Sensorless Operation of Permanent Magnet Machine with Low Saliency Ratio Utilizing Orthogonal High-Frequency Voltage Injection

The rim-driven permanent magnet synchronous machine(PMSM) is integrated with the propeller blade, which makes the air gap length larger and the saturation saliency effect lower, resulting in the traditional high-frequency(HF) voltage injection method at zero-low speed difficult to ensure operation. In order to achieve reliable control at zero-low speed, an orthogonal HF voltage injection method and a position signal demodulation strategy are proposed to achieve high signal-to-noise ratio rotor position error information feedback. On this basis, in order to optimize HF signal processing, a rotor position extraction strategy based on second-order generalized integrator(SOGI) combined with PLL is proposed to ensure the improvement of dynamic performance of position observation loop under high filtering accuracy. Finally, the effectiveness of the proposed method is verified on a rim-driven PMSM platform.