A zero-current-transition (ZCT) strategy is proposed herein. This strategy is applied to a two-phase boost converter with isolated gate bipolar transistors (IGBTs) used as main switches. However, IGBTs have a current tail during the switch-off interval. Consequently, the proposed constant-frequency ZCT strategy along with common-ground auxiliary switches is employed to decrease the switching loss generated by the current tail. Furthermore, the light-load efficiency can be upgraded by regulating the switch-off instants and switch-on times of the two auxiliary switches. Moreover, two phases are interleaved with one phase having a phase difference of 180° from the other phase, and controlled by a current-sharing controller so that the input current can be distributed between the two phases as evenly as possible. Moreover, only one current sensing circuit is required to obtain information on currents in the two main switches. Above all, the number of phases can be extended with easy control of the ZCT and current balance.
Keywords: IGBT; current balance; interleaved; two-phase boost converter.