锯齿型压电梁的电响应分析

压电振子的工作频带宽度是影响压电振动能量收集器发电效率的关键指标。该文旨在分析一种锯齿型阵列式压电振动能量收集器结构模态频率,为压电振子的动力学设计提供参考。首先,基于弹性梁振动理论,推导了锯齿型压电梁的动力学方程,并分析了影响压电梁模态频率的因素。然后,通过COMSOL建立锯齿形压电梁的有限元模型,分析了其频响特性、功率与负载阻抗匹配特性及加速度依赖性。最后,通过实验研究测试了锯齿型压电梁的电压幅频特性曲线,验证了理论分析与仿真模拟结果的合理性。结果表明,锯齿型阵列式压电振动能量收集器能够有效地拓宽工作频带,进而提高发电效率。     

压电能量收集器的研究现状

压电能量收集器是能量转换的核心器件之一,其性能的好坏直接决定输出能量的大小及能量转换效率的高低。综述了压电能量收集器的组成部分和各个方面:压电材料、器件结构及振动模式的特性、应用状况和存在的问题,分析了各部分的优缺点,并对压电能量收集器的研究方向作了展望。     

关于钹式压电复合换能器基阵的研究

研究了钹式压电复合换能器平面均匀串联基阵及并联基阵的等静压压电性能。钹式压电复合换能器平面均匀基阵具有1－3连通型复合结构的性能特点。连接阵元的基体材料是影响换能器基阵的等静压压电性能的关键,基体越柔软实测值与理论值越接近。钹式压电复合换能器平面均匀串联基阵及并联基阵的等效等静压压电常数及等效等静压灵敏值与阵列 单个钹式换能器的相同。     

基于钹式压电阵列的新型引信发电装置设计

设计了一种基于钹式压电换能器阵列的新型引信用发电装置,使用等静压压电常效法研究了钹式换能器及其阵列的发电特性,分析了发电装置在弹药发射环境下的电能输出特性.研究结果表明,该发电装置能有效收集发射环境中的冲击能,并将其先转换为振动能再转换为持续的电能,延长了压电换能器的电能输出时间,解决了现有引信压电电源电能输出小,供电时间短等问题.     

多模态下压电振动能量收集器的等效电路仿真

结合有限元分析法和电子电路分析法建立了多模态下压电振动能量收集器与交流-直流（AC-DC）非线性负载电路相连接的等效电路仿真模型。利用有限元分析软件ANSYS确定了压电能量收集器的等效电路参数,根据这些等效电路参数,在PSPICE软件中建立了非线性负载电路条件下压电振动能量收集器的等效电路仿真模型,并实现了其输出电压和功率的快速仿真。仿真结果表明,等效电路仿真模型可得非线性负载电路条件下压电振动能量收集器的输出电压和功率,而这是单独使用ANSYS软件完全不能解决的。这为多模态下压电振动能量收集器的电能预测提供了一种简便而有效的分析方法,更为解决任意复杂非线性负载电路条件下压电振动能量收集器的输出电能预测打下了基础。     

组合压电材料发电性能及力学特性研究

采用组合式压电材料的方法优化调节压电式能量收集器中压电结构的发电性能、刚度及振动特性,并在PZT-5H的单晶压电片中引入压电材料PZT-51与PVDF,通过调整组合形式改变了压电结构的机械刚度,通过模态分析优化了压电结构的振动特性。结果表明：合理的组合形式能够充分发挥压电材料的力电性能,提高压电能量收集器对复杂工作场景的适应性。引入压电材料PZT-51可以有效提高压电能量收集器的刚度;引入压电材料PVDF可以有效调节压电结构的一阶特征频率,在54～115 Hz范围内进行优化,有助于调节压电能量收集器的性能参数。     

一种应用于TPMS的梯形阵列式能量收集器

基于汽车运动过程,研究了宽车速范围的微型振动能量收集器,提出了一种应用于胎压监测系统(TPMS)的梯形阵列式压电振动能量收集器。在优化固有频率的情况下,对能量收集器的结构参数进行了仿真优化设计。仿真结果表明,在最优结构参数下,车速范围为80~120 km/h时,能量收集器的输出功率范围为1 620~9 600 μW。该能量收集器可以工作在较宽车速范围,输出功率高。这为TPMS的无线供电提供了新的设计思路。     

