A Novel CSOGI Approach for Improved Sensorless SPMSM Control at Low Speed with High-Frequency Signal Injection

For surface-mounted permanent magnet synchronous motor (SPMSM) operating at zero/low speed, the conventional high-frequency voltage injection method encounters challenges in rotor position estimation due to their inherent low saliency characteristics. Although the dual demodulation strategy of high-frequency positive/negative sequence current components improves position estimation accuracy, its implementation still requires multiple filters whose inherent phase delays inevitably introduce rotor position errors. This paper proposes a novel cascaded filtering structure based on a composite second order generalized integrator (CSOGI), which capitalizes on the dual band-pass/band-stop filtering characteristics of CSOGI. This configuration mitigates the impact of conventional filtering stages on rotor position signals. Experimental validation confirms the effectiveness of the proposed method, with results demonstrating a notable reduction in rotor position estimation errors compared to conventional approaches.