A Family of Inverting Buck-Boost Converters With Extended Conversion Ratios

In this paper, two inverting buck-boost converters which possess wide conversion ratios are proposed. At the proper duty cycles, the inverting buck 2 -boost converter (IB2BC) achieves high step-down gain while the inverting buck-boost 2 converter (IBB2C) realizes high step-up gain. Advantages of the IB2BC and the IBB2C also include fourth-order simple common-ground structures to increase the power density and operability, low components stress to decrease the corresponding losses and then to improve the system efficiency, no sudden changings on capacitors voltage to prevent the instantaneous overcurrent phenomenon. Owing to the special structures of the IB2BC and the IBB2C, their improved single-switch topologies with reduced number of switch and extensional topologies with wider conversion ratios are constructed, respectively. Operational principles and corresponding comparisons of the above mentioned buck-boost converters are deeply studied and analyzed. As the representative, the single-switch inverting buck-boost 2 converter (SIBB2C) is designed and experimented in step-down/up modes for verifying the family of buck-boost converters performance.