2015 年 4 巻 5 号 p. 619-625
This paper proposes a novel control method in the flux-weakening region. The proposed method utilizes a maximum torque per flux (MTPF) control at full load, and an efficient flux-weakening control at light load. In order to simplify the MTPF control, the approximate method of MTPF curve is proposed. In the flux-weakening control, a more efficient control obtained by minimizing the armature current at light load is applied. In the flux-weakening region, it is possible to operate at the maximum torque by applying the MTPF control. In addition, if the load torque is light, operation along a constant voltage ellipse is more efficient compared to the operation of the MTPF control along the MTPF curve owing to the decrease in copper loss with decreasing armature current. In the proposed efficient flux-weakening control, a current command generation method in which the armature current ampere is adopted for operation along the constant voltage ellipse is also proposed. The validity of the proposed control method is verified by simulation and experimental results.