Power flow architecture in electric vehicles must be designed to achieve high efficiency and power density while delivering a rated torque-speed envelop. When a battery is directly connected to the traction inverter dc link, the torque-speed envelop shrinks as the battery discharges. A plausible solution to retain the torque-speed capability can be to add a dc-dc converter between the battery and the traction inverter. This architecture needs the dc-dc converter to process the full traction power, making the overall system bulky and lossy. This digest proposes re-purposing the onboard charger to regulate the inverter dc-link during motoring. The analysis in the digest proves that even with only a 15% power rating of the onboard charger compared to the traction motor, it is possible to deliver the rated torque speed even up to 20% battery SOC. The functionality of the proposed architecture is explained, and the efficiency color maps are plotted, which shows a 2% improvement in efficiency over the entire torque-speed envelop. Experimental results comparing the conventional boost converter with the proposed architecture corroborate the analysis.
