Investigation of fully digital controlled Li-ion battery power recovery system

This paper proposes a design scheme for grid-connected Li-ion battery power recovery system which is utilized for battery formation during the production process of Li-ion battery. The proposed scheme based on a compound dc-dc converter with cascade structure and a three-phase grid-connected inverter with LCL filter is able to interface between low dc voltage of batteries and ac grid. The system is digital controlled, and the design of the digital control scheme is discussed in detail. Voltage-oriented PI controller and active damping method are adopted for regulating the grid currents. The restrictions of the digital compensator design are concluded. The proposed system scheme and the design considerations are both proved by the implementation of a 5 kVA prototype.