智能燃料電池蓄電池混合動力應(yīng)急電源系統(tǒng)畢業(yè)論文外文翻譯

1、<p><b>　　外文翻譯</b></p><p>　　智能燃料電池/蓄電池混合動力應(yīng)急電源系統(tǒng)</p><p>　　Yuedong Zhan, Youguang Guo, Jianguo Zhu, Hua Wang</p><p>　　中國，昆明650093，昆明科技大學(xué)自動化系</p><p>　　澳大利

2、亞，悉尼，科技大學(xué)工程學(xué)院，新南威爾士州，郵政信箱123</p><p>　　發(fā)表時間2008年1月12日</p><p><b>　　摘要</b></p><p>　　本文介紹了智能應(yīng)急電源系統(tǒng)的混合電源，包括燃料電池(PEMFC)和蓄電池。主要介紹了應(yīng)急電源的混合動力系統(tǒng)的數(shù)據(jù)采集并對燃料電池進(jìn)行控制。一個混合型應(yīng)急電源系統(tǒng)包括一個低成本的

3、60-300W的燃料電池堆，一個有源功率因數(shù)校正AC/DC整流器，一個半橋式DC/AC逆變器，一個DC/DC轉(zhuǎn)換器，一個使用數(shù)字信號處理器TMS320F240控制的AC/DC充電器，一些其他集成電路芯片和一個簡單的網(wǎng)絡(luò)管理協(xié)議適配器來進(jìn)行試驗測試和理論研究。首先，對試驗得到的燃料電池主要參數(shù)進(jìn)行評估。接下來，提出并實現(xiàn)對燃料電池的智能控制策略。最后，對應(yīng)急電源系統(tǒng)性能進(jìn)行測量和分析。</p><p><b&

4、gt;　　一、介紹</b></p><p>　　作為備用的應(yīng)急供電設(shè)備，應(yīng)急電源在很多地方發(fā)揮了非常重要的作用，如計算機(jī)、醫(yī)療系統(tǒng)、通訊系統(tǒng)、辦公設(shè)備、醫(yī)療儀器、工業(yè)控制和集成數(shù)據(jù)中心。在市電停電的情況下，應(yīng)急電源系統(tǒng)能夠提供可靠的恒壓恒頻電源。一個理想的高性能應(yīng)急電源應(yīng)該提供規(guī)范的正弦輸出電壓，不論是對于線性還是非線性負(fù)載，都有較低的諧波失真，能夠快速響應(yīng)輸入電壓或負(fù)載的突然變化，在線操作能快速轉(zhuǎn)換

5、于正常工作模式和緊急供電模式，反之亦然。正弦輸入電流和單位功率因數(shù)同樣有較低的諧波失真，還有可靠性好、高效率、低電磁干擾、低噪聲、低維護(hù)費(fèi)用、較小的體型和重量等優(yōu)點。在個人電腦、信息技術(shù)和網(wǎng)絡(luò)通信技術(shù)的飛速發(fā)展下。應(yīng)急電源在工業(yè)市場的份額會越來越大，現(xiàn)代應(yīng)急電源電源技術(shù)正在發(fā)展高開關(guān)頻率、小型化、數(shù)字化、智能化和聯(lián)網(wǎng)。重點體現(xiàn)在智能應(yīng)急電源系統(tǒng)功能豐富的硬件和軟件。</p><p>　　對于一些關(guān)鍵負(fù)載，應(yīng)急電源

6、僅使用電池有時難以提供足夠的后備電源，特別是需要相對長時間的持續(xù)供給。因此，需要發(fā)展其他能源存儲技術(shù)，如燃料電池去取代普通電池。由于燃料電池提供的電能具有高能量、高效率、無污染的優(yōu)點，被認(rèn)為是一種很有前途的技術(shù)產(chǎn)品。由于質(zhì)子交換膜燃料電池（PEMFC）和甲醇燃料電池（DMFC）具有良好的動態(tài)特性，普遍被業(yè)界看好。</p><p>　　應(yīng)急電源的混合電源應(yīng)該確保有足夠的燃料和電池容量對外部負(fù)載提供電能。當(dāng)市電中斷時

