Three‐Phase Line‐Frequency Rectifier With Multiple Input Voltage Levels

ABSTRACT A three‐phase line‐frequency rectifier suitable for multiple input‐voltage levels is proposed in this research. The proposed circuit is composed of a three‐phase bridge rectifier and controllable semiconductor switches. The rectifier actually behaves like a voltage doubler due to the conduction scheme of controllable switches under line‐frequency. When the input line voltage is lower, for example, 190 or 110 V, the switch conduction angle is adjusted to double the input line voltage, and therefore, the output DC voltage would align to rectified 220 V line‐in level. That is, for manifold line‐in level, adequate control should be applied to align the DC output to a higher level to reduce the current stress of the following stage. Firstly, this paper analyzes the operation of circuit under three control modes, explains the operation principle of sampling circuit, and clarifies the process of overall control system. Subsequently, feasibility of the control strategy is verified by a prototype circuit. The experimental results show that the output voltage is consistent and kept at the high level by the proposed feedback control at rated 500 W output power.