A Flexible Voltage Bus Converter for the 48-/12-V Dual Supply System in Electrified Vehicles

Due to an increasing in-vehicle electric load demand, a new 48-V electric system architecture proposed by German premier car manufacturers has been gaining increasing attention recently for electrified vehicles. In this paper, a multiple-voltage bus converter for the 48-V and existing 12-V dual supply system, providing additional flexible dc bus voltages, is proposed. The proposed converter can provide a dual flexible dc voltage bus and an additional dependent voltage bus while simultaneously managing the 12-V supply net using only one single-leg switch pole and a diode. The additional dc voltage buses will provide more options to accommodate variable electric load components in a vehicle, improving their power density. Due to the multiple control objectives, the single-leg pole requires a multimode switching strategy to regulate the additional bus voltages. To improve the onboard vehicle system reliability and performance, an impedance network structure is implemented in the converter to obtain a dead-time-free pulsewidth modulation (PWM). Simulation and experimental results are presented to verify the feasibility and effectiveness of the proposed structure and control method.