Initial Rotor Position Estimation Method for Aircraft Three-Stage Starter/Generator Based on Self-Injected Harmonic Signal

In this article, an initial rotor position estimation method for an aircraft three-stage starter/generator (TSSG) based on self-injected harmonic signal (SIHS) is proposed. Different from the traditional method in which an external high-frequency signal is injected into the stator winding of the main generator (MG), the second harmonic voltage caused by the rotating rectifier in the ac excitation is regarded as the self-injected high-frequency signal into the rotor field winding of MG at standstill. The high-frequency response signals in the stator winding of MG are extracted by a designed bandpass filter (BPF), and the signals orthogonal to the response signals are generated by a cascaded all-pass filter (APF). Then, based on the obtained response signals and orthogonal signals containing rotor position information, a practical approach to estimate the initial rotor position is implemented, where the induced currents in the excitation establishment of MG are detected to identify the polarity of the initial rotor position angle. Finally, the feasibility and effectiveness of the proposed method are verified by simulation and experimental results.