Patent ID: 6107762
Filing Date: 2000-08-22
Classification: H02P,Y10S

Abstract:
An electric motor speed control circuit for controlling the operation of an electric motor that is responsive to application of an alternating current power source, comprising:frequency sensing means for sensing a frequency of power delivered from the alternating current power source and producing a cyclic digital count corresponding to the sensed frequency;a load measurement circuit for producing a digital load count representing a load experienced by the electric motor;command count means for producing a command count representing a discrete operational speed of the electric motor;reference count means for producing a reference count by combining the command count and the digital load count;a comparator for comparing the reference count to the cyclic digital count and producing an output signal synchronized to the cyclic digital count; anda semiconductor switching device for controlling a percentage of ON time for the electric motor, said semiconductor switching device modulating in accordance with the output signal from said comparator.