Patent ID: 6400119
Filing Date: 2002-06-04
Classification: G05F,H02J,H02P,Y02P

Abstract:
A controller for dynamically matching energy use by an AC induction motor having at least one motor winding and an AC voltage applied thereacross to the load on said motor comprising:first and second SCRs, each having a respective gate and connected in parallel with each other in opposing polarities between a first node and a second node, for each phase of said AC voltage wherein said first node is connected to a source of said AC voltage and said second node is connected to said at least one motor winding of the motor; and a trigger generator coupled to said respective gates, said applied voltage and said motor winding for controlling each said first and second SCRs, responsive to the respective timing of sensed zero-crossing events of said AC voltage and an AC current in said motor winding corresponding to said AC voltage, wherein said first and second SCRs, alternately triggered into a conductive state during each alternation of said AC voltage, are alternately inhibited from said conductive state for a time proportional to a measured difference in time between the time said AC voltage of the present said alternation across said motor winding passes through a first zero-crossing and the time said corresponding AC current of said present alternation in said motor winding passes through a second zero-crossing, said measured difference determined as the time difference between successive first and second interrupts corresponding to said times said sensed zero-crossing events of said AC voltage and said corresponding AC current are coupled to said trigger generator and compared with a continuously running time base.