Patent ID: 9140253
Filing Date: 2015-09-22
Classification: F04B

Abstract:
1. A method of operating an oil well where a pump attached to an end of a rod is raised and lowered by a drive mechanism through a stroke cycle, said method comprising the steps of operating the drive mechanism by means of an AC electric motor having a motor controller including a regenerative variable frequency drive, said regenerative variable frequency drive applying AC electrical energy from a power grid to the AC electric motor, decreasing motor speed by transferring the electrical energy from the motor to the power grid and increasing motor speed by transferring electrical energy from the power grid to the motor, said motor controller regulating the motor speed as determined by a program designed for said oil well that is encoded at setup with a speed map that contains a speed reference for positions of the drive mechanism from 0° to 360°, over the course of said stroke cycle, calculating said positions of the drive mechanism according to the following mathematical formula: where at each said calculated position setting the motor speed to correspond to the speed reference called for by the speed map at said calculated position.