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

Unity power factor zero-voltage-switched (ZVS) AC-to-DC power converters with an active filter are proposed. The line voltage is supplied to AC-to-DC power converters through a 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. Forward ZVS multiresonant power converters (ZVS-MRCs) 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 power converters     

Bridgeless Boost Rectifier With Low Conduction Losses and Reduced Diode Reverse-Recovery Problems

A bridgeless boost rectifier with low conduction losses and reduced diode reverse-recovery problems is proposed for power-factor correction. The proposed boost rectifier can reduce the conduction losses and alleviate the diode reverse-recovery problems by using a coupled inductor and two additional diodes. Zero-current turn-off of the output diodes is achieved, and the reverse-recovery currents of the additional diodes are slowed down to reduce the diode reverse-recovery losses. All inductive components are realized on a single magnetic core by utilizing the leakage inductance of the coupled inductor. Furthermore, for the use of this topology in the practical design, the linear peak current mode control is employed for the proposed boost rectifier. A detailed analysis and a control strategy are presented. Experimental results for a 300-W prototype are also discussed to show the performance of the proposed boost rectifier