The Virtual Continuous TEG Model: Efficient Optimization of Thermogenerators

Dimensioning a thermoelectric generator for vehicle applications poses major challenges. Besides the fundamental process of determining the layout, an optimization procedure is necessary to harness the maximum potential from a thermoelectric system under given boundary conditions. The thermal boundary conditions encountered in this application are not constant. In this context, a multichannel thermogenerator shows benefits by distributing individual mass flows in relation to the operating point maximizing power output across the entire range of operating points. The innovative approach underlying the continuous thermogenerator model supports the process of global optimization. The parameters to be optimized are configured as dimensionless variables. The model not only guarantees very short computation times but also maintains high quality. The optimization method is presented in detail using an example of searching for an optimum material layout, variable fin geometry, and variable leg height across and along the direction of gas flow. The materials or material combinations to be analyzed are lead and bismuth telluride. The heat exchanger has a reference geometry. The article describes the combination of dimensionless optimization parameters that provides the greatest increase in thermoelectric power output compared with the basic concept. The discussion concludes with a cost–benefit analysis of the measures chosen.     

Development of Low-Cost Remote-Control Generators Based on BiTe Thermoelectric Modules

This paper presents a new thermogenerator based on moderate-temperature (up to 175°C) BiTe modules available on the open market. Despite this handicap relative to commercial thermogenerators based on high-temperature proprietary-technology PbBi modules (up to 560°C), this new design may become economically competitive due to its innovative thermal sink. Our thermal sink is based on a free-convection water loop built with standard tubing and household hot-water radiators, leading to a more practical, modular design. So, the specific cost of about 55,000 USD/kW obtained for this 120-W prototype is improved to 33,000 USD/kW for a 1-kW unit, which represents about half the price of commercial thermogenerators. Moreover, considering recently launched BiTe modules (that withstand up to 320°C), our proposition could have an even more favorable outlook.     

Novel Heat Controller for Thermogenerators Working on Uncontrolled Stoves

This paper describes the development of a thermogenerator designed for uncontrolled firewood household stoves. It was built on BiTe thermoelectric (TE) modules, and it uses a water pot as a cooling device that also serves as a hot water source. An original heat controller was developed; it has low thermal resistance (R) during low-power operation, but its R can be continuously increased according to the stove temperature so that the TE never overheats while its power generation is optimized.     

One-Dimensional Modeling of Thermogenerator Elements with Linear Material Profiles

Graded and segmented thermoelectric elements have been studied for a long time with the aim of improving the performance of thermogenerators that are exposed to a large temperature difference. However, it has been shown that simply adjusting the maximum figure of merit ZT in each segment of a stacked or graded thermoelectric (TE) element is not a sufficient strategy to maximize thermoelectric device performance. Global optimization of a performance parameter is commonly based on a one-dimensional continua-theoretical model. Following the proposal by Müller and coworkers, the temperature profile T(x) can be calculated within a model-free setup directly from the one-dimensional (1D) thermal energy balance, e.g., based on continuous monotonic gradient functions for all material profiles, and independent and free variability of the material parameters S(x), σ(x), and κ(x) is assumed primarily, where S is the Seebeck coefficient, and σ and κ are the electrical and thermal conductivities, respectively. Thus the optimum current density can be determined from the maximum of the global performance parameter. This has been done up to now by means of numerical procedures using a 1D thermoelectric (TE) finite-element method (FEM) code or the algorithm of multisegmented elements. Herein, an analytical solution of the 1D thermal energy balance has been found for constant gradients, based on Bessel functions. For a constant electrical conductivity but linear profiles S(x) and κ(x), first results for the electrical power output of a thermogenerator are presented.     

