Battery ripple current reduction in a three-phase interleaved dc-dc converter for 5kW battery charger

This paper proposes a battery ripple current reduction method and design of three-phase interleaved dc-dc converter for 5kW battery charger, which is applied for stabilizing a wind-power generating system. The charger consists of three-phase interleaved dc-dc converter, which is the interface of batteries and DC link, and a grid connected inverter. Lead-acid battery is modeled in the first order R-C model by MATLAB/Simulink and battery parameters are measured by the pulsed current and constant current discharge test. The battery is connected to the three-phase interleaved dc-dc converter in order for reduction of ripple current to 8% from 32.5%, increase of battery lifetime and reduction of total size of inductors. The ripple current is further reduced to 2% from 8% by connecting a filter capacitor and design rule of filter capacitor is analyzed. The controller for charging and discharging mode is designed and the proposed reduction methods of battery ripple currents are verified in a 5kW charger.