Voltage-Behind-Reactance Model of Hybrid-Excitation Dual Three-Phase Main Machine in Aircraft Synchronous Starter Generator Based on Equivalent Field Current of Permanent Magnet

Accurate modeling for the hybrid-excitation dual three-phase main machine (HEDTP-MM) in aircraft synchronous starter-generator system serves as the foundation for system analysis and control strategy research. Considering the complex hybrid-excitation characteristics of the HEDTP-MM and the requirement that both the stator and rotor windings can be directly interfaced with the external power circuit, the air gap flux characteristics generated by the permanent-magnet (PM) excitation is first analyzed based on the equivalent magnetic circuit method in this paper. Then, the PM excitation is converted into an equivalent field current, which enables a unified description of PM excitation and wound field (WF) excitation in the HEDTP-MM. Based on this equivalent field current of PM, a decoupled constant-parameter double-side voltage-behind reactance (VBR) model of the HEDTP-MM considering magnetic saturation is derived and established. This model enables the direct connection of stator and rotor windings to external circuits and maintains high modeling accuracy. Experimental results under steady-state and transient operating conditions verified the validity and accuracy of the proposed VBR model in this paper.