Research and design of semi-active synchronized switch on power harvesting and power loss

• Main Authors: Kai-Wei Shi, 施凱崴
• Other Authors: 李世光
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/81987577128768774364

碩士 === 國立臺灣大學 === 應用力學研究所 === 98 === Piezoelectric generator is a combination of cantilever beam and piezoelectric thin slip. The property of piezoelectric material has two basic characteristics, which are Direct Piezoelectric Effect and Converse Piezoelectric Effect. Direct piezoelectric effect turns mechanical energy into electric energy. Direct piezoelectric effect is being applied in Power Harvesting technology. Combined with piezoelectric generator, semi-active power harvesting circuitry is adopted to raise the output power harvested. There are two basic circuitry configurations adopted in semi-active power harvesting technology. One is SSHI-P (Synchronized Switch Harvesting on Inductor-Parallel) and another is SSHI-S (Synchronized Switch Harvesting on Inductor-Series). The above-mentioned circuitry configuration gets 4~9 times the power gains than the standard passive power harvesting circuit on average. Piezoelectric generator produces high frequency signal which happens while the switch is turned on during the harvesting process. As the voltage of piezoelectric produces inversion when switch turns on, piezoelectric generator is excited by voltage inversion that produces high frequency signal. Choosing high-value inductor reduces high frequency signal, but power dissipated on the electrical element of circuitry actually increases. Choosing inductor with high quality factor not only rises output power but also reduces the power dissipated on the electrical elements.