| 摘要 |
A step-down autotransformer for a power distribution system with 1-phase non-linear loads according to the invention provides at least one output for each phase. In two-output embodiments the outputs in each output pair have a different voltage than the input voltage and are phase-shifted by 30 degrees to cancel or substantially reduce the 5th and 7th harmonic currents. The autotransformer of the invention also cancels or substantially reduces zero phase sequence (ZPS) harmonic currents by providing a number of turns of windings between the neutral and each output oriented in a positive direction to be substantially equal to the number of turns of windings between the neutral and each output oriented in a negative direction. A single-output embodiment provides one output for each phase and therefore does not introduce a 30 degree phase shift for cancellation of 5th and 7th harmonic currents, but cancels or substantially reduces zero phase sequence (ZPS) harmonic currents by providing a lower impedance path. The zig-zag connections provide a neutral return path for 1-phase ground faults. |
