LVDT Stepped Booster Windings for Linearity
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Solution Overview
Problem
Conventional linear variable displacement transformer (LVDT) position sensors face limitations in extending their linear transducing range and maintaining accuracy due to end effects in magnetic coupling between primary and secondary coils.
Innovation Solution
The implementation of stepped complementary secondary coils with booster windings at their ends, which taper in opposite directions, compensates for end effects, extending the linear transducing range by up to 20% and enhancing accuracy across the entire range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional uniform secondary coils are used in LVDT, then the structure is simple and easy to manufacture, but the linear transducing range is limited and accuracy deteriorates at the ends due to end effects
Solution Approach 1:
The patent applies local quality by making the secondary coils non-uniform with stepped windings that have different turn densities at different positions. The booster windings at the ends have higher turn density to compensate for end effects, while the middle section maintains lower turn density. This local variation in winding density optimizes the magnetic coupling characteristics at different positions along the coil, thereby improving position sensing accuracy across the entire range.
Solution Approach 2:
The patent changes the physical parameter of turn density along the length of the secondary coils. By varying the number of turns per unit length (creating stepped windings with booster sections), the magnetic coupling parameter is optimized at different positions. The booster windings increase the turn count at the ends to compensate for the weaker magnetic coupling that occurs at the extremities of the LVDT structure.
2Length of moving object
If the linear transducing range is extended, then more booster windings are needed which increases manufacturing complexity, but without booster windings the range remains limited
Solution Approach 1:
The patent segments the secondary coil into distinct sections: middle sections with standard turn density and end sections (booster windings) with higher turn density. This segmentation allows the complex booster sections to be concentrated at specific locations rather than distributed throughout, making the manufacturing process more manageable. The stepped winding technique divides the coil into discrete segments with different characteristics.
Solution Approach 2:
The booster windings are pre-configured at the end sections of the secondary coils during the manufacturing process. By establishing the higher turn density regions in advance at the critical end positions, the design prepares the coil structure to handle the extended range requirements before the actual measurement operation begins.
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 ensures a more linear voltage versus voltage curve, thereby increasing the accuracy and range of position sensing in LVDT sensors, making them suitable for various aerospace and electromechanical applications.
Implementation Method 1
As the primary transformer winding is excited with an alternating current (AC) voltage signal, it generates a magnetic field that couples into the two secondary transformer windings, establishing an AC voltage signal across the two secondary windings.
Implementation Method 2
A moveable core that is free to move linearly along the common axis of the windings affects the amount of magnetic coupling between the primary windings and each of the secondary windings.
Data Source
AI summary
A linear variable displacement transformer (LVDT) position sensor. The position sensor comprises a bobbin, a primary coil of wire wound on the bobbin, a first secondary coil wound in stepped layers on the bobbin, and a second secondary coil wound in stepped layers on the bobbin. The first secondary coil comprises a plurality of booster windings at an end of the first secondary coil. The second secondary coil comprises a plurality of booster windings at an end of the second secondary coil opposite the end of the first secondary coil booster windings. The stepped windings of the second secondary coil are complementary to the stepped windings of the first secondary coil.