关键词: 永磁同步电机, 低载波比, 解耦策略

Abstract: In high-power electric drive systems, permanent magnet synchronous motor ( PMSM ) is often operated under low carrier ratio conditions to reduce inverter switching losses. However,the resulting digital control delays and strong cross-coupling effects may significantly degrade the current-loop performance and even compromise system stability. To address these challenges,this paper presents a comprehensive investigation into the discrete-time modeling of PMSM current controllers and a comparative analysis of various decoupling strategies. A discrete-time PMSM model incorporating digital delay effects is established based on a complex vector representation. Subsequently, based on the closed-loop pole-zero
distribution,the performance of different decoupling strategies is systematically analyzed, indicating that both the statefeedback decoupling strategy and the continuous-time complex-vector decoupling strategy exhibit limitations in terms of robustness and stability,whereas the decoupling strategy based on the discrete-time model achieves pole-zero cancellation over the entire speed range, thereby enhancing system stability and robustness. A current decoupling regulator directly designed in the discrete domain is investigated, enabling full-speed-range cancellation. The decoupling performance of different strategies is comparatively validated through simulations under multiple operating conditions. The results demonstrate that the direct discrete-domain decoupling strategy effectively mitigates delay-induced phase distortion,achieves
efficient dynamic decoupling of the d-axis and q-axis currents, suppresses transient current overshoot, and enhances the disturbance rejection capability and robustness.

Key words: permanent magnet synchronous motor, low carrier ratio, decoupling strategy