智能燃料电池蓄电池混合动力应急电源系统毕业论文外文翻译.doc

外文翻译智能燃料电池/蓄电池混合动力应急电源系统Yuedong Zhan, Youguang Guo, Jianguo Zhu, Hua Wang中国，昆明650093，昆明科技大学自动化系澳大利亚，悉尼，科技大学工程学院，新南威尔士州，邮政信箱123发表时间2008年1月12日摘要本文介绍了智能应急电源系统的混合电源，包括燃料电池(PEMFC)和蓄电池。主要介绍了应急电源的混合动力系统的数据采集并对燃料电池进行控制。一个混合型应急电源系统包括一个低成本的60-300W的燃料电池堆，一个有源功率因数校正AC/DC整流器，一个半桥式DC/AC逆变器，一个DC/DC转换器，一个使用数字信号处理器TMS320F240控制的AC/DC充电器，一些其他集成电路芯片和一个简单的网络管理协议适配器来进行试验测试和理论研究。首先，对试验得到的燃料电池主要参数进行评估。接下来，提出并实现对燃料电池的智能控制策略。最后，对应急电源系统性能进行测量和分析。一、介绍 作为备用的应急供电设备，应急电源在很多地方发挥了非常重要的作用，如计算机、医疗系统、通讯系统、办公设备、医疗仪器、工业控制和集成数据中心。在市电停电的情况下，应急电源系统能够提供可靠的恒压恒频电源。一个理想的高性能应急电源应该提供规范的正弦输出电压，不论是对于线性还是非线性负载，都有较低的谐波失真，能够快速响应输入电压或负载的突然变化，在线操作能快速转换于正常工作模式和紧急供电模式，反之亦然。正弦输入电流和单位功率因数同样有较低的谐波失真，还有可靠性好、高效率、低电磁干扰、低噪声、低维护费用、较小的体型和重量等优点。在个人电脑、信息技术和网络通信技术的飞速发展下。应急电源在工业市场的份额会越来越大，现代应急电源电源技术正在发展高开关频率、小型化、数字化、智能化和联网。重点体现在智能应急电源系统功能丰富的硬件和软件。对于一些关键负载，应急电源仅使用电池有时难以提供足够的后备电源，特别是需要相对长时间的持续供给。因此，需要发展其他能源存储技术，如燃料电池去取代普通电池。由于燃料电池提供的电能具有高能量、高效率、无污染的优点，被认为是一种很有前途的技术产品。由于质子交换膜燃料电池（PEMFC）和甲醇燃料电池（DMFC）具有良好的动态特性，普遍被业界看好。应急电源的混合电源应该确保有足够的燃料和电池容量对外部负载提供电能。当市电中断时，氢被立刻供给燃料电池，然而，面对启动过程中燃料电池或外部负载的突然变化，氢的供给速度有限，燃料电池的反应可能需要几秒钟，以达到所需的输出电压。为了克服这个问题，充电电池或超级电容器快速响应外部的负载，从而防止燃料电池的过度使用。在这项研究中，混合燃料电池技术发展已经可以应用于应急电源，如图1所示的系统原理图，其中包括一个300W的燃料电池堆、三层铅酸蓄电池、一个单相高频应急电源、智能控制单元和通信单元。组成应急电源的AC/DC整流器、DC/AC 充电器和DC/AC逆变器可以给负载提供线性以及非线性的不间断交流电源。图1 应急电源的系统原理燃料电池需要依赖空气和氢气的运行，由于其动态性能缓慢，用小容量电池来提高对应负载变化的响应时间。智能控制器可自动运行，当市电出现故障时，蓄电池将连接DC/DC变换器和DC/AC逆变器，向负载提供不间断的交流电，并启动燃料电池提供能量，直至市电恢复。应急电源的混合动力系统通过RS-232或USB接口，连接适配器和专门设计的软件，可以实现远程控制和电源管理的功能。二混合电源的设计2.1 设计要素设计应急电源的混合电源，遵循以下几点：（1）采用技术成熟的组件；（2）使用易开发的模块化产品；（3）采用多功能智能化控制和网络通信；（4）采用数字信号处理器（DSP）作为智能控制器；（5）通过双向DC/DC变换器给混合电池充电；（6）收集数据设置燃料电池的参数；（7）选择合适的电池电压、功率、型号，以便节约设计成本。2.2 燃料电池测试电池的测试系统由燃料电池堆、空气冷却装置、氢气加湿过滤装置和温度压力检测装置构成。数据采集和控制设备可以根据参数来控制整个系统的运行，如：工作温度、燃料电池的电压、电流等等。实验采用了一个300W的燃料电池，它可以实现自加湿，60层堆叠，整体大小为10.5cm*7.0cm*22.0cm，使用三个风扇提供冷却作用，该电池堆的最高工作温度为65，氢气操作压力为4.55-5.5帕斯卡。2.3 储能组件如上所述，能量存储单元如电池或超级电容器，在应急电源系统中是关键的组成部分。市电正常时燃料电池不工作，当电池或超级电容器需要提供额外的能量给负载时，燃料电池启动。在应急电源系统中，使用的电池型号为LC-R127R2CH 12V/7.2Ah/20HR，或者，使用15个串联连接的超级电容器主要规格为1000F（±20），控制电压为2.5V，最大电流为150A。图2 燃料电池的测试系统原理图2.4 应急电源系统的硬件设计2.4.1 DC/DC变化器随着现代电力电子技术的飞速发展，采用先进的DSP数字控制的转换器已成为研究领域的一个主题。漂移对数字控制器没有影响，不敏感元件容差也容易实现，而且软件更新很方便。与模拟控制相比，数字控制应急电源更容易实现。在应急电源系统中，如图4所示，由TMS320F240 DSP控制的DC/AC逆变器为负载提供正弦波。半桥逆变器、LC滤波器和负载作为控制的关键参数。由于开关频率远高于固有振动频率和调制频率，它主要取决于DC/AC逆变器的LC滤波器参数。死区时间和不可避免的消耗导致逆变器的阻尼很小，阻尼效应可以考虑通过串联一个小电阻与滤波电感来抑制。使用正弦脉宽调制（SPWM）原理，逆变器的±380V直流电转换成220V的交流正弦波。图4 DC/AC逆变器电路原理2.4.2 DC/DC变换器应急电源的DC/DC转换器使用UC3525提供脉冲宽度调节，燃料电池和蓄电池是两种类型的低电压高电流电源，所以应用升压电路提高其输出电压，36V直流提高到约380V直流，再经过DC/AC逆变器主管称220V、50赫兹的交流电源。升压由DC/DC转换器转换，如图5所示。电源开关Q1和Q2的工作频率为20千赫。图5 DC/DC转换原理图2.4.3 AC/DC充电器和燃料电池充电开关电源系统的通用输入电压和可调输出电压电池充电器的设计基于一个高性能PWM控制器UC3845。如图6所示为AC/DC充电器电路。这个应急电源系统仅在理论分析上，还需要通过实验来不断改进，这个连接图只是类似于实际的燃料电池蓄电池连接图。图6 AC/DC充电器示意图三、智能网络控制3.1 智能网络应急电源的概念除了正常的功能，开发的智能应急电源混合动力系统还具有以下功能：(1) 检测燃料电池堆的电压电流，然后再决定是否给应急电源提供燃料电池的能量。(2) 检测电池的电压电流，然后决定是否由电池提供应急电源的电能，或者电池是否由AC/DC充电器或燃料电池充电。