一种圆弧螺旋压电能量收集器

为了降低谐振频率,实现多方向收集和提高输出性能,提出了一种4π圆弧螺旋压电能量收集器。通过分析器件尺寸与输出性能之间的关系来提高器件性能,将优化后的模型进行COMSOL仿真,分析振动位移、应力以及谐振频率。相对于2π圆弧螺旋压电能量收集器,4π圆弧螺旋压电能量收集器具有更低的谐振频率和更高的输出电压。4π圆弧螺旋压电能量收集器的谐振频率为48 Hz,输出电压达到12.3 V,输出功率达到400μW。     

一种基于防震锤的新型压电复合能量收集方法

为了解决智能电网环境下输电线有害振动与工况检测传感器的供电及续航问题,该文设计了一种压电式振动与磁场复合能量收集的防震锤。防震锤的主压电梁收集输电线振动能量,副压电梁通过安装磁铁收集输电线电流产生的变化磁场能量,摆脱了传统收集磁场能量时线圈的使用。对收集器进行有限元仿真分析与实验测试。结果表明,收集器工作频带更宽,比传统的单梁输出高54%,主压电悬臂梁最大输出功率可达到874 μW,副压电梁最大功率可达到683 μW。     

可穿戴式筒壳型压电能量收集器的研究与设计

针对可穿戴设备电源的供电及续航问题,采用了筒壳结构的压电能量收集器.探究了可穿戴筒壳结构压电能量收集器俘能的本质,并提出结构优化设计方案.首先指出筒壳结构的承载能力和初始能量与厚度成正比,且随着跨度的增大而减小;其次通过有限元仿真研究了基底和聚偏二氟乙烯(PVDF)压电薄膜尺寸与应力、应变的关系,指出PVDF的尺寸应尽...     

城市综合管廊智能井盖监测系统与移动特征提取模型

为解决城市井盖丢失形成的“陷阱”问题,文中基于地磁场检测的原理,提出了一种多传感器数据融合的智能井盖监控系统及移动特征提取方法。首先构建了智能井盖监控系统,实现了智能井盖监测数据的分布式采集;其次基于模糊推理方法提出了智能井盖多传感器移动特征提取模型;最后,利用COMSOL软件对井盖移动引起的地磁场强度变化进行了仿真。结果表明,文中提出的方法可以实现对智能井盖的位置监测,且结果准确、易于使用     

High-performance online UPS using three-leg-type converter

A high-performance single-phase online uninterruptible power supply (UPS) is proposed. The UPS is composed of a three-leg-type converter which operates as a battery charger and an inverter. The first leg is controlled to charge the battery, and the third leg is controlled to make the output voltage. The common leg is controlled in line frequency. The charger and the inverter are controlled independently. The charger has the capability of power-factor correction while charging a battery. The inverter regulates output voltage and limits output current under an impulsive load. The three-leg-type converter reduces the number of switching devices. As a result, the system has less power loss and a low-cost structure. In the determination of the charger voltage, the nominal voltage is derived using the feedback linearization concept and then a perturbed voltage is determined for the reactive power control. The disturbance of input voltage is detected using a fast sensing technique of the input voltage. Experimental results obtained with a 3-VA prototype show a normal efficiency of over 87% and an input power factor of over 99%.     

城市窨井盖远程监控系统

本文从现代城市中重要的公共基础设施管理现状入手,通过对城市窨井盖远程监控管理系统建设意义的分析,对城市窨井盖远程监控管理系统进行了解决方案的研究、关键技术的研究,深入分析了城市窨井盖远程监控管理系统在物联网应用中的重要意义.     

Energy-efficient digital and wireless IC design for wireless smart sensing

Wireless smart sensing is now widely used in various applications such as health monitoring and structural monitoring. In conventional wireless sensor nodes, significant power is consumed in wirelessly transmitting the raw data. Smart sensing adds local intelligence to the sensor node and reduces the amount of wireless data transmission via on-node digital signal processing. While the total power consumption is reduced compared to conventional wireless sensing, the power consumption of the digital processing becomes as dominant as wireless data transmission. This paper reviews the state-of-the-art energy-efficient digital and wireless IC design techniques for reducing the power consumption of the wireless smart sensor node to prolong battery life and enable self-powered applications.     

