Deadbeat Direct Flux Control: Plug-and-Play Torque Controllers for Electrically Excited Synchronous Motors

Permanent magnet synchronous machines (PMSMs) have long been regarded as the benchmark technology for electric powertrains due to their superior torque density and efficiency. However, the growing demand to reduce reliance on rare-earth materials has drawn attention to electrically excited synchronous machines (EESMs) as a competitive alternative for traction applications. EESMs offer greater control flexibility, as their magnetic flux can be actively regulated and optimized via the rotor field current. However, limited control solutions are reported in the literature, primarily based on current vector controllers and only partially addressing optimal torque regulation. Furthermore, the cross-coupling introduced by the magnetic interaction between stator and rotor increases the complexity of the inner loops’ design, whose performance is significantly affected by the magnetic saturation. As a consequence, EESM drives for traction applications often require the execution of demanding calibration and certification procedures. Therefore, this article proposes cutting-edge self-calibrated torque controllers for traction EESMs based on a deadbeat direct flux control approach. The proposed solution eliminates the need for any tuning efforts for the inner control loops while achieving high-performance of torque regulation and minimizing the overall copper losses, thus resulting in minimum-tuning torque controllers. The experimental validation is carried out on a 100 kW commercial EESM used in the Renault Zoe EV R135, confirming the effectiveness and the added value of the proposed torque controllers in traction applications.