基于静电纺丝法制备P(VDF-TRFE) /石墨烯(GR)薄膜的柔性复合压电纳米发电机

提出了一种利用静电纺丝工艺制备P(VDF-TRFE)/石墨烯(Graphene,以下简称GR)复合纳米纤维薄膜的方法并对其压电性能进行了研究。首先,以复合薄膜为功能层设计并制备了柔性压电纳米发电机。使用扫描电镜(SEM)表征了复合纤维薄膜表面的微观形貌。其次,对各纳米发电机样品进行了压电响应对比实验,含0.2%石墨烯的P(VDF-TRFE)/GR纳米发电机的开路输出电压、短路输出电流峰值分别为12.3 V、1.41 μA,比纯P(VDF-TRFE)样品分别增加了大约2.0倍、2.2倍。此外,通过理论分析和周期激振测试探究了纳米发电机电响应输出的影响因素和规律,证实在激振器驱动信号150 mV^300 mV振幅、10 Hz^30 Hz频率的范围内,其开路输出电压随着其振幅和振动频率增大而增大,电容充电效率随其振幅增大而增大。     

MEMS结构中碳纳米管的电泳沉积及其场发射特性研究

利用电泳沉积的方法在MEMS结构特定位置上组装碳纳米管薄膜,以此作为发射体研制基于碳纳米管场发射的传感器,并对其场发射进行了测试和分析.电镜观测与场发射实验结果表明,利用电泳沉积方法可以只在MEMS结构的特定位置沉积碳纳米管薄膜,对于4μm的发射间隙、该薄膜的场发射开启电压约为3.6V～4V,发射电压20V时的发射电流可至28μA.这种“post-MEMS“的碳纳米管薄膜组装方法具有工艺简单的特点,同时避免了碳纳米管生长对MEMS工艺环境以及器件的污染、破坏,实现了纳米材料组装与MEMS工艺的兼容.     

基于钳位电路的碳纳米管薄膜声源系统优化

碳纳米管薄膜是一种由碳原子组成的新型纳米材料,可被制作成一种基于热致发声效应的扬声器。针对碳纳米管薄膜电-热-声系统的频率失真问题,提出添加钳位电路的解决方法,并进行了理论研究和实验验证。结果表明,加入钳位电路后,系统输出的声波频率与输入电压频率变为一致,且声能量显著增大,声压级提高约5 d B。与传统叠加直流偏置电压的方法相比,无需直流电源,降低了系统功耗。     

基于BTO／CNTs复合压电薄膜制备

介绍了一种新型的钛酸钡／碳纳米管（BTO／CNTs）压电薄膜的制备方法及其特性研究,利用BTO纳米颗粒、CNTs和聚二甲基硅氧烷（PDMS）作为原材料,采用改进的sol—gel法制备出厚度均匀的复合薄膜,使用油浴极化法在一定条件下对复合薄膜极化。并利用SEM表征制备复合薄膜的掺杂效果,发现CNTs的加入加快了电子的转移速率。在周期性的外力作用下,发现其电压输出波形符合阻尼振荡模型,并测试不同配比下复合薄膜的压电电压输出,得出最佳BTO／CNTs质量比为10：l时,薄膜的输出电压最高可达4V。     

交错并联三绕组耦合Buck变换器设计

针对传统交错并联Buck变换器存在占空比小的问题,将三绕组耦合电感引入反激变换器,设计了一种交错并联三绕组耦合Buck变换器。分析了该变换器中开关管和输出二极管的电压应力,进而得到该变换器的输出电压增益,并对该变换器拓扑进行了优化。仿真和实验结果表明,该优化拓扑可有效抑制开关管两端的电压波动,降低开关管的电压应力。     

