I. Introduction
Due to the advantages of small volume, light weight, simple structure, and high integration, aircraft integrated starter–generators have become research hotspot in the field of aviation power system, with the rapid development of aircraft electrification [1]. Three-stage wound-rotor synchronous starter-generator (WRSSG) has the advantages of high reliability and mature power generation technology, which makes it great potential candidate for the aircraft integrated starter–generator system [2], [3].