Direct torque control of permanent-magnet synchronous machine drives with reduced torque ripple and strong robustness

Conventional direct torque control (DTC) achieves faster dynamic response compared to field-oriented control in permanent magnet synchronous motor drives (PMSM). However, it usually features large torque and stator flux ripple which deteriorates the steady performance of PSM drive. Various duty- based DTC schemes have been proposed to reduce torque ripple at the expense of increased complexity and parameter dependent. According to the perspective of flux vectors and load angle, a simple yet efficient method is proposed to calculate the duty ratio of active vector. The proposed scheme is able to reduce torque ripple significantly and is insensitive to variations in PMSM parameters, while the inherent merits of the conventional DTC, e.g., fast transient performance and simple control structure, are maintained. Simulations results are provided to confirm the valid of the proposed method.