A novel voltage balancing method of cascaded H-bridge rectifiers for locomotive traction applications

Cascaded H-bridge rectifier paves the way of high-voltage applications without input transformer such as locomotive tractions. In the current study, a novel voltage balancing method based on improved PD-SPWM (phase-disposition sinusoidal pulse width modulation) is proposed that eliminates the multiple PI regulators in traditional balancing algorithms. This algorithm is simple to realize and effective for voltage balancing in the condition of unbalanced loads and locomotive regenerations. The validity of the proposed method has been verified by simulation and experiments.