Integrated Fast Battery Charger Using an Electrically Excited Synchronous Machine-Based Drive System

Abstract

This thesis investigates an integrated off-board fast battery charging system utilizing an Electrically Excited Synchronous Machine (EESM)-based drive topology. The aim is to reuse the existing traction inverter and machine windings as part of a DC/DC boost converter, thereby reducing system cost, volume, and component redundancy. To achieve this goal, three levels of simulation were carried out. First, an excitation-based Finite Element Analysis (FEA) in ANSYS Maxwell was per formed to determine losses and inductances of the EESM under various operating conditions. Second, a system-level co-simulation between Maxwell and ANSYS Simplorer/Simulink was conducted, in which the electromagnetic model of the machine interacted dynamically with the converter and control system. This enabled real time calculation of inductances and losses under variations in both shift angle and rotor position. Finally, a Simulink-based system simulation was carried out to analyze current ripple, torque generation, and efficiency across different frequencies. The results show that phase-shift modulation predominantly affects the current waveform and ripple behavior, while the magnetic coupling and inductance remain almost constant. Increasing the switching frequency reduces stator core losses but has minimal impact on copper losses. Overall, the proposed integrated EESM-based fast charger demonstrates high feasibility and efficiency. It achieves compact system integration, stable electromagnetic performance, and effective control of current ripple and core losses - offering a sustainable approach for future electric vehicle charging architectures.