Flux switching permanent magnet generator design and optimization using response surface methodology

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.