A novel start-up method for full-bridge isolated DC-DC converter in RES applications

A novel start-up method for an isolated full-bridge boost converter with modified phase-shift technique, for RES and automotive applications is proposed. In order to avoid the high inrush currents, the converter is operated in flyback mode at start-up. For precharging the output capacitor no auxiliary circuits or modified switching strategy is necessary. All the power switches of the isolated boost converter are soft switched (ZVS or ZCS), for the whole duty cycle. One single control circuit is used for control, protection and start-up. The voltage-fed control circuit is modified to be applied to the current-fed full-bridge DC-DC converter.