Modeling and Analysis of PWM-Induced Current Ripple in Wound-Field Synchronous Machine

This paper presents the analytical modeling method of high-frequency current ripple induced by pulsewidth modulation (PWM) in wound field synchronous machine (WFSM) for traction applications. Due to the presence of windings in both stator and rotor side, the cross-coupling phenomenon occurs when the PWM switching is implemented on either side, resulting in additional current harmonics. The proposed method is used to comprehensively investigate current ripple characteristics over varying motor operating conditions. High-fidelity Software-In-The-Loop (SIL) testing is provided to validate the analytical predictions. These results confirm the validity of the proposed method and emphasize the critical impact of the cross-coupling between the stator and rotor windings in WFSM for PWM-induced current ripple modeling. The collected current ripple data are then used to explore the impact of current ripple on electric motor performance.