Adaptive Maximum Torque per Ampere Control for IPMSM Drives With Load Varying Over Mechanical Revolution

This article proposes an adaptive maximum torque per ampere (MTPA) control algorithm for interior permanent magnet synchronous machines (IPMSM) drives. This algorithm is insensitive to motor parameters variation due to operating conditions that are important for systems, which prioritizes reliability and efficiency. The proposed algorithm is designed to improve conventional control schemes, where the output of the speed controller is the commanded quadrature current, and direct current is calculated using an MTPA equation. However, in distinction from the conventional MTPA approach, the proposed algorithm does not use any motor parameters. It implements a seeking technique and continuously varies the stator current phase angle while trying to minimize the magnitude of the current. The main contribution of this article is the development of the method to overcome the main disadvantage of seeking algorithms—the necessity of stable disturbances at the consecutive measurement intervals. This article adopts the seeking technique for the operation with the load torque varying over the mechanical revolution, which is typical for many applications, such as compressors, washing machines, robots, mechanical manipulators, servodrives, and so on. The feasibility of the proposed algorithm is proven with experimental results shown and described in the corresponding section.