This paper proposes an improved dual-mode fast charger for supercapacitors that utilizes both continuous and fine-tuned pulse currents for fast charging. By tuning the voltage across the output inductor, the proposed charger improves the pulse characteristics of the conventional forward converter in that the transitions between the continuous and pulse currents are much faster. Moreover, the proposed charger removes two switches in a similar topology, which leads to a simpler topology, a more robust control strategy, and a lower cost. Simulation results verify the dual-mode operation of the proposed charger and show that the charging time is significantly reduced. A prototype is built and preliminary experimental results further demonstrate the dual-mode operation and the fine-tuned charging current pulses with much sharper rising and falling edges.
