Variable-Speed Motor Drives with Digital Control

Energy efficiency is a continuing focus of the power electronics industry. Motors consume the most electricity in commercial and industrial applications (followed at a distant second by lighting). More than 85 percent of electric motors are single-phase motors that are installed in numerous applications - fans, pumps, compressors - that would benefit from variable speed control. Traditional approaches have been to complicate the motor design by tapping the motor windings and using electromechanical switches to change the number of windings, thus changing speed.