基于LC-L补偿的UPT系统设计

无线电能传输（Wireless Power Transmission,WPT）技术近年来在电气工程领域得到了广泛的应用。基于超声波的无线电能传输（Ultrasonic Power Transfer,UPT）技术，主要是利用发射和接收换能器，把能量从发射端传送到接收端。超声波方向性强、能量集中，可以在空气、水、金属等各种介质中传播，因此，基于超声波的无线电能传输技术具有很好的应用前景。基于此，研究在UPT系统中通过加入LC-L补偿结构来实现系统调谐和阻抗匹配，通过仿真和实验，验证基于LC-L补偿的UPT系统可以实现更高的传输效率。     

超声调制的声频定向传输指向性分析

音频信号的指向性要求是声频定向传输系统的根本要求。使用单个超声波换能器很难达到指向性要求,需要使用超声波换能器阵列。超声换能器阵列的参数性质在一定程度上决定了声频定向传输的指向性。本文通过详细的理论推导与计算,分析了影响超声调制的声频定向传输指向性的相关参数。通过分析计算得到,声频定向传输指向性与超声波换能器阵列排列形式、换能器阵列中各个振元的间距、振元个数以及载波频率等有关。在设计声频定向传输系统时需要结合实际要求,综合考虑定向传输的指向性和传输效率选择载波频率和设计超声波换能器阵列。     

超声调制的声频定向传输指向性分析

音频信号的指向性要求是声频定向传输系统的根本要求。使用单个超声波换能器很难达到指向性要求,需要使用超声波换能器阵列。超声换能器阵列的参数性质在一定程度上决定了声频定向传输的指向性。本文通过详细的理论推导与计算,分析了影响超声调制的声频定向传输指向性的相关参数。通过分析计算得到,声频定向传输指向性与超声波换能器阵列排列形式、换能器阵列中各个振元的间距、振元个数以及载波频率等有关。在设计声频定向传输系统时需要结合实际要求,综合考虑定向传输的指向性和传输效率选择载波频率和设计超声波换能器阵列。     

超声波在换能器接触界面传播的特性研究

在研究超声换能系统的过程中发现,系统存在非线性特性.引起超声波非线性的主要因素是换能器子结构接触界面上传递的不连续造成的.该文对超声波在超声键合换能器中的传播为研究对象,建立了超声波在单一均质材料和两种材料接触界面传递的一维数学模型,并采用机械动力学软件进行了仿真,推导出界面预紧力和超声波传播的关系,并试验测试了超声换能器在不同预紧力条件下,换能器换能杆末端振动速度和键合强度的变化规律.为超声键合换能器系统的设计、安装和维护提供了可靠依据.     

超声耦合无线电能传输用发射换能器优化设计

针对超声耦合无线电能传输系统研究的需要,对水下超声耦合无线电能传输系统发射换能器进行选型,确定换能器类型及工作频率。基于夹心式纵振压电换能器一维设计理论对发射换能器进行优化设计,在深入分析圆锥形前盖板延展系数对换能器振速比和等效机电耦合系数影响的基础上,选取的延展系数能同时兼顾换能器振速比和等效机电耦合系数均为较优值,并据此进一步确定换能器全部结构尺寸。实际测试结果表明,试制的发射换能器实际谐振频率为38.552 kHz,等效机电耦合系数为0.149,满足实际需要。     

磁耦合谐振式无线电能传输技术新进展

随着科学技术的发展和进步,近些年来,无线电传输技术已经受到广泛的关注和应用。磁耦合谐振式无线电能传输是一种新型的无线电能传输方式,传输的距离为几十厘米,传输的效率高达85%以上。磁耦合谐振式无线电能传输技术集合多种学科技术,达到安全、高效和便捷的电能传输过程。本文通过对无线电能传输技术的介绍,对磁耦合谐共振式无线电能传输技术进行简述。     

无线电能传输装置的设计与分析

无线电能传输是借助于电磁场或者电磁波进行能量传输的一种技术。电能给人类带来巨大的发展和便利,然而错综复杂的输电线分布在生活的各个角落,既不美观又不方便,因此人类一直想要摆脱电线的束缚而能够实现电能无线传输的梦想。本文章介绍了无线电能传输的几种方式,并通过比较他们的利与弊,选择最合适的方式,以追求最大的利益。     

无线电能传输中能量与信息的优化研究

现阶段,研究与分析无线电能和信息同步传输系统的相关文献摘要关注的实现方式,而无线电能的传输系统信息和能量之间的关系及优化方案分析研究比较少。若是无线电能和信息传输系统的信道容量以及传输效率遭受限制,就必须对信道容量进行优化。文章主要对信道容量遭受限制时,制定了传输效率优化对策,同时也对传输效率遭受影响时信道铜梁的优化进行了研究。     

基于Leach模型的空气耦合超声换能器声阻抗匹配特性研究

压电陶瓷与空气之间的声阻抗差异巨大，导致声波在固-气介质间的能量传输效率低，研究匹配层特性对提升换能器能量传输效率具有重要意义。文章通过Leach模型仿真，研究了空气耦合超声换能器阻抗与瞬态响应，并搭建实验平台进行测试验证。仿真和实验结果表明，增加一层匹配层可将接收信号幅值增大约280%,增加两层匹配层可将接收信号幅值增大约363%。通过采用经声阻抗匹配后的换能器对碳纤维板缺陷进行检测，能明显检测出深度为0.5 mm、直径为1 mm凹槽缺陷的变化，验证了通过等效电路模型研究换能器匹配特性方法的有效性。     

磁耦合谐振式无线电能传输系统建模与分析

磁耦合谐振式无线电能传输技术具有传输距离中等、传输效率高、能穿过非磁导性障碍物传输电能等优点,使其有望取代电池为物联网中的传感器节点无线供电。本文通过研究磁耦合谐振式无线电能传输机理,构建了传输系统的集总参数电路模型,对各模型参数进行了理论计算,并根据模型对不同传输距离下系统的传输效率与负载功率进行了分析,得出了不同耦合状态下系统获得最大负载功率的条件。     

水位自动监测系统的研究与设计

利用超声波技术设计了一种多从结构的水位自动监测系统,系统主要由数据中转站和水位数据采集终端两部分组成。水位采集终端通过超声波方式采集水位,将采集的水位数据通过无线传输给数据中转站,然后由数据中转站发送至远程终端。实验表明,系统能够实现水电站水位监测和数据传输功能,且系统具有传输数据精度高和无线传输及远程监控的能力。     

基于微加速度计的无线教鞭的设计

为弥补多媒体教学中激光笔的不足,提出了一种基于微加速度计的无线教鞭系统,它不仅具有激光笔上下翻页的功能,而且能在空中自由灵活移动实现高精度点击的功能,该系统以微加速度计ADXL345作为信号检测元件,并采用低功耗低成本微控制器AT89S52和RF芯片nRF24L01进行信息处理与无线传输,符合人体工程学设计,最大限度地满足人们使用鼠标时在手感以及舒适度和使用习惯方面的要求。     

基于超声波的水下无线能量传输初探

近年来,无线能量传输已成为一个热点的应用研究方向,而围绕水下机器人,水下探测器等特殊目标的无线供电方式研究却鲜有报道。对基于超声波共振方式的水下无线能量传输的原理、可行性进行了初步的分析探讨,给出了实现的原理框图及实现方式。通过理论推导重点分析了传输效率和传输功率与频率、距离的关系。研究表明当选取超声波传输频率20 k Hz时,在距离40 m以内可达到10%以上的传输效率,具有一定的实际应用价值。     

Selection of maximum power transfer region for resonant inductively coupled wireless charging system

In order to uphold the maximum power transfer in a resonant inductively coupled wireless power transfer system, an operating region has been proposed based on the coupling coefficient, frequency and electric load. The effectiveness of the proposed condition has been examined both theoretically and experimentally. The obtained results are in well agreement with each other. It has been seen that the operating frequency region is different for different electric loads corresponding to the coupling coefficient between the transmitter and receiver coils of the resonant inductive link. The operating frequency region shifts to lower frequency side for lower value of electric load at larger value of coupling coefficient even maintaining the optimum power transfer. The obtained knowledge reveals the design modus operandi through which an effective wireless charging system can be intended not only for low power device applications but also for high power EV charging.     

Metasurface Patch for Wireless Power Transfer in Implantable Devices

Wireless power transfer (WPT) systems enable the long-term operation and miniaturization of implantable devices by eliminating the need for battery replacement and wired power supplies. Although wireless power transfer systems for implantable devices are extensively studied, their practical application is still challenging owing to the constraints and requirements of the human body, such as reflection loss owing to differences in the tissue dielectric properties, mm-sized devices, and electromagnetic (EM) wave attenuation of the tissue. Here, a phase-gradient metasurface patch is presented to achieve 5.8 GHz EM power focusing at a focal point of depth 10 mm in the tissue via EM wavefront modulation at the skin–air interface. The proposed metasurface patch is fabricated by arranging subwavelength-thickness (<λ/10) unit cell structures composed of four metallic layers separated by dielectric substrates that exhibit high-Q resonance properties and a sufficient phase modulation range with enhanced transmission. By applying the fabricated metasurface patch to a wireless power transfer system for implantable devices, it is experimentally confirmed that the transmission coefficient (S₂₁) is improved by 6.37 dB compared with that of a wireless power transfer system without the metasurface patch. Furthermore, it is confirmed that the transmission coefficient can be maintained for an incident angle variation up to 30° from the transmitter to the metasurface patch, resulting in a stable power delivery of the proposed wireless power transfer system.     

Single frequency wireless power transfer and full-duplex communication system for intracranial epilepsy monitoring

Current clinical neural recording methods which employ wired connections to the external world can be improved by eliminating the wires thanks to integrated circuit and microsystems technology. This study presents design and implementation of such a system which performs wireless power transfer and data transmission for intracranial epilepsy monitoring. Proposed system provides power to the implant by inductive coupling. Full-duplex communication is also performed at the same frequency as the power transfer. Consequently, a system which can transfer power from 10 mm distance with 30% efficiency has been realized. The system supports 400 kbps uplink communication while downlink communication is performed with 1 kbps at the same time. Design challenges for uplink communication in terms of energy-per-bit and interaction between uplink and downlink communication have been discussed in detail to give an insight about the design trade-offs for a full-duplex communication system superposed on a wireless power transfer link.     

应用于流场测量的激光高频空气超声声光偏转效应

研制了适用于产生空气超声相位光栅的大功率高频超声换能器，采用位移灵敏接收器，在换能器发射面前方适当位置加声匹配器以加强声场干涉提高发射方向性，获得了明显的激光空气超声声光偏转效应。可应用于风洞试验中测量空气旋涡流场参量．     

ROF系统中单边带光载OFDM信号传输性能研究

研究了一种光纤无线通信系统中用单边带产生光载波并传输的OFDM-ROF方案.将2Gbit/s的OFDM信号与10GHz的射频信号混频驱动电光调制器,产生单边带调制信号,调制后的信号经光纤传输至基站,通过光电转换后再进行无线传输.实验证实,2Gbit/s的基带OFDM信号在10GHz-ROF系统中通过光纤传输200km后不经无线传输,其功率代价仅为1dB.不经过光纤仅经过8m无线传输后功率代价大约只有0.3 dB.产生的信号既经过200km光纤传输又经过8m无线传输后接收星座图也很好.     

Multifunctional High‐Power Sources for Smart Contact Lenses

Powering an electrical contact lens is a significant challenge for wearable applications such as augmented reality displays and iontophoretic drug delivery to the eye. Here a hybrid power generation device is developed comprising a wireless power transfer system and a bioabsorbable metal–air primary battery, which provides a multifunctional direct current (DC) and/or alternating current (AC) output. The DC power is generated by Zn loop anode and a bilirubin oxidase (BOD) biocathode in an artificial tear. The Zn‐based loop anode is also used as the antenna of a wireless power transfer system that results in high power transfer efficiency of 17.6% at 13.56 MHz. The wireless‐powered AC voltage is boosted from 1.5 to 1.5 V + 0.5 V_pp by a DC offset, enabling red light‐emitting diode (LED) emission. Furthermore, the hybrid AC and DC offset voltages are boosted to 2.3 V + 0.5 V_pp by a capacitive booster circuit that provides blue LED emission. No hydrogen evolution or pH change is observed in the tear electrolyte. The present hybrid power source can potentially power wearable electronics in body fluids.