Present and future trends in wind turbine generator designs

Various wind turbine generators have been designed and manufactured in recent years, such as the traditional induction generator, the doubly fed induction generator, the field excited synchronous generator and the permanent magnet synchronous generator. Generators are coupled to the turbine by either a gearbox or without one (so-called direct drive), and there are four different kinds of interfaces between the generator and the grid, depending on the type of power electronic converters used. This paper reviews recent developments in the different generator topologies and their connections to the turbine. A new generator design concept without a gear box or any power electronics is proposed and the feasibility is illustrated in this paper.