Zero-Sequence-Component-Based Rotor Position Estimation for a Wound-Field Synchronous Starter/Generator in the Low-Speed Region

A novel on-line rotor position estimation method for an aircraft wound-field synchronous starter/generator in the low-speed region is proposed in this paper. Unlike that of High-frequency signal injection, the new method utilizes zero-sequence component for rotor position estimation, which is inherently produced by the space-vector pulsewidth modulator. In this way, no modification is required in the PWM and there is no additional torque ripple. The new method is based on the multi-stage structure and the mutual inductance between stator and rotor windings of the main machine, so it is independent of magnetic saliency.The rotor position information is extracted from the zero-sequence response current signals in the stator windings of the main exciter. Theoretical expressions of the zero-sequence response current signals containing rotor position information in the rotor windings of the main machine and stator windings of the main exciter are derived. Also, a novel signal processing method is adopted to extract rotor position information. The performance of the proposed method is verified by the simulation results, and accuracy can be guaranteed even if the magnetic saliency of the main machine changes greatly during the start-up process.