DEVELOPMENT OF A DIRECT-DRIVE ELECTRICAL TRANSMISSION SYSTEM FOR A KENYAN MANUFACTURED VERTICAL AXIS WIND TURBINE

Abstract

The major reason for the continued low penetration of Small Wind Turbines (SWTs) in Kenya is the high cost of the technology particularly the drive train (gearbox and/or generator). Subsequently, the main objective of this research was to design and develop a direct-drive generator that eliminates the need of gearbox, is affordable/low cost and easy to manufacture and assemble. Secondly the research also sought to determine the optimal economic cost of production of the generator. In achieving this, the methodology used involved: computational electro-mechanical design using FEMM 4.2 software, followed by prototype development and testing. In addition, stratified random sampling, questionnaires and face to face interviews of SWT manufacturers was also done. Materials used included permanent magnets, coil windings, steel rotor discs, used vehicle hub bearing, generator mounting frame, polyester resin, epoxy hardener and talcum powder. The results of the research are in form of 1 kW direct drive Axial Flux Permanent Magnet (AFPM) generator, which costs between 5 – 20% cheaper than the existing SWT transmission systems in the market. Its performance ranges above average as compared to the current ones and its manufacturing process technology is simpler and faster than the existing approaches. In conclusion the use of AFPM direct drive generator reduces transmission system costs of SWTs which can greatly accelerate the adoption of vertical axis SWTs in rural off-grid regions of Kenya. The generator is also quite easy to construct, operate and maintain by people with basic technical skills. Its adoption will also create employment opportunities in the manufacturing and service delivery sectors.