7、，氫被立刻供給燃料電池，然而，面對啟動過程中燃料電池或外部負(fù)載的突然變化，氫的供給速度有限，燃料電池的反應(yīng)可能需要幾秒鐘，以達(dá)到所需的輸出電壓。為了克服這個問題，充電電池或超級電容器快速響應(yīng)外部的負(fù)載，從而防止燃料電池的過度使用。</p><p>　　在這項研究中，混合燃料電池技術(shù)發(fā)展已經(jīng)可以應(yīng)用于應(yīng)急電源，如圖1所示的系統(tǒng)原理圖，其中包括一個300W的燃料電池堆、三層鉛酸蓄電池、一個單相高頻應(yīng)急電源、智能控制單

8、元和通信單元。組成應(yīng)急電源的AC/DC整流器、DC/AC 充電器和DC/AC逆變器可以給負(fù)載提供線性以及非線性的不間斷交流電源。</p><p>　　圖1 應(yīng)急電源的系統(tǒng)原理</p><p>　　燃料電池需要依賴空氣和氫氣的運(yùn)行，由于其動態(tài)性能緩慢，用小容量電池來提高對應(yīng)負(fù)載變化的響應(yīng)時間。智能控制器可自動運(yùn)行，當(dāng)市電出現(xiàn)故障時，蓄電池將連接DC/DC變換器和DC/AC逆變器，向負(fù)載提供不

9、間斷的交流電，并啟動燃料電池提供能量，直至市電恢復(fù)。應(yīng)急電源的混合動力系統(tǒng)通過RS-232或USB接口，連接適配器和專門設(shè)計的軟件，可以實現(xiàn)遠(yuǎn)程控制和電源管理的功能。</p><p><b>　　二．混合電源的設(shè)計</b></p><p><b>　　2.1 設(shè)計要素</b></p><p>　　設(shè)計應(yīng)急電源的混合電源，遵

10、循以下幾點：（1）采用技術(shù)成熟的組件；（2）使用易開發(fā)的模塊化產(chǎn)品；（3）采用多功能智能化控制和網(wǎng)絡(luò)通信；（4）采用數(shù)字信號處理器（DSP）作為智能控制器；（5）通過雙向DC/DC變換器給混合電池充電；（6）收集數(shù)據(jù)設(shè)置燃料電池的參數(shù)；（7）選擇合適的電池電壓、功率、型號，以便節(jié)約設(shè)計成本。</p><p>　　2.2 燃料電池測試</p><p>　　電池的測試系統(tǒng)由燃料電池堆、空氣冷卻

11、裝置、氫氣加濕過濾裝置和溫度壓力檢測裝置構(gòu)成。數(shù)據(jù)采集和控制設(shè)備可以根據(jù)參數(shù)來控制整個系統(tǒng)的運(yùn)行，如：工作溫度、燃料電池的電壓、電流等等。</p><p>　　實驗采用了一個300W的燃料電池，它可以實現(xiàn)自加濕，60層堆疊，整體大小為10.5cm*7.0cm*22.0cm，使用三個風(fēng)扇提供冷卻作用，該電池堆的最高工作溫度為65℃，氫氣操作壓力為4.55-5.5帕斯卡。</p><p>&l

12、t;b>　　2.3 儲能組件</b></p><p>　　如上所述，能量存儲單元如電池或超級電容器，在應(yīng)急電源系統(tǒng)中是關(guān)鍵的組成部分。市電正常時燃料電池不工作，當(dāng)電池或超級電容器需要提供額外的能量給負(fù)載時，燃料電池啟動。在應(yīng)急電源系統(tǒng)中，使用的電池型號為LC-R127R2CH 12V/7.2Ah/20HR，或者，使用15個串聯(lián)連接的超級電容器主要規(guī)格為1000F（±20％），控制電壓為

