A Reference Flux Calculation Method for MTPA Control in DTC-based IPMSM Drive System

Abstract

Interior permanent magnet synchronous motors (IPMSMs) are widely used for many applications because of their many attractive characteristics. In order to realize high power and high efficiency, maximum torque per ampere (MTPA) control has been proposed for current-controlled IPMSM drive systems. On the other hand, direct torque control (DTC) is also used for IPMSM drive systems. However, DTC requires not current but torque and stator flux linkage as references. Therefore, it is difficult to make references for MTPA control, and a look-up table is often used instead. This paper proposes an MTPA control strategy for DTC-based IPMSM drive systems that does not rely on a look-up table. The proposed method is based on a motor model in a d-q rotating frame, which is often used in synchronous motor drives. This method does not require any look-up tables, so estimated parameters can be applied easily. In addition, inductance variation can be considered if inductances are modeled as functions of the current. The simulation and experimental results validated the proposed method.