EP732798-A  CONFERENCE RECORD OF THE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETI, SEATTLE, OCT. 7 - 12, 1990, vol. VOL. 1, no. MEETING 25, 7 October 1990, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, pages 703-710, XP000204099 SALMON J C: "SELECTING STEPPED REFERENCE WAVEFORMS FOR PWM INVERTER DRIVES TO MINIMIZE THE CURRENT DISTORTION";  CONFERENCE RECORD OF THE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETING. (IAS), SAN DIEGO, OCT. 1 - 5, 1989, vol. PART 1, 1 October 1989, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, pages 753-759, XP000093259 SALMON J C ET AL: "A 3-PHASE PWM STRATEGY USING A STEPPED REFERENCE WAVEFORM"EP732798-A1  "Self-Exciting Inverters", Chapter 6, in "Semiconductor Power Conversion Circuits", edited by Japan Electrical Engineers Society;  CONFERENCE RECORD OF THE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETI, SEATTLE, 07/10/1990 - 12/10/1990, vol. VOL. 1, no. MEETING 25, 07/10/1990, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, pages 703-710, XP000204099 SALMON J C: "SELECTING STEPPED REFERENCE WAVEFORMS FOR PWM INVERTER DRIVES TO MINIMIZE THE CURRENT DISTORTION";  CONFERENCE RECORD OF THE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETI, SEATTLE, OCT. 7 - 12, 1990, vol. VOL. 1, no. MEETING 25, 7 October 1990, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, pages 703-710, XP000204099 SALMON J C: &quot;SELECTING STEPPED REFERENCE WAVEFORMS FOR PWM INVERTER DRIVES TO MINIMIZE THE CURRENT DISTORTION&quot;;  CONFERENCE RECORD OF THE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETING. (IAS), SAN DIEGO, 01/10/1989 - 05/10/1989, vol. PART 1, 01/10/1989, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, pages 753-759, XP000093259 SALMON J C ET AL: "A 3-PHASE PWM STRATEGY USING A STEPPED REFERENCE WAVEFORM";  CONFERENCE RECORD OF THE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETING. (IAS), SAN DIEGO, OCT. 1 - 5, 1989, vol. PART 1, 1 October 1989, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, pages 753-759, XP000093259 SALMON J C ET AL: &quot;A 3-PHASE PWM STRATEGY USING A STEPPED REFERENCE WAVEFORM&quot;