Analytical Calculation and Improvement Method for Short-Circuit Torque of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor (PMSM) can generate braking torque through stator three-phase short circuit, which can slow down the motor out of control in motion. In this paper, the steady-state mathematical model of PMSM under three-phase short circuit is established, and the accurate parameters of the machine are obtained by combining the finite element method simulation. The steady-state torque of the motor during three-phase short circuit under different speeds is calculated analytically, and the speed-torque curve is obtained. A series capacitor method is proposed to improve the maximum short-circuit torque, and the appropriate capacitance value is deduced theoretically. Finally, the three-phase short-circuit and series capacitance experiments of an 11.4kW permanent magnet synchronous motor are carried out to verify the accuracy of the calculation and the effectiveness of the proposed method.