An Improved Discrete-Time Complex Vector Current Regulator for Position Sensorless UhsPMSM Based on Enhanced Active Damping Function

The complex vector current regulator (CVCR) has been increasingly applied in PMSM drives recently. Furthermore, the active damping compensation is introduced to improve the insufficient disturbance rejection ability of CVCR. However, conventional active damping methods usually set the damping term to a constant, and its performance will degrade as the switching-to-fundamental frequency ratio (f_ratio) decreases, which makes it difficult to meet the requirements of advanced driving systems such as ultra-high-speed PMSM (UhsPMSM). To solve such problem, this paper proposes a CVCR based on enhanced active damping function. Firstly, the damping structure is reconstructed to fully determine the plant poles in disturbance transfer function while keeping the structure as simple as possible without the lead operator. Secondly, the coefficients in the damping term are designed to ensure that the plant poles remain in the high damping region even at high speeds and low f_ratio. Then, the CVCR is redesigned in the discrete-time domain to ensure satisfactory command tracking performance. Finally, the implementation form of the proposed method in digital systems is derived. The experimental results have verified the effectiveness of the proposed method and demonstrated its superiority over traditional methods.