High-Performance Transformerless Online UPS

In this paper, a high-performance single-phase transformerless online uninterruptible power supply (UPS) is proposed. The proposed UPS is composed of a four-leg-type converter, which operates as a rectifier, a battery charger/discharger, and an inverter. The rectifier has the capability of power-factor collection and regulates a constant dc-link voltage. The battery charger/discharger eliminates the need for the transformer and the increase of the number of battery and supplies the power demanded by the load to the dc-link capacitor in the event of the input-power failure or abrupt decrease of the input voltage. The inverter provides a regulated sinusoidal output voltage to the load and limits the output current under an impulsive load. The control of the dc-link voltage enhances the transient response of the output voltage and the utilization of the input power. By utilizing the battery charger/discharger, the overall efficiency of the system is improved, and the size, weight, and cost of the system are significantly reduced. Experimental results obtained with a 3-kVA prototype show a normal efficiency of over 95.6% and an input power factor of over 99.7%.      

太阳能最大功率机械跟踪系统的设计

针对太阳能光伏电池光电转换效率低的问题,设计了一套太阳能机械跟踪系统装置。以STC12C5A60S2单片机为核心控制器,通过闭环双轴跟踪调整电池板姿态角,使之垂直接收太阳光线,提高电池板方阵的输出功率。编写上位机软件,通过无线蓝牙实现远程通信,完成系统状态监控和数据记录的功能。实验结果表明,该装置能稳定跟踪太阳运行轨迹,从而有效提高太阳能光伏板的输出功率,具有较高的实用价值。     

A constant-power battery charger with inherent soft switching and power factor correction

A battery charging circuit, which operates as a constant power source, is proposed in this paper. By maintaining a constant output power throughout the charging process, the circuit reduces the size of thermal installation which would normally be required in the cases of constant-voltage or constant-current charging. The proposed circuit takes the form of a half-bridge converter with an additional small inductor and two extra diodes connected in parallel to two dividing capacitors. Constant power delivery is achieved by the discontinuous-voltage-mode operation of the two dividing capacitors, each of which is connected in parallel with a diode. The circuit enjoys low voltage and current stresses, and achieves soft switching with no extra components. When used off-line, the converter maintains a high input power factor and a low level of input current harmonic distortion that meets international regulations. All the above characteristics are determined only by the values of the circuit parameters, the control mechanism being noncritical. A 12 V 65 W prototype was built to demonstrate the merits of this circuit.     

A TEG Efficiency Booster with Buck–Boost Conversion

A thermoelectric generator (TEG) efficiency booster with buck–boost conversion and power management is proposed as a TEG battery power conditioner suitable for a wide TEG output voltage range. An inverse-coupled inductor is employed in the buck–boost converter, which is used to achieve smooth current with low ripple on both the TEG and battery sides. Furthermore, benefiting from the magnetic flux counteraction of the two windings on the coupled inductor, the core size and power losses of the filter inductor are reduced, which can achieve both high efficiency and high power density. A power management strategy is proposed for this power conditioning system, which involves maximum power point tracking (MPPT), battery voltage control, and battery current control. A control method is employed to ensure smooth switching among different working modes. A modified MPPT control algorithm with improved dynamic and steady-state characteristics is presented and applied to the TEG battery power conditioning system to maximize energy harvesting. A 500-W prototype has been built, and experimental tests carried out on it. The power efficiency of the prototype at full load is higher than 96%, and peak efficiency of 99% is attained.     

Accurate Power Loss Model Derivation of a High-Current Dual Active Bridge Converter for an Automotive Application

An accurate power loss model for a high-efficiency dual active bridge converter, which provides a bidirectional electrical interface between a 12-V battery and a high-voltage (HV) dc bus in a fuel cell car, is derived. The nominal power is 2 kW, the HV dc bus varies between 240 and 450 V, and the battery voltage range is between 11 and 16 V. Consequently, battery currents of up to 200 A occur at nominal power. In automotive applications, high converter efficiency and high power densities are required. Thus, it is necessary to accurately predict the dissipated power for each power component in order to identify and to properly design the heavily loaded parts of the converter. In combination with measured efficiency values, it is shown that conventional converter analysis predicts substantially inaccurate efficiencies for the given converter. This paper describes the main reasons why the conventional method fails and documents the different steps required to predict the power losses more accurately. With the presented converter prototype, an efficiency of more than 92% is achieved at an output power of 2 kW in a wide input/output voltage range.      

一种超低功耗锂离子电池保护电路设计

基于减少锂离子电池能量的额外损耗,本文设计了一款超低功耗锂离子电池保护电路。本电路不仅可以对锂离子电池进行全面有效的保护,而且实现了低功耗。利用MOSFET的亚阈值导电特性,使电路消耗的电流小于3μA;并且芯片在检测到过放电时进入到休眠状态,此时电路消耗的电流仅为0．2μA左右,大大减少了不必要的能量损耗。