| 摘要 |
The invention relates to an autotransformer for transforming a three-phase power supply into a nine-phase power supply, notably for use in a rectifier. The autotransformer is a, step-up or step-down transformer. For a step-down application, the three-phase input terminals E 1, E 2, E 3 are connected to one of the three main windings in delta configuration, mounted on respective magnetic branches M 12, M 23, M 31 of a magnetic circuit. Te main winding B 12 of one branch has intermediate taps K 1, K' 1, K'' 1 from which auxiliary windings X 31, Y 23, Z 31, mounted on the other branches, start. These auxiliary windings produce, on three output terminals A 1, B 1, C 1, voltages one of which is in phase with the three-phase supply voltage at E 1, the other phase-shifted by +40°, and the third by +80°. The number of turns in the auxiliary windings and the position of the intermediate taps are calculated so as to obtain this result. The identical windings of the other branches produce the other output voltages on the terminals A 2, B 2, C 2, A 3, B 3 in order to produce a system with nine phases.
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