Analysis of Limiting Output Capacity of Low-Speed and High-Torque Surface-Mounted Permanent Magnet Motor Considering Resistance Voltage Drop.

Drive motors in certain applications often require heavy load starting or short-time overload operation, so the limiting output capacity of the motor is worthy of attention. In this paper, the limiting output torque and input current of low-speed and high-torque external rotor surface-mounted permanent magnet synchronous motor(SMPMSM) under $i_{d}$ = 0 and field weakening(FW) control strategies are studied considering the resistance voltage drop. Firstly, the output characteristics of SMPMSM are analyzed when the resistance is considered, and the relationships between the limiting $i_{q}$ , limiting output torque and the electromagnetic parameters are analyzed when the $i_{d}$ = 0 and the FW control are adopted under the voltage limit. Next, the finite element method(FEM) is used to analyze and compare the impact of different machine parameters of the SMPMSM on the limiting output torque under the two control strategies. Finally, the correctness of theoretical analysis and FEM results are verified by prototype experiments.