Energy saving system and method for devices with rotating or reciprocating masses
First Claim
1. A method of saving energy for an electric motor coupled to a rotating mass, the method comprising:
- detecting a line voltage and a current supplied to the electric motor;
observing a phase angle between the line voltage and the current;
comparing the observed phase angle with a target phase angle;
switching-off the line voltage to the electric motor when the observed phase angle is greater than the target phase angle;
monitoring a motor voltage generated at the electric motor while the line voltage is switched off;
determining a period of the voltage generated at the electric motor;
determining a period of the line voltage;
determining a line zero crossing point corresponding to the line voltage;
determining a motor zero crossing point corresponding to the voltage generated at the electric motor; and
switching-on the line voltage to the electric motor when;
the period of the voltage generated at the electric motor is substantially equal to the period of the line voltage; and
the line zero crossing point substantially matches the motor zero crossing point.
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Accused Products
Abstract
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.
351 Citations
20 Claims
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1. A method of saving energy for an electric motor coupled to a rotating mass, the method comprising:
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detecting a line voltage and a current supplied to the electric motor; observing a phase angle between the line voltage and the current; comparing the observed phase angle with a target phase angle; switching-off the line voltage to the electric motor when the observed phase angle is greater than the target phase angle; monitoring a motor voltage generated at the electric motor while the line voltage is switched off; determining a period of the voltage generated at the electric motor; determining a period of the line voltage; determining a line zero crossing point corresponding to the line voltage; determining a motor zero crossing point corresponding to the voltage generated at the electric motor; and switching-on the line voltage to the electric motor when; the period of the voltage generated at the electric motor is substantially equal to the period of the line voltage; and the line zero crossing point substantially matches the motor zero crossing point. - View Dependent Claims (2, 3, 4, 5)
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6. A system for saving energy for an electric motor coupled to a rotating or reciprocating mass, the system comprising:
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a processor; and a non-transitory computer-readable storage medium that stores instructions for controlling the processor to perform steps comprising; detecting a line voltage and a current supplied to the electric motor; observing a phase angle between the line voltage and the current; comparing the observed phase angle with a target phase angle; switching-off the line voltage to the electric motor when the observed phase angle is greater than the target phase angle; monitoring a motor voltage generated at the electric motor while the line voltage is switched off; determining a period of the voltage generated at the electric motor; determining a period of the line voltage; and switching-on the line voltage to the electric motor when the period of the voltage generated at the electric motor is substantially equal to the period of the line voltage. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A non-transitory computer-readable storage medium storing instructions which, when executed by a device having an electric motor and a processor, cause the processor to perform steps comprising:
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detecting a line voltage and a current supplied to the electric motor; observing a phase angle between the line voltage and the current; comparing the observed phase angle with a target phase angle; switching-off the line voltage to the electric motor when the observed phase angle is greater than the target phase angle; monitoring a motor voltage generated at the electric motor when the line voltage is switched off; determining a period of the voltage generated at the electric motor; determining a period of the line voltage; and switching-on the line voltage to the electric motor when the period of the voltage generated at the electric motor is substantially equal to the period of the line voltage. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification