Patent ID: 8502492

Claim:
A system for controlling power from an AC voltage to an induction motor, the system comprising: a processor; a means for switching power to the induction motor, the means for switching power including a trigger, the trigger controlled by the processor to enable the means for switching at point within a half-cycle of the AC voltage based upon a trigger delay, whereas a full power is supplied to the induction motor when the trigger delay is zero; a means for measuring current drawn by the motor; a means for measuring the AC voltage at the source; a means for measuring a phase difference between a phase of the AC voltage and a phase of the current drawn by the motor; a means for initializing power provided to the induction motor, the means for initializing determining a minimum phase angle, a minimum trigger delay, a maximum trigger delay and an over-current value; and a means for continuously varying the trigger delay between the minimum trigger delay and the maximum trigger delay, if the trigger delay is greater than zero the trigger delay is decreased when the phase difference is less than the minimum phase angle and if the trigger delay is less than the maximum trigger delay, the trigger delay is increased when the phase difference is greater or equal to the minimum phase angle and the trigger delay.