Wind Turbine Yaw Drive Torque Control
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Solution Overview
Problem
Conventional wind turbine generator systems experience undesirable vibrations, uneven wear on electric motors, and potential brake failure due to rapid torque changes and varying backlash in yaw rotation systems, leading to reduced component lifetime and operational inefficiencies.
Innovation Solution
A control system that detects external load conditions to engage mechanical brakes and adjust motor power to generate counter-torque, maintaining output torque and rotational speed within predetermined ranges, and ensures all pinion gears are fully engaged before reaching full torque, thereby reducing vibrations and wear on motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical brakes are used to counteract turning moments from shear forces, then the blade assembly can be retained at the desired yaw angle, but the brakes may fail or slip under large shear forces leading to brake failure
Solution Approach 1:
The patent replaces the mechanical brake system with an electric motor-based yaw drive system that uses controlled electromagnetic torque to counteract turning moments. The electric motor generates the necessary counter-torque through electrical control rather than mechanical friction, eliminating the risk of brake slip and failure associated with mechanical brakes under large shear forces.
Solution Approach 2:
The patent changes the operating parameters of the yaw system by using variable speed control of the electric motor to generate appropriate counter-torque. The motor speed and torque are dynamically adjusted based on wind conditions and yaw position, allowing the system to maintain reliable operation across varying load conditions without the limitations of mechanical brake friction coefficients.
2Reliability
If electric motors are used to generate counter-torque, then brake wear is reduced, but the torque required is subject to rapid shear force changes causing undesirable vibrations
Solution Approach 1:
The patent implements a feedback control system that continuously monitors yaw position, wind conditions, and motor performance. The control system adjusts motor torque in real-time based on feedback from sensors, smoothing out rapid torque changes and reducing vibrations while maintaining the benefits of electric motor operation without mechanical brake wear.
Solution Approach 2:
The patent employs dynamic torque control where the electric motor's torque output is continuously adjusted based on operating conditions. The system dynamically adapts the torque profile to match actual wind loads and yaw requirements, preventing excessive or rapid torque changes that would cause vibrations while maintaining effective counter-torque generation.
3Ease of operation
If pinion gears are engaged with the main gear wheel, then yaw rotation can be achieved, but backlash causes lost motion and requires higher torque from some motors during reversal
Solution Approach 1:
The patent applies preliminary action by pre-loading the pinion gears onto the main gear wheel before yaw rotation begins. The control system ensures all pinion gears are properly engaged and bearing load before initiating motor operation, eliminating backlash and ensuring uniform torque distribution across all motors from the start of rotation.
Solution Approach 2:
The patent merges the operation of multiple electric motors working together on the same main gear wheel with pre-loaded pinion gears. By combining the torque output of multiple motors that are all properly engaged, the system achieves the necessary total torque while distributing the load evenly, avoiding the need for individual motors to compensate for backlash.
4Ease of manufacture
If manufacturing tolerances are maintained, then the gear system can be assembled, but the degree of backlash varies for each pinion gear leading to uneven motor wear
Solution Approach 1:
The patent changes the operational parameters by applying pre-load to all pinion gears, which compensates for variations in manufacturing tolerances and backlash. The pre-load ensures that all gears start in a consistent engaged state, making the system insensitive to minor variations in gear tooth dimensions and ensuring uniform torque distribution and wear across all motors.
Solution Approach 2:
The patent applies local quality by ensuring each pinion gear receives appropriate pre-load and engagement force individually before operation. The control system monitors and adjusts the engagement state of each motor-gear interface, ensuring that local conditions at each pinion gear are optimized for uniform wear, rather than relying on global manufacturing tolerances alone.
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 control system mitigates vibrations, reduces motor wear, and optimizes efficiency by maintaining stable torque and speed ranges, extending component lifespan and improving operational stability.
Implementation Method 1
In response to a first sensed operating condition, the mechanical brake is engaged so as to brake the relative rotation of the nacelle and the tower
Implementation Method 2
In response to a second sensed operating condition, the power supplied to the motor is controlled so that the motor generates a counter-torque which acts on the blade assembly in the sense opposite to that of the turning moments
Data Source
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AI summary
Systems for controlling yaw rotation of a horizontal-axis wind turbine generator are provided. In one system, yaw rotation is generated by motors 10, the output torque of which is maintained substantially constant when the motor speed is within a predetermined range, so as to reduce the variation in the output torque. In another system, yaw rotation is generated by pinion gears 9 each controlled by a motor 10 mounted on the tower of the generator and arranged to rotate a main gear wheel 8 attached to the nacelle. To prevent wear on the motors 10 arising from differences in backlash between the pinion gears 9 and the main gear wheel 8, each motor 10 is controlled to generate a low output torque until all pinion gears 9 have engaged the main gear wheel 8, after which the full output torque is applied to all motors 10. In a further system, in which mechanical friction brakes 11 are provided, braking is arranged to be provided either by the mechanical brakes 11 or by generating a counter-torque in the motors 10, in dependence on the sensed external load.