Analytical Topology Comparison for a Single Stage On-Board EV-Battery Converter

DC-DC converters connecting the traction battery with the conventional auxiliary battery in EVs are characterized by a major challenge: The required voltage ratio (gain range) depends on the input and output voltages, both varying considerably with the state of charge (SOC) of their batteries. However, the properties of new wide-bandgap semiconductors lead to modified design requirements of the converter, offering some additional design freedom. This paper presents an analytical converter comparison based on a modified component stress factor analysis. Five converters are compared: The phase-shifted full bridge (PSFB), the LLC resonant converter (half bridge and full bridge with varying operating modes), and the active clamp forward converter (ACFC) (non-interleaved and interleaved). The comparison shows that the ACFC and the LLC with varying operating modes are attractive topologies while the half-bridge LLC converter and the PSFB have generally higher stress values.