Switching Regulator Based on a Non-Inverting Step-Down/Up DC–DC Converter for Lithium-Ion Battery Applications

A regulator based on a converter with step-down/up characteristics is discussed in this paper, which is suitable for processing energy from a lithium-ion battery pack, where the voltage fluctuates from above or below the nominal value. However, this regulator can also be used for applications such as unregulated line rectifiers and renewable energy sources, among others. The converter consists of a non-cascaded interconnection of boost and buck–boost converters such that part of the input energy is transferred directly to the output without reprocessing. Furthermore, it has a non-pulsating input current and a non-inverting output voltage, making it easier to feed the power to other devices. For control purposes, non-linear and linear converter models are derived. The transfer functions of the linear model are used to implement the regulator using a current-mode control scheme. Finally, experimental results for a nominal output voltage of 48 V at 500 W are obtained for the converter in open-loop and closed-loop tests.