2012 Volume 1 Issue 3 Pages 164-171
This paper discusses a high-efficiency AC-DC converter developed for implementation under low-voltage and high-current conditions for sintering applications. First, the circuit configuration and the control principle for the proposed low-voltage, high-current AC-DC converter are described. The proposed system consists of four 2,500-A units of the AC-DC converter connected in parallel. The input current harmonics are suppressed by using multiple transformers on the input side. Further, imbalance issues in the transformer parameters and the output wiring are discussed. The proposed system demonstrates that each individual circuit yields a balanced 2,500-A output. In addition, loss analysis shows that the power loss on the secondary rectifier is 49% and is dominated by semiconductor loss. Furthermore, it is shown that by implementing a MOSFET synchronous rectifier, instead of a Schottky barrier diode, the loss reduces by 35%. Finally, the input current harmonics are reduced by using multiple transformers, and the validity of this result is demonstrated.