Interleaved Active Clamp Forward Converters as Single Stage On-Board DC-DC Converters for EVs - an Accurate Model and Design Considerations

Wide-bandgap semiconductors qualify the active clamp forward converter (ACFC) as an attractive solution for electric vehicle (EV) on-board DC-DC converters. Recent publications have presented an analytical steady state model allowing the accurately calculation of the clamp capacitor voltage. This is a key design requirement as the voltage is highly dependent on the output current and represents together with the input voltage, the blocking voltage of the primary switches. For higher output powers, two ACFC rails can be operated interleaved on a common output inductor, significantly reducing the size of this coil. In this paper, the model of the ACFC is adapted to its interleaved version resulting in a maximum error of only 2.2 % compared to a switched-model simulation. A component stress analysis based on the model demonstrates the potential of interleaved ACFC in the application of high-power EV onboard DC-DC-converters.