Application of the ZCS auxiliary commutation circuits in a interleaved boost converters operating in critical conduction mode

A power-factor-correction (PFC) circuit based on interleaved boost converters in critical conduction mode (C-DCM) with a zero current switching (ZCS) technique is investigated. The main switches turn-on occurs naturally in ZCS, due to the operation in C-DCM. In addition, C-DCM also reduces the reverse recovery losses of the boost diodes. The use of auxiliary commutation circuits provides ZCS at the main switches turn-off. These circuits are activated only during the main switches commutations. By using the interleaved converters technique, the input current ripple is minimized. The control circuit of the converters has been implemented using a single erasable programmable logic device (EPLD) EPM7128SLC84-15 from Altera Corporation. The experimental results obtained using a 1.2 kW prototype operating from an AC input voltage source of 120 V RMS are presented.