一种ZVZCS交错并联Boost变换器

提出了一种ZVZCS交错并联Boost变换器。在所提辅助电路的帮助下所有开关管均实现了零电压关断,同时变换器通过电感电流断续导通模式使得所有开关管均实现了零电流导通,各个二极管也均实现了零电流关断,显著降低了由开关管和二极管引起的损耗,变换器整体的工作效率得到了提高。最后,对所提变换器的工作原理及性能特点进行了详细分析,并通过搭建输出功率为200 W的实验样机对理论分析进行了实验验证。     

温差电器件低温余热发电的实验研究

本文报道以常见低温热源做能源，通过温差电技术使之转换为电能的技术途径及样机的研制，并通过对样机性能的测试对这种发电方式的社会与经济效益的初步分析评估。     

多输入交错并联Boost变换器功率分配控制策略

针对功率分配底层功能提出一种新型控制策略,该控制策略在传统的双闭环平均电流均流法上加以改进。首先电流内环修改为功率内环,将电压外环的输出除以输入电压再乘以功率分配系数作为新的功率给定值来实现功率分配功能。同时将自抗扰技术应用到电压外环提高母线电压的响应速度。最后基于模块化思想并利用氮化镓功率开关器件,搭建一台三输入交错并联Boost实验样机,其额定功率为1500 W,额定工作频率为500 kHz,峰值效率为98.3%。实验验证结果表明,在相同输入电压或不同输入电压的情况下均能实现功率分配功能,并具有良好的动态响应。     

半导体温差发电技术在铝电解槽中的应用研究

介绍了铝电解槽的结构与散热特点,通过计算侧部散热量及测试槽壁热流密度与温度,对温差发电技术在铝电解过程中的应用可行性进行研究。根据电解槽结构特点和温差发电的要求,设计加工温差发电装置,并在电解槽上进行现场实验,对发电装置的输出功率、热电转换效率进行测试计算。数据表明,温差发电在铝电解中应用是可行的,为铝电解过程的节能探索一条新途径。     

温差发电技术及其一些应用

简要地介绍了温差发电的原理,热电材料方面的研究进展,并对这一技术的应用现状作了综述,指出作为利用热电转换材料将热能转化为电能的绿色发电技术,温差发电技术正引起越来越多的关注。     

基于温差发电技术的空调冷凝器余热利用系统

本文项目基于半导体温差发电技术,针对压缩式空调的外机散热进行余热回收利用,将热能转换为电能,利用蓄电池进行存储。所设计的系统将温差发电系统安装在空调外机排风口,利用排风口温度与发电系统低温端之间的温差进行发电,发电量利用导线引出到电能处理单元,对蓄电池进行充电。该项目的设计是将空调冷凝器的余热回收再利用,这为减少空调能源损耗提供了一条可行性道路,具有很高的实用性和可靠性。     

温差发电技术及其在节能领域的应用

温差发电技术是利用热电转换材料直接将热能转化为电能的发电技术,具有无运动部件、体积小、重量轻、移动方便和可靠性高等特点,是绿色环保的发电方式。随着能源与环境问题的日益突出,温差发电技术在节能领域的应用日新月异,它是合理利用太阳能、地热能、海洋温差、余热和废热等热能转换为电能的有效方式。     

在极端工况下Boost电路的光伏MPPT可靠性分析

Boost电路是最常用的进行光伏最大功率点追踪(MPPT)的阻抗变换电路,但在高太阳辐照度和低太阳辐照度工况下,存在无法实现光伏MPPT的情况。针对该问题,通过对Boost电路进行工作原理理论分析和实际应用分析,开展了在极端工况下Boost电路的光伏MPPT可靠性研究,并通过实验证明了特殊工况会造成Boost电路光伏MPPT的不可靠性,最后根据研究结果有针对性地给出了解决Boost电路存在问题的建议。研究结果表明：基于Boost电路的光伏MPPT会受限于3个主要因素：一是脉冲宽度调制(PWM)信号的极限占空比;二是Boost电路的阻抗变换范围受到所带负载大小的影响;三是Boost电路能够实现的最大升压比。在低太阳辐照度下,Boost电路带大负载时与光伏组件内阻的匹配效果不佳;在高太阳辐照度下,Boost电路带小负载时与光伏组件内阻的匹配效果不佳。     

