Smooth Transition Strategy for PMSM Field-Weakening Operation Based on Adaptive Voltage Reference Asymptotic Cutback

When operating a permanent magnet synchronous motor (PMSM) from the base speed region to the field-weakening region in an extremely short time, the excessive voltage overshoot often leads to slim voltage margin, which deteriorates the current control and poses a risk of losing controllability. To mitigate this issue, a smooth transition strategy is proposed to improve the dynamics of the voltage-regulated field-weakening scheme. The voltage trajectory is analyzed and depicted on the voltage plane, featuring the dynamic characteristics during the fast transition from motor standstill to the field-weakening region. Through an asymptotic cutback of voltage reference, the voltage regulator can be desaturated in advance with sufficient voltage margin, and the dynamic performance will be smoothed without sacrificing much rapidity. The proposed method can effectively suppress voltage and torque overshoot during fast acceleration, with experimental validation on a 2.2 kW PMSM test bench.