Publication: Analytical and experimental study of an electromagnatic generator
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Date
2012-06-01
Authors
SK Abd Aziz, Mastura
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Abstract
The objective of this project is to understand the research and development (R&D) of an electromagnetic micro generator which designed to harvest energy from the vibrations present in the application of environment into electrical energy. Vibration energy harvesting from ambient sources is an attractive alternative to batteries and is receiving a considerable amount of interest to power up an electronic devices. A study of electromagnetic generator via Finite Element Analysis (FEA) is presented in this project which involves the investigation of magnetic behaviour. Finite element models are developed and further analysed via OPERA Vector field software. Analyses are conducted prior to investigate the magnetic behaviour such as the flux lines and the magnetic flux density. Working principles of the electromagnetic generator is through theoretical characterization, 2D models using OPERA vector field software and also experimental with the electromagnetic generator prototype using shaker as a vibration source. OPERA 2D software presents the analysis only for the three types of magnets which are Neodymium Iron Boron (NdFeB), Samarium Cobalt (SmCo) and Ceramic magnet. The magnetic flux density and field distribution were obtained from these analyses which are also the mainframe to the designation of an electromagnetic generator. In the case of my project, the basic electromagnetic generator structure was formed by two permanent magnets NdFeB with different polarities at the one end of a fixed cantilever to provide an oscillation during vibration. Permalloy is added to analyse its effect towards the flux density. Experimental part using shaker as a vibration generator to supply mechanical vibration to the sample under test, an oscilloscope to show the voltage and frequency produce, and an accelerometer to provide data on the amplitude of vibration applied to the sample. Later, the current will be measured in order to calculate the power generated. Three prototypes with two types of bases (wooden and stainless steel) have been made using aluminium and stainless steel cantilever as a source for vibration. Theoretically, the calculated resonance frequency for the aluminium cantilever is at 15.22Hz and 39.66Hz is for the stainless steel cantilever. Meanwhile the highest output power is at 2.463mW using stainless steel base (N=600) with stainless steel cantilever and the lowest output power is at 0.04mW using wooden base (N=400) with aluminium cantilever. In conclusion, generator performance can be improved by increasing the number of coil turns, adding the high permeability material and use a high density cantilever.