融合最大功率点追踪的光伏发电功率全局控制研究

不确定自然环境因素的影响下,光伏发电输出功率的非线性特征增加了其控制难度,导致新能源发电的利用率偏低。为解决该问题,基于最大功率点追踪技术,提出光伏发电功率全局控制新方法。结合辐照强度、光照温度等外界条件,建立光伏发电模型。利用均匀光照下的最大功率点追踪方法,构建比例因子对追踪动态响应速度的影响模型。在光照不均匀条件下,将单峰值非线性特征曲线转变为多峰值非线性特征曲线,求解多峰值非线性特征的全局最大值问题,利用蚁群算法选取高信息素路径作为最优解,实现发电功率全局控制。采用simulink软件构建光伏发电仿真模型,分析不同辐照强度条件下的光伏发电功率控制效果。经实验验证,所提方法能够适应多辐照强度与变化辐照强度等条件,提升了新能源利用率与新能源发电的效益回报,具备投入实践应用的条件。     

热电偶技术及其温差直接发电的应用分析

温差直接发电技术是一种基于塞贝克效应直接将热能转化为电能的新型发电技术。从热电偶的工作原理入手,讨论利用热电偶产生电能时影响发电性能指标的相关因素,分析国内外相关技术的研究状况及其发展趋势。     

Evaluation of thermoelectric modules for power generation

A procedure is developed to assess the potential of thermoelectric modules when used for electrical power generation. The generating performance of a thermoelectric module is evaluated in terms of its power output, conversion efficiency and reliability, while the potential for improving its performance is investigated based upon the power-per-area, cost-per-watt and manufacture quality factor. The methods employed in determining these parameters are described and used to evaluate several commercially available modules. The results show that a thermoelectric module is a promising device for low temperature waste heat recovery.     

The potential impacts of climate-change policy on freshwater use in thermoelectric power generation

Climate change policy involving a price on carbon would change the mix of power plants and the amount of water they withdraw and consume to generate electricity. We analyze what these changes could entail for electricity generation in the United States under four climate policy scenarios that involve different costs for emitting CO₂ and different technology options for reducing emissions out to the year 2030. The potential impacts of the scenarios on the U.S. electric system are modeled using a modified version of the U.S. National Energy Modeling System and water-use factors for thermoelectric power plants derived from electric utility data compiled by the U.S. Energy Information Administration. Under all the climate-policy scenarios, freshwater withdrawals decline 2–14% relative to a business-as-usual (BAU) scenario of no U.S. climate policy. Furthermore, water use decreases as the price on CO₂ under the climate policies increases. At relatively high carbon prices (>$50/tonne CO₂), however, retrofitting coal plants to capture CO₂ increases freshwater consumption compared to BAU in 2030. Our analysis suggests that climate policies and a carbon price will reduce both electricity generation and freshwater withdrawals compared to BAU unless a substantial number of coal plants are retrofitted to capture CO₂.     

一种功率因数校正电路在LED驱动器上的应用研究

论述了功率因数校正的原理,讨论了功率因数校正的一些方法,提出了一种应用于LED驱动器的新型功率因数校正电路.试制了一个用于100 W LED驱动电路的功率因数校正样机,实验表明,该样机的功率因数大于0.99,电流总谐波小于6％.     

Design and analysis of solar thermoelectric power generation system

This article reports on the design and performance analysis of a solar thermoelectric power generation plant (STEPG). The system considers both truncated compound parabolic collectors (CPCs) with a flat receiver and conventional flat-plate collectors, thermoelectric (TE) cooling and power generator modules and appropriate connecting pipes and control devices. The design tool uses TRNSYS IIsibat-15 program with a new component we developed for the TE modules. The main input data of the system are the specifications of TE module, the maximum hot side temperature of TE modules, and the desired power output. Examples of the design using truncated CPC and flat-plate collectors are reported and discussed for various slope angle and half-acceptance angle of CPC. To minimize system cost, seasonal adjustment of the slope angle between 0° and 30° was considered, which could give relatively high power output under Bangkok ambient condition. Two small-scale STEPGs were built. One of them uses electrical heater, whereas the other used a CPC with locally made aluminum foil reflector. Measured data showed reasonable agreement with the model outputs. TE cooling modules were found to be more appropriate. Therefore, the TRNSYS software and the developed TE component offer an extremely powerful tool for the design and performance analysis of STEPG plant.     

