Thrust Magnetic Bearing Stator Flux Saturation Optimization
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Solution Overview
Problem
Existing thrust bearing designs for active magnetic bearing systems suffer from inefficient use of stator magnetic material due to non-uniform flux saturation, leading to sub-optimal force capacity and increased material stress at high rotational speeds.
Innovation Solution
A geometrical parameterization of the thrust actuator stator that adjusts the cross-sectional area along the flux path to achieve uniform flux saturation, maximizing force capacity while minimizing size and weight, using a reference area and multiplicative factors to optimize the dimensions of the inner, outer poles, and back face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional one-dimensional equations are used to determine stator pole area, then the design process is simple, but the stator magnetic material is not uniformly saturated leading to wasted volume and reduced force capacity
Solution Approach 1:
The patent transforms the traditional one-dimensional pole area calculation into a multi-dimensional geometric parameterization system. By introducing radial thickness variations and axial length variations as adjustable parameters, the design enables uniform flux saturation throughout the stator volume while maintaining computational tractability through systematic parameter relationships.
Solution Approach 2:
The patent applies different geometric characteristics to different regions of the stator. The radial thickness and axial length are varied locally to match the flux distribution pattern, ensuring that each region of the stator is optimally saturated. This creates non-uniform geometric parameters that correspond to the non-uniform flux density distribution in the magnetic circuit.
2Force
If the coil area is increased to provide more capacity, then the force capacity improves, but the stator volume is wasted due to premature saturation at the inner pole-back face transition
Solution Approach 1:
The patent uses parameter relationships where the radial thickness and axial length at the inner pole and back face are specifically adjusted to delay saturation in these regions. This allows the coil area to be fully utilized without premature saturation, maximizing the ratio of force capacity to stator volume.
3Strength
If the stator and thrust disk dimensions are increased to handle high rotational speeds, then the structural strength improves, but the device becomes larger and heavier
Solution Approach 1:
The patent optimizes the geometric parameters to achieve uniform flux saturation, which maximizes the force density (force per unit volume) of the magnetic material. This allows the actuator to generate the required force with smaller dimensions, reducing weight while maintaining the structural strength needed for high-speed operation.
Solution Approach 2:
The patent employs magnetic materials with specific saturation flux density properties and combines them with non-magnetic structural materials in a composite stator design. This allows the magnetic material to be optimized for force generation while the structural material provides the mechanical strength required for high-speed rotation, achieving high strength-to-weight ratio.
4Volume of stationary object
If the stator cross-sectional area is reduced to minimize size, then the device becomes more compact, but the force capacity decreases
Solution Approach 1:
The patent uses a systematic parameterization approach where the radial thickness and axial length are optimized to achieve uniform flux saturation. This maximizes the force capacity per unit volume of the stator, allowing compact dimensions while maintaining high force output through efficient magnetic material utilization.
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 optimized design achieves a 30.8% higher force capacity compared to prior art, allowing for smaller, lighter actuators that can operate at higher speeds with reduced stress and increased bending stiffness, enabling more efficient use of magnetic material and improved rotor performance.
Implementation Method 1
When a current passes through the coil, it creates a magnetic flux that travels through the horseshoe shaped cross section of the stator, across the air gap, radially through the thrust disk
Implementation Method 2
the force developed when the magnetic material in the stator is saturated with flux and it coincides with the maximum current density in the coil
Data Source
AI summary
A specific force capacity thrust bearing and a method for producing such a design for a particular application are disclosed. The magnetic flux density in the stator material is maximized by varying cross-sectional area normal to the flux path. After a set of initial parameters are chosen, the design can be improved upon by changing the design variables and then verifying the force capacity using a finite element program. By linking the finite element program to a model of the geometry and using some basic algorithms, it is possible to automatically iterate until an optimal design is reached. The resulting design has a much higher force capacity than designs typical of the prior art.