Control Strategy for a 42-V Waste-Heat Thermoelectric Vehicle

A 42-V waste-heat thermoelectric vehicle is employed as a potential application of thermoelectric generators for fuel economy improvement and emissions reduction. The 42-V waste-heat thermoelectric vehicle currently in development employs an assemblage driving system consisting of a waste-heat thermoelectric generator, a 42-V powernet, and an integrated starter and generator (ISG). The waste-heat thermoelectric generator also functions as a power supply. To optimize the utilization of the waste-heat energy generated by the thermoelectric generator, an electric assist control strategy and a torque split control strategy are proposed herein. Through the development of relevant systems and strategies, including the thermoelectric generator and an electric bus system, two vehicle models are established and compared using the ADVISOR platform based on MATLAB/Simulink. The calculation results show improved fuel economy and emissions performance resulting from the integration of the torque split control strategy into the 42-V waste-heat thermoelectric vehicle.     

基于混合优化的车载三轴光电跟踪策略

由于存在一个冗余横倾轴,三轴光电跟踪系统能够解决两轴光电跟踪系统的跟踪盲区问题,实现针对目标的全空间跟踪。针对车载三轴光电跟踪系统,在分析系统运动学特性的基础上,建立了系统的运动学模型,并提出一种基于混合优化算法的车载三轴联动全空间光电跟踪策略。通过对系统运动学模型的研究,分析三轴转动角度之间的关系,从而将三轴转角增量组合的三变量优化问题简化为求解单变量最优问题,然后应用混合优化算法得到最优的三轴角增量组合。仿真和实验结果证明,所设计的三轴跟踪策略可以得到更小的三轴转动角增量组合,能够实现车载三轴光电跟踪系统的三轴联动全空间连续跟踪运动,提高了系统的跟踪性能,具有良好的实际应用价值。     

Geometry Optimization of a Segmented Thermoelectric Generator Based on Multi-parameter and Nonlinear Optimization Method

As no single thermoelectric material has presented a high figure-of-merit (ZT) over a very wide temperature range, segmented thermoelectric generators (STEGs), where the p- and n-legs are formed of different thermoelectric material segments joined in series, have been developed to improve the performance of thermoelectric generators. A crucial but difficult problem in a STEG design is to determine the optimal values of the geometrical parameters, like the relative lengths of each segment and the cross-sectional area ratio of the n- and p-legs. Herein, a multi-parameter and nonlinear optimization method, based on the Improved Powell Algorithm in conjunction with the discrete numerical model, was implemented to solve the STEG’s geometrical optimization problem. The multi-parameter optimal results were validated by comparison with the optimal outcomes obtained from the single-parameter optimization method. Finally, the effect of the hot- and cold-junction temperatures on the geometry optimization was investigated. Results show that the optimal geometry parameters for maximizing the specific output power of a STEG are different from those for maximizing the conversion efficiency. Data also suggest that the optimal geometry parameters and the interfacial temperatures of the adjacent segments optimized for maximum specific output power or conversion efficiency vary with changing hot- and cold-junction temperatures. Through the geometry optimization, the CoSb₃/Bi₂Te₃-based STEG can obtain a maximum specific output power up to 1725.3 W/kg and a maximum efficiency of 13.4% when operating at a hot-junction temperature of 823 K and a cold-junction temperature of 298 K.     

Fabrication of High-Temperature-Stable Thermoelectric Generator Modules Based on Nanocrystalline Silicon

High-temperature-stable thermoelectric generator modules (TGMs) based on nanocrystalline silicon have been fabricated, characterized by the Harman technique, and measured in a generator test facility at the German Aerospace Center. Starting with highly doped p- and n-type silicon nanoparticles from a scalable gas-phase process, nanocrystalline bulk silicon was obtained using a current-activated sintering technique. Electrochemical plating methods were employed to metalize the nanocrystalline silicon. The specific electrical contact resistance ρ _c of the semiconductor–metal interface was characterized by a transfer length method. Values as low as ρ _c < 1 × 10^?6 Ω cm² were measured. The device figure of merit of a TGM with 64 legs was approximately ZT = 0.13 at 600°C as measured by the Harman technique. Using a generator test facility, the maximum electrical power output of a TGM with 100 legs was measured to be roughly 1 W at hot-side temperature of 600°C and cold-side temperature of 300°C.     

