A Reference Flux Calculation Method for Realizing Maximum Efficiency Operation in Direct Torque Controlled PMSM Drives

This paper proposes a maximum efficiency operation strategy for direct-torque-controlled interior permanent magnet synchronous motor drives. The proposed method is based on the solutions of a quartic equation, a motor model in the d-q rotating frame often used for the synchronous motor controllers, and a well-known equation for maximum efficiency operation. Therefore, the proposed method does not use a look-up table that depends on parameters of the motor and that has to be created in advance. In addition, the stator flux observer considering iron losses is proposed and analyzed the effectiveness with the consideration of iron losses. The simulation results validate that the proposed method can achieve the maximum efficiency operation by the iron losses considered in the stator flux observer.