Grid Connected PM Machines for Wind Energy 

The focus of the study in this paper is on the design of unconventional, directly-grid connected PM wind generators without power electronicconverters. As a case study, this analysis is based on a novel direct-drive wind generator system known as a slip synchronous permanent magnet wind generator. Attention is given to the definition of the design requirements of the directly grid connected synchronous generator unit from the relevant grid code specifications, and to find the optimum design subject to these requirements.

Due to the direct grid connection there are clear differences in the design requirements of this machine and those of conventional permanent magnet wind generators connected to the grid via a converter. Four different generator topologies are evaluated with regard to ease of manufacturing, active mass, permanent magnet content and suitability for direct grid connection. Both simulated and measured results are given for an experimental direct-grid slip synchronous permanent magnet generator.