Parametric study of asymmetric thermoelectric devices for power generation

Thermoelectric devices are considered a promising technique for recycling waste heat. In the present work, a three-dimensional numerical model is developed to study the output performance of thermoelectric devices. A comprehensive analysis is performed based on a conventional π-type thermoelectric couple. The results indicate that the maximum power of thermoelectric devices generally increases with a decrease in height and an increase in cross-sectional area; the maximum efficiency exhibits the opposite trends. The best way to reduce heat losses is by using ceramic plates with higher thermal conductivity. Moreover, the parasitic internal resistance exists in the thermoelements, and its influencing factors are studied. To minimize electric losses, an asymmetric structure is proposed for thermoelectric devices. The results exhibit that the optimal cross-sectional area ratio of the p-type and n-type legs (S_p/S_n) is mainly contingent upon the thermoelectric material parameters; the greater the differences in the parameters of p-type and n-type thermoelectric materials, the greater the gains provided by the asymmetric structure. Furthermore, the experimental data present great consistency with the numerical results. The research results may help guide the design of thermoelectric devices with relatively lower power losses.     

Design optimization of thermoelectric devices for solar power generation

We present an improved theoretical model of a thermoelectric device which has been developed for geometrical optimization of the thermoelectric element legs and prediction of the performance of an optimum device in power generation mode. In contrast to the currently available methods, this model takes into account the effect of all the parameters contributing to the heat transfer process associated with the thermoelectric device.The model is used for a comparative evaluation of four thermoelectric modules. One of these is commercially available and the others are assumed to have an optimum geometry but with different design parameters (thermal and electrical contact layer properties).Results from the model are compared with experimental data of the commercial thermoelectric module in power generation mode with temperature gradient consistent with those achievable from a solar concentrator system. These show that it is important to have devices optimized specifically for generation, and to improve the contact layer of the thermoelements accordingly.     

Electric power generation by super-adiabatic combustion in thermoelectric porous element

A new system for converting combustion heat into electric power was proposed on the basis of reciprocating-flow super-adiabatic combustion in a catalytic and thermoelectric porous element. Self-sustaining combustion of an extremely low-calorific gas was successfully achieved in the element; because a reciprocating flow in the porous element recirculated energy, effectively regenerating combustion gas enthalpy into an enthalpy increase in the low-calorific gas. In the combustion system, a trapezoidal temperature distribution was established along the flow direction, resulting in a steep temperature gradient in the thermoelectric porous element. Numerical simulation showed that 94% of the combustion heat was transferred through the thermoelectric element by conduction. As a result, the total thermal efficiency, which was defined as the ratio of the electric power generated to the combustion heat, attained a value close to the conversion efficiency of the thermoelectric device itself.     

A novel maximum power point tracker for thermoelectric generation system

In this paper, a novel hybrid maximum power point tracking (MPPT) method is proposed and investigated. The proposed MPPT technique combines the simplicity of perturb and observe (P&O) method and the fast tracking ability of open circuit voltage (OCV) method. The advantages of the proposed MPPT approach include fast tracking speed, no additional circuit required and no temporary power loss. To validate the feasibility of the proposed MPPT technique, an 1.2 kW thermoelectric generation system for industrial waste heat recovery is also constructed, experimental results show that comparing with conventional P&O technique, the proposed method can improve the tracking speed for 42.9% and 86.2% when temperature differences are ΔT = 60 °C and ΔT = 180 °C, respectively. Moreover, the energy loss can be improved by 24.0% and 87.0% when temperature differences are ΔT = 60 °C and ΔT = 180 °C, respectively.     

Mathematic simulation on power generation by roll cake type of thermoelectric double cylinders

Analytical expression of electric power was deduced in case of the large-scale thermoelectric device that consists of the cylindrical double tubes like roll cake and is exposed to the two thermal fluids. The output powers of 16 systems were mathematically described by the simultaneous equations based on heat exchange. The temperature profiles in the device depend on the flow directions of hot and cold fluids, but the flow directions did not change the output power. Resultantly, eight sets of solutions for the output power were deduced. The maximum output power was the largest in the two systems (V2CC-I and V2CC-II system), where two fluids flow in counter directions and one of the fluids goes into the system from the inside of the inner cylinder. These chosen systems can generate the thermoelectric power equivalent with the single cylinder system (V1C system) using only 36% material of V1C.