Low-order Harmonic Suppression Strategy in Sensorless Starting Control of Wound-Rotor Synchronous Starter/Generator

Wound-rotor synchronous starter/generator (WSSG) contains lots of low-order harmonics, caused by the inverter, on the stator side of the main generator (MG) during the starting stage, which would affect the performance of sensorless starting control with high-frequency injection. To solve this problem, a harmonic detection, based on synchronous rotating frame transformations (SFT), and compensation method is presented first to suppress the 5th and 7th harmonic current during their generation. Besides, a second-order generalized integrator (SOGI) is applied to further reduce the influence of harmonics on the observer of high-frequency response signals, the source and the transmission path suppression of the low-order harmonics are combined in this paper, and the simulation results show that the proposed strategy can effectively suppress the low-order harmonics and reduce the rotor position estimation error caused by them.