Experimental Investigations on Improving the Accuracy of MTPA Strategy by Considering System Nonlinearities in Practical IPMSM Drives for Electric Vehicle

Abstract

Interior mounted permanent magnet synchronous machines (IPMSMs) are commonly preferred by electric vehicle manufacturers due to their reluctance torque production capability, high efficiency, and so on. The use of the maximum torque per ampere (MTPA) strategy, which allows maximizing the torque production in IPMSMs, is mandatory for high efficiency operation in the constant torque region. However, the parameters used in the implementation of the MTPA strategy significantly vary depending on the operating conditions. Although the improvement of the MTPA strategy by addressing parameter variations is widely discussed in the literature, mostly errors occur in the production of command currents due to the neglected partial derivatives of the parameters with respect to the current angle. Besides, high-fidelity machine models are not provided by the manufacturer in most commercial machines. This article presents a method for determining MTPA points in IPMSMs in real time. Even without prior knowledge of machine parameters, accurate MTPA can be obtained through focused experimental testing.