Multivariable Decoupling Current Control for Open-End Winding Permanent Magnet Motor Drives

This article presents a current controller design for an open-end winding permanent magnet synchronous motor (OEW-PMSM) supplied by a common DC source. Conventional control approaches for OEW-PMSMs have typically treated the zero-sequence (n-axis) component as an independent variable, ignoring its dynamic influence on the dq components. In this work, a unified dqn motor model is first established by incorporating mutual inductances and rotor position-dependent spatial harmonics across all axes. Then, based on the proposed model, a multivariable controller is analytically derived to achieve fully decoupled current dynamics while ensuring stable operation under load variations. The proposed controller accounts for interaxis coupling in its structure, enabling active regulation of the zero-sequence current. This leads to improved steady-state and transient performance. Experimental validation is conducted on a motor developed for electric vehicle applications. The results confirm the effectiveness of the proposed method over conventional control, demonstrating improved steady-state waveform quality, and a reduction in total harmonic distortion (THD) of the current from 6.61% to 4.86%. In addition, the transient response is significantly enhanced. Even during abrupt torque changes, the zero-sequence current remains stable, unaffected by disturbances in the d–q currents.