A new soft-switching technique using a modified PWM scheme requiring no extra hardware

Daniel John Tooth, Neville McNeill, Stephen J. Finney, Barry W. Williams

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


A new soft-switching PWM scheme for a three-phase, ac-dc, step-down, unity power factor converter is described. The main advantage of the scheme is that it requires no additional hardware components to achieve a combination of zero current and voltage turn-off and zero and reduced voltage turn-on. The scheme relies on the repositioning of the PWM pulses within the carrier period to obtain natural commutation from one switching device to the next. The theoretical reduction in the total switching losses is mathematically shown to be 42% compared with the standard center-aligned PWM scheme used with the converter. A PSpice™ simulation of the new scheme reveals soft-switching waveforms. Practical results are given to support the simulation results and heatsink temperature rise results show a reduction in heatsink temperature rise for the new scheme compared to the old.

Original languageEnglish
Pages (from-to)686-693
Number of pages8
JournalIEEE Transactions on Power Electronics
Issue number5
Publication statusPublished - Sept 2001


  • Insulated gate bipolar junction transistors
  • Power conditioning
  • Power conversion
  • Power quality
  • Power supplies
  • Pulse width modulated power converters
  • Pulse width modulation
  • Switching transients


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