Maximum torque per ampere and flux-weakening control for PMSM based on curve fitting

This paper describes the MTPA (maximum torque per ampere) control strategy of Salient-pole PMSM (permanent magnet synchronous motor) and its flux-weaking control strategy. Salient-pole PMSM often used the MTPA control strategy, the method that MTPA curves obtained from look-up table is usually used, but it will reduce the real-time performance and reliability of the system. In this paper, electromagnetic torque Tem and the relationship of the AC-DC-axis currents id, iq can be derived with the curve fitting method directly. It approximates the original nonlinear equations into a set of two-dimensional linear equation, and the error analysis shows that the error in line with engineering requirements, so it is greatly simplifies and facilitates the actual operation. On this basis, the paper also introduces the phase-shifting controlled manner to achieve flux-weakening control. The control performance of motor with improved algorithm is analyzed through simulation, and the simulation results verify the validity and feasibility of the algorithm and theory.