温差发电系统电能变换及能量匹配技术研究

发布时间：2018-10-29 16:00

【摘要】：废热的耗散带来能源的浪费。近年来,各种对废热能量进行收集的技术逐渐出现。温差发电技术就是一种能将废热转变为电能的技术,具有安静环保、吸热降温等优点,可用在电力电子器件散热等领域,在增强散热的同时,利用废热所产生的温差发出电能。作为一种新型的能源利用与散热技术,温差发电技术越来越受到企业和学术界的关注。温差发电片作为温差发电的基本元件,其输出电压受温差影响,具有不确定性,无法直接供给负载。同时温差发电系统作为一种独立发电系统,有着固有的能量失配问题。针对上述问题,本文设计了一种恒电压输出变换器,利用闭环控制实现恒电压输出,供给负载稳定的电能;在功率分析的基础上设计了能量匹配系统,利用功耗匹配单元,实现了能量匹配,改善了系统的散热效果。本文具体的研究工作有:首先,为了更好地设计合适的变换器,利用热电物理效应理论建立了温差发电片热电模型。又在实验研究和数据拟合基础上,研究了温差发电片的输出特性,根据此特性,建立了温差发电片的等效电路模型。该模型能反映出温差发电片中的电路参数与温差和负载之间的关系。在此基础上,为了获得恒定的电压来供给负载,设计了低压启动的恒电压输出变换器,能够在较大的输入电压和负载变化范围内实现电压闭环输出。为了快速应对温度变化带来的输入电压波动,变换器采用前馈-反馈控制方式。同时,针对温差发电系统作为独立供电系统固有的能量失配问题,建立了一种受控功率源模型,研究了温差发电系统能量失配的产生机理,得到温差发电系统的三个工作区。为了避免系统进入危害较大的轻载失配工作区,设计了能量匹配系统,根据需求产生功耗,平衡发电与用电能量。在此过程中,系统将母线电压控制在上限阈值以下,增强了散热效果。最后,根据理论分析和设计计算结果,搭建实验样机。实验样机中的能量匹配电路采用直流供电的风扇作为能耗单元,以便于在消耗多余电能的同时,又能通过风冷,进一步改善散热效果。实验验证了电路模型的合理性,证明了主电路与控制器设计的有效性。
[Abstract]:The dissipation of waste heat brings about a waste of energy. In recent years, a variety of waste heat energy collection technology gradually emerged. Thermoelectric power generation technology is a kind of technology which can transform waste heat into electric energy. It has the advantages of quiet environmental protection, endothermic cooling and so on. It can be used in the field of heat dissipation of power electronic devices, while enhancing heat dissipation, at the same time, using the temperature difference generated by waste heat to emit electric energy. As a new energy utilization and heat dissipation technology, thermoelectric power generation technology has attracted more and more attention from enterprises and academia. As the basic component of thermoelectric power generation, the output voltage of thermoelectric plate is uncertain and can not be directly supplied to the load. At the same time, as an independent generation system, thermoelectric power generation system has inherent energy mismatch problem. Aiming at the above problems, this paper designs a constant voltage output converter, which uses closed loop control to realize the constant voltage output and supply the power with stable load. Based on the power analysis, the energy matching system is designed. The energy matching is realized by using the power matching unit, and the heat dissipation effect of the system is improved. The main work of this paper is as follows: firstly, in order to better design the suitable converter, the thermoelectric model of thermoelectric plate is established by using thermoelectric physical effect theory. On the basis of experimental research and data fitting, the output characteristics of thermoelectric plate are studied. According to this characteristic, the equivalent circuit model of thermoelectric plate is established. The model can reflect the relationship between circuit parameters, temperature difference and load. On this basis, in order to obtain a constant voltage to supply the load, a low-voltage start-up constant voltage output converter is designed, which can realize the closed-loop voltage output in a large range of input voltage and load variation. In order to deal with the fluctuation of input voltage caused by temperature change fast, the converter adopts feedforward-feedback control method. At the same time, aiming at the inherent energy mismatch problem of thermoelectric power generation system as an independent power supply system, a controlled power source model is established, and the generation mechanism of thermal differential power generation system energy mismatch is studied, and three working areas of thermoelectricity generation system are obtained. In order to avoid the system from entering the riskier light-load mismatch working area, an energy matching system is designed, which generates power consumption according to the demand and balances the power generation with the electric energy. In the process, the bus voltage is controlled below the upper threshold, which enhances the heat dissipation effect. Finally, according to the theoretical analysis and design calculation results, build the experimental prototype. The energy matching circuit in the experimental prototype uses a direct current power supply fan as the energy consumption unit, so as to further improve the heat dissipation effect by air cooling while consuming excess energy. The rationality of the circuit model is verified by experiments, and the validity of the design of the main circuit and the controller is proved.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM913

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