Sigurd Övrebö

Review of modeling methods in electromagnetic and thermal design of permanent magnet generators for wind turbines

The rapidly developing wind power industry demands high power generators. Direct driven permanent magnet synchronous generator (PMSG), which has the advantages of high drive train efficiency and high reliability, is promising in wind turbine applications, especially offshore. It is known, that direct driven PMSG is heavier than its geared counterparts, which increases the cost and may bring up engineering challenges. Integrating the active parts of PMSG with the blades, hub or nacelle and sharing the carrying structures can give considerable reduction of the top head mass. Integrated design challenges the electromagnetic and thermal analysis of PMSG from the perspective of whole system and the design approach may differ from the conventional. This paper presents an overview of the modeling methods for the design of PMSG. First, the drive train technology is discussed and challenges in the design of PMSG are identified. Secondly, the electromagnetic and thermal design methods are reviewed. Finally, development of simulation software is investigated.

New self sensing scheme based on INFORM, heterodyning and Luenberger observer

Self sensing techniques for AC machines has been a research topic for almost two decades. Two promising methods are found in injection of high frequency carrier and the INFORM method. Both schemes are based on utilization of saliency in order to make position estimate. The excitation and signal processing for these methods differs. A new scheme based on the INFORM measurements a tracking observer is presented. The new scheme gives the modified INFORM method a close to zero phase lag in rotor position estimate. The new scheme is implemented and evaluated with a 32 kW IPMSM.