ESP Permanent Magnet Rotor Assembly for High-Speed Balance
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Solution Overview
Problem
Existing electrical submersible pump (ESP) motors, including permanent magnet motors, face challenges in achieving high-speed operation without compromising balance and reducing vibration, which leads to reduced motor and pump lifespan.
Innovation Solution
The ESP motor design incorporates a stator with laminations and windings, a shaft with rotor sections featuring tubular cores, shrunk-fit end rings, and strategically arranged magnets, along with non-magnetic titanium sleeves and bearings with integrally formed ribs for rotational stability, allowing for high-speed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ESP motors operate at higher speeds (10,000 RPM or more), then productivity and power output are improved, but balance and vibration control deteriorate, leading to reduced motor and pump lifespan
Solution Approach 1:
The rotor is divided into multiple rotor sections (first rotor section, second rotor section, etc.) separated by radial bearings. Each rotor section contains magnets arranged in specific patterns (e.g., alternating polarity patterns) to achieve dynamic balance at high speeds. This segmentation allows independent balancing of each section while maintaining overall rotor functionality.
Solution Approach 2:
Magnets in adjacent rotor sections are arranged with alternating polarities (e.g., north-south-north pattern in one section, south-north-south in the next) to create counterbalancing magnetic forces. This anti-weight arrangement of magnetic poles compensates for centrifugal forces and reduces vibration at high operating speeds.
2Ease of manufacture
If the rotor is made up of multiple rotor sections separated by radial bearings, then ease of assembly and manufacturing are improved, but device complexity increases
Solution Approach 1:
The rotor is constructed from multiple discrete rotor sections that can be manufactured separately and assembled radially around the shaft. Each section contains a subset of the total magnets, allowing for modular manufacturing and simplified assembly processes compared to creating a single large rotor.
Solution Approach 2:
The radial bearings serving between rotor sections perform multiple functions: they support the rotor sections, allow relative movement for assembly, and contribute to the magnetic circuit. This multi-functionality reduces the need for additional separate components.
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 design enhances balance and reduces vibration, enabling ESP motors to operate at higher speeds, such as 10,000 RPM, thereby extending the motor and pump's lifespan and improving torque capacity and power factor.
Implementation Method 1
a pair of end rings, each of the end rings having an initial inner diameter greater than an outer diameter of the end ring sections and being shrunk fit onto one of the end ring sections
Implementation Method 2
Supplying power to windings in the stator causes the magnets to rotate the drive shaft
Implementation Method 3
Another type uses permanent magnets in the rotor, each providing one pole of the motor
Implementation Method 4
In an alternative, the motor further includes first and second outer sleeves that enclose the array of magnets and have lengths less than a length of the array of magnets, and where the outer sleeves are made of titanium
Implementation Method 5
a bearing located between adjacent ends of two of the rotor sections, the bearing having a rib integrally formed thereon and that projects radially outward into the groove, so that the bearing is rotationally coupled with the stator
Data Source
AI summary
A motor for an electrical submersible pump includes a stator and rotor, where the rotor is made up of adjacent columns of magnets affixed onto an annular core. End rings on opposite ends of the core provide axial backstops for magnet columns. Thin coaxial sleeves are shrunk fit over the magnets and end rings and that radially compress the magnets. Apertures in a column are formed radially through the core and receive fasteners for securing a guide bar to the core. The guide bar simulates an installed column of magnets to guide placement of adjacent columns of magnets as the guide bar width is substantially the same as a column of magnets, and aperture locations are strategically positioned so that when the guide bar is secured onto the core. After the guide bar is removed the one of the columns of magnets is then adhered to the core.