A PFC with high power factor at low load or high mains voltage

This paper describes a boost power factor corrector (PFC) with high power factor at low load or high mains voltage. The power factor is improved by compensating the current of the EMI filter after the bridge rectifier so that the current drawn from the mains deviates less from the desired shape. This compensation is realized by controlling the current distribution of the boost converter over each half mains cycle. Measurements based on the PFC application board designed for universal mains supply and 300W full load show that the described new control strategy results in power factor of 0.85 at 30W load with 230V ac mains supply (50Hz) and 400V DC output voltage. This measured power factor is about 12% higher than that of the traditional PFC with the same key application conditions.