Frequency-Insensitive Rotor Position Estimation Method for Three-Stage Synchronous Machine Based on Indirect High-Frequency Signal Injection

A frequency-insensitive rotor position estimation method for the three-stage synchronous machine (TSM) in the starting procedure is proposed in this article, where the high-frequency signals (HFSs) are injected into the main exciter (ME), and response signals for the rotor position estimation are extracted from the main generator (MG). Due to the specific structure, the frequency of the response HFSs is distorted by the intermediate links of the ME and rotating rectifier, the frequency-response characteristics of the response signals with information of rotor position are analyzed, and the frequency-insensitive demodulation method for the rotor position estimation based on the second-order generalized integrator (SOGI) is given. Finally, the simulation and experiment results are implemented to verify the effectiveness and feasibility of the proposed frequency-insensitive rotor position estimation method for TSM.