PWM based modulation strategy with variable switching frequency for an active rectifier stage with flexible DC-voltage output
This paper proposes a new DC-link voltage optimization method for SOC balancing control of a battery energy storage system based on a 7-level cascaded PWM converter. Factors used for minimizing an exceeding utilization of DC-link voltage by rated power operating during SOC balancing are analyzed and presented. The proposed individual SOC balancing control and leveled SOC balancing control are developed. To verify the effectiveness of the proposed method, the mathematical model of the battery energy storage system has been developed and simulated. The major simulation results have consistently indicated the validity and effectiveness of the proposed method.