(3) 检测应急电源的参数，包括电网的输入、DC/AC逆变器的输出电压和频率、AC/DC整流器和DC/DC转换器输出、应急电源的温度等。(4) 参数显示，记录故障信息，如市电中断或应急电源工作不当。(5) 实时控制燃料电池的启动和关闭，实现自动操作。(6) 通过RS-232或USB接口与电脑，工作站或服务器交换信息。(7) 通过SNMP适配器与局域网互联，实现网络的监控和管理。3.2 智能控制器的新概念先进的应急电源系统中，使用了基于DSP智能控制器TMS320F240，控制程序被写入到它的内存中。该控制器将信号发送到外部的DSP中以产生正弦脉宽调制脉冲，以及测量和记录应急电源系统的状态。当发生故障时，如元件过热，过载或过电压，燃料电池和蓄电池电压不足，智能控制器输出控制信号，封锁DC/AC逆变器，应急电源的动力系统将会被切换到旁路状态。智能控制器还可以产生一个报警信号，当上述故障消失，系统可以自动切换到逆变器状态。智能控制器可决定电池的充电模式，市电正常时，当电池电压低于预定值时AC-DC充电器工作。市电中断时，控制器控制燃料电池在必要时对蓄电池进行充电。3.3 网络通信应急电源的运行状态可以传送到远程监控站和关键负载设备上。无电压触点通常用于提供简单的状态信息，而RS-232串行或USB连接提供详细信息。在SNMP适配器的帮助下，详细信息可以直接发送到计算机网络，从而可以通过网络实现开关控制。智能网络软件可以控制应急电源系统和其外围设备，并自动停机在以下三个阶段：阶段1：该软件通过服务器上保存的数据指示互联网上的工作站，保存还没有被保存的程序。阶段2：该软件与其它通信装置一起运行来存储所有的数据，然后关闭转换装置。阶段3：软件可以运行足够长的时间将数据从服务器上写入到硬盘里，然后关闭服务器。四、实验装置实验装置由应急电源的混合动力系统及其智能控制器、铅酸电池、燃料电池发电系统及数据采集设备、包括一个多功能的I/O单元NI6036E，模拟电压输出单元NI6713，并行数字I/O接口PCI-6503和模拟多路复用AMUX-64T组成。应急电源系统使用燃料电池和蓄电池提供交流电源，控制线性和非线性负载，同时数据采集系统测量和记录所需要的信息。在燃料电池测试系统中，氢气和空气都受质量流量控制器控制。进气口的空气和氢的温度和湿度可以由液力变矩器，以及通过阴极和阳极的入口之间的压力变送器测量。应急电源的连接到照明负载时输出是恒压模式。所有的物理参数如应急电源燃料电池和蓄电池的电流电压、空气和氢气的压力、相对湿度和温度都可通过数据采集设备记录。五、实验结果应急电源混合动力系统的仿真分析分为三个阶段。第一阶段，通过缓慢变化可变电阻代替的负载，测量燃料电池电压-电流、功率-电流的性能。第二阶段，市电断电时，采用智能控制燃料电池堆。第三阶段，在照明负载和电脑负载下分别测试应急电源的性能。应急电源系统通过一个RS-232接口或USB连接到网络。5.1 燃料电池测试基于燃料电池测试系统上发展起来的，燃料电池堆的性能测试包括电压、电流、功率-电流、温度-电流。图7为测得电压-电流和功率-电流曲线。图7 电压-电流和功率-电流曲线5.2 智能控制测试预设的控制为，市电断电时，智能控制系统控制电池为应急电源供电，并启动燃料电池，如图8。在蓄电池和燃料电池供电时，智能控制使供电电压稳定，如图9。 图8 燃料电池工作性能 图9 应急电源切换为燃料电池供电5.3 应急电源混合动力系统测试通过建立一个具有以下规格的实验装置来评估应急电源的性能：市电输入160-275V交流电压，频率50Hz，燃料电池额定电压为36V直流电，负载的输入功率为286W，负载为DELL电脑和监视器，还有照明补充负载。图10所示为市电不正常时应急电源恢复供电。数据显示，不间断的输出没有过电压或欠电压，表明应急电源提供了一个高质量的输出电压。可以看出对于过电压状况有非常快的动态响应。应急电源系统要验证的性能有：输出电压为220V交流，频率50Hz，输入功率因数>0.92，输出功率因数为0.7，零转换时间。图10 电网恢复时过度波形六、结论 本文提出了一个使用蓄电池燃料电池混合电源智能应急电源系统的设计，它的结构包括燃料电池系统、数据采集设备、AC/DC整流器、DC/AC逆变器、DC/DC转换器和相关智能控制器。使用了TMS320F240 DSP芯片和SNMP技术以实现智能网络控制应急电源系统。在设计系统的基础上进行了三个阶段的试验检测。1、通过实验获得燃料电池的参数设计；2、设计并仿真智能控制燃料电池堆；3、对应急电源系统的性能进行评估。理论分析和实验结果表明，智能燃料电池/蓄电池混合动力应急电源更加便携，适合紧急应用。附录5英文文献Intelligent uninterruptible power supply system with back-up fuel cell/battery hybrid power sourceYuedong Zhan, Youguang Guo, Jianguo Zhu, Hua WangDepartment of Automation, Kunming University of Science and Technology, Kunming 650093, ChinaFaculty of Engineering, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, AustraliaAvailable online 12 January 2008AbstractThis paper presents the development of an intelligent uninterruptible power supply (UPS) system with a hybrid power source that comprises a proton-exchange membrane fuel cell (PEMFC) and a battery. Attention is focused on the architecture of the UPS hybrid system and the data acquisition and control of the PEMFC. Specifically, the hybrid UPS system consists of a low-cost 60-cell 300W PEMFC stack, a 3-cell leadacid battery, an active power factor correction acdc rectifier, a half-bridge dcac inverter, a dcdc converter, an acdc charger and their control units based on a digital signal processor TMS320F240, other integrated circuit chips, and a simple network management protocol adapter. Experimental tests and theoretical studies are conducted. First, the major parameters of the PEMFC are experimentally obtained and evaluated. Then an intelligent control strategy for the PEMFC stack is proposed and implemented. Finally, the performance of the hybrid UPS system is measured and analyzed. 