A Power Decoupling Control Stragegy for CHB-BESS Based on NLM

The common used modulation method for cascaded H-bridge converter battery energy storage system (CHB-BESS) is carrier phase shift pulse width modulation (CPS-PWM). However, with the increasing of voltage level, the number of submodules will increase greatly. Therefore, the nearest level modulation (NLM) is promising in high voltage transformerless battery energy storage system. To solve the problem of capacitor voltage balance and battery state of charge (SOC) balance, this paper proposed a power decoupling method based on NLM. The capacitor voltage and the SOC of batteries are balanced well in this method. And the CHB-BESS can provide reactive power compensation to grid. The simulation results from MATLAB/Simulink verified the effectiveness of proposed method.