降低永磁式發電機頓轉扭矩之研究

Abstract

本文旨在探討在永磁式發電機中頓轉扭矩的降低方法。因應現今風力發電機所使用的有鐵芯式永磁式發電機不可避免的會產生頓轉扭矩，造成啟動必須另外克服此扭矩的負面影響，因此本文將探討降低頓轉扭矩的方法，第一部分設計發電機之轉子並建立分析方法，接著進行實驗量測，以車用發電機改裝驗證，分析比對發電機磁通、電壓、頓動扭矩的準確性，以實作的發電機問題深入探討，找出降低此發電機頓轉扭矩的方法，第二部分則為降低頓轉扭矩的設計，比較不同方法對頓轉扭矩的影響，分別為磁石的不規則排列、磁石表面修弧、可變氣隙的機構三種方法，在可實驗的範圍內實測各方法的實用性，並從中探討發電機的優點以及缺點進行討論，為提高發電機的性能提出了建議。

The purpose of this thesis is to explore the methods that can reduce the cogging torque of permanent magnet (PM) generators. Nowadays, permanent magnet generators have been used as wind turbines. The generator will inevitably produce a cogging torque which can lead to some negative effects on the starting wind speed of the wind turbine. This thesis will explore methods to reduce such cogging torque. The first part is to design the rotor of a car alternator to change it to a PM generator. The finite element method is used to predict the static magnetic flux, voltage, and cogging torque of the PM generator and the accuracies of the FE models are verified by experimental results. The second part is to study how to reduce the cogging torque of the generator. Three methods, namely, the irregular arrangement of magnets, the use of curve shape magnets, and the varying air gap technique are used separately or in combination to design the generator. The feasibility and effectiveness of these methods are studied via the theoretical or experimental approaches. The advantages as well as disadvantages of the methods are discussed and suggestions for improving the performance of the generator are given in the thesis.