1. IntroductionUninterruptible power supply system play a very important role as back-up and emergency power supplies for important applications such as computers, medical/life support systems, communication systems, office equipment, hospital instruments, industrial controls and integrated data centre. The UPS systems provide reliable constant voltage and constant frequency power in case of mains failure. An ideal high performance UPS system should provide a clean and regulated sinusoidal output voltage with low total harmonic distortion (THD) for both linear and non-linear loads, a fast transient response to sudden changes of the input voltage or load, online operation with zero switching time from normal to back-up mode and vice versa, a low THD sinusoidal input current and unity power factor, high power density, high reliability, high efficiency, low electromagnetic interference and acoustic noise, electric isolation, low maintenance, low cost and weight, and small size. With the fast development of personal computers, information technology and network communications technology, UPS products will take an increasing share of industrial and domestic markets. Modern UPS power source technologies are being developed in terms of high switching frequency, miniaturization, redundancy, digitalization, intelligence and networking. The key embodiment of the intelligent UPS system is the monitoring functions of abundant hardware and software.A UPS system based solely on the use of batteries finds difficulty in providing sufficient back-up power to critical loads, especially when a supply for a relatively long duration is required. Hence, other energy sources and storage technologies, such as the fuel cell, have been investigated to replace the batteries. Since fuel cells can provide electrical power with high specific energy, high efficiency and no pollution, they are considered as a promising technology for UPS products. The proton-exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) are considered to be promising technologies due to their excellent dynamic characteristics. The present lifetime capabilities of PEMFC are suitable for back-up UPS applications. Furthermore, the PEMFC complies with the demand for a fast cold start.A UPS system with a PEMFC and battery hybrid power source should ensure that there is sufficient fuel and battery capacity to provide the power needed by the external load. When power from the utility grid is interrupted, hydrogen will be supplied to the PEMFC stack. During