An Analytical Solution to Optimal Stator Current Design for PMSM Torque Ripple Minimization With Minimal Machine Losses

Abstract

This paper investigates torque ripple minimization for permanent-magnet synchronous machines (PMSM), and proposes a novel analytical solution of optimal stator current design for torque ripple minimization. The proposed design is theoretically proven to be able to minimize the torque ripple with minimal machine losses. Moreover, the optimal stator current is computed from analytical expression, which is computationally efficient. Therefore, the proposed approach is applicable for torque ripple minimization under both transient state and steady state. However, existing approaches usually employ optimization algorithm to optimize the stator current, which is computationally complex and involves iterative computation, so their applicability is limited under transient state, because the optimal stator current must be adaptively updated with respect to operating conditions. Moreover, magnetic saturation is considered in the proposed approach by employing a novel linear model to model the relation between the inductance and the stator current under maximum torque per ampere (MTPA) control. In this way, the proposed analytical solution does not involve inductance, and thus, the influence of magnetic saturation can be effectively reduced. The proposed approach is validated on a laboratory PMSM drive system under both transient state and steady state.