Online Maximum Torque per Ampere Control Method for Synchronous Reluctance Motor Based on Nonlinear Flux Model

Abstract

In this thesis, a maximum torque per ampere (MTPA) torque control method is developed for synchronous reluctance motor (SynRM). The flux linkage of SynRM has strong nonlinear characteristics due to the core saturation. The inductances are derived from the analytical expression of the flux linkage data, which are obtained from finite element analysis (FEA). The resulting inductances are expressed as polynomial functions of d,q currents, while satisfying the reciprocity condition, which is required for integrability of the flux. The MTPA condition is derived by differentiating the torque with respect to the current angle, which includes inductance functions and inductance differentiation functions. The analytic MTPA solutions are compared with FEA and experimental results. They showed good agreements even in the heavy saturation region.