Unity power factor ZVS AC-to-DC converters with an active filter

Unity power factor zero-voltage-switched ac-to-dc converters with an active filter are proposed, The line voltage is supplied to ac-to-dc converters through the rectifier circuit with an input filter, to reduce high-frequency ripple components, The line current is almost synchronized to the line voltage, due to the low impedance of the input filter. The forward zero-voltage-switched multiresonant converters (ZVS-MRC's) are utilized for high-frequency operation and lossless switching, An active filter is introduced to minimize the twice line-frequency ripple component of the output voltage without large-size passive filters, Experimental results show that the proposed scheme gives good steady-state performances of the ac-to-dc converters.