應用於自然排風發電之永磁無刷發電機的開發

自然排風扇有良好的排出室內的熱氣及引導室外清新空氣對流之功用，當熱氣排出室外的同時並沒有利用其產生之動能，所以本研究利用加裝永磁無刷發電機於自然排風扇主軸，當風力帶動風扇轉動時，磁鐵盤跟著風扇轉動，使靜止的線圈盤切割磁力線而發電，以達到散熱兼具發電的雙重功效。研究方法分為三個部份，一是分析永磁無刷發電機之磁場強度及磁通密度，二是永磁無刷發電機結構的設計，設計以二個磁鐵盤對應一個線圈盤，其中磁鐵盤放置8個銣鐵硼的強力磁鐵及線圈盤放置12個感應線圈來產生電力，三是能量的轉換與儲存。解析的永磁無刷發電機之型式為2：1(永久磁鐵：感應線圈)與1：2(永久磁鐵：感應線圈)，分析結果得知2：1(永久磁鐵：感應線圈)的磁通密度較好，其磁通密度極小值為0.1068T，極大值為0.3489T；實驗結果得知當自然排風扇轉速於60rpm時，可以輸出電壓交流電18.83V及直流電 10V；轉速於300rpm時，可以輸出電壓交流電121.83V及直流電55V。對於目前廠房類的建築物屋頂所裝設自然排風扇，可利用此發電系統作為電力的產生，所產生之電力輸入至蓄電池，再經由蓄電池輸出提供廠房內部照明，以達到提供散熱及照明的功能。

關鍵字

永磁無刷發電機；電磁感應；自然排風扇；永磁分析

並列摘要

Naturally exhaust fans have both good effects of exhausting indoor heat and guiding outdoor fresh air convection, however, the kinetic energy generated by them while exhausting heat to outside is wasted; therefore, this study used a permanent magnet brushless generator additionally installed on the main shaft of a natural exhaust fan to achieve the double effects of both heat dissipation and power generation. When the fan is rotated by wind power, the magnet disc will rotate along with the fan, so that the stationary coil disc will cut through magnetic field lines to generate power. The research method was divided into three parts, the first part is to analyze the magnetic field strength and the magnetic flux density of the permanent magnet brushless generator; the second part is the structural design of the permanent magnet brushless generator, 2 magnet discs were designed to correspond with 1 coil disc, wherein 8 strong rubidium-iron-boron magnets were placed on the magnet discs and 12 induction coils were placed on the coil disc to generate electricity; and the third part is the conversion and the storage of the generated energy. The types of the analyzed permanent magnet brushless generators are 2:1 (permanent magnet: induction coil) and 1:2 (permanent magnet: induction coil). From the analysis results, it is known that the magnetic flux density of type 2:1 (permanent magnet: induction coil) is better, its minimum value of magnetic flux density is 0.1068T and maximum value is 0.3489T; from the experimental results, it is known that it can output AC voltage 18.83V and DC voltage 10V when the rotation speed of the natural exhaust fan is at 60rpm, and can output AC voltage 121.83V and DC voltage 55V when the rotation speed is at 300rpm. Existing natural exhaust fans installed on roof of plant category buildings can take advantage of this power system to generate electricity, the electricity generated can be inputted into storage battery, and then outputted through the battery to provide lighting inside plant, such that both cooling and lighting functions can be achieved at the same time.