Direct-Drive Screw Pump Motor Speed Control
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Solution Overview
Problem
The existing oil extracting rod ground screw pump driving systems face limitations in power transmission, mechanical maintenance, efficiency, speed regulation, noise, and space occupancy, particularly due to belt transmission and asynchronous motor inefficiencies.
Innovation Solution
A direct drive screw pump system utilizing a vertical three-phase permanent magnet brushless DC motor with a hollow shaft and advanced motor controller, enabling precise speed adjustment from zero to maximum, reducing reactive power loss, and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If belt transmission and gear box are used to drive the screw pump, then the motor can provide high starting torque, but the transmitted power is limited and the reliability deteriorates due to belt slippage and gear tooth damage
Solution Approach 1:
The patent removes the belt transmission and gear box from the system, directly coupling the motor shaft to the pump shaft through a hollow polished rod. This extraction of intermediate transmission components eliminates belt slippage and gear tooth damage while maintaining the motor's ability to provide high starting torque directly to the pump.
Solution Approach 2:
The motor and pump are merged into a direct-drive system where the motor shaft is directly connected to the pump shaft through the hollow polished rod. This merging eliminates the need for separate transmission components (belt, pulley, gear box) and creates a more reliable integrated system that maintains high torque capability.
2Speed
If belt transmission and gear box are used, then speed reduction can be achieved, but mechanical maintenance increases and operation cost rises due to lubricating oil leakage and component wear
Solution Approach 1:
The patent extracts the gear box and belt transmission system from the drive mechanism, eliminating the need for lubricating oil and associated maintenance issues. The direct-drive configuration removes all rotating seals and gear components that require periodic maintenance, significantly reducing operational complexity and cost.
3Reliability
If asynchronous motor with 3 times power is used for starting convenience, then the motor can start reliably, but the efficiency deteriorates due to operation under low load rate
Solution Approach 1:
The patent employs a variable frequency drive (VFD) to dynamically control the motor speed and torque output according to actual pump requirements. This dynamic control allows the motor to operate at optimal efficiency points during normal operation while providing high starting torque when needed, eliminating the need for oversized motors running at low load rates.
Solution Approach 2:
The patent changes the motor operating parameters by using a variable frequency drive to adjust the motor's speed and torque characteristics in real-time. This allows the motor to adapt its output to match the actual load requirements, maintaining high efficiency during operation while ensuring reliable starting capability when required.
4Speed
If variable pole adjustable speed motor or belt pulley changing is used for speed regulation, then the motor speed can be adjusted, but the device complexity increases and operation becomes inconvenient
Solution Approach 1:
The patent replaces mechanical speed regulation methods (variable pole motors, belt pulley changes) with electronic speed control through a variable frequency drive. This substitution eliminates the need for mechanical components and complex gear systems, providing smooth and convenient speed regulation through electronic controls while reducing overall device complexity.
5Speed
If mechanical speed reducing devices and high speed asynchronous motor are used, then the motor can operate at high speed, but the noise increases making it unsuitable for residential districts
Solution Approach 1:
The patent replaces high-speed mechanical motors with mechanical speed reducers (which generate noise) with a direct-drive system using a permanent magnet synchronous motor controlled by variable frequency drive. This electronic control method allows the motor to operate at optimal speeds without mechanical gear engagement, significantly reducing noise generation while maintaining the required motor speed performance.
6Speed
If belt pulley system is used for speed adjustment, then the motor speed can be changed, but the occupied area increases making it unsuitable for offshore platforms and cluster wells
Solution Approach 1:
The patent extracts the belt pulley system and associated speed adjustment mechanisms from the drive system, replacing them with a compact direct-drive configuration. This removal of bulky mechanical components significantly reduces the equipment's occupied area while maintaining speed adjustment capability through electronic variable frequency control, making the system suitable for space-constrained applications like offshore platforms.
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
The system achieves high efficiency, reduced noise, and convenient operation with precise speed control, while being compact and suitable for hazardous environments, with improved reliability and reduced operational costs.
Implementation Method 1
motor which is a vertical three phase permanent magnet brushless direct current motor
Data Source
AI summary
A surface motor direct-drive sucker-rod screw pump device is driven by a vertical three-phase permanent magnet brush-less DC motor, and comprises a motor controller (6), a rectifying circuit, an inversion circuit, a CPU and a driving circuit. The motor controller (6) is used to adjust the voltage and frequency of the motor by the rectifying circuit, the inversion circuit, the CPU and the driving circuit. Thus, the speed of the motor can vary from zero to the maximum. The device is easy to operate and has a higher efficiency.