Study of SVPWM control algorithm with voltage balancing based on simplified vector for cascaded H-bridge energy storage converters

DC-side voltage balancing is a critical problem to be solved for cascaded H-bridge energy storage converters. Aiming at inner-phase voltage balancing problem, a space vector pulse width modulation (SVPWM) algorithm with voltage balancing based on simplified vector is proposed. Firstly, the number of voltage vector is simplified by the proposed algorithm. Secondly, the action time of each level is calculated based on the volt-second balance, and the output vector is determined by comparing the DC-side voltage magnitude. Furthermore, the change of module level is minimal at the time of level change, and leapfrog hopping of the module level is prevented. Then, the inner-phase voltage balance can be achieved using vector selection. Due to the simplified SVPWM with voltage balancing, the algorithm is simpler, the switching losses is smaller, and it is easy to extend to cascaded H-bridge converters with more modules. Regarding the mutual-phase voltage balancing problem, the additional power generated by the zero-sequence voltage injection changes the power distribution among the three phases, so that the mutual-phase voltages is balanced. Finally, the effectiveness of the proposed control algorithm is verified by simulation and experimental results.