13、2.5V，最大電流為150A。</p><p>　　圖2 燃料電池的測試系統(tǒng)原理圖</p><p>　　2.4 應(yīng)急電源系統(tǒng)的硬件設(shè)計</p><p>　　2.4.1 DC/DC變化器</p><p>　　隨著現(xiàn)代電力電子技術(shù)的飛速發(fā)展，采用先進(jìn)的DSP數(shù)字控制的轉(zhuǎn)換器已成為研究領(lǐng)域的一個主題。漂移對數(shù)字控制器沒有影響，不敏感元件容差也容易實

14、現(xiàn)，而且軟件更新很方便。與模擬控制相比，數(shù)字控制應(yīng)急電源更容易實現(xiàn)。</p><p>　　在應(yīng)急電源系統(tǒng)中，如圖4所示，由TMS320F240 DSP控制的DC/AC逆變器為負(fù)載提供正弦波。半橋逆變器、LC濾波器和負(fù)載作為控制的關(guān)鍵參數(shù)。由于開關(guān)頻率遠(yuǎn)高于固有振動頻率和調(diào)制頻率，它主要取決于DC/AC逆變器的LC濾波器參數(shù)。死區(qū)時間和不可避免的消耗導(dǎo)致逆變器的阻尼很小，阻尼效應(yīng)可以考慮通過串聯(lián)一個小電阻與濾波電感

15、來抑制。使用正弦脈寬調(diào)制（SPWM）原理，逆變器的±380V直流電轉(zhuǎn)換成220V的交流正弦波。</p><p>　　圖4 DC/AC逆變器電路原理</p><p>　　2.4.2 DC/DC變換器</p><p>　　應(yīng)急電源的DC/DC轉(zhuǎn)換器使用UC3525提供脈沖寬度調(diào)節(jié)，燃料電池和蓄電池是兩種類型的低電壓高電流電源，所以應(yīng)用升壓電路提高其輸出電壓，3

16、6V直流提高到約380V直流，再經(jīng)過DC/AC逆變器主管稱220V、50赫茲的交流電源。升壓由DC/DC轉(zhuǎn)換器轉(zhuǎn)換，如圖5所示。電源開關(guān)Q1和Q2的工作頻率為20千赫。</p><p>　　圖5 DC/DC轉(zhuǎn)換原理圖</p><p>　　2.4.3 AC/DC充電器和燃料電池充電</p><p>　　開關(guān)電源系統(tǒng)的通用輸入電壓和可調(diào)輸出電壓電池充電器的設(shè)計基于一個高

17、性能PWM控制器UC3845。如圖6所示為AC/DC充電器電路。這個應(yīng)急電源系統(tǒng)僅在理論分析上，還需要通過實驗來不斷改進(jìn)，這個連接圖只是類似于實際的燃料電池蓄電池連接圖。</p><p>　　圖6 AC/DC充電器示意圖</p><p><b>　　三、智能網(wǎng)絡(luò)控制</b></p><p>　　3.1 智能網(wǎng)絡(luò)應(yīng)急電源的概念</p>

18、<p>　　除了正常的功能，開發(fā)的智能應(yīng)急電源混合動力系統(tǒng)還具有以下功能：</p><p>　　(1) 檢測燃料電池堆的電壓電流，然后再決定是否給應(yīng)急電源提供燃料電池的能量。</p><p>　　(2) 檢測電池的電壓電流，然后決定是否由電池提供應(yīng)急電源的電能，或者電池是否由AC/DC充電器或燃料電池充電。</p><p>　　(3) 檢測應(yīng)急電源的參

19、數(shù)，包括電網(wǎng)的輸入、DC/AC逆變器的輸出電壓和頻率、AC/DC整流器和DC/DC轉(zhuǎn)換器輸出、應(yīng)急電源的溫度等。</p><p>　　(4) 參數(shù)顯示，記錄故障信息，如市電中斷或應(yīng)急電源工作不當(dāng)。</p><p>　　(5) 實時控制燃料電池的啟動和關(guān)閉，實現(xiàn)自動操作。</p><p>　　(6) 通過RS-232或USB接口與電腦，工作站或服務(wù)器交換信息。<

