本文探討疊層型降壓式壓電變壓器之設計、製作與性能測試，並將其應用於充電器上，以提供產品所需之低壓直流電源。首先利用壓電材料製作出直徑為25mm的圓盤型環狀電極壓電變壓器，藉由改變厚度、輸出入電極面積比、疊層數等，觀察其壓電等效電路的變化，研究其對降壓式壓電變壓器特性的影響。再利用matlab模擬驗證等效電路理論推導所得到的結果。最後發現在厚度0.5mm，疊層數為3，輸出入電極面積比1 : 3的壓電變壓器，其匹配負載電阻為10Ω情況下有最高輸出功率有3.5W、電壓增益約0.05V/V及元件效率約92%，與濾波整流電路結合，成功的製作出充電器並成功的使一般市用手機充電。

The purpose of this paper is to investigate the design, fabrication and performance test of the step-down multi-layer piezoelectric transformers (PT). It can provide a low voltage DC power and applie to a charger. First of all, we use piezoelectric material to produce the disk-type PT which diameter is 25mm and has a ring-shaped gap circle on the silver electrode. We observed the variations of the PT equivalent circuit with varying thickness, electrode area ratio of input and output, laminated. Besides we study the effects of that on step-down PT. Later, we use Matlab to simulate, analyze and test the inferential results of PT equivalent circuit. We finally found that the PT with thickness of 0.5mm, level 3, the input and output electrode area ratio is 1:3, and it’s matched load is 10Ω which has the highest output power 3.5W, voltage gain is about 0.05V/V and the efficiency can reach about 92%, which can combine with the rectifier to produce the charger, and mobile phone can be charged successfully.

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