This paper presented a novel ultrasonic wireless power link (UWPL) to provide power supply for embedded condition monitoring of enclosed metallic structures, where recharging or replacing batteries can be problematic. Two piezoelectric transducers are adopted to establish the wireless power links, within which one transducer is used to generate ultrasonic waves and the other is to receive the transferred ultrasonic energy and to energize the associated embedded condition monitoring units. A power management solution is established to regulate the receiver output into a constant voltage suitable for sensing application. A theoretical model was established to understand the UWPL dynamics and to analyze the energy budget balance between the UWPL and the sensing power demands. A finite element model was built to validate the proposed idea. The UWPL was then experimentally implemented using two piezoelectric transducers and tested in aluminium plates with different thickness. A power management sub-system was developed and tested for sensing applications. An output power of 1.73 mW was obtained on a 1.5 k$\mathrm{\Omega }$ resister with the input voltage of 15 V at 42.6 kHz through a 6 mm-thick aluminium plate. Sufficient power can be transferred over a large distance via metallic structures, showing the capability in implementing battery-free condition monitoring of enclosed metallic structures, such as petroleum pipelines, engines, and aluminium airframe.

本文提出了一种新颖的超声波无线电源链路（UWPL），可为封闭的金属结构的嵌入式状态监视提供电源，在这种情况下，充电或更换电池可能会出现问题。采用两个压电换能器建立无线电力链路，其中一个换能器用于产生超声波，另一个换能器接收转移的超声能量并为相关的嵌入式状态监视单元供电。建立了电源管理解决方案，以将接收器输出调节为适合于传感应用的恒定电压。建立了一个理论模型来理解UWPL动态，并分析了UWPL和感测功率需求之间的能量预算平衡。建立了一个有限元模型来验证所提出的想法。然后，使用两个压电换能器对UWPL进行了实验，并在具有不同厚度的铝板上进行了测试。开发了电源管理子系统，并针对传感应用进行了测试。在1.5 k的功率下获得1.73 mW的输出功率$\mathrm{\Omega }$电阻通过6mm厚的铝板在42.6 kHz的频率下具有15 V的输入电压。可以通过金属结构在足够长的距离上传输足够的功率，这显示了对封闭的金属结构（如石油管道，发动机和铝制机身）实施无电池状态监测的能力。