ENERGY SAVING SYSTEM AND METHOD FOR DEVICES WITH ROTATING OR RECIPROCATING MASSES

摘要

A system and method are provided for reducing the energy consumed by a pump jack electric motor by reducing the supply voltage to the motor when the motor would be generating energy in open loop mode. By substantially eliminating the energy generation mode, the braking action of the utility grid in limiting the acceleration of the motor and system that would otherwise occur is substantially removed. The motor and system will speed up, allowing the natural kinetic energy of the cyclic motion to perform part of the pumping action. In particular, when the energy consumption for the electric motor connected with the device having a rotating or reciprocating mass goes to zero, the line voltage to the motor is switched off, causing the frequency of the voltage across the motor terminals to increase. When the period of the voltage across the motor terminals returns to substantially the same as the period of the line voltage, the line voltage is switched on or reapplied to the motor.

主权项

1. A method of saving energy for a pump jack with a counterweight disposed with a well, comprising the steps of:
supplying a line voltage and current to an electric motor connected with the pump jack during a first time segment; rotating the pump jack counterweight with the electric motor during the first time segment; observing the phase angle between the line voltage and current supplied to the electric motor during the first time segment; comparing the observed phase angle with a target phase angle during the first time segment; switching off the line voltage and current to the electric motor when the observed phase angle is greater than the target phase angle; monitoring a generated motor voltage of the electric motor during a second time segment initiated by the switching off of the line voltage and current to the electric motor; determining a period of the generated motor voltage of the electric motor during the second time segment; determining a period of the line voltage during the second time segment; comparing the period of the generated motor voltage during the second time segment with the period of the line voltage during the second time segment; and switching on the line voltage and current to the electric motor when the period of the generated motor voltage becomes substantially equal to the period of the line voltage.