功率超音波驅動電路模組應用於霧化器

Abstract

近年來，伴隨著高功率轉換裝置和微處理技術的發展，功率超音波的應用變得十分的廣泛。其應用的範圍包括，超音波水下聲納的信號發射、超音波霧化技術，超音波清洗技術，超音波燒灼，超音波醫療等等。但配合這些功率超聲應用的高品質超音波驅動電路卻是十分缺乏的。一般而言，大功率的驅動電路其可動作的頻率範圍最高只到幾百千赫茲。而運用於高頻範圍的驅動電路其可供給的功率卻也有限。長時間穩定的工作也是目前功率超音波驅動電路在設計上和使用上普遍存在的問題。因此，本論文將開發一個功率超音波驅動電路模組並詳細敘述此電路模組每一細部功能電路之設計概念與設計方法。此驅動模組可在輸出大功率的條件下，以幾百千赫茲到數百萬赫茲的驅動信號驅動，擁有高機電的轉換效率，並可以長時間穩定的高效能作動。而本實驗室正在進行超音波霧化加濕技術應用於燃料電池系統的計畫，故本論文將會將此模組化的電路設計應用在超音波霧化器系統之上。此霧化器之超音波驅動電路可驅動500KHz到2MHz之換能器，其輸出電壓可調整，最高額定輸出功率為30W。本論文也會觀察與討論此霧化器的霧化現象。包括霧滴顆粒大小與驅動頻率之關係，霧化速率、霧滴粒徑分佈與驅動電壓之關係。

In recent years, accompanying with the development of the high-speed switch device and microprocessor technology, the range of high power ultrasonic application becomes very broad. The power ultrasonic usually applies to sonar, atomization, cleaning technology, and medical instrument, etc. However, a good designed ultrasonic driving circuits for the power ultrasonic system is very deficient. In General, frequency of high power ultrasonic circuit reaches a maximum of hundreds of thousands hertz, whereas the high frequency circuit can just provide limited power. Long-term steady-going operating is also a problem for power ultrasonic driving circuit on design and in use. Therefore, this paper shows a high power ultrasonic driving circuit model and describes the concepts and manners in detail of each subtle circuit in this circuit model. This circuit model can drive from hundreds of thousands to several millions hertz on the high power condition, and it has high conversion efficiency between mechanical terminals and electrical ones. Even though the application of ultrasonic atomization in engineering is more general and more important, it is rare to have a good ultrasonic atomization system with high efficiency and excellent atomization effect. As result, in this paper, we are going to apply this circuit model to the ultrasonic atomization system. This circuit can drive transducers with resonance frequency between 500KHz to 2MHz. Its output voltage can be adjusted and the maximum rated output power is 30W. Besides, we’re going to observe and discuss the atomization phenomenon of this atomizer, which includes the relationship between the sizes of droplet and driving frequency, the atomization velocity, and the relationship between the droplet size distribution and the driving voltage.