Design of a Permanent Magnet Synchronous Generator for a Vertical Axis Wind Turbine

Abstract: Different types of permanent magnet generators for wind power application have been subject of research during last two decades. In this thesis different topologies of electrical generators have been investigated for small scale vertical axis wind turbine application. A two stage induction generator is proposed as a alternative solution with respect to the cost of such a system. However, a biggest emphasis in the report has been put on the design of Permanent Magnet Synchronous Generator (PMSG) suitable for a small scale Vertical Axis Wind Turbine (VAWT)T˙ he characteristics of PMSG makes it highly compatible for variable speed Wind Energy Conversion System (WECS) without any pitch mechanism. Chapters 2 and 3 summarize a thorough literature survey on wind energy systems and corresponding electrical machines. The principles of wind aerodynamics is preceded by a review on wind turbine characteristics and challenges with emphasis on VAWT s. Further different topologies of electrical machines with focus on PMSG s including Permanent Magnet (PM) configurations, different windings and thermal behavior is presented. In chapter 4 a brief review on an alternative solution which includes an Induction Generator (IG) for fixed speed WECS is given. Next, In chapters 5, 6 and 7, a PMSG is designed and the design is verified by means of Finite Element Method (FEM) analysis and thermal modeling. Chapter 5 describes an analytical optimisation of a longitudinal, inner rotor, radial flux, surface mounted PMSG with concentrated winding and natural air cooling system. Cost of active material is chosen as the optimisation criterion. Concepts like "constraints", "requirements", "parameters" (including material, geometry and winding) and procedure of the design are described here. In chapter 6, a FEM model of the optimised machine is developed and the results are illustrated. The iron losses, calculated in this chapter are utilised in thermal analysis in chapter 7 . Thermal model developed is based on a lumped parameter circuit . It ensures the safe thermal behavior of the machine in nominal operation mode.