Minimum DC-Link Energy Storage Requirement of Half-Bridge Interleaved based Integrated On-board EV Charger

The simplest onboard integrated electric vehicle chargers, which utilize the same circuitry for both traction and charging purposes, fundamentally consist of three-interleaved half-bridges and split DC-link capacitors. This paper presents the calculation of the minimum DC-link capacitance for the front-end half-bridge AC-DC converter. Using the calculated value allows for significant size and cost reductions by employing this minimum capacitance. The proposed design can be applied to the cascade connection of converters, where the load converter is characterised as a constant power load. The minimum capacitance value is derived as a function of the mains voltage and frequency, the maximum power transferred to the load converter, and the desired DC-link voltage. The resulting capacitance is approximately four times smaller than that obtained through conventional design methods. Moreover, theoretical analysis are verified through simulations.