A survey on low speed low power axial flux generator design and optimization using simulation

Axial Flux Generator is a permanent magnet generator commonly used for low-speed power generation using wind power. This generator can generate useful amount of power even under very low revolutions per minute (rpm). Over the last three decades, many researchers and engineers have developed plethora of designs with varying success. Due to the commercial availability of rare-earth magnets such as NdFeB with very high magnetic flux density at very low prices, the propensity to develop new designs have sky rocketed. Yet, many designs even with the availability of many advanced analytical software tools have failed to produce useful amount of power under very low wind speeds. When the world is heading towards a more conscionable climate policy, wind power remains in the forefront of green energy. However, one major challenge in utilizing wind power is the inability of the small-scale generators to generate useful amount of power at very low wind speeds. This poses a formidable challenge to the scientific community to come up with the simplest, affordable and the most efficient design in harnessing wind power at very low wind speeds; that is the most common situation around the world. This research is the result of comprehensive and an exhaustive effort in bringing the best designs into the forefront of research by critiquing innovative designs for their strengths and weaknesses. Almost all the work in the literature has failed to realize the impact of the crucial parameters such as coil shape, coil distance and rare-earth magnet shape and their distances from each other on the eventual generator efficiency. This has resulted in most of the designs producing a very low output at very low revolutions. This article will present a comprehensive survey of best designs in axial flux generators followed by a mathematical analysis of coil shapes, magnet shapes and gaps between these coils and magnets. Then the article will present a very comprehensive electromagnetic simulations with multiple iterations in an effort to optimize the many parameters which have not been analysed in previous works. This new insight will open the research to a new height in achieving high efficiency in future designs.