Single-Axis Solar Tracker Eddy-Current Damper for Torsional Vibration
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Solution Overview
Problem
Single axis solar trackers experience torsional vibrations due to wind, leading to resonance and potential damage, as existing damping solutions require coaxial attachment to the rotation shaft and may not effectively dampen vibrations across the entire structure.
Innovation Solution
A torsional vibration damping device with a moving member connected to the rotating shaft and a stationary member attached to the fixed structure, utilizing magnetic field-generating elements and electrically conductive, non-ferromagnetic materials to produce Foucault currents, creating a damping torque that counteracts torsional vibrations, with optimal placement of damper connection points along the rotating shaft to enhance damping effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional torsional damping device with coaxial attachment is used, then the device structure is simple, but it cannot effectively dampen vibrations across the entire rotating shaft
Solution Approach 1:
The damping device is divided into separate functional components: magnetic field-generating elements (permanent magnets or electromagnets) mounted on the rotating shaft, and electrically conductive non-ferromagnetic damping elements (such as aluminum or copper plates) positioned adjacent to the magnetic fields. This segmentation allows each component to perform its specific function independently while working together to provide distributed damping along the shaft length.
Solution Approach 2:
The patent replaces traditional mechanical damping mechanisms (such as viscous fluid dampers or friction-based devices) with an electromagnetic damping system. The damping effect is achieved through electromagnetic induction: motion of the conducting elements through the magnetic field generates eddy currents, which in turn create opposing magnetic fields that dampen the vibrations without mechanical contact.
2Reliability
If the damper connection points are positioned closer to the motor connection point, then the device complexity is reduced, but the damping effectiveness decreases
Solution Approach 1:
The damping elements are strategically positioned at locations along the rotating shaft where torsional vibrations have the greatest amplitude, such as near the ends of the shaft or at points of maximum bending moment. This local placement optimizes the damping effect at the most critical locations rather than distributing damping uniformly along the entire shaft length.
Solution Approach 2:
The damping mechanism operates in a different dimensional approach by creating a distributed electromagnetic damping field along the shaft length, rather than relying on a single point attachment. Multiple damping elements can be positioned at different axial and radial locations to address vibrations in multiple modes and directions simultaneously.
3Strength
If the rotating shaft has high torsional rigidity, then the structural strength is improved, but torsional vibrations propagate along the shaft
Solution Approach 1:
The patent converts the harmful torsional vibrations into useful electromagnetic energy through eddy current damping. The mechanical vibration energy is transformed into electrical current in the conducting elements, which then dissipates as heat through electrical resistance, effectively converting the harmful vibrational energy into a harmless thermal form.
Solution Approach 2:
The magnetic field acts as an intermediary between the rotating shaft and the damping elements. The magnetic field couples the mechanical motion of the shaft to the electromagnetic response of the conducting elements, enabling energy transfer and damping without direct mechanical contact or structural modification of the shaft itself.
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
Effectively prevents and dampens torsional vibrations along the rotating shaft, reducing the risk of resonance and damage, by applying damping torque through Foucault currents, with improved performance as the damper connection points are positioned further away from the motor connection point and closer to the ends of the shaft.
Implementation Method 1
utilizing magnetic field-generating elements and electrically conductive, non-ferromagnetic materials to produce Foucault currents
Implementation Method 2
relative movement between the magnetic field-generating elements and the section made of an electrically conductive, non-ferromagnetic material produces a damping torque
Data Source
Figure 1
Figure 2~3
Figure 4~7
AI summary
The solar tracker includes a pivoting assembly (2) having solar panels (3) fixed to a rotating shaft (1), a fixed structure with support elements (4, 5, 6) rotationally supporting the rotating shaft (1), a motor-reducer assembly (7) having an irreversible reducer (24) connected to the rotating shaft (1) at a motor connection point (12), and a torsional vibration damping device (8) having a moving member (9) rigidly connected to the rotating shaft (1) at a damper connection point (13) spaced apart from the motor connection point (12) and a stationary member (10) rigidly attached to the fixed structure. One member selected between the moving member (9) and the stationary member (10) comprises magnetic field-generating elements (11) and the other member comprises a section made of an electrically conductive, non-ferromagnetic material. Relative movement between the two members close to one another without contact produces a damping torque by Foucault currents effect.