Initial Rotor Position Estimation of Brushless Synchronous Starter/Generators Based on the Excitation System

For sensorless starting control of the brushless synchronous starter/generator (BSSG), signal injection is commonly adopted to estimate the initial rotor position of the main generator (MG). Due to the special structure of BSSG, signal transmission link between MG and the main exciter (ME) is a rotating rectifier that has a complicated operating principle. The lack of theoretical analysis of this complex transmission path leads to unreliability and inaccuracy for the methods based on it. In this paper, the transmission mechanism of injected signals from the field winding of MG to the stator windings of ME is clarified. According to this theory, a novel initial rotor position estimation method of MG is proposed. Both the simulation and experiment results show that this approach can provide initial rotor position of MG with reasonable accuracy.