Patent ID: 9124169
Filing Date: 2015-09-01
Classification: H01F,H02M,H02P

Abstract:
1. A method to reduce total harmonic distortion input in a 24-pulse autotransformer system configured to receive an input of a first voltage and produce an output voltage of a second voltage, wherein the second voltage is less than the first voltage, the method comprising: coupling a first three-phase autotransformer to an AC power source, the first autotransformer comprising twenty-one windings having three input terminals and six output terminals; coupling a first pair of rectifier units to the output terminals of the first three-phase autotransformer, each rectifier having three input terminals and a positive and a negative output terminal; coupling a second three-phase autotransformer to the AC power source, the second autotransformer having three input terminals and six output terminals with the second three-phase autotransformer input terminals coupled to the first three-phase autotransformer input terminals in a reversed phase sequence configuration; coupling a second pair of rectifier units to the output terminals of the second three-phase autotransformer; adjusting turn ratios of two windings of each phase of the first and second three-phase autotransformers to effect a decrease in the voltage across said two windings leg from a symmetric voltage value resulting in a reduced input THD without a zero sequence blocking transformer; and coupling each of the positive and negative output terminals of each of the rectifier units to an electrical load.