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Controlling currents in parallel AC/DC converters

  • US 5,956,244 A
  • Filed: 03/05/1998
  • Issued: 09/21/1999
  • Est. Priority Date: 03/05/1998
  • Status: Expired due to Term
First Claim
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1. An apparatus for converting AC voltage on first, second and third supply lines to DC voltage between positive and negative DC buses, the apparatus comprising:

  • a voltage regulator providing a current command signal;

    a carrier generator for generating a carrier signal;

    a master converter subsystem including a master current regulator, a master PWM modulator and a master converter, the master converter including six switches arranged to form master first, second and third series switch pairs between the positive and negative DC buses, a first input node between the first master pair linked to the first supply line, a second input node between the second master pair linked to the second supply line and a third input node between the third master pair linked to the third supply line, the master regulator using the current command signal to generate master modulating signals, the master PWM modulator using the master modulating signals and the carrier signal to generate control signals for controlling the master converter switches;

    a slave converter subsystem including a slave current regulator, a slave PWM modulator and a slave converter, the slave converter including six switches arranged to form slave first, second and third series switch pairs between the positive and negative DC buses, a fourth input node between the first slave pair linked to the first supply line via a first intermediate line, a fifth input node between the second slave pair linked to the second supply line via a second intermediate line and a sixth input node between the third slave pair linked to the third supply line via a third intermediate line, the slave regulator using the current command signal to generate slave modulating signals, the slave PWM modulator using the slave modulating signals and the carrier signal to generate control signals for controlling the slave converter switches; and

    a common mode choke linked to the first, second and third intermediate lines to essentially eliminate common mode currents in the first, second and third intermediate lines.

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