Active-Power Control of Individual Converter Cells for a Battery Energy Storage System Based on a Multilevel Cascade PWM Converter

The battery energy storage system is an essential enabling device of the smart grid, because it helps grid connection of massive renewable energy resources. This paper has a brief discussion on a battery energy storage system based on a multilevel cascade pulsewidth-modulated (PWM) converter for its practical use. The active-power control of individual converter cells is presented to make it possible to charge and discharge the battery units at different power levels while producing a three-phase balanced line-to-line voltage. This results in the maximum utilization of battery energy even when the power-handling capabilities of the battery units differ. Experimental results obtained from a 200-V, 10-kW, 3.6-kWh battery energy storage system verify the effectiveness of the presented active-power control.