Design and Experimental Verification of a 48 V 20 kW Electrically Excited Synchronous Machine for Mild Hybrid Vehicles

Paper i proceeding, 2018

Electrically Excited Synchronous Machines (EESM) have become an attractive solution to Electric Vehicles (EV). This work aims to develop a 48 V 20 kW EESM for mild hybrid vehicles (MHV), which prioritizes torque production ability during start-up. An H-bridge converter including an H-bridge inverter, a rotating transformer and a diode rectifier is employed for magnetic field excitation on the rotor side. Efforts have been made to maximize torque production and to estimate field current and field winding temperature without physical contact. The EESM is manufactured after having been designed with the help of FEM, and then verified by practical experiments. The back-EMF waveforms, flux linkage distributions and the produced torque levels from the experiments are compared with the FEM results. Field current estimation by DC-link current of the excitation H-bridge converter is developed, and solutions for field winding temperature estimation have been investigated as well.