控制风力发电蓄电系统并联Boost电路

同步发电机在低风速时输出电压较低,无法达到蓄电池的额定电压值,因此,对一种适用于风力发电蓄电的带耦合电感并联Boost电路进行了研究。通过将耦合电感与Boost电路相结合,建立了控制风力发电蓄电系统电路。阐述了Boost电路的原理,设计了三段式充电电路的控制方法。Matlab仿真结果表明,相对于传统Boost电路,该电路很好地降低了输入电流的波纹,同时能够有效提高蓄电池的使用寿命。     

基于高压静电纺丝法制备P(VDF-TrFE)/ZnO/GR复合膜压电性能的研究

提出了一种利用高压静电纺丝法制备P(VDF-TrFE)/ZnO/Graphene(以下简称GR)复合纳米纤维薄膜的方法，并对其压电性能进行了研究。首先，利用扫描电镜（SEM）观测复合薄膜的表面形貌并分析其X射线衍射（XRD）图谱。其次，将薄膜封装为三明治结构的压电纳米发电机(PNG)并研究了其压电性能。结果表明，含10%ZnO、0.1%GR的P(VDF-TrFE)/ZnO/GR复合薄膜压电纳米发电机开路输出电压和短路输出电流峰值为12.6V、7.88μA，约是纯P(VDF-TrFE)薄膜的2.7倍、3.1倍。在激振力大小3.5N，频率为5HZ的条件下P(VDF-TrFE)/ZnO/GR压电纳米发电机的最大瞬时输出功率为33.85μW，持续激振21分钟后，LTC3588-1毫微功率能量收集电源可以稳定输出3.3V电压1.5s。P(VDF-TrFE)/ZnO/GR压电纳米发电机具有良好的压电性能，具有成为自供电设备的潜力。     

基于励磁绕组回路特性的发电机充电耦合电路设计

针对励磁发电机在发动机启动瞬间易造成充电过程中发电机输入轴断裂等充电故障,拟采用对发电机输出电压和蓄电池的端电压进行采样耦合等手段,设计耦合型充电辅助电路,并串接于原充电链路中,按照一定的耦合条件对发电机的负载进行通断控制,从而实时采样监控并保护发电机和蓄电池的双重作用,减少发动机启动瞬间发电机输入轴断裂引起的充电故障,样机经实际验证使用,在发动机启动瞬间样机可有效控制发电机的负载通断,从而达到预期效果,为类励磁发电机的输入轴断裂故障提供一种解决思路和方案。     

MEMS薄膜热流传感器研制

基于微加工技术设计制备了一种微机电系统(MEMS)薄膜热流传感器。采用COMSOL软件,对不同结构参数MEMS薄膜热流计进行仿真模拟,通过对仿真结果对比和分析,优化热流传感器的设计参数。根据优化的设计参数利用MEMS工艺制备薄膜热流计。搭建了标定系统,对所制备的MEMS薄膜热流计进行性能测试和标定。实验结果表明:薄膜热流计的电压输出响应曲线的变化趋势和仿真结果一致,此外,薄膜热流计的输出电压和热流密度呈良好的线性关系。     

基于DSP的离网型永磁同步发电机电压调节器

针对目前离网型永磁同步发电机输出电压不稳定及难以调节的问题,先将输出电压整流成直流电压,再将直流电压逆变为交流电压输出。逆变电路采用SPWM算法,并以DSP作为控制核心。经过整流、逆变后,发电机的输出电压稳定,并且能对输出电压方便地进行调节。     

Wireless sensor node powered by aircraft specific thermoelectric energy harvesting

An energy autonomous wireless sensor system consisting of an energy harvesting power source, an energy management unit and a low power wireless sensor node is tested for aircraft applications. The autonomous power source combines aircraft specific outside temperature changes with a thermoelectric generator (TEG) and a heat storage unit. The temperature difference generated with the latter component artificially at the TEG is used to power the sensor node by thermoelectricity. Additionally, a high efficient low input voltage power management circuit is necessary to store the generated energy and to convert it to higher voltage levels needed to operate the sensor. The experimental data are compared with results from numerical simulation models to predict the energy conversion in the heat storage - TEG system. A new TEG prototype is tested and the energy output is improved by 14%. The power management storage capacitors are adapted to the available energy, thereby increasing storage voltage and conversion efficiency. Doing so, the efficiency of the complete system can be increased by around 50%.     

