Magnetostrictive-Piezoelectric Generator Axis Alignment
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Solution Overview
Problem
Existing electricity generators using magnetostrictive-piezoelectric converters face inefficiencies due to the need for strong magnetic fields to saturate anisotropic materials, leading to large size and low conversion efficiency, and lack of compactness and robustness.
Innovation Solution
A compact electricity generator design utilizing a stack of anisotropic magnetostrictive and piezoelectric layers with controlled alignment of preferential axes, allowing efficient energy conversion with a weak magnetic field, and incorporating a Halbach cylinder magnetic field source to maintain compactness and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a strong magnetic field is used to magnetically saturate the anisotropic magnetostrictive material, then the conversion efficiency is improved, but the device size increases and compactness is reduced
Solution Approach 1:
The patent changes the magnetic field strength parameter from saturation level to a weaker non-saturating field, while simultaneously optimizing the alignment between the preferential axis of deformation of the magnetostrictive material and the polarization axis of the piezoelectric material. This parameter change allows efficient energy conversion without requiring a large magnetic field source, thus reducing device size while maintaining compactness.
2Loss of energy
If the preferential axis of deformation is aligned with the polarization axis, then the conversion efficiency is enhanced, but the manufacturing precision requirement increases
Solution Approach 1:
The patent incorporates marking means on the magnetostrictive material layer before assembly, which indicates the direction of the preferential axis of deformation. This preliminary marking action enables precise alignment with the piezoelectric layer's polarization axis during the assembly process, ensuring optimal conversion efficiency while providing a practical method to achieve the required alignment precision.
3Device complexity
If isotropic magnetostrictive material is used, then the device complexity is reduced, but the conversion efficiency decreases
Solution Approach 1:
The patent uses anisotropic magnetostrictive material with specific crystallographic orientation to create local quality enhancement in the deformation response. The anisotropic material provides preferential deformation along specific axes when exposed to magnetic fields, which can be aligned with the piezoelectric polarization axis. This localized directional property increases conversion efficiency while the overall device structure remains relatively simple.
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 solution achieves enhanced conversion efficiency and compactness by aligning the preferential axis of deformation of the magnetostrictive layer with the polarization axis of the piezoelectric layer, allowing for efficient energy harvesting with reduced magnetic field strength, improving mechanical resistance and longevity.
Implementation Method 1
Magnetostriction generally involves a reversible exchange of energy between a mechanical form and a magnetic form. The best known magnetostriction effect is the Joule effect.
Implementation Method 2
Piezoelectricity is the generation of electrical charges under the influence of mechanical stress.
Implementation Method 3
A Halbach cylinder magnetic field source to maintain compactness and efficiency
Data Source
AI summary
An electrical generator comprises a converter including two electrical terminals for converting a variation in a magnetic field into a potential difference between the terminals. The generator includes a stack of a first layer comprising an anisotropic magnetostrictive material defining a reference plane and a second layer comprising a piezoelectric material. The first layer has at least one preferential axis of deformation in the reference plane and the second layer has a polarization axis parallel to the reference plane, the preferential axis of deformation of the first layer being aligned to within 15° with the polarization axis of the second layer. The generator includes a source that generates the magnetic field, the strength of which is insufficient to magnetically saturate the material of the first layer. The source and converter are able to rotate with respect to each other so as to vary the orientation of the magnetic field.