A Non-Cascading Step-up/down DC-DC Converter with Non-Pulsating input Current for Lithium-ion Battery Applications: Analysis and Design

This paper discusses a step-up/down converter based on reduced redundant power processing such that part of the energy is transferred directly to the output without any reprocessing. This non-inverting converter is suitable for applications where the voltage delivered by a dc source varies from above or below the nominal value. The converter exhibits a non-pulsating input current improving the lifetime and performance of the source. The above converter is a good choice for processing energy from lithium-ion batteries like in electric vehicles. The steady-state values for the voltages and currents are given within. These relationships allow the proper selection of the converter elements for specific applications. The averaged nonlinear and linear models are derived as well as the corresponding transfer functions of possible variables to be used for control purposes. Simulation and experimental results for a 48 V @ 500 W prototype are shown to verify the design relationships and models.