20、/p><p>　　(7) 通過SNMP適配器與局域網(wǎng)互聯(lián)，實現(xiàn)網(wǎng)絡(luò)的監(jiān)控和管理。</p><p>　　3.2 智能控制器的新概念</p><p>　　先進(jìn)的應(yīng)急電源系統(tǒng)中，使用了基于DSP智能控制器TMS320F240，控制程序被寫入到它的內(nèi)存中。該控制器將信號發(fā)送到外部的DSP中以產(chǎn)生正弦脈寬調(diào)制脈沖，以及測量和記錄應(yīng)急電源系統(tǒng)的狀態(tài)。當(dāng)發(fā)生故障時，如元件過熱，過載或

21、過電壓，燃料電池和蓄電池電壓不足，智能控制器輸出控制信號，封鎖DC/AC逆變器，應(yīng)急電源的動力系統(tǒng)將會被切換到旁路狀態(tài)。智能控制器還可以產(chǎn)生一個報警信號，當(dāng)上述故障消失，系統(tǒng)可以自動切換到逆變器狀態(tài)。</p><p>　　智能控制器可決定電池的充電模式，市電正常時，當(dāng)電池電壓低于預(yù)定值時AC-DC充電器工作。市電中斷時，控制器控制燃料電池在必要時對蓄電池進(jìn)行充電。</p><p><

22、b>　　3.3 網(wǎng)絡(luò)通信</b></p><p>　　應(yīng)急電源的運(yùn)行狀態(tài)可以傳送到遠(yuǎn)程監(jiān)控站和關(guān)鍵負(fù)載設(shè)備上。無電壓觸點通常用于提供簡單的狀態(tài)信息，而RS-232串行或USB連接提供詳細(xì)信息。在SNMP適配器的幫助下，詳細(xì)信息可以直接發(fā)送到計算機(jī)網(wǎng)絡(luò)，從而可以通過網(wǎng)絡(luò)實現(xiàn)開關(guān)控制。智能網(wǎng)絡(luò)軟件可以控制應(yīng)急電源系統(tǒng)和其外圍設(shè)備，并自動停機(jī)在以下三個階段：</p><p>　

23、　階段1：該軟件通過服務(wù)器上保存的數(shù)據(jù)指示互聯(lián)網(wǎng)上的工作站，保存還沒有被保存的程序。</p><p>　　階段2：該軟件與其它通信裝置一起運(yùn)行來存儲所有的數(shù)據(jù)，然后關(guān)閉轉(zhuǎn)換裝置。</p><p>　　階段3：軟件可以運(yùn)行足夠長的時間將數(shù)據(jù)從服務(wù)器上寫入到硬盤里，然后關(guān)閉服務(wù)器。</p><p><b>　　四、實驗裝置</b></p>

24、;<p>　　實驗裝置由應(yīng)急電源的混合動力系統(tǒng)及其智能控制器、鉛酸電池、燃料電池發(fā)電系統(tǒng)及數(shù)據(jù)采集設(shè)備、包括一個多功能的I/O單元NI6036E，模擬電壓輸出單元NI6713，并行數(shù)字I/O接口PCI-6503和模擬多路復(fù)用AMUX-64T組成。應(yīng)急電源系統(tǒng)使用燃料電池和蓄電池提供交流電源，控制線性和非線性負(fù)載，同時數(shù)據(jù)采集系統(tǒng)測量和記錄所需要的信息。在燃料電池測試系統(tǒng)中，氫氣和空氣都受質(zhì)量流量控制器控制。進(jìn)氣口的空氣和氫

25、的溫度和濕度可以由液力變矩器，以及通過陰極和陽極的入口之間的壓力變送器測量。應(yīng)急電源的連接到照明負(fù)載時輸出是恒壓模式。所有的物理參數(shù)如應(yīng)急電源燃料電池和蓄電池的電流電壓、空氣和氫氣的壓力、相對濕度和溫度都可通過數(shù)據(jù)采集設(shè)備記錄。</p><p><b>　　五、實驗結(jié)果</b></p><p>　　應(yīng)急電源混合動力系統(tǒng)的仿真分析分為三個階段。第一階段，通過緩慢變化可變

