Low temperature co-fired multilayer piezoelectric transformers for high power applications
Low temperature co-fired multilayer piezoelectric transformers for high power applications
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DOI：
10.1016/j.matdes.2017.07.030
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发表时间：
2017-10-15
影响因子：
8.4
通讯作者：
Randall, C. A.
中科院分区：
文献类型：
--
作者：
Gurdal, A. Erkan;Tuncdemir, S.;Randall, C. A.
与电磁变压器相比，压电变压器（PT）体积紧凑，效率高。特别地，当多层PT由硬压电陶瓷制成时，它们可以提供效率和更高的功率。然而，硬压电陶瓷通常具有高烧结温度（类似于1200 ℃），这将多层结构的内电极限制为贵金属，例如具有高Pd含量的银钯（Ag/Pd）或铂（Pt）。高Pd含量或Pt显著增加了器件价格，并且它们的电/热性能对于高功率多层应用来说不令人满意。因此，通过利用商业上可获得的硬压电陶瓷（APC 841）开发了两种组合物，并且通过将基本的高功率特性保持在令人满意的水平（机械品质因子类似于1000，平面耦合系数>0.5，并且介电损耗< 0.02），将烧结温度降低到1000 ℃或以下。然后，将环点降压多层PT原型化并相应地与Ag/Pd：90/10电极共烧。PT能够达到30 W cm（-3）（P输出/体积）的输出功率密度水平，效率（P输出/P输入）>96%，温升20 ℃。此外，PT在更高的输出功率水平下进行了测试，并且能够分别在40摄氏度和80摄氏度的温升下产生45 Wcm-3和60 Wcm（-3）。(C)2017爱思唯尔有限公司版权所有
Piezoelectric transformers (PT's) offer high efficiency in compact volumes compared to their electromagnetic counterparts. In particular, multilayer PT's can deliver both efficiency and higher power when they are made of hard-piezoceramics. However, hard-piezoceramics usually have high sintering temperatures (similar to 1200 degrees C), which limit the inner electrode of the multilayer structure to precious metals such as silver palladium (Ag/Pd) with high Pd content or platinum (Pt). High Pd content or Pt increases device price dramatically and their electrical/thermal performances are not satisfactory for high power multilayer applications. Therefore, two compositions were developed by utilizing a commercially available hard-piezoelectric ceramic (APC 841) and sintering temperature-was brought down to 1000 degrees C or belowby keeping essential high power properties at satisfactory levels (mechanical quality factor similar to 1000, planar coupling coefficient >0.5, and dielectric loss < 0.02). Then, ring-dot step-down multilayer PT's were prototyped and co-fired with Ag/Pd:90/10 electrodes accordingly. PT's were able to reach an output power density level of 30 W cm(-3) (P-output/Volume) with >96% efficiency (P-output/P-input) and a 20 degrees C temperature rise. In addition, PT's were tested at higher output power levels and were able to generate 45Wcm-3 and 60 W cm(-3) with a temperature rise of 40 degrees C and 80 degrees C, respectively. (C) 2017 Elsevier Ltd. All rights reserved.