Permanent Magnet Rotor Section Clocking for Shaft Twist Compensation
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Solution Overview
Problem
Permanent-magnet motors in ESP systems face inefficiencies due to shaft twisting, which misaligns rotor sections, leading to reduced torque and power output, and existing solutions are complex and costly to manufacture and assemble.
Innovation Solution
The use of identically configured rotor sections with static keyways that allow for predetermined angular orientations, enabling each rotor section to be positioned in multiple circumferential positions relative to the motor shaft, thereby mitigating misalignment during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rotor sections are aligned when the motor is at rest, then assembly is simple, but shaft twisting causes misalignment during operation reducing torque and efficiency
Solution Approach 1:
The rotor sections are pre-positioned at specific angular offsets during assembly so that when the shaft twists under operational torque, the magnets realign with the stator fields. This preliminary angular positioning compensates for the expected shaft deformation, maintaining synchronization between rotor magnets and stator magnetic fields during operation.
Solution Approach 2:
The invention changes the angular parameter (circumferential position) of rotor sections relative to each other. By offsetting rotor sections by specific angles (e.g., 30 degrees for four-section rotors), the system compensates for shaft twist, transforming the static alignment parameter into a dynamically compensated configuration that maintains operational efficiency.
2Reliability
If mechanisms are used to clock individual rotor sections, then misalignment is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of using complex adjustable clocking mechanisms, the invention pre-positions rotor sections at fixed angular offsets during manufacturing. This eliminates the need for complex adjustment mechanisms while achieving the same alignment compensation effect, simplifying both the device structure and assembly process.
Solution Approach 2:
The invention uses identical rotor section designs with standardized mounting features, allowing mass production of interchangeable components. Each rotor section is a copy of the others, simplifying manufacturing and assembly while maintaining the angular offset configuration needed for compensation.
3Loss of energy
If rotor sections are offset to compensate for shaft twist, then torque efficiency improves, but assembly precision requirements increase
Solution Approach 1:
The invention establishes specific angular parameter values for rotor section offsets (e.g., 30 degrees for four-section rotors, 45 degrees for two-section rotors). These standardized parameter values simplify the manufacturing process by providing clear target positions, reducing the actual precision burden while maintaining compensation effectiveness.
Solution Approach 2:
The invention applies different angular offset parameters to different rotor sections based on their position in the stack. Each rotor section has a specific local angular configuration optimized for its position, allowing precision to be managed locally at each section rather than requiring high precision across the entire assembly process.
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 simplifies the manufacturing and assembly process while effectively reducing torque losses by allowing rotor sections to maintain alignment, resulting in improved efficiency and practical implementation.
Implementation Method 1
When the coils are energized, the windings generate magnetic fields that interact with the magnets of the rotor sections
Implementation Method 2
the windings generate magnetic fields that interact with the magnets of the rotor sections. The power provided to the stator windings is controlled to cause the magnetic fields of the stator to drive the rotor sections to rotate
Implementation Method 3
each rotor section in the motor develops torque which is applied to the shaft
Implementation Method 4
Because the shaft is long and not completely rigid, this causes the shaft to twist
Data Source
AI summary
Systems and methods for constructing a motor having a stator, and a plurality of rotor sections secured to a shaft which is positioned to rotate within a bore of the stator. Each rotor section has permanent magnets forming corresponding magnetic poles. Each rotor section has first and second inwardly facing keyways which are identically positioned in each rotor section and are configured to enable each rotor section to be alternately positioned in at least three distinct circumferential orientations with respect to a key of the shaft. A first subset of the rotor sections is secured to the shaft in a first one of the circumferential orientations, a second subset of the rotor sections is secured to the shaft in a second one of the circumferential orientations, and a third subset of the rotor sections is secured to the shaft in a third one of the circumferential orientations.