26、電阻代替的負(fù)載，測量燃料電池電壓-電流、功率-電流的性能。第二階段，市電斷電時，采用智能控制燃料電池堆。第三階段，在照明負(fù)載和電腦負(fù)載下分別測試應(yīng)急電源的性能。應(yīng)急電源系統(tǒng)通過一個RS-232接口或USB連接到網(wǎng)絡(luò)。</p><p>　　5.1 燃料電池測試</p><p>　　基于燃料電池測試系統(tǒng)上發(fā)展起來的，燃料電池堆的性能測試包括電壓、電流、功率-電流、溫度-電流。圖7為測得電壓-電

27、流和功率-電流曲線。</p><p>　　圖7 電壓-電流和功率-電流曲線</p><p>　　5.2 智能控制測試</p><p>　　預(yù)設(shè)的控制為，市電斷電時，智能控制系統(tǒng)控制電池為應(yīng)急電源供電，并啟動燃料電池，如圖8。在蓄電池和燃料電池供電時，智能控制使供電電壓穩(wěn)定，如圖9。</p><p>　　圖8 燃料電池工作性能

28、 圖9 應(yīng)急電源切換為燃料電池供電</p><p>　　5.3 應(yīng)急電源混合動力系統(tǒng)測試</p><p>　　通過建立一個具有以下規(guī)格的實驗裝置來評估應(yīng)急電源的性能：市電輸入160-275V交流電壓，頻率50Hz，燃料電池額定電壓為36V直流電，負(fù)載的輸入功率為286W，負(fù)載為DELL電腦和監(jiān)視器，還有照明補(bǔ)充負(fù)載。</p><p>　　圖10所示為市電不正

29、常時應(yīng)急電源恢復(fù)供電。數(shù)據(jù)顯示，不間斷的輸出沒有過電壓或欠電壓，表明應(yīng)急電源提供了一個高質(zhì)量的輸出電壓?？梢钥闯鰧τ谶^電壓狀況有非?？斓膭討B(tài)響應(yīng)。應(yīng)急電源系統(tǒng)要驗證的性能有：輸出電壓為220V交流，頻率50Hz，輸入功率因數(shù)>0.92，輸出功率因數(shù)為0.7，零轉(zhuǎn)換時間。</p><p>　　圖10 電網(wǎng)恢復(fù)時過度波形</p><p><b>　　六、結(jié)論</b>

30、</p><p>　　本文提出了一個使用蓄電池燃料電池混合電源智能應(yīng)急電源系統(tǒng)的設(shè)計，它的結(jié)構(gòu)包括燃料電池系統(tǒng)、數(shù)據(jù)采集設(shè)備、AC/DC整流器、DC/AC逆變器、DC/DC轉(zhuǎn)換器和相關(guān)智能控制器。使用了TMS320F240 DSP芯片和SNMP技術(shù)以實現(xiàn)智能網(wǎng)絡(luò)控制應(yīng)急電源系統(tǒng)。在設(shè)計系統(tǒng)的基礎(chǔ)上進(jìn)行了三個階段的試驗檢測。1、通過實驗獲得燃料電池的參數(shù)設(shè)計；2、設(shè)計并仿真智能控制燃料電池堆；3、對應(yīng)急電源系統(tǒng)的性

31、能進(jìn)行評估。理論分析和實驗結(jié)果表明，智能燃料電池/蓄電池混合動力應(yīng)急電源更加便攜，適合緊急應(yīng)用。</p><p><b>　　附錄5</b></p><p><b>　　英文文獻(xiàn)</b></p><p>　　Intelligent uninterruptible power supply system with back-

32、up fuel cell/battery hybrid power source</p><p>　　Yuedong Zhan, Youguang Guo, Jianguo Zhu, Hua Wang</p><p>　　Department of Automation, Kunming University of Science and Technology, Kunming 65009

33、3, China</p><p>　　Faculty of Engineering, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia</p><p>　　Available online 12 January 2008</p><p><b>　　Abs

