Improved Synchronous Demodulation Method for Three-stage Synchronous Machine Based on D-axis Response High-Frequency Voltage

An improved synchronous demodulation method based on d-axis response high-frequency (HF) voltage is proposed for sensorless starting control of three-stage synchronous machine (TSSM) in the low-speed range. The synchronous demodulation signal (SDS) is obtained by converging the d-axis response high-frequency signal (HFS). An improved synchronous demodulation method is proposed to optimize the signal processing, employing the improved second-order generalized integrator (ISOGI) to extract the response HFSs and their quadrature signals for the purpose of rotor position estimation. Finally, the corresponding experimental results are implemented to validate the effectiveness of the proposed method for TSSM.