Low-speed Position Estimation of the Brushless Synchronous Starter/Generator by Using the Main Exciter as a Quasi Resolver

Traditional rotor position estimation methods of the brushless synchronous starter/generator (BSSG) perform signal injection and detection only from the stator of the main generator (MG), suffering from interference of high-frequency signals and unreliability of the reversible magnetic saliency of MG. These problems could be solved when position estimation is conducted on the main exciter (ME), mounted on the same shaft with MG and thus sharing the same mechanical rotation angle with MG. Since high-frequency signals, brought by the rotating rectifier of BSSG, already exist in ME, ME can be regarded as a quasi resolver of MG. Features of this quasi resolver are studied by analyzing the commutation intervals of the rotating rectifier and then a position extraction method of MG is proposed in this paper. The effectiveness of this method is verified by experiments.