34、tract</b></p><p>　　This 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)

35、 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

36、3-cell lead–acid battery, an active power factor correction ac–dc rectifier, a half-bridge dc–ac i</p><p>　　1. Introduction</p><p>　　Uninterruptible power supply system play a very important rol

37、e 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

38、 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 &

39、lt;/p><p>　　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

40、, 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 pol

41、lution, they are considered as a promising technology for UPS products. The proton</p><p>　　A UPS system with a PEMFC and battery hybrid power source should ensure that there is sufficient fuel and battery c

42、apacity 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 l

43、oad, 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 rec</p><p>　　In this study, an intelligent hy

44、brid 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 lead

45、–acid battery, a single-phase high frequency UPS, and intelligent control and communication units. The UPS is composed of an ac–dc rectifier, an ac–dc charger, a dc–ac inverter and a dc–dc converter, and can supply linea

46、r and non-linear loads with </p><p>　　Fig.1. Intelligent UPS system with a PEMFC and battery power source</p><p>　　2. Design and architecture of UPS hybrid system</p><p>　　2.1. Desi

47、gn considerations</p><p>　　In designing a UPS system with a PEMFC/battery hybrid power source, the following criteria have to be addressed: </p><p>　　(1) adopting matured technology for the comp

48、onents; (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

49、charging of the battery through the ac–dc 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 sta

50、ck with respect </p><p>　　2.2. PEMFC testing system</p><p>　　The PEMFC testing system, as shown in Fig. 2, consists of a PEMFC stack, water-cooling components, air-cooling, H2 humidifying and fi

51、ltering, 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 syst

52、em with measurement of operational parameters, such as: the working temperature; voltage and current of the PEMFC; the pressure, input/output mass </p><p>　　Fig.2. Schematic diagram of PEMFC testing system&l

53、t;/p><p>　　2.3. Energy-storage component</p><p>　　A 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

54、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. A

55、lternatively, 15 series-connected super capacitors can be used with the main specifications of 1000 F (±20%), control voltage of 2.5V</p><p>　　2.4. Hardware designs of UPS system</p><p>　　2

56、.4.1. dc–ac inverter</p><p>　　With 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 cont

57、rollers 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

58、 for advanced operations. In the UPS hybrid system, a dc–ac inverter controlled by the TMS320F240 DSP i</p><p>　　Fig.3. Circuit schematic model of dc–ac inverter</p><p>　　2.4.2. ac–dc rectifier&

59、lt;/p><p>　　A boost active power factor corrector (PFC) with a 160–275V ac input voltage and a fixed output voltage (±BUS =±380Vdc) was designed based on a high power factor pre-regular UC3854, which

60、can control the input power factor (PF) of the ac–dc boost PWM rectifier to be close to 1, the THD of the input current less than 5%, and the frequency band of its current amplifier to be wide by adopting the average cur

61、rent control and constant frequency control. </p><p>　　2.4.3. dc–dc converter</p><p>　　A general and practical dc–dc converter for the UPS hybrid system was designed based on a regulating pulse-

62、width modulator UC3525. The PEMFC and battery are two types of low-voltage and high-current power source, so their output voltage (36V dc) should be boosted up to about ±380V dc before the UPS dc–ac inverter convert

63、s them into a 220V, 50-Hz ac source. This boosting action is performed by the dc–dc converter. Fig. 4 shows a schematic diagram of the converter. The operating frequency of power</p><p>　　Fig.4. Schematic di

64、agram of dc–dc converter</p><p>　　2.4.4. ac–dc charger and PEMFC charging</p><p>　　A basic switch power system with universal input voltage and adjustable output voltage is designed as the batte

65、ry charger based on a high-performance current mode PWM controller UC3845. Fig. 5 shows the schematic circuit model of the ac–dc charger.</p><p>　　In this UPS hybrid system, for the needs of theoretical anal

66、ysis, experimental study and practical product development, a passive connection diagram is designed similar to the actual one by implementing a device that connects the PEMFC and battery. When the utility grid power fai

