Common-Mode Current Prediction in a Non-isolated Onboard EV Fast Charger

Integrated chargers eliminate the need for a dedicated onboard charger by repurposing drivetrain components for charging, thereby reducing the cost and weight of an EV. The dual inverter drive (DID)-based integrated charger further improves efficiency by eliminating the isolation stage. However, the lack of isolation leads to higher common-mode (CM) currents, which poses a challenge in complying with the strict safety standards associated with EV charging. This challenge can be overcome using an appropriate modulation scheme and the proper design of a CM filter. This paper presents a comprehensive analytical model that accurately predicts and analyzes these CM currents, providing a full understanding of their quantitative and qualitative nature. Additionally, an extensive experimental validation of the model is presented, offering practical insights for the development of DID-based integrated chargers.