Power analysis and minimization techniques for embedded DSPsoftware

Power is becoming a critical constraint for designing embedded applications. Current power analysis techniques based on circuit-level or architectural-level simulation are either impractical or inaccurate to estimate the power cost for a given piece of application software. In this paper, an instruction-level power analysis model is developed for an embedded digital signal processor (DSP) based on physical current measurements. Significant points of difference have been observed between the software power model for this custom DSP processor and the power models that have been developed earlier for some general purpose commercial microprocessors. In particular, the effect of circuit state on the power cost of an instruction stream is more marked in the case of this DSP processor. In addition, the processor has special architectural features that allow dual memory accesses and packing of instructions into pairs. The energy reduction possible through the use of these features is studied. The on-chip Booth multiplier on the processor is a major source of energy consumption for DSP programs. A microarchitectural power model for the multiplier is developed and analyzed for further power minimization. In order to exploit all of the above effects, a scheduling technique based on the new instruction-level power model is proposed. Several example programs are provided to illustrate the effectiveness of this approach. Energy reductions varying from 26% to 73% have been observed. These energy savings are real and have been verified through physical measurement. It should be noted that the energy reduction essentially comes for free. It is obtained through software modification, and thus, entails no hardware overhead. In addition, there is no loss of performance since the running times of the modified programs either improve or remain unchanged     

Photovoltaic module reliability model based on field degradation studies

Crystalline silicon photovoltaic (PV) modules are often stated as being the most reliable element in PV systems. This presumable high reliability is reflected by their long power warranty periods. In agreement with these long warranty times, PV modules have a very low total number of returns, the exceptions usually being the result of catastrophic failures. Up to now, failures resulting from degradation are not typically taken into consideration because of the difficulties in measuring the power of an individual module in a system. However, lasting recent years PV systems are changing from small isolated systems to large grid‐connected power stations. In this new scenario, customers will become more sensitive to power losses and the need for a reliability model based on degradation may become of utmost importance. In this paper, a PV module reliability model based on degradation studies is presented. The main analytical functions of reliability engineering are evaluated using this model and applied to a practical case, based on state‐of‐the‐art parameters of crystalline silicon PV technology. Relevant and defensible power warranties and other reliability data are obtained with this model based on measured degradation rates and time‐dependent power variability. In the derivation of the model some assumptions are made about the future behaviour of the products—i.e. linear degradation rates—although the approach can be used for other assumed functional profiles as well. The method documented in this paper explicitly shows manufacturers how to make reasonable and sensible warranty projections. Copyright © 2008 John Wiley & Sons, Ltd.     

一种改进型Gysel功率分配／合成器的设计

为了获得带宽更宽、隔离度更好的功率分配／合成器,通过对Gysel功分器拓扑结构的改进,提出一种新型的功率分配／合成器;给出它的拓扑结构和设计参数,用奇偶模分析法分析了其工作原理,并借助微波CAD软件对该结构和Gysel功分器进行了对比分析。结果表明,该功率分配／合成器比传统的Gysel功分器具有更宽的带宽、更高的隔离度、以及更小的回波损耗。最后,设计并制作了C波段四路功分器并进行验证,测试结果表明其性能指标符合预期要求。     

High Seebeck Coefficient in Mixtures of Conjugated Polymers

A universal method to obtain record‐high electronic Seebeck coefficients is demonstrated while preserving reasonable conductivities in doped blends of organic semiconductors through rational design of the density of states (DOSs). A polymer semiconductor with a shallow highest occupied molecular orbital (HOMO) level‐poly(3‐hexylthiophene) (P3HT) is mixed with materials with a deeper HOMO (PTB7, TQ1) to form binary blends of the type P3HT_x:B_1‐x (0 ≤ x ≤ 1) that is p‐type doped by F₄TCNQ. For B = PTB7, a Seebeck coefficient S = 1100 µV K^?1 with conductivity σ = 0.3 S m^?1 at x = 0.10 is achieved, while for B = TQ1, S = 2000 µV K^?1 and σ = 0.03 S m^?1 at x = 0.05 is found. Kinetic Monte Carlo simulations with parameters based on experiments show good agreement with the experimental results, confirming the intended mechanism. The simulations are used to derive a design rule for parameter tuning. These results can become relevant for low‐power, low‐cost applications like (providing power to) autonomous sensors, in which a high Seebeck coefficient translates directly to a proportionally reduced number of legs in the thermogenerator, and hence in reduced fabrication cost and complexity.     

