Torque-Current Lookup Table Establishment Method for PMSM Considering Parameter Nonlinear Characteristics

An accurate torque-current lookup table (LuT) makes great significance to approve the output performance of permanent magnet synchronous motor (PMSM). In this paper, a new torque-current LuT establishment method is proposed, which considers the motor parameter nonlinear variation under different current conditions. Different from traditional methods, which often require driving test motor rotating to acquire its speed, the proposed method works when motor is at install. In offline experiment, test motor is stall and kept two-phase conducted. Current and voltage of test motor are recorded at different rotor position to calculate flux linkage and torque. The discrete calculated torque is fit by Fourier and polynomial method successively, to obtain a torque function with respect to current and rotor position. Then, the LuT records the optimal reference current under different torque by Newton iteration method. Finally, experiments are carried out on a 40kW PMSM for electric vehicle (EV) application, and experimental results show that the proposed method can achieve good torque tracing performance.