Direct Flux Vector Control of Electrically Excited Synchronous Machines for Electrical Vehicles

Permanent Magnet Synchronous Machines (PMSM) utilizing rare-earth magnets are currently the most prevalent solution for electric powertrains due to their high torque density and efficiency. To reduce the reliance on rare-earth materials, Electrically Excited Synchronous Machines (EESMs) have emerged as a viable alternative for automotive powertrains. The EESM offer a higher degree of freedom compared to PMSMs, as the machine flux can be regulated through the rotor field current. However, the literature provides few EESM torque control solutions with optimal torque production. Therefore this paper presents a Direct Flux Vector Control (DFVC) strategy applied to EESMs for electric vehicles with a total copper loss-minimizing scheme able to take into account both stator and rotor copper losses. Experimental validation is conducted using a commercial 100 kW EESM employed by the Renault Zoe EV.