A Balance Control Strategy for H-Bridge Cascaded Energy Storage Converter Battery Pack

H-bridge cascade structure is a typical way for energy storage equipment to achieve high voltage and large capacity. It is difficult to ensure that each battery operates in accordance with the same charge-discharge curve because of the difference of the parameters of each battery. It is very easy to cause overcharge and over discharge of single battery and reduce the life and performance of energy storage equipment. Aiming at the above problems, a balancing control strategy of cascaded H-bridge energy storage converter is proposed. Firstly, the working principle and internal energy transfer mode of cascaded H-bridge energy storage converter are explained. Secondly, the working state of each battery pack and the sub-module electricity are calculated by the current charge state and average charge-discharge curve of each battery pack. Capacitance voltage command value is combined with sorting algorithm and nearest level approximation method to realize the sub-module capacitance voltage stability and make N-1 battery pack work according to the average electric curve (N is the number of H-bridge modules). Finally, in the MATLAB/Simulation software, a small simulation model is built to verify the feasibility of the control algorithm and provide a reference for large-capacity multi-module storage.