移动环境视频编码功率-码率-失真模型研究

在前期建立视频编码动态功耗模型的基础上,将功率因子引入到经典率失真理论,并对经典码率模型及失真模型进行修正,进而建立视频编码功率-码率-失真模型.实验结果表明,该模型具有较高的精确性,为实现功耗约束条件下视频质量、带宽、功耗达到动态平衡的最优提供理论指导.     

基于最佳功率给定的永磁直驱同步风力发电系统控制策略研究

直驱型风力发电系统由于不需要增速箱,在风电场中得到广泛的发展和应用.该文研究了发电机和风机的特性分析,提出了基于最佳功率给定的最大风能控制策略,该方法通过对发电机进行闭环控制,使输出功率按照最优功率曲线进行输出,实现最大风能跟踪.并研究了永磁直驱风电系统的双PWM变流器控制策略;搭建了直驱型风电机组整体模型,该系统能够实现并风能最大功率跟踪及并网控制,仿真验证了控制系统的正确性.     

基于神经网络的宽带功放动态非线性行为建模

文章主要讨论了如何利用神经网络对宽带功放进行动态非线性行为建模的问题。首先简述了功放的动态非线性特性及行为建模的方法。然后回顾了基于实数时延前馈神经网络、径向基函数神经网络等浅层神经网络构建的功放动态非线性行为模型。在此基础上,针对5G/6G宽带功放具有更强的记忆效应的问题,重点分析了如何使用长短期记忆(LSTM)神经网络对功放的动态非线性进行精确的行为建模。最后展望了构建具有普适性的功放非线性行为模型将是5G/6G通信时代功放非线性建模的一个重要发展方向。     

An adaptive digital predistortion for compensating nonlinear distortions in RF power amplifier with memory effects

In this paper, an adaptive digital predistortion based on a memory polynomial model is proposed in order to linearize the power amplifier with memory effect. The coefficients of the power amplifier model have been extracted using a least square method and those of predistortion have been identified by applying an indirect learning structure. Finally, the performance of digital predistortion has been demonstrated using the simulation of the power amplifier and the digital predistortion excited by a modulated 16 QAM signal in Matlab software. According to the simulation results, the criterion of adjacent channel power ratio (ACPR) declined by around 15 dB and the input/output power spectrum density of the power amplifier has quite similar curves. The linearized power amplifier output spectrum demonstrates the superiority of the proposed predistorter in eliminating the spectral regrowth which is caused by the memory effect in comparison to the other linearization methods.     

Power-Conditioning Circuitry for a Self-Powered System Based on Micro PZT Generators in a 0.13-$muhbox{m}$ Low-Voltage Low-Power Technology

The concept and design of a power-conditioning circuit for an autonomous low-power System-in-Package (SiP) is presented in this paper. The SiP's main power source is based on the use of micropiezoelectric generators. The electrical model of the power source, which has been obtained based on experimental measurements and implemented on Cadence Analog Artist's Spectre simulation environment, is explained. The model has been used to simulate the power source with the power-conditioning electronics over the entire design process. Finally, the simulated and experimental results of the developed integrated power circuits, which are formed by a rectifier and a low-power bandgap reference voltage source to define the threshold voltage for the closed-loop regulation process, are also shown. These circuits have been designed using a commercial 0.13-$muhbox{m}$ technology from ST Microelectronics through the Multi-Projects Circuits (CMP) Techniques of Informatics and Microelectronics for Integrated Systems Architecture (TIMA) service.      

