Eliminating High-Voltage Pre-Charge Circuits in Electric Vehicles Using Bidirectional DC-DC Converters

Pre-charge circuits play a critical role in ensuring electric vehicle (EV) safety by preventing excessive inrush currents during the initial connection between the high-voltage (HV) battery and power electronic systems.Conventional pre-charge architectures rely on resistors and contactors to charge the DC-link capacitors; however, these solutions introduce notable drawbacks, including thermal losses, increased system complexity, contactor wear, slower start-up dynamics, and reduced long-term reliability.This paper presents an enhanced approach that eliminates traditional pre-charge circuits by utilizing a bidirectional DC-DC converter to perform controlled HV bus charging.By regulating the voltage ramp from the low-voltage (LV) side and shaping the inrush current through inductor-based control, the converter replicates and improves upon conventional pre-charge functionality while reducing hardware count.The method incorporates isolated gate drivers for the 400 V side, RC/TVS snubber networks across switching devices, and proper grounding practices to mitigate noise coupling-addressing practical implementation concerns typically overlooked in existing literature.The proposed approach is validated through simulation, testing, and controlled experimental scenarios.Additional analyses are conducted on electromagnetic compatibility (EMC) performance, energy consumption impact during pre-charge, and baseline comparisons against resistor-contactor pre-charge methods.Key parameters such as inrush current suppression, voltage ramp profile, and system protection behaviour are analysed.The results demonstrate that the bidirectional DC-DC-based pre-charge approach satisfies safety requirements, reduces losses, improves EMC behaviour, and enhances system compactness.This positions the technique as a promising solution for next-generation EV powertrain architectures.