque is an essential requirement. However, presence of the air gap flux harmonics gives rise to undesirable torque pulsations. These torque pulsations result in performance deterioration in high-performance drive applications. In this paper, we present a systematic way to design and implement a new instantaneous torque controller using discrete iterative learning control (ILC) scheme with the objective of achieving torque ripple minimization. In the proposed scheme, the ILC-based dynamic torque controller compares the desired and the instantaneous motor torques and generates the reference q-axis current (i/sub qs_ref/) that is required to produce ripple-free torque. The instantaneous motor torque is estimated by using an estimator based on MRAS technique. The proposed ILC torque controller is simple to implement from a computational point of view. The effectiveness of the proposed torque controller is demonstrated through computer simulation studies and results obtained verify the effectiveness of the proposed scheme.