67、ls and the PEMFC supplies the UPS hybrid system in the normal mode, the PEMFC can also charge the battery if the voltage of the latter is less than the rated value.</p><p>　　Fig .5. Schematic diagram of ac–d

68、c charger</p><p>　　3. Intelligent network and control</p><p>　　3.1. Concept of intelligent network UPS</p><p>　　Besides normal functions, the developed intelligent UPS hybrid system

69、 has the following capabilities:</p><p>　　(1) Monitoring of the voltage and current of the PEMFC stack, and then deciding whether the UPS is supplied by the PEMFC.</p><p>　　(2) Monitoring of the

70、 voltage and current of the battery, and then deciding whether the UPS is supplied by the battery, and whether the battery is recharged by the ac–dc charger or the PEMFC.</p><p>　　(3) Monitoring of the param

71、eters of the UPS, including the voltages and frequencies of the utility grid input and dc–ac inverter output, the positive and negative output voltages of the ac–dc rectifier and dc–dc converter, the UPS temperature, etc

72、.</p><p>　　(4) Display of the parameters, and controlling and recording the failure information when the utility grid power is interrupted or the UPS is improperly working.</p><p>　　(5) Real-tim

73、e controlling of the start-up and shut down of the PEMFC and UPS, and realizing automatic operations.</p><p>　　(6) Through the RS-232 or USB interface, exchange of information with the computers, workstation

74、s and servers. </p><p>　　(7) Through the SNMP adapter, interconnection with the LAN and realizing the network monitoring and management.</p><p>　　3.2. New concepts of intelligent controller</

75、p><p>　　In the developed UPS hybrid system, the intelligent controller is designed based on a TMS320F240 DSP, in which the controlling programs are written into its EPROM. The controller sends signals to the ex

76、ternal circuits of the DSP to generate the modulated pulses of the SPWM, as well as to measure and record the status of the UPS hybrid system. When faults occur, such as overheated components, overload and over-voltage o

77、f the UPS, under-voltage of PEMFC stack and battery, the intelligent controlle</p><p>　　3.3. Network communications</p><p>　　The operational status and activity of the traditional UPS system can

78、 be transmitted to remote monitoring stations and critical load equipment. Volt-free contacts are usually used for providing simple status information, while an RS-232 serial or USB connection is employed for more detail

79、ed information. With the help of an SNMP adaptor, detailed information can be sent directly to a computer network and thus enables information management and shutdown action across the network. The designed soft</p>

80、;<p>　　Stage 1: The software directs the workstations on the Internet to send data from their RAM memories to the server, and stores all the programs that have not been saved in the WINDOWS.</p><p>　　

81、Stage 2: The software runs together with the other communication devices to store all the data and then shut down the devices in turn.</p><p>　　Stage 3: The software can work long enough time for the server

82、to write the data into the hard disc and then shut down the server.</p><p>　　4. Experimental set-up</p><p>　　The experimental set-up consists of the UPS hybrid system and its intelligent control

83、ler, lead–acid battery, PEMFC generating system and the data-acquisition devices including a multifunction I/O unit NI6036E, an analogue voltage output unit NI6713, a parallel digital I/O interface PCI-6503 and an analog

84、ue multiplexer with a temperature sensor AMUX-64T. The UPS hybrid system with back-up PEMFC and battery provides the ac power source and controls the linear loads (e.g., lamp box) and non-linear </p><p>　　5.

85、 Experimental results</p><p>　　There are three stages of experimental tests and analyses of the UPS hybrid system. At the first stage, the voltage–current and power–current performance of the FEMFC is measur

86、ed by varying slowly the load with a rheostat. At the second stage, the proposed intelligent control strategy of the PEMFC stack is employed when the utility grid power is interrupted. In the final stage, the performance

87、 of the UPS hybrid system is measured with the load of a lamp box and a Dell type of PC computer. The UP</p><p>　　5.1. PEMFC stack tests</p><p>　　Based on the developed PEMFC testing system, the

88、 performance of the PEMFC stack is tested, including voltage–current, power–current, and temperature–current. The measured voltage–current and power–current curves are given in