High step-up DC-DC converter with coupled inductor and reduced switch-voltage stress

This paper investigates a high step-up dc-dc buck-boost converter with reduced switch-voltage stress. The traditional dcdc buck-boost converter can not provide the very high voltage gain function by itself. By replacing the inductor of a classical buck-boost converter with a cell formed by a coupled inductor and one diode, a new converter with high voltage ratio is obtained. The energy accumulated in the leakage inductance is transferred to the load in a non-oscillatory manner. The essential problem of this circuit is a very high voltage stresses on the transistor and on the diodes. The splitting of the secondary inductor into two windings significantly reduces these voltage stresses. The DC gain and maximal voltage stresses expressions are obtained. Simulation and experimental results confirm the theoretical analysis and the advantages of the proposed converters.