Novel symmetrical step-down topologies of zigzag autotransformer

Abstract

Purpose This paper aims to obtain a symmetrical step-down topology with lower equivalent capacity and wider step-down range under the condition of the same output. Three new symmetrical step-down topologies of zigzag autotransformer are proposed in this paper. Taking the equivalent capacity as the main parameter, the obtained topologies are modeled and analyzed in detail. Design/methodology/approach This paper adopts the research methods of design, modeling, analysis and simulation verification. First, the zigzag autotransformer is redesigned according to the design objective of symmetrical step-down topology. Second, the mathematical model of the designed topology is established, and the detailed theoretical analysis is carried out. Finally, the theoretical results are verified by simulation. Findings Three symmetrical zigzag autotransformer step-down topologies are designed, the winding configurations of the corresponding topology are presented, the step-down ranges of these three topologies are calculated and the influence of step-down ratio on equivalent capacity of autotransformer is analyzed. Through analysis, the target step-down topologies are obtained when the step-down ratio is [0.969, 1.414] and [1.414, 8]. Research limitations/implications Because the selected research object is only zigzag autotransformer, the research results may lack generality. Therefore, researchers are encouraged to further study topologies of other autotransformers. Practical implications This paper includes the implications of step-down ratio on the equivalent capacity of autotransformer and the configuration of transformer windings. Originality/value The topologies designed in this paper enable zigzag autotransformer to be applied in step-down circumstances.