MODULAR TRANSFORMER APPARATUS FOR MULTILEVEL POWER CONVERTER

PROBLEM TO BE SOLVED: To provide a modular transformer apparatus for a multilevel power converter, i.e., a modular three-dimensional transformer apparatus which is used for a high-power system and comprises low-power transformers of high-power density as to satisfy the necessary condition of a variable power for various equipments, and in other words, provide the modular three-dimensional transformer apparatus whose manufacture, installation and replacement are made easy. SOLUTION: A modular transformer apparatus for feeding power to a multilevel power converter 122, 124, 126 has a plurality of three-phase transformer modules 120 each of which has primary windings of a delta connection or an extended delta connection and secondary windings of a delta connection, an extended delta connection, a star connection, a zig-zag connection, or the like. In order that the multilevel power converter 122, 124, 126 feeds to a motor of a load increased voltages/currents or many phases each of which can be shifted relatively to the input of the modular transformer apparatus, the multilevel power converter 122, 124, 126 has full-bridge power modules 130 each of which has its input connected with the insulated secondary coil of the three-phase transformer module 120 and its output connected in series/in parallel with the outputs of other full-bridge power modules 130.