Axial Gap Rotating Electrical Machine with Rolling Supports
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Solution Overview
Problem
Direct drive generators with radial air gaps face challenges in maintaining a uniform air gap due to their large diameter, which complicates the management of mechanical forces and stability, especially in applications like wind turbines where the rotor diameter can be 2 meters or more and the air gap is typically 5 to 10 millimeters.
Innovation Solution
The implementation of a rotating electrical machine design featuring a rotatable rotor ring and stator ring with an axial air gap, where rolling gap supports are used along the periphery to maintain the air gap, allowing for the rotor ring to be mounted on a hub with wind-driven blades, and incorporating multiple air gaps with magnetic elements and stator teeth to balance mechanical forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a radial air gap is used in direct drive generators with large rotor diameters (2 meters or more), then the generator can produce adequate electricity at slower rotation speeds, but maintaining a uniform air gap becomes difficult due to the large diameter-to-gap ratio (5 to 10 millimeters gap over 2+ meters diameter)
Solution Approach 1:
The patent inverts the traditional radial air gap configuration to an axial air gap configuration. Instead of having the air gap extend radially from the rotor center to the stator, the air gap now extends axially between the rotor face and stator face. This inversion allows the use of rolling support elements that can maintain precise axial spacing while accommodating the large rotor diameter, thereby resolving the air gap uniformity problem in direct drive generators.
Solution Approach 2:
The patent introduces rolling support elements as intermediary components between the rotor and stator. These rolling supports act as mediators that maintain the precise axial air gap spacing while allowing for thermal expansion, manufacturing tolerances, and operational variations. The rolling supports replace the need for rigid mechanical spacing structures that would be difficult to implement at the scale of 2-meter diameter rotors with 5-10 millimeter gaps.
2Speed
If the rotor diameter is increased to 2 meters or more in direct drive generators, then the generator can operate at slower speeds suitable for wind turbine applications, but the difficulty of maintaining mechanical stability and uniform air gap increases
Solution Approach 1:
The patent inverts the traditional radial air gap configuration to an axial air gap configuration. Instead of having the air gap extend radially from the rotor center to the stator, the air gap now extends axially between the rotor face and stator face. This inversion allows the use of rolling support elements that can maintain precise axial spacing while accommodating the large rotor diameter, thereby resolving the air gap uniformity problem in direct drive generators.
Solution Approach 2:
The patent replaces rigid mechanical spacing structures with rolling support elements that use rolling motion to maintain precise axial spacing. This substitution allows for easier accommodation of thermal expansion, manufacturing tolerances, and operational variations while maintaining mechanical stability. The rolling supports can accommodate small variations in rotor-stator relative positions without compromising the uniformity of the air gap, thereby enhancing mechanical stability in large-diameter direct drive generators.
3Manufacturing precision
If a axial air gap design with rolling gap supports is implemented, then the air gap uniformity and mechanical stability are improved, but the device complexity increases due to the addition of rolling support mechanisms
Solution Approach 1:
The rolling support elements serve multiple functions simultaneously: they maintain precise axial air gap spacing, accommodate thermal expansion, compensate for manufacturing tolerances, and support the rotor-stator assembly. This multi-functionality reduces the need for separate components for each function, thereby mitigating the increase in device complexity while achieving improved air gap uniformity and mechanical stability.
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 effectively maintains the axial air gap, enhances stability, and balances mechanical forces, making the generators more robust and suitable for applications with varying angular positions and accelerations, such as floating underwater wind turbines.
Implementation Method 1
One or more sets of rolling gap supports bear between the rotor ring and the stator ring along the periphery of the rotor ring and the stator ring in the direction of the axial air gap so as to maintain the axial air gap
Implementation Method 2
a rotor ring with an array of magnetic elements, such as permanent magnets, is driven by a mechanical force to rotate in close proximity to a stationary stator, which carries metallic windings
Data Source
AI summary
Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.