The isolated dc–dc converters with primary-side phase shifting (PPS) provides severely narrow soft-switching range for main devices in the primary side leg of full bridge converter. The leakage inductance of the high frequency transformer should be large enough for providing the energy needed for soft switching operations and also the idling power loss due to circulating current in the converter legs under large phase-shift angle, which makes reduction of conversion efficiency and complicated in designing the parameters of transformer. Furthermore, the turn-off diode commutations in the output-side rectifier are performed by hard-switching mode. To overcome all these drawbacks, a secondary side phase shifting (SPS) technique has been developed for two-level isolated DC-DC converter. This scheme provides wider soft switching range and reduced power loss due to elimination of circulating current in the primary side of high frequency transformer. In addition, SPS control also provide no reverse recovery current in diodes and hence no power losses in the secondary rectifier circuit. The control switches operate under soft switching even under rated load and short circuit conditions.
Single Input Single Output Two Level Isolated Dc-Dc Converter With Secondary Side Phase Shifting For Solar Applications
