Improving Transient Response of a Battery Energy Storage System with Minimized DC Capacitors

Battery Energy Storage Systems (BESSs) are widely adopted in electric vehicles, aircraft, and residential units. Current market trends for low and medium-power BESSs require the achievement of maximum efficiency and power density to enhance cost-effectiveness and long-term energy savings. The DC-link capacitance of the charger-inverter system can be reduced through the application of advanced control systems. However, this reduction in the energy storage capacity can result in over/under voltage issues during sudden load changes. To address this, the control system must maintain the bus voltage within an acceptable range by ensuring rapid transient response and efficient energy transfer to the battery. To overcome this challenge, two nested control loops are proposed and designed in this paper which enhance the transient response and offer a systematic design approach. The paper covers discussions on system modeling, the control design methodology, as well as simulation and experimental results. The experimental results reveal that the proposed approach can significantly improve the bus voltage transients, compared with the conventional methods.