Maximum Power Factor Tracking Technique for LCC-Capacitor Charging Converter Through Variable DC Link Voltage

In this paper, a maximum power factor tracking (MPFT) technique through variable DC link voltage is proposed for the LCC resonant converter for capacitor charging power supply (CCPS) with an ultra-wide output voltage range. The DC link voltage follows the output capacitor voltage to minimize the turn-off current of MOSFETS to reduce the turn-off switching loss, and the circulating current to decrease the instantaneous reactive power in the resonant tank. In comparison with fixed DC link voltage, the proposed variable DC link voltage technique demonstrates the efficiency improvement in constant current (CC) charging and constant power (CP) charging strategy. When using CC charging strategy, the efficiency can be improved by up to 26.84% under light load condition. When using CP charging strategy, the efficiency can be improved by up to 11.63% under light load condition and 2.66% under heavy load condition.