start-up of the PEMFC stack or a sudden change of external load, however, hydrogen cannot be fed fast enough and the fuel cell stack may take a few seconds to reach the required output voltage. To overcome this problem, a rechargeable battery or super capacitor can be employed to respond quickly to the external load and thereby protect the PEMFC from excessive use.In this study, an intelligent hybrid UPS system with a PEMFC/battery hybrid power source has been developed for back-up and emergency power applications. Fig. 1 shows the schematic diagram of the system, which includes a 300W PEMFC stack, a 3-cell leadacid battery, a single-phase high frequency UPS, and intelligent control and communication units. The UPS is composed of an acdc rectifier, an acdc charger, a dcac inverter and a dcdc converter, and can supply linear and non-linear loads with uninterruptible ac power. The PEMFC stack operates on hydrogen and air. Because of the slow dynamic performance of the PEMFC stack, a small capacity battery is employed to improve the response time to sudden changes in load. The intelligent controller enables automatic operation of the whole system that, when there is a power failure, includes disconnecting the system from the utility grid supply, connecting the battery to the dcdc converter and dcac inverter to maintain the uninterrupted ac power supply to the load, starting the PEMFC to provide power for longer periods, and switching the power supply back to the grid when utility power is restored. Through an RS-232 or USB interface, a simple network management protocol (SNMP) adapter and specially designed software, the UPS hybrid system can realize the functions of telecommunications, control and power management.Fig.1. Intelligent UPS system with a PEMFC and battery power source2. Design and architecture of UPS hybrid system2.1. Design considerationsIn designing a UPS system with a PEMFC/battery hybrid power source, the following criteria have to be addressed: (1) adopting matured technology for the components; (2) easiness to develop modular products; (3) multiple functions of intelligent controls and network communications; (4) employing a digital signal processor (DSP) as the intelligent network controller; (5) dual charging of the battery through the acdc charger and/or the PEMFC; (6) convenience to collect the data and set-up parameters for the PEMFC and the UPS; (7) correctly choosing the power, voltage and size of the PEMFC stack with respect to cost, the battery voltage, and the design of the dcdc converter.2.2. PEMFC testing system The PEMFC testing system, as shown in Fig. 2, consists of a PEMFC stack, water-cooling components, air-cooling, H2 humidifying and filtering, and temperature and pressure monitoring. Three types of gases: hydrogen, nitrogen and air/oxygen, are used. The data-acquisition and control devices and software have been designed and can control