Patent ID: 8698447
Filing Date: 2014-04-15
Classification: F04B,H02P

Abstract:
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.