Development of Variable-Speed Wind Generators Using Magnetic Modulation Effects of Multiple-Barrier Rotors

本文研制了双绕组磁阻发电机（DWRG）作为一种新型的变速风力发电机。所研制的DWRG由两个不同极数的定子绕组（电枢绕组和磁场绕组）和一个多势垒转子组成。通过MB转子调制气隙磁通，实现了两个定子绕组之间的磁耦合。研究结果总结如下。实验验证研制了一台1kva样机，并对其基本特性进行了实验研究。结果表明：(1)通过改变磁场电流，可以在较宽的转速范围内实现恒压控制；(2)虽然原型机的设计不是最优的，但它的效率是合理的；(3)磁场绕组中的铜损耗占内部损耗的比例较大，铁芯损耗的数值相对较小。因此，降低磁场绕组中的铜损耗是提高效率的有效方法。基础理论的发展为了从理论上预测DWRG的稳态性能，建立了一个简单的数学模型，并在样机上进行了实验验证。该模型考虑了磁饱和和铁芯损耗，能够根据空载试验数据对负载特性进行定量预测。设计考虑采用有限元分析方法，研究了磁通屏障对气隙磁通的影响。分析表明，增加磁通屏障层数可以减小漏磁量，主磁通的幅值在很大程度上取决于磁通屏障的曲率半径。

In this study, a dual-winding reluctance generator (DWRG) was developed as a new type of variable-speed wind generator. The developed DWRG consists of two stator windings (armature winding and field winding) with different pole numbers and a multiple-barrier (MB) rotor. The air-gap flux is modulated by the MB rotor, and magnetic coupling between the two stator windings is realized. The findings of the study are summarized below.1. Experimental VerificationA 1-kVA prototype machine was built, and its basic characteristics were investigated experimentally. The results showed that :(1) By changing the field current, the constant-voltage control was easily achieved over a wide range of speeds ;(2) Although the design of the prototype machine was not optimal, it was reasonably efficient ;(3) The copper loss in the field winding comprised a large percentage of internal losses, and the value of the core loss was relatively small. Therefore, reducing the copper loss in the field winding is effective in raising the efficiency.2. Development of the Basic TheoryTo predict the steady-state performance of the DWRG theoretically, a simple mathematical model was developed and verified with experimental results on the prototype machine. The developed model takes into account the magnetic saturation and core loss and enables a quantitative prediction of load characteristics from the no-load test data.3. Design ConsiderationUsing FE analysis, the influence of flux barriers on the air-gap flux was investigated. The analysis showed that increasing the number of layers of flux barriers reduces the amount of the leakage magnetic flux and that the amplitude of the main magnetic flux is dependent on the curvature radius of flux barriers to a great extent.