基于ADPSS的发电机励磁系统数字物理混合仿真

ADPSS是中国电力科学研究院自主研发的电力系统仿真软件,通过计算机分网并行计算技术,可以实现电力系统的实时仿真及数字物理混合仿真。分析了EXC6000型励磁装置的工作原理.最后将EXC6000型励磁装置与ADPSS进行物理连接,在单机无穷大系统中进行数字物理混合仿真。     

基于GSM的车载图像监控系统

介绍一种采用图像压缩与GSM数字通信技术的车载图像监控系统。该监控系统的车载设备利用数字信号处理器和现场可编程门阵列对运营车辆的乘客完成拍照、图像压缩和存储,并在必要时通过GSM网络向系统控制中心传送乘客经压缩的彩色图像和车辆特征等信息。监控系统的控制中心还可以对运营车辆内部状况进行远程监控。该系统不仅能够提供犯罪嫌疑人的图像,还可以提供适当精度的车辆定位信息。     

Detailed Modeling and Irreversible Transfer Process Analysis of a Multi-Element Thermoelectric Generator System

Thermoelectric (TE) power generation technology, due to its several advantages, is becoming a noteworthy research direction. Many researchers conduct their performance analysis and optimization of TE devices and related applications based on the generalized thermoelectric energy balance equations. These generalized TE equations involve the internal irreversibility of Joule heating inside the thermoelectric device and heat leakage through the thermoelectric couple leg. However, it is assumed that the thermoelectric generator (TEG) is thermally isolated from the surroundings except for the heat flows at the cold and hot junctions. Since the thermoelectric generator is a multi-element device in practice, being composed of many fundamental TE couple legs, the effect of heat transfer between the TE couple leg and the ambient environment is not negligible. In this paper, based on basic theories of thermoelectric power generation and thermal science, detailed modeling of a thermoelectric generator taking account of the phenomenon of energy loss from the TE couple leg is reported. The revised generalized thermoelectric energy balance equations considering the effect of heat transfer between the TE couple leg and the ambient environment have been derived. Furthermore, characteristics of a multi-element thermoelectric generator with irreversibility have been investigated on the basis of the new derived TE equations. In the present investigation, second-law-based thermodynamic analysis (exergy analysis) has been applied to the irreversible heat transfer process in particular. It is found that the existence of the irreversible heat convection process causes a large loss of heat exergy in the TEG system, and using thermoelectric generators for low-grade waste heat recovery has promising potential. The results of irreversibility analysis, especially irreversible effects on generator system performance, based on the system model established in detail have guiding significance for the development and application of thermoelectric generators, particularly for the design and optimization of TE modules.     

基于ADSP-BF561车载多媒体系统

给出一套新的车载多媒体系统设计方案,该系统是基于美国模拟器件公司(AnalogDeviceInc.,ADI)最新发布的ADSP-BF561嵌入式多媒体处理器设计出的支持嵌入式音视频应用,GPS,GPRS,HFCK,网口,USB,CAN总线,I2C控制和海量存储等功能,是功能强大的多媒体系统,尤其适用于车载环境,亦可作为个人数字助理应用。     

Milliwatt-Power Radioisotope Thermoelectric Generator (RTG) Based on Plutonium-238

Results of design and experimental studies aimed at developing a milliwatt-power radioisotope thermoelectric generator (RTG) based on plutonium-238 for space power are considered and analyzed. Milliwatt-power RTGs based on plutonium-238 are completely self-contained electric power sources offering a long proven service lifetime (>15 years) and high reliability. Such electric power sources find application both for space exploration and in terrestrial equipment, especially with the advance of microsystem technologies.     

Effect of Thermoelectric and Electrical Properties on the Cooling Performance of a Micro Thermoelectric Cooler

Active cooling has been studied to prevent microprocessor temperature rise due to hot spots, and a micro thermoelectric cooler is a promising candidate for this spot cooling since it can be used to effectively cool the small area near the hot spot. Numerical analysis has been conducted to determine the effect of thermoelectric and electrical properties on the cooling performance of such a micro thermoelectric cooler. In the cooler considered herein, Bi₂Te₃ and Sb₂Te₃ were selected as the n- and p-type thermoelectric materials, respectively. The thermoelectric column considered was 20 μm thick. The coefficient of performance (COP) and cooling rate were the primary factors used to evaluate the performance of the cooler. Although cooling performance varies with thermal conditions such as thermophysical properties and temperature difference, the present study only focuses on the effect of thermoelectric and electrical properties such as the Seebeck coefficient and electrical resistivity.     

