Using Pulse Width and Pulse Shape Modulation to Enhance Power Conversion Efficiency under Constraint of Low Input Power

• Main Authors: Yu-LinYang, 楊育林
• Other Authors: Chin-Lung Yang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/35106277220989774774

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 100 === This thesis presents a novel wireless power transmission (WPT) technique by using pulse width and pulse shape modulations under constraint of low input power for biomedical applications. Instead of using continuous wave for WPT, we could enhance the output voltage (Vout) and power conversion efficiency (PCE) of RF-DC rectifier by adjusting duty cycles and pulse shapes. According to theoretical models of the diode and RF-DC voltage doubler rectifier, we could predict the optimal load, Vout, and PCE by using numerical analysis software (Matlab) within the error of less than 10 %. The PCE improvement of the RF-DC voltage doubler rectifier using the technique of pulse width can be simulated by Advanced Design System (ADS). Furthermore, the technique of pulse shape modulation is proposed. Several different types of waveforms can be systematically modeled with a single shape parameter. The effects of different duty cycles and pulse shapes on the PCE of the RF-DC voltage doubler rectifier are thoroughly investigated. From the experiment results of the wired transmission and the LED loads, we could determine the optimal duty cycle and waveform to achieve the best performance according to the current through the load. Therefore, we would reduce the input power and improve the PCE. As for the study of biomedical applications, this thesis creates a simple analytical biomedical channel model under the consideration of the main attenuation factors to predict the receiving microwave power from receiving antenna buried inside the biological tissues. The WPT system and biomedical WPT system were established to perform wireless biomedical experiments. The the Vout and PCE using different duty cycles, and waveforms are wirelessly measured through in different thicknesses of biomedical tissus. The wireless biomedical experiment results are closely matched to both the wired and wireless experiment results. The PCE of RF-DC voltage doubler rectifier can be improved 3.5 times under constraint of low input power. The performance of using pulse width and pulse shape modulation WPT is verified to optimize the PCE under constraint of low input power in biomedical applications.