Motor Controller Voltage Reduction for Pump Jack Energy Recovery
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Solution Overview
Problem
Pump jack electric motors inefficiently consume energy during energy generation modes, leading to excessive power usage and braking actions that hinder kinetic energy utilization for pumping actions.
Innovation Solution
A closed-loop motor controller system that reduces supply voltage when the motor is generating energy, using pulse width modulation to minimize real power consumption and maintain a target phase angle between voltage and current, allowing for adaptive energy management based on motor load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the motor operates in energy generation mode, then kinetic energy is recovered, but braking actions occur that hinder pumping efficiency
Solution Approach 1:
The patent converts the harmful braking effect during energy generation mode into a beneficial control strategy. By detecting when the motor enters generation mode and actively reducing voltage during these periods, the system prevents the braking action from hindering pumping efficiency while still allowing kinetic energy recovery to occur.
Solution Approach 2:
The patent implements dynamic voltage control that adjusts the supply voltage to the motor in real-time based on operating conditions. During energy generation mode, the controller reduces voltage dynamically to eliminate braking effects, while maintaining normal voltage during other operational phases to ensure pumping efficiency.
2Use of energy by moving object
If supply voltage is reduced during energy generation mode, then energy consumption is minimized, but motor control complexity increases
Solution Approach 1:
The patent employs a closed-loop feedback control system that continuously monitors motor operating conditions and adjusts supply voltage accordingly. The controller detects when the motor enters energy generation mode and automatically reduces voltage during these periods, providing adaptive energy management without requiring complex manual intervention.
Solution Approach 2:
The control system automatically detects and responds to energy generation mode conditions without external intervention. The motor controller monitors its own operating state and self-adjusts the supply voltage to minimize energy consumption during generation periods, making the system self-regulating.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces energy consumption by minimizing braking actions and utilizing natural kinetic energy for pumping, resulting in energy savings and improved motor efficiency.
Implementation Method 1
Through pulse width modulation techniques, the real power component may be reduced virtually to zero, leaving a reactive component greater than zero
Implementation Method 2
It is well known that electric motors can enter an energy generation mode of operation. For an electric motor used with a pump jack, an energy generation mode can occur at any time during the rotation of the counterweight, depending on the condition of the balance between the counterweight and the tubular or rod string
Implementation Method 3
When the counterweight reaches the top of its rotation, it swings around and assists the motor to rotate the walking beam in the opposite direction using the counterweight's momentum and mass (kinetic energy)
Implementation Method 4
During periods of generation, a motor will attempt to attain a voltage that exceeds the utility's line voltage, thereby causing current to flow in the opposite direction. The load provided by the utility grid serves as a brake, limiting the acceleration of the motor that would have otherwise occurred
Data Source
AI summary
A system and method are provided for saving energy for an electric motor having periodic load variations by reducing the supply voltage to the motor during an open loop mode. The motor and system will speed up, allowing the natural kinetic energy of the cyclic motion to perform part of the pumping action. A closed loop controller computes information from the observed phase angle between the voltage and current supplied to the motor. By reducing the supply voltage to the motor, the observed phase angle may be reduced to a target phase angle value. By allowing some current flow, primarily of a reactive nature, an observable feedback parameter may be used in the closed loop control system as an indication of the load condition, to which the closed loop motor controller may react, supplying power when needed, such as in the energy consumption mode.