Design Optimization of a HTS-Modulated PM Wind Generator

The flux-modulated machine based on air-gap magnetic flux modulation theory has become a focus in low speed and high torque density applications. In this paper, the optimal design of a large scale flux modulation (FM) permanent magnet (PM) generator with high temperature superconducting (HTS) bucks for wind energy conversion systems is presented. Firstly, the working performances of the generator with and without HTS bucks sandwiched between iron segments are analyzed and compared through finite element analyses (FEA). The FM effect enhancement by employing the HTS bucks is proved through the comparisons. Secondly, the sensitivities of the generator structural parameters on the back electromotive force (EMF) and the cogging torque amplitude are analyzed by Taguchi method to decide the optimization variables and their variation ranges. Thirdly, the structural parameters determined by the sensitivity analyses are optimized through the coupling of genetic algorithm (GA) and FEA to maximum the generator output power capacity. The calculation burden during optimization is reduced with a reduction on the optimization variable number through the Taguchi method based sensitivity analyses. Finally, the electromagnetic characteristics of the FMPM generator with optimized structural sizes are numerically investigated.