Micro solar energy harvesting using thin film selective absorber coating and thermoelectric generators

The use of a nanometer-scale solar selective absorber coating to enhance the performance of a thermoelectric generation (TEG) module in solar thermal energy harvesting is presented. The thin film coating is fabricated by electrochemical deposition of a bimetallic layer of tin and nickel on copper substrate. The coating has a dendrite structure with grain size of 100 nm. Testing indicates the ability of these collectors to transform incident radiation into thermal energy. The collectors utilizing the selective coating achieved a final temperature 10 °C higher than the baseline copper device. More importantly, the coating demonstrates the ability to collect and transmit over 90 % of the available heat flux. The harvested thermal energy is applied to drive a TEG module for useful power generation. The device utilized with selective absorber coating shows an output power 4.5 times more than the baseline device. Overall area of the collector plate is 16 cm².     

基于传热理论的热电能量转换系统集成分析

热电能量转换系统可实现热能和电能的直接转换。在一个完整的热电系统中,热电器件与冷热端换热器组成热阻网络,该热阻网络与冷热源之间的换热对系统性能具有决定性影响。该文从网络节点间的耦合传热关系出发,分析了外部换热对系统内部温度分布的影响,得到了实际热环境中热电系统输出性能的近似理论表达式。在此基础上,该文建立了外部换热条件与系统峰值输出功率的直接关系,并提出一套热电能量转换系统设计策略,可用于热电发电系统的快速设计。     

Maximum Power Extraction Control Algorithm for Hybrid Renewable Energy System

In this research, a modified fractional order proportional integral derivate (FOPID) control method is proposed for the photovoltaic (PV) and thermoelectric generator (TEG) combined hybrid renewable energy system. The faster tracking and steady-state output are aimed at the suggested maximum power point tracking (MPPT) control technique. The derivative order number (µ) value in the improved FOPID (also known as PI^λD^µ) control structure will be dynamically updated utilizing the value of change in PV array voltage output. During the transient, the value of µ is changeable; it’s one at the start and after reaching the maximum power point (MPP), allowing for strong tracking characteristics. TEG will use the freely available waste thermal energy created surrounding the PV array for additional power generation, increasing the system’s energy conversion efficiency. A high-gain DC-DC converter circuit is included in the system to maintain a high amplitude DC input voltage to the inverter circuit. The proposed approach’s performance was investigated using an extensive MATLAB software simulation and validated by comparing findings with the perturbation and observation (P&O) type MPPT control method. The study results demonstrate that the FOPID controller-based MPPT control outperforms the P&O method in harvesting the maximum power achievable from the PV-TEG hybrid source. There is also a better control action and a faster response.     

利用环境余热供电的无线温度测量系统设计

无线测量节点的供电是无线测量系统在实际应用中受限制的主要问题之一.为解决此问题提出了一种收集工业生产现场环境余热并转换成电能为无线测量节点供电的方法.设计了由多个无线温度测量节点和一个Sink节点组成的无线温度测量系统.无线温度测量节点以CC2530为核心处理器,用热电偶测量温度,节点电源由能量收集模块供给.能量收集模块用热电片收集环境余热,以LTC3109为核心构成电源管理模块从而获得3.3 V输出电压.设计了上位机软件实时显示和保存Sink节点收到的各测温节点的温度数据.实验表明,在一定环境条件下能量收集模块可以为无线温度测量节点提供工作电源,为无线测量节点供电提供了一种参考解决方案.     

