ZVS Turn-on integrated Triangular Current Mode Three-phase AC-DC PFC for EV On-board Chargers

MSc thesis of Jian Sun

An efficient, compact, and lightweight three-phase AC-DC power factor correction (PFC) converter becomes a necessity for the On-board chargers (OBCs) of the electric vehicle (EV) in conventional grid-to-vehicle (G2V) and vehicle-to-grid (V2G) charging scenarios. The commercially available OBCs have very limited power density despite the moderate efficiency under specific power levels.

In this dissertation, the integrated triangular current mode (iTCM) control is implemented to improve the power density (kW/L) and specific power (kW/kg) of the three- phase PFC converter (the front stage of OBCs) while maintaining high efficiency. Zero voltage switching (ZVS) turn-on is realized in the iTCM control with a higher switching frequency to reduce the LCL filter size without sacrificing efficiency.

By adding an LC branch between the bridge leg and the mid-point of the DC link, the high-frequency and low-frequency current is split to minimize the inductor loss and to achieve a better inductor design. Finally, the designed 11 kW three-phase AC-DC PFC converter, including the input LCL filter, achieves an efficiency of 98.61%, a power density of 6.5 kW/L and a specific power per weight of 0.72 kW/kg.