Flexible Bearing Connection for Direct Drive Generator Air Gap Control
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Solution Overview
Problem
Direct drive wind turbines face challenges in maintaining a stable air gap between the rotor and stator due to magnetic forces, leading to bearing wear and noise, as prior solutions with rigid bearings fail to effectively manage bending moments and misalignment.
Innovation Solution
A direct drive generator design featuring a flexible connection between the bearing and stator, allowing the bearing to transfer bending moments to the stator instead of absorbing them, with a flexible structure that includes a ball-and-socket joint or spring elements to maintain a consistent air gap and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid bearings are mounted to the stator to maintain the air gap, then the air gap can be maintained, but the bearings become tilted and wear increases due to the rigid stator resisting magnetic forces
Solution Approach 1:
The patent changes the flexibility parameter of the bearing-stator connection from rigid to flexible. The flexible connection allows the bearing to accommodate small deflections in the stator caused by magnetic forces without tilting, thereby maintaining the air gap while reducing bearing wear. This parameter change resolves the contradiction by allowing the stator to deflect slightly under magnetic load while the flexible bearing connection absorbs the movement rather than creating tilt and wear.
2Reliability
If rigid bearings are used to maintain the air gap, then the air gap can be maintained, but noise is generated by the connection between the bearing and rotor
Solution Approach 1:
The patent changes the stiffness parameter of the bearing connection from rigid to flexible. This flexible connection acts as a noise dampener by allowing small movements and absorbing vibrations between the bearing and stator, thereby reducing noise generation while still maintaining the air gap. The flexibility parameter change enables the system to tolerate small deflections without transmitting noise through rigid connections.
3Strength
If the stator is made rigid to resist magnetic forces, then the stator can resist the forces, but portions of the stator deflect and bearings become tilted
Solution Approach 1:
The patent changes the flexibility parameter of the bearing connection to accommodate stator deflection. While the stator remains rigid to resist magnetic forces, the flexible bearing connection allows the bearing to follow the stator's slight deflections without becoming tilted. This resolves the contradiction by decoupling the stator's structural rigidity from the bearing's alignment requirements through the flexible connection intermediate layer.
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 bearing wear and noise while maintaining a consistent air gap, enhancing the efficiency and longevity of the wind turbine by distributing magnetic forces effectively across the stator.
Implementation Method 1
Due to the magnetic force between the rotor and the stator, the rotor and stator are drawn to each other
Implementation Method 2
Having a flexible connection between the bearing and the stator enables the bearing to transfer bending moments from magnetic attraction forces to the stator part
Data Source
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AI summary
The present invention relates to a direct drive generator (1) for a wind turbine, the generator comprising a rotor (6) configured to rotate about an axis of rotation, a stator (2) configured to remain stationary relative to the rotor, and at least one bearing (5) connected to the stator (2). The rotor (6) comprises at least one rotor part (7) extending circumferentially about the axis of rotation and a plurality of active materials arranged on a side of the at least one rotor part. The stator (2) comprises at least one stator part (3) extending circumferentially about the axis of rotation and positioned adjacent to the at least one rotor part (7), and at least one winding arrangement (4) supported by the at least one stator part (3) and facing the plurality of active materials. The bearing (5) is flexibly connected to the at least one stator part (7), wherein the bearing (5) abuts the rotor part (3) to help maintain a gap (10) between the at least one winding arrangement (4) and the active materials.