| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 102 === This thesis is devoted to design a multi-phase hybrid excitation synchronous generator for small wind power applications. The excitation of rotor consists of permanent magnet and dc excitation winding. The output voltage of generator can be changed by adjusting dc excitation current. Specifically, appropriate output voltage level can be maintained by increasing and decreasing excitation current at low and high speeds, respectively. The structure of stator and rotor is doubly salient with fully opening slots. This will not only ease winding insertion but also enhance reluctance power arising from saliency effect which yields large difference between the direct- and quadrature-axis inductances. The generator can be configured to be three-phase or six-phase by changing the winding connection for different output voltage applications. Analysis of various pole shapes and magnet heights with Maxwell 2D are given to obtain desired fundamental peak value of induced voltage as well as total harmonic distortion.
A hybrid excitation synchronous generator with 24 slots and 20 poles is built. At 300 rpm, the fundamental peak value of no-load phase voltage of the generator under three-phase and six-phase connections are 40.55V and 21.45V, respectively with excitation current of 3A, and are 23.50V and 12.29V, respectively without excitation current. Enhancement of output voltage with excitation current is thus observed. Moreover, in diode rectifier test, the output voltage of three-phase and six-phase connections are 26.7V and 19.7V, respectively at 400 rpm with resistive load of 10 . Suitable output voltage level can be maintained by adjusting excitation current when the speed ranges from 200 to 350 rpm. Finally, experimental results verify the feasibility of the proposed system.
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