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

本研究提出一种双绕组磁阻风力发电机，作为一种新型的变速风力发电机。所开发的DWRG由两个不同极数的定子绕组（电枢绕组和励磁绕组）和多屏障（MB）转子组成。磁悬浮转子对气隙磁链进行调制，实现两定子绕组间的磁耦合。研究结果概述如下。实验验证建立了1-kVA的样机，并对其基本特性进行了实验研究。结果表明：（1）通过改变励磁电流，可以在较宽的转速范围内实现恒压控制;（2）样机的设计虽然不是最优的，但效率相当高;（3）励磁绕组中的铜损占内损的很大比例，而铁损的值相对较小。因此，降低励磁绕组中的铜损对提高效率是有效的.基本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损的影响，能够根据空载试验数据定量预测负荷特性.设计考虑采用有限元分析，磁通屏障的气隙磁通的影响进行了研究。分析表明，增加隔磁层的层数可以减少漏磁通量，且主磁通的幅值在很大程度上取决于隔磁层的曲率半径。

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.