A Seamless Position-Sensorless Field-Oriented-Control-Based Flying Start Method for Permanent Magnet Synchronous Motors

Flying start refers to the resumption of motor current control by reapplying power to an inverter when the motor continues to rotate at a nonzero speed after a power interruption. This issue is particularly critical for permanent magnet synchronous motors operating under position-sensorless control, where large initial position estimiation errors can induce electromotive-force-driven inrush currents and trigger overcurrent protection. Previous studies have shown that existing flying-start algorithms often require extended settling times and mode switching to address this problem. In this paper, we propose a seamless flying start algorithm that operates entirely within position-sensorless field-oriented control, eliminating the need for mode switching and significantly reducing the settling time. The proposed method exploits the unique initial position estimate provided by a model-based position estimator formulated in the stationary reference frame under specific inverter voltage conditions. Experimental results validate the effectiveness of the proposed algorithm.