適用於超音波頻段D類及E類功率放大器之設計及比較

Design & Comparison of the Class D & Class E Power Amplifiers for Ultrasonic Frequencies

張晉漢(Chin-Han Chang)

指導教授 ： 陳昭宏

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.03032

摘要

超音波技術於十九世紀末期後開始顯著的發展，配合了各相關領域的研究也有許多相關應用與整合，例如本篇論文提到的將功率放大器訊號轉換為聲能傳播再將聲能轉換為電能作為計算，為一機電整合相關的整合研究。首先要了解超音波壓電換能器在工作時正確阻抗值，為了使在有限環境下的量測越趨於在無反射干擾下的量測阻抗值，我們採用了新的計算方式，探討在有限環境下的干擾是否會造成影響及阻抗的比較誤差。
一般來說在發射端系統中，耗能的部分不外乎功率放大器(PA)上，而在功率放大器效率上如越高，不必要的消耗就越少，在裝置上也可以使用更久。應用於超音波之功率放大器多為D類功率放大器，鮮少有E類功率放大器應用研究。D類輸出為方波而E類輸出為弦波所以在負載端接收時會有效率上的差，而非理論上的100%；本文將針對D類功率放大器及E類放大器設計在相同負載時比較其功率及效率上的優劣，E類放大器整體傳輸效率比較上也較D類功率放大器為佳，功率也較大。

關鍵字

超音波壓電換能器 ； 超音波阻抗 ； 功率放大器 ； E類功率放大器 ； 1MHz

並列摘要

Ultrasound technology began to develop in the late 19 century. With the related study, there are many applications and integrations; for example, one of mechanical and electrical integration method in thesis mentioned that PA signals transform into acoustic energy and spread the energy, and then the acoustic energy converts into electrical energy as computing. In this case, we must know the correct ultrasounic piezoelectric transducer impedance values during working time first. In order to make the measurement of impedance values in limited environment more close to the measurement of impedance values in the no-flection interference, we have adopted a new method of calculation, discussing in whether limited environment will cause the impedance error.
Generally speaking, in the transmitting system, it cause much more energy in the power amplifier. The higher efficiency the power amplifier can reach, the less unnecessary consumption the system can reduce and the device can also be used longer. There are more Class D PAs applications deigned than Class E PAs for ultrasounic frequencies, so we want to design Class D & E power amplifiers and compare them in overall transfer efficiency. Compared with Class E sine wave signal, Class D output is square wave signal and the latter efficiency will not be 100 % correspond to the theory. This article will focus on designing Class D & E power amplifiers and compare with their advantages & disadvantages in the same load; moreover, Class E PAs have better power and efficiency than Class D PAs for ultrasoundic frequencies.

並列關鍵字

Power Amplifier ； Class E ； Ultrasounic Piezoelectric Transformer ； Ultrasounic Piezoelectric Impedance ； 1 MHz

參考文獻

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