Simulation of maximum power in the wearable thermoelectric generator with a small thermopile

Miniature thermopiles that could be fabricated by using modern thin- and thick-film technologies are discussed as a power supply to wearable devices. The maximum power that can be produced by a thermopile of a medium-to-small size was simulated in case of typical thermal properties of humans and their living environment. The local thermal resistances of human being required for the simulation were obtained experimentally. The designs of wearable thermoelectric generators are discussed. The general design optimization of wearable thermoelectric energy harvester with a miniature thermopile was performed in case of near-maximum power generated per unit volume of thermoelectric generator. The obtained performance characteristics allow prediction of the application area for wearable energy harvesters of human body heat and the perspectives of their market success.     

Carbon emission impact on the operation of virtual power plant with combined heat and power system

A virtual power plant (VPP) can realize the aggregation of distributed generation in a certain region, and represent distributed generation to participate in the power market of the main grid. With the expansion of VPPs and ever-growing heat demand of consumers, managing the effect of fluctuations in the amount of available renewable resources on the operation of VPPs and maintaining an economical supply of electric power and heat energy to users have been important issues. This paper proposes the allocation of an electric boiler to realize wind power directly converted for supplying heat, which can not only overcome the limitation of heat output from a combined heat and power (CHP) unit, but also reduce carbon emissions from a VPP. After the electric boiler is considered in the VPP operation model of the combined heat and power system, a multi-objective model is built, which includes the costs of carbon emissions, total operation of the VPP and the electricity traded between the VPP and the main grid. The model is solved by the CPLEX package using the fuzzy membership function in Matlab, and a case study is presented. The power output of each unit in the case study is analyzed under four scenarios. The results show that after carbon emission is taken into account, the output of low carbon units is significantly increased, and the allocation of an electric boiler can facilitate the maximum absorption of renewable energy, which also reduces carbon emissions from the VPP.     

A radio frequency and vibration energy harvesting antenna based on piezoelectric material

This article proposes a novel hybrid energy harvesting antenna that can be used to harvest radio frequency (RF) and vibration energy in ambience. A microstrip antenna is designed on the piezoelectric film with the material of polyvinylidene fluoride (PVDF). Due to the high dielectric constant of PVDF, the antenna size can be reduced efficiently. The shape of designed microstrip antenna is trapezoidal, the final antenna size is reduced to 50 mm × 30 mm × 0.2 mm. To improve the efficiency, the rectifier with matching network is optimized and the modes of the piezoelectric film are analyzed. The experimental results show that the frequency bandwidth of the antenna is 2.1 to 2.5 GHz. For a RF source at distance of 1 m away, with a 0.25 W EIRP 2.4 GHz transmitter, the output power of the antenna can reach 17.2 μW. While under 17 Hz vibration excitation, the output voltage and power can reach 1.44 V and 15.3 μW, respectively.     

基于柔性基底的压电能量收集器的设计

以PDMS为柔性基底设计的PVDF压电薄膜新型压电能量收集器压电性能良好,柔韧性强,可适应复杂的振动环境,具有广阔的应用前景.首先设计了具有柔性基底的压电能量收集器的结构;其次,用PVDF颗粒采用静电纺丝法制备了PVDF压电薄膜;最后,实验表明设计的压电能量收集器在振动频率为25 Hz,振动幅度为2 mm的激励下,开路输出峰值电压为8.38 V,输出功率密度为6.32 μW/cm2;经Ansys有限元分析,发现增大激励源的振动幅度,可以提高压电能量收集器的开路输出电压和输出功率.     

New thermoelectric components using microsystem technologies

This paper describes the first thermoelectric devices based on the V-VI-compounds Bi/sub 2/Te/sub 3/ and (Bi,Sb)/sub 2/Te/sub 3/ which can be manufactured by means of regular thin film technology in combination with microsystem technology. Fabrication concept, material deposition for some 10-/spl mu/m-thick layers and the properties of the deposited thermoelectric materials will be reported. First device properties for Peltier-coolers and thermogenerators will be shown as well as investigations on long term and cycling stability. Data on metal/semiconductor contact resistance were extracted form device data. Device characteristics like response time for a Peltier-cooler and power output for a thermogenerator will be compared to commercial devices.