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Zero-voltage-switched, three-phase PWM rectifier inverter circuit

  • US 5,432,695 A
  • Filed: 09/17/1993
  • Issued: 07/11/1995
  • Est. Priority Date: 09/17/1993
  • Status: Expired due to Fees
First Claim
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1. A three-phase, 6-stepped pulse-width-modulated, boost rectifier/buck inverter circuit including a bridge comprised of three pairs of semiconductor switches with parallel connected diodes connecting respectively a node to which each phase of a three-phase input is connected to a pair of d.c. output rails, one of said semiconductor switches remaining open and one remaining closed during thirty-degree segments of the three-phase input while the remaining semiconductor switches are turned on and off by a pulse-width-modulating signal, the improvement comprising:

  • a commutation circuit including an inductance coupled to each of said nodes by means of an auxiliary switch means so that, when said auxiliary switch means is closed, current flow in said parallel diodes is gradually reduced and a resonant circuit comprised of said inductance and a parasitic capacitance of said semiconductor switches at said nodes generates a zero voltage across said switches at a turn-on of said semiconductor switches by said pulse-width-modulating signal; and

    means to turn-on said auxiliary switch means for a short interval prior to turn-on of said semiconductor switch by said pulse-width-modulating signal.

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