Operating Areas Overview of Electrically Excited Synchronous Motors

Increasing environmental concerns are driving the development of electric vehicles. Permanent Magnet Synchronous Motors (PMSMs) and Electrically Excited Synchronous Motors (EESMs) have been widely sought after for their potential use in these vehicles. This paper presents a comprehensive overview of salient poles rotor EESMs operating areas defined by: Minimum Current Per Torque (minCPT), Field-weakening maximum voltage limit area, Field-weakening maximum current and maximum voltage limit area and Maximum Torque per Voltage (MTPV). The latter are analyzed and showcased in both d-q and torque-speed domains. The minCLPT (Minimum Copper Losses per Torque) novel optimization method, which uses the EESM excitation current as third degree of freedom, is then explored while investigating the impact of applying negative d-axis current results of the latter algorithm. Findings emphasize on the potential benefits of using the EESM excitation current to extend the machine speed range while providing opportunities of experimenting how the optimal reference field current calculated by minCLPT algorithm can affect the forementioned operating areas. The paper provides valuable insight for researchers and engineers working in the field of electric vehicle propulsion systems.