More than half of the total energy produced in developed countries is consumedby electric motors or more precisely converted into mechanical energyfreeing socie... » 

More than half of the total energy produced in developed countries is consumedby electric motors or more precisely converted into mechanical energyfreeing society from the tedious burden of physical labor. Among the many typesof motors induction machines still have the unparalleled popularity that theydid a century ago. At least 90 of industrial drive systems employ inductionmotors.Most of the motors are uncontrolled but the share of adjustable speedinduction motor drives fed from power electronic converters is steadilyincreasing phasing out dc drives. It is estimated that more than 50 billiondollars could be saved annually by replacing all dumb motors with controlledones. «