×

System for reducing harmonics by harmonic current injection

  • US 5,499,178 A
  • Filed: 02/10/1994
  • Issued: 03/12/1996
  • Est. Priority Date: 12/16/1991
  • Status: Expired due to Fees
First Claim
Patent Images

1. A harmonic reducing system for reducing harmonic currents generated from power conversion means connected between a multiphase alternating current power system having a base fundamental frequency and a direct current power system having terminals carrying a direct current, said power conversion means operating at the base fundamental frequency, said harmonic reducing system comprising:

  • current modulating means connected between said direct current power system and said power conversion means, said current modulating means being connected to receive at least a portion of the direct current carried through the terminals and modulating said at least a portion of the direct current with first and second superimposed sinusoidal currents at a selected harmonic frequency of the fundamental frequency greater than the fundamental frequency, wherein the first and second superimposed sinusoidal currents have an amplitude proportional to the direct current to reduce the selected harmonic currents; and

    means connected to the current modulating means for combining said first and second superimposed currents to form a sinusoidal injection current at the selected harmonic frequency, said injection current having an amplitude substantially equal to twice the amplitude of the first superimposed sinusoidal current; and

    coupling means connected between said means for combining and said multiphase alternating current power system for injecting a portion of said injection current through said coupling means into each phase of the multiphase alternating current system, the coupling means including a set of windings connected in a zigzag arrangement having a neutral connected to the means for combining for receiving the injection current.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×