Power-Generation Performance and Durability of a Skutterudite Thermoelectric Generator

By using a p-type (La, Ba, Ga, Ti)₁(Fe, Co)₄Sb₁₂ skutterudite with a dimensionless figure of merit, ZT, = 0.75 at 500°C and an n-type (Yb, Ca, Al, Ga, In)_0.7(Co, Fe)₄Sb₁₂ skutterudite with ZT = 1.0 at 500°C, we fabricated a thermoelectric power-generation module capable of working at high temperatures (up to 600°C). When its hot and cold sides were at 600°C and 30°C, respectively, the power output of a 50 mm × 50 mm × 7.6 mm skutterudite module was 34 W and its thermoelectric conversion efficiency was 8%. In a durability test with the module’s hot and cold sides continuously maintained at 600°C and 80°C, respectively, for 8000 h, power generation first decreased by approximately 6% in the initial 300 h then remained constant.     

基于WAVE的车载通信系统介绍

车载通信网络,由于其在智能交通和车载娱乐方面的广泛应用前景,受到了业界的广泛关注。车载通信具有车辆高速行驶、移动区域受限、网络拓扑变化快、通信过程频繁中断、以及要求私密性等特点。而基于WAVE的应用更容易部署,成本更低,更加符合商业模式,同时WAVE的标准化工作正在顺利进行中,所以关于WAVE的架构及通信过程成为了研究者们首先要关注的问题。     

Hybrid Solid Oxide Fuel Cell and Thermoelectric Generator for Maximum Power Output in Micro-CHP Systems

One of the most obvious early market applications for thermoelectric generators (TEG) is decentralized micro combined heat and power (CHP) installations of 0.5 kWe to 5 kWe based on fuel cell technology. Through the use of TEG technology for waste heat recovery it is possible to increase the electricity production in micro-CHP systems by more than 15%, corresponding to system electrical efficiency increases of some 4 to 5 percentage points. This will make fuel cell-based micro-CHP systems very competitive and profitable and will also open opportunities in a number of other potential business and market segments which are not yet quantified. This paper quantifies a micro-CHP system based on a solid oxide fuel cell (SOFC) and a high-performance TE generator. Based on a 3 kW fuel input, the hybrid SOFC implementation boosts electrical output from 945 W to 1085 W, with 1794 W available for heating purposes.     

基于DDS+PLL技术的高频时钟发生器

针对直接数字频率合成(DDS)和集成锁相环(PLL)技术的特性，提出了一种新的DDS激励PLL系统频率合成时钟发生嚣方案。分析了频率合成系统相位噪声和杂散抑制的方法，介绍了主要器件AD9854和ADF4106的性能。     

System Modeling and Validation of a Thermoelectric Fluidic Power Source: Proton Exchange Membrane Fuel Cell and Thermoelectric Generator (PEMFC-TEG)

To facilitate the co-design and co-optimization of fluid or combustion systems and thermoelectric devices, a three-dimensional (3D) thermoelectric generator (TEG) model has been proposed and implemented in a computational fluid dynamics (CFD) simulation environment. The model includes all temperature-dependent characteristics of the materials and nonlinear fluid–thermal– electric multiphysics coupled effects. In this paper, the device-level model is first extended to the module level by taking a general geometry, identifying regions such as positive and negative thermoelements, and assigning properties to them. The system-level model is then demonstrated by coupling the module-level model with a fluidic–thermal system model in a single CFD simulator to predict the generation performance based on the thermal equilibrium that is achieved. The linked models are validated experimentally at the system level using data from three real thermoelectric modules installed on the surface of an exhaust pipe-like rig, where the temperature profile as well as the electricity generated can be measured and compared with the simulation results. The rig is intended not only to verify the proposed system model but also to mimic a practical exhaust recovery apparatus for a proton exchange membrane fuel cell (PEMFC). Based on the data obtained from the system-level test rig, a novel low-temperature low-cost application for auxiliary electric power appliances based on the waste heat of the PEMFC can be envisaged. Within the common simulator, it is shown that the thermoelectric model can be connected to various continuum-domain CFD models of the fuel cell itself, thus enabling further possibilities to optimize system efficiency and performance.     

一种基于物理噪声源的复合加密算法

 为解决短长度航天器测控数据的安全传输问题,提出了基于物理噪声源、序列密码算法和分组加密算法的复合加密算法CES;分析了CES算法中物理噪声源、序列密码和分组密码算法的作用;指出了序列密码给同长度明文的密文长度加熵、物理噪声源给相同明文的密文形式加熵.CES算法确保了短小指令集传输的安全性并具有安全可靠的认证功能.