the whole system with measurement of operational parameters, such as: the working temperature; voltage and current of the PEMFC; the pressure, input/output mass flows and humidity of the hydrogen and air/oxygen; the voltage and current of the battery. Many functions can be selected, e.g., humidification of the hydrogen and air, use of air rather than oxygen, and water-cooling or air cooling. For the experimental set-up, a 300W PEMFC stack is employed. It is a self-humidified, air-breathing, 60-cell stack with an overall size 10.5 cm×7.0 cm×22.0 cm. Three fans are used to supply the air and cool the stack, which has a maximum operating temperature of 65and an operating pressure of 4.555.5 psi for hydrogen. Fig.2. Schematic diagram of PEMFC testing system2.3. Energy-storage componentA super capacitor， is a key component of the UPS hybrid system. The PEMFC plays the role of main power supply under normal conditions, whereas the battery or super capacitor provides the (extra) power required when the load varies suddenly and the power when the PEMFC starts up. In this UPS hybrid system, the PANASONIC LC-R127R2CH, 12V/7.2Ah/20HR battery is used. Alternatively, 15 series-connected super capacitors can be used with the main specifications of 1000 F (±20%), control voltage of 2.5V, and maximum current of 150A .2.4. Hardware designs of UPS system2.4.1. dcac inverterWith the rapid development of modern power electronics technology, the digital control of power converters using advanced DSP has become a subject of research area. Digital controllers are immune to drifts, insensitive to component tolerances, easy to implement, and flexible with control rules by software updating. Compared with the analogue control, the digital control UPS is easier to realize for advanced operations. In the UPS hybrid system, a dcac inverter controlled by the TMS320F240 DSP is designed to supply the load with a pure sine wave, as shown in Fig. 3, where the half-bridge inverter, LC filter and load are considered as the plant to be controlled. Since the switching frequency (the designed operating frequency = 20 kHz) is much higher than the natural frequency and the modulation frequency, the dynamics of the dcac inverter are mainly determined by its LC filter. The dead-time effect and inevitable loss in every part of the inverter cause little damping. The damping effect can be considered by using a small resistor connected in series with the filter inductor. Using the sinusoidal pulse-width modulation (SPWM) control principle, the inverter can convert the ±380V dc into a 220V ac pure sine wave.Fig.3. Circuit schematic model of dcac inverter2.4.2. acdc rectifierA boost active power factor corrector (PFC) with a 160275V ac input voltage and a fixed output voltage (±BUS =±380Vdc) was designed based on a high power factor pre-regular UC3854, which can control the input power factor (PF) of the acdc boost PWM