Line Start Permanent Magnet Motor for Downhole Pumping
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Solution Overview
Problem
Permanent magnet motors require elaborate controls and are susceptible to damage in wellbore environments due to the need for rotor position transducers and control electronics to start directly on line, increasing complexity and cost, and are prone to time delays and expenses from long cables.
Innovation Solution
A combination of an induction motor and a permanent magnet motor, where the induction motor acts as a starter to enable direct on-line starting without position transducers or control electronics, allowing the permanent magnet motor to operate efficiently once synchronized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a permanent magnet motor is used for direct on-line starting, then the motor efficiency is improved, but the device complexity increases due to the need for rotor position transducers and control electronics
Solution Approach 1:
The motor system is segmented into two independent motor units: an induction motor and a permanent magnet motor. Each motor has its own stator and rotor components, allowing them to function independently yet contribute to the same mechanical output. This segmentation enables the induction motor to handle starting functions while the permanent magnet motor handles efficient operation, eliminating the need for complex control electronics.
Solution Approach 2:
The induction motor serves multiple functions: it provides starting torque for the combined system and can independently drive the load during certain operating conditions. The permanent magnet motor similarly provides both starting capability and efficient continuous operation. This multi-functionality eliminates the need for separate starting devices and complex control systems.
2Ease of operation
If rotor position transducers and control electronics are added to enable direct on-line starting, then the starting capability is improved, but the susceptibility to damage in wellbore environment increases
Solution Approach 1:
The vulnerable control electronics and rotor position transducers are completely extracted from the motor system. The invention achieves direct on-line starting capability through purely electromagnetic means using the induction motor, eliminating any electronic components that would be susceptible to damage in the harsh wellbore environment.
Solution Approach 2:
The induction motor acts as a disposable starting mechanism that is only needed during startup. After the permanent magnet motor is running, the induction motor's role is complete. This approach replaces expensive, fragile electronic control systems with a robust, simple electromagnetic starting mechanism.
3Adaptability or versatility
If control electronics and long cables are used for motor control, then the control capability is improved, but the cost and time delays increase
Solution Approach 1:
The motor system is self-starting and self-regulating. The induction motor automatically provides starting torque without external control signals, and the permanent magnet motor automatically maintains synchronous operation. The system serves itself without requiring external control electronics or communication cables, eliminating time delays associated with long-distance signal transmission.
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 solution eliminates the need for complex controls, reduces costs and susceptibility to damage, and achieves significant energy savings by allowing the permanent magnet motor to run at synchronous speed with minimal power consumption, regaining synchronization if lost.
Implementation Method 1
the induction motor is able to get the rotor turning in the correct direction
Implementation Method 2
once the permanent magnet rotor is in synchronisation no power is absorbed by the induction motor
Data Source
AI summary
A downhole electric submersible pump, with at least one pump unit having a pump inlet, and an electric motor system to power the pump, the electric motor system comprising an induction motor and permanent magnet motor. The induction motor and permanent magnet motor share a common power supply, connected in series.