Abstract
Flux Switching Permanent Magnet Generators (FRPMGs) have been used increasingly in direct drive variable speed wind turbines due to their merit such as their high torque density, easy flux weakening operation and robust rotor structure. Generally, the quality of output power in direct drive systems is lower than multi stage fixed speed systems, because of removing the gears, so it’s important to design these kinds of generators with low ripple and lowest harmful harmonics and cogging torque. This aim is one of the most important terms in increasing the quality of output power of generator simultaneously with back-EMF improvement. The objective of this paper is introducing a simple design method and optimization of high power FRPMG applied in direct drive wind turbine system by lowest possible amplitude of cogging torque and highest possible power factor, efficiency and power density. For optimization reason an optimum method called combined response surface methodology (RSM) and design of experiment has been applied. Also in order to extract the output values of generator and sensitivity analysis for design, 3D-Finite element model, was used. This method has high accuracy and gives us a better insight of generator performance and presents back EMF, cogging torque, flux density and FFT of the FSPMG. This study can help in design approach of such machines.
Highlights
During last two decades, renewable energy sources have become crucial due to the traditional energy sources
The most important part of these kinds of systems are permanent magnet type generators that have less weight and volume and less cooper and iron losses, more TPC, power factor and efficiency, less mechanical problems and more longevity than their rivals. [4,5,6,7] Among all kinds of permanent magnet synchronous generator types, Flux Switching Permanent Magnet Generators are one of the most top options for variable speed wind turbines because of merit below [4,8,9,10]: 1) managing temperature rise of magnets which is on the stator
Flux density in the airgap region could reach to 2.5 Tesla, besides, the PM orientation and windings are magnetically parallel and it can remove the armature reaction effect in working point and increase the electric loading. [4,10,11,12,13,14] Because of removing the gears, it’s important to design these kinds of generators with low ripple and lowest harmful harmonics and cogging torque that is one of the most important terms in increasing the quality of output power of generator [11,12,13,14,15,16]
Summary
Renewable energy sources have become crucial due to the traditional energy sources. [4,10,11,12,13,14] Because of removing the gears, it’s important to design these kinds of generators with low ripple and lowest harmful harmonics and cogging torque that is one of the most important terms in increasing the quality of output power of generator [11,12,13,14,15,16] Cogging torque in these machines is quite dependent on the geometry of teeth in both sides (rotor and stator) and volume of PMs in each stator tooth. [17,18] This paper implemented a simple design and optimization method of high power FSPMG applied in direct drive wind turbine system by lowest possible amplitude of cogging torque and highest possible power factor, efficiency and power density For this purpose, a 2D-finite element model and an optimum method called combined response surface methodology (RSM) was applied. This method can achieve excellent performance and low costs by optimizing multiple design variables of FSPMG [16], and has high level of accuracy and gives a better insight of generator performance
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