Multiport Converter Integrating Automatic Current Balancing Interleaved PWM Converter and DAB Converter with Improved Transformer Utilization for Electric Vehicles

Abstract

Multiport converters (MPCs) that integrate multiple converters into a single unit have been proposed to reduce the converter count in electric vehicle power systems where multiple batteries are employed. However, conventional MPCs comprising a dual active bridge (DAB) converter and an interleaved PWM converter require feedback control loops and current sensors to balance the inductor currents. Furthermore, the transformer utilization decreases as the duty cycle of the interleaved PWM converter drifts away from 0.5. This paper proposes a novel MPC that integrates a DAB converter and an interleaved PWM converter with an automatic current balancing capability and improved transformer utilization. A 1-kW prototype with a half-bridge or full-bridge circuit on the high-voltage side was built for the experimental verification, and loss analysis was performed. The results demonstrated the automatic current balancing capability, improved transformer utilization, and flexible power exchange among three ports.