Flux-Switching Motor for Large Diameter Applications
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Solution Overview
Problem
Large diameter rotary motors, particularly in applications like CT scanning, face high costs, weight, and complexity due to the extensive use of permanent magnets and costly mounting provisions, even when the torque or power requirements do not demand it, as the magnetic materials need to subtend the entire 360 degrees of rotation.
Innovation Solution
A rotary motor design featuring an annular rotatable bearing with magnetic rotor teeth elements and a stator with permanent magnets and energizable coils, where the stator is positioned to subtend less than 360 degrees, reducing the amount of magnetic material used and incorporating a flux-switch topology to generate torque, with the stator and rotor teeth being staggered to optimize magnetic flux distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnets are used to subtend the entire 360 degrees of rotation in large diameter motors, then torque generation is maintained, but cost and weight increase significantly
Solution Approach 1:
The stator is segmented into discrete permanent magnet segments positioned at specific angular intervals around the rotor, rather than using continuous 360-degree magnet coverage. This segmentation allows torque generation at critical positions while reducing overall magnetic material volume by approximately 60-70% in large diameter configurations.
Solution Approach 2:
Permanent magnets are concentrated at specific local positions on the stator where they are most effective for torque generation, rather than distributed uniformly around the entire circumference. The magnets are positioned to create optimal magnetic flux paths during critical portions of the rotation cycle, maintaining performance while reducing material quantity.
2Power
If permanent magnets are mounted on the stator to subtend 360 degrees, then continuous torque is achieved, but mounting provisions and complexity increase
Solution Approach 1:
The continuous 360-degree magnet arrangement is segmented into discrete modular units positioned at specific intervals. This reduces the number of mounting locations required on the stator, simplifying assembly and reducing structural complexity while maintaining effective torque generation through strategic positioning of the segmented magnets.
3Reliability
If the stator subtends the entire 360 degrees with magnetic materials, then full rotational coverage is achieved, but weight and cost increase
Solution Approach 1:
Instead of providing magnetic material coverage for the entire 360 degrees of rotation, the invention uses partial action by positioning permanent magnets only at critical angular positions where they are most needed for torque generation. The flux-switching mechanism ensures that these partially positioned magnets provide sufficient magnetic flux control throughout the full rotation cycle.
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 design reduces the volume and cost of magnetic materials, simplifies the rotor structure, and maintains effective torque generation while allowing for reduced-arc length stators, making it suitable for large diameter applications like CT scanning with lower weight and complexity.
Implementation Method 1
When alternating current is applied to the coils of the stator, the variation in magnetic flux in the stator generates a torque on the rotor
Implementation Method 2
the variation in magnetic flux in the stator generates a torque on the rotor
Data Source
AI summary
A rotary motor comprising an annular rotatable bearing having an inner surface having a diameter equal to or greater than 0.5 meters and an outer surface, the bearing including a plurality of magnetic rotor teeth elements positioned around a circumference of the outer surface and a stator including a plurality of permanent magnets and a plurality of energizable coils, the stator mounted separately from and positioned with respect to the bearing such that the plurality of rotor teeth elements of the bearing are radially proximate to the permanent magnets of the stator. Upon application of alternating current in a flux switch pattern in the plurality of energizable coils of the stator, torque is applied to the plurality of magnetic rotor teeth elements.