High-Fidelity Voltage-Behind-Reactance Model of Electrically Excited Synchronous Machines Using Flux Maps

Electrically excited synchronous machines (EESMs) have historically been used as effi- cient and reliable synchronous generators. However, the actual need for cost-effective, sustainable motors without rare-earth magnets has notably increased the interest in EESMs, which are considered a valid replacement for permanent magnet synchronous machines (PMSMs) in electrified powertrains. As the elec- trical machines employed in automotive applications exhibit deep magnetic saturation, the EESM introduces significant challenges in properly modeling the magnetic behavior, especially considering the cross-coupling effects between stator and rotor. EESM-based electrical drive development requires accurate circuital models to predict EESM behavior. Therefore, this article proposes a novel voltage-behind-reactance (VBR) model based on flux maps provided by finite element analysis (FEA) or experimental identification procedures. The proposed VBR model has been validated in simulation and experimentally on a commercial 100 kW EESM currently used on the Renault Zoe EV R135, demonstrating its potential for accurately modeling EESMs designed for traction applications.