功耗分析攻击中的功耗与数据相关性模型

在对密码设备进行功耗分析攻击时,攻击者需要建立密钥或者与密钥关联的数据值与被攻击设备的功耗相关性模型,藉此通过对功耗的分析破解出敏感信息。从攻击者的角度对器件功耗物理特性分析的基础上,重构了汉明距离模型和汉明重量模型,并从理论上证明了汉明重量模型的正确性,并建立起MCU功耗采集平台,验证了汉明重量模型的有效性和实用性。     

基于PWM整流器的功率控制器的仿真研究

文章研究了一种基于PWM整流器的功率控制器。由三相电压型整流器在三相静止坐标系中的数学模型,导出其在两相旋转坐标系的数学模型,并在此基础上引入了基于电网电压前馈解耦的三相PWM整流器控制系统,实现对于有功电流和无功电流的单独控制,从而达到对于有功、无功功率控制的目的。     

DFP算法在CDMA移动通信上行链路功率控制中的应用研究

本文提出了一种基于DFP算法的功率控制方案。详细研究了该方案在CDMA移动通信中,进行融合基站分配的上行链路功率控制的应用理论。首先导出了最小发送功率控制模型。而后,提出了用DFP算法求解该模型的原理框图,并分析了用该方案进行最小发送功率控制的基本理论和实际性能,探讨了该方案中进行一维搜索的方法。最后用计算机仿真法模拟出该方案的运行性能。结果表明与最小功率控制算法相比,DFP功率控制算法可以提高基站接收信号的平均信扰比,降低信扰比的平均偏差,减小信扰比低于目标信扰比一定比例的用户数量,从而可以降低用户信号的中断概率、提高信道容量。     

基于电费异常的潜在投诉风险预警方法

针对利用传统方法发现电力用户电费异常已经难以满足维权意识越来越强的电力用户需求的问题,本文基于大数据技术和智能算法开展电力用户电费异常的潜在风险挖掘。本文首先介绍了大数据挖掘技术的数据异常分析理论;其次,基于FCM算法和电量分析法建立了电力用户电费异常数学模型;最后,通过具体算例验证了本文所建立的基于FCM智能算法和电量分析法建立电力用户用电电费异常数学模型可以实现电力用户电费异常潜在风险的挖掘,从而有效的避免不必要的投诉风险,对于提升电力公司的服务水平和服务质量具有十分重要的意义。     

柴油发电机组-脉冲负载系统运行行为仿真

柴油发电机组-整流器供电系统是重要的移动装备电源形式,可作为重要工程的备用电源,也可作为直流微电网的重要支撑电源。脉冲负载集成了大量电力电子器件,是一类功率波动明显且切换频繁的负载形式,以含大功率收发组件的数字式雷达为代表。在脉冲负载工作过程中,线路中电流与电压呈强烈非线性,系统动态过程复杂,难以运用解析方法表示柴油发电机组内部的机电过渡过程与电磁暂态。文中建立了基于Matlab/ Simulink 的系统模型,分析了脉冲负载在不同工作模式时,柴油发电机组输出电压与频率的瞬态和稳态指标,结果表明:该模型能够较真实地反映柴油发电机组-整流器-脉冲负载系统的运行行为。     

Monte Carlo simulation of arsenic ion implantation in (100)single-crystal silicon

In this paper is reported a new physically based Monte Carlo model and simulator for accurate simulation of arsenic ion implantation in (100) single-crystal silicon. A new damage generation model and an improved electronic stopping power model have been developed. These new physically based models greatly improve the capability for predicting arsenic as-implanted profiles. This new Monte Carlo model predicts very well the detailed profile dependence on the implant tilt and rotation angles as well as on the implant dose and energy over the energy range 15-180 keV     

Power Reduction Technique in Coefficient Multiplications Through Multiplier Characterization

This paper presents a multiplier power reduction technique for low-power DSP applications through utilization of coefficient optimization. The optimization is implementation dependent in that the multipliers are assumed to be designed in either ASIC or full-custom architectures for general purpose multiplication. The paper first describes a model characterizing the power consumption of the multiplier. Then the coefficient optimized made based on this model. This methodology is applicable to multiplications requiring a large set of coefficients and random data sets. We can accurately estimate the actual power dissipation of the multipliers using the characterization technique. The coefficient optimization based on the power model can save as much as 34.02%.