Robust Maximum Torque per Ampere Strategy for Permanent Magnet Synchronous Motor Based on PI-Sliding Mode Controller

Since the applications of Permanent Magnet Synchronous Machines (PMSMs) are developing in various industries, stator loss minimization in these machines is significantly important. In this regard, the d and q axis currents should be controlled where the load torque is provided with minimum stator current. This paper proposes a novel Maximum Torque per Ampere (MTPA) strategy for PMSMs based on a PI-Sliding Mode Controller (SMC) considering machine parameter variations. In the proposed drive system, the speed is controlled by the q axis current. Moreover, the d axis current is controlled via a two layer controller. In the first layer of the proposed controller, the minimum stator current is determined based on the machine nominal parameters through a PI-SMC. With due attention to the machine parameters are varied, the minimum stator current is not precise. Hence, the second layer controller is applied in order to shift the operation point to the correct minimum current point. Consequently, the load torque is precisely provided with minimum stator current followed by the absence of any steady-state torque and speed ripples. The proposed control scheme is simulated in MATLAB/Simulink environment. Simulation results validate the performance of the proposed control system.