Variable-Reference Voltage Balancing Control for Four-Level Rectifiers

Four-level rectifiers suffer from severe imbalanced capacitor voltages. Taking a hybrid Detroit rectifier as an example, a variable-reference modulation scheme is presented and analyzed in detail. Based on the variable-reference modulation scheme, a closed-loop control strategy is developed for the hybrid Detroit rectifier. Finally, simulation results have been provided to verify the variable-reference modulation based closed loop control strategy for four-level rectifiers.