Voltage Balancing Control and Implementation of Detroit Rectifier

This article presents a voltage balancing control method for Detroit rectifier which is featured with four voltage levels and reduced components. First, a simplified circuit model of Detroit rectifier is built and then a switching function model is developed. Then, theoretical analysis based on the simplified circuit model indicates that the over-charge of the middle capacitor is the root cause of the capacitor voltage imbalance issue and there is triple-fundamental-frequency voltage oscillation on the upper and lower capacitors. To overcome the two issues, this article proposes a voltage balancing method “variable-reference + zero-sequence voltage (ZSV) injection.” Subsequently, a closed loop control strategy is developed for Detroit rectifier based on the proposed voltage balancing method. Finally, both simulation and experimental results have been provided and analyzed to verify the proposed voltage balancing method of Detroit rectifier.