High efficiency battery charger for photovoltaic inverters

This paper analyzes a bidirectional, isolated boost topology that is used as the battery charger/discharger in a photovoltaic generator interface converter with built-in energy storage. The converter interfaces a 48 V, 6 kWh lead acid battery stack to a 400 V dc bus, and is designed for a ± 1.5 kW peak power. The steady-state circuit analysis is presented and a possible design procedure for the power stage is derived. Experimental results from a prototype of the converter are presented, showing a 96 % peak efficiency at 1 kW, in both charging and discharging operation modes.