Wind Turbine Drive Train Layout for Air Gap Stability
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Solution Overview
Problem
The design of direct drive wind turbines faces challenges in optimizing air gap stability, weight reduction, manufacturability, and maintenance due to complex interdependencies of structural requirements and constraints, particularly in large offshore turbines, where efficient cooling and load transmission are critical.
Innovation Solution
A drive train assembly with a rotor hub and generator module featuring a generator stator, stationary frame, and a bearing assembly with a front and rear bearing, where the shaft is removably connected to the generator rotor and the generator module is positioned downwind from the rotor hub, improving air gap stability and facilitating manufacturing and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the generator is arranged upwind from the tower in direct drive wind turbines, then the combined weight of rotor and generator creates significant bending loads on the tower, but this configuration allows for direct drive operation without gearbox
Solution Approach 1:
The patent inverts the conventional upwind arrangement by positioning the generator downwind from the tower. This reversal changes the load transmission path and reduces bending moments on the tower while maintaining direct drive operation. The downwind positioning allows the rotor hub to be located upwind, optimizing aerodynamic performance while the generator sits downwind, reducing structural loads.
Solution Approach 2:
The patent repositions the generator along the wind direction axis (another dimension) rather than maintaining it directly above the tower. By placing the generator downwind, the load path is extended along the longitudinal axis, converting some bending loads into axial loads that the tower can better withstand, thereby reducing overall structural stress.
2Loss of energy
If the air gap between rotor and stator is made as small as possible for electromagnetic efficiency, then efficiency improves, but the risk of contact and damage increases
Solution Approach 1:
The patent introduces an active control system with sensors and actuators as intermediaries between the rotor and stator. These control mechanisms continuously monitor air gap variations and actively adjust positioning to maintain optimal gap distance, preventing both excessive gaps that reduce efficiency and insufficient gaps that cause contact damage.
Solution Approach 2:
The patent transforms the static air gap into a dynamically controlled parameter. The air gap is no longer fixed but is actively adjusted in real-time based on operating conditions, allowing the system to optimize electromagnetic efficiency while preventing mechanical contact through continuous adaptation.
3Power
If the generator rotor diameter is increased to accommodate low rotational speed in direct drive, then power generation capability improves, but the overall size and weight of the generator increases
Solution Approach 1:
The patent changes key electromagnetic parameters including using high-energy permanent magnets and optimized winding configurations to increase power density. By altering these parameters, the generator achieves high power output with a smaller, lighter rotor diameter, overcoming the conventional trade-off between size and power capability in direct drive systems.
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 configuration enhances air gap stability, reduces the overall weight of the drive train, and simplifies manufacturing and maintenance, leading to a more compact and efficient design that maintains air gap integrity under various operating conditions.
Implementation Method 1
a bearing assembly for rotatably mounting the shaft on the stationary frame
Implementation Method 2
The generator generally comprises a rotor or rotary structure and a stator or stationary structure. Both the rotor and the stator structure carry electromagnetic elements
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
The present disclosure relates to drive train assemblies for a wind turbine. These assemblies may comprise a rotor hub and a generator module. The generator module comprises a generator stator, and a stationary frame for supporting the generator stator. The generator further comprises a generator rotor, a shaft for supporting the generator rotor, and a bearing assembly for rotatably mounting the shaft on the stationary frame. The shaft is removably connected to the generator rotor, and the bearing assembly comprises a front bearing and a rear bearing. An upwind end of the generator module is attached to a downwind end of the rotor hub. The present disclosure further relates to wind turbines including such wind turbine assemblies and to methods for assembling drive train assemblies.