基于MEMS技术的直流合成电场传感器研究

DC total electric field has become a major parameter characterizing the electromagnetic environment effects of objects near DC transmission lines, and is also an important consideration factor during DC insulators, cables, GIS equipment designing. Because of the high electric potential and the presence of charged particles, the space field strength is very difficult to measure. The field mill used recently have obvious weakness on reliability, occasion's adaptability and accuracy, cannot used to measure electric field in the space or near other devices. Electric field sensor based on Micro-Electro-Mechanical Systems (MEMS) has advantages such as low electric disturbances, high precision, ease of integration, but has not solve the problem of space charge impact, and the function and signal transmission cannot meet the requirements of high-potential measurements. Based on MEMS and integrated microelectronics technology, this project focuses on the new stand-alone micro total electric field measuring device, adapting to the harsh environments, high intensity fields and whole domain measuring. An Electrically driven micro-machined resonant structure for the strong DC field detection will be designed, as well as the vibrational structure, drive electrodes , detecting electrodes and the sensing electrodes. The electric field formation mechanism in the media excited by the ion flow field under HVDC Transmission Line will be studied. Composite MEMS multi- unit structures and surface charge control structures will be developed, addressing the impact of the ion flow and conducting current on the measurement. The sampling and processing method for the small output current from the structure will be developed, wireless energy supply circuit and signal transmission circuit based on medium-range RF technology will be solved, structure-circuit integrated solutions will be proposed. Based on microelectronic processing technology, the stand-alone chip-level total electric field measurement sensor will be processed and optimized. The results may solve total electric field measurement accuracy and standardization issues，and can be directly applied to the HVDC transmission project construction, EME assessments, online detection and measuring of high-voltage intelligent devices

空间直流合成电场是表征直流输电线路和高压设备电磁环境效应的重要参数。由于电位高且空间存在带电粒子，目前使用的场磨不能测量空间场强。微机电系统（MEMS）电场传感器具有扰动小、精度高、便于集成的优点，但目前还无法解决空间电荷的影响，不能用于直流合成电场测量。本项目基于微机电系统（MEMS）和集成微电子工艺，研究适应复杂、恶劣环境及高强度的全场域、独立式、芯片级直流合成场强传感器。重点研究直流离子流场中介质表面和内部直流电场特性，解决离子流和电磁干扰对测量结果的影响；研究适用于强直流电场检测的电驱动共振式微机械结构，设计复合式多单元MEMS结构和表面电荷控制结构；研究微信号采样和处理电路及基于中程射频技术的无线供能和信号传输电路，提出结构-电路一体化集成技术方案，完成传感器制备和优化。成果将解决空间直流合成场强测量难题，可广泛应用于直流输电系统的电磁环境评估、在线监测和高压智能设备量测。

直流合成电场是高压直流输电线路和直流变电设备设计、运行的关键控制指标，由于电位高且空间存在离子流，线路和设备附近的空间直流合成场强特性复杂，现有手段无法解决在离子流场中脱离参考电位进行自由空间电场测量的难题。微机电系统（MEMS）电场传感器具有扰动小、精度高、便于集成的优点，但同样无法解决空间电荷的影响问题。.本项目基于微机电系统（MEMS）和集成微电子工艺，面向高场强、复杂带电粒子分布的全场域、独立式、芯片级直流合成电场传感器开展研究。研究了直流离子流场中介质表面和内部直流电场特性，考虑空间离子流场域中带电粒子反应机制和介质的电荷附着机理，建立了直流线路下方物体附近三维泊松场分析模型，获得了介质内外部电场特性及导体对空间离子流场的影响规律，发现了离子流场中会产生“电荷空区”现象。.提出了基于合成场、附着电荷以及电荷空区附加场解耦模型的传感方法，设计了适用于强离子流电场的差分式双独立电位隔离复合传感方案；基于力-热-电多场耦合分析方法，分析了结构的振动模态、场路传导和击穿特性、阻尼和能耗特性，设计并提出了基于强制静电驱动结合水平振动侧壁感应结构的MEMS传感器结构方案和技术参数，研发MEMS传感器的芯片微机械结构。针对大深度SOI埋氧层释放难题，研发了起伏表面真空辅助旋涂聚酰亚胺工艺，建立了背面释放悬空结构的保护方法，提出了面向MEMS传感器的加工工艺并完成加工。.研究了传感器的信号处理、供能和信号传输技术。提出了基于中程射频技术的能量-数据复合传输结构，设计研发了高增益微型天线；提出了面向极微弱信号的处理电路结构方案；设计了前端结构-后端电路的集成技术方案和工艺流程。.针对离子流电场的特殊性，设计实现了隔离式直流电场校准系统，搭建了离子流环境下直流合成电场测试平台；依托特高压直流试验线段，测试分析了合成电场的分布规律及环境参数的影响。.成果可解决空间直流合成场强测量难题，可用于直流输电系统的电磁环境评估和高压设备在线监测，也可内嵌于电力设备和可穿戴设备中实现电场测量。