*Article* **Comparison of Flux-Switching and Interior Permanent Magnet Synchronous Generators for Direct-Driven Wind Applications Based on Nelder–Mead Optimal Designing**

**Vladimir Prakht 1,\*, Vladimir Dmitrievskii 1, Vadim Kazakbaev 1 and Ekaterina Andriushchenko 2**


**Abstract:** The permanent magne<sup>t</sup> flux-switching machine (PMFSM) is one of the most promising machines with magnets inserted into the stator. To determine in which applications the use of PMFSM is promising, it is essential to compare the PMFSM with machines of other types. This study provides a theoretical comparison of the PMFSM with a conventional interior permanent magne<sup>t</sup> synchronous machine (IPMSM) in the gearless generator of a low-power wind turbine (332 rpm, 51.4 Nm). To provide a fair comparison, both machines are optimized using the Nelder–Mead algorithm. The minimized optimization objectives are the required power of frequency converter, cost of active materials, torque ripple and losses of a generator averaged over the working profile of the wind turbine. In order to reduce the computational time, the substituting profile method is applied. Based on the results of the calculations, the advantages and disadvantages of the considered machines were revealed: the IPMSM has significantly lower losses and higher efficiency than the PMFSM, and the PMFSM requires much less rare-earth magnets and copper and is, therefore, cheaper in mass production.

**Keywords:** direct-drive; electric machine analysis computing; interior permanent magne<sup>t</sup> machine; mathematical model; optimal-design; permanent magne<sup>t</sup> flux-switching machine; wind generator
