Dynamic Process Analysis of a High-Power Bidirectional DC/DC Converter for Electric Vehicles

Auxiliary Power Module (APM) bridges the high voltage battery with the low voltage auxiliary battery in Electrical Vehicles (EV). This paper designed such APM for EV rated at 3.5kW with a peak power of >6kW, covering 250-400V input and 10-16V output. One key dynamic process lies in the pre-charge mode, i.e., charging the DC bus capacitor before the full operation. Another challenge lies in the DC bias current for the bridge based circuit. A novel and simply DC bias detection circuit is proposed to sense the unbalanced current in the transformer. Both simulation and test results verified that the proposed method can effectively detect and eliminate the DC bias in the transformer.