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A power control system for a turbogenerator which provides electrical power to pump-jack oil well. When the induction motor of a pump-jack is powered by three-phase utility power, the speed of the shaft varies only slightly over the pumping cycle but the utility power requirements can vary by four t

A power control system for a turbogenerator which provides electrical power to pump-jack oil well. When the induction motor of a pump-jack is powered by three-phase utility power, the speed of the shaft varies only slightly over the pumping cycle but the utility power requirements can vary by four times the average pumping power. This variation makes it impractical to power a pump-jack oil well with a stand-alone turbogenerator controlled by a conventional power control system. This control system comprises a turbogenerator inverter, a load inverter, and a central processing unit which controls the frequency and voltage/current of each inverter. Throughout the pumping cycle, the processing unit increases or decreases the frequency of the load inverter in order to axially accelerate and decelerate the masses of the down hole pump rods and oil, and to rotationally accelerate and decelerate the motor rotors and counter balance weights. This allows kinetic energy to be alternately stored in and extracted from the moving masses of the oil well and allows the pumping power to be precisely controlled, resulting in a constant turbogenerator power requirement.

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[ What we claim is:] [52.]52. A method to reduce variations in the power level provided to a cyclic motion machine having cyclically varying power requirements, comprising:connecting an induction motor to the cyclic motion machine to drive the machine;connecting a load inverter to the motor to provi

[ What we claim is:] [52.]52. A method to reduce variations in the power level provided to a cyclic motion machine having cyclically varying power requirements, comprising:connecting an induction motor to the cyclic motion machine to drive the machine;connecting a load inverter to the motor to provide power to the motor; andconnecting a controller to the load inverter to control the power provided to the motor by varying the load inverter frequency, the controller varying the load inverter frequency over each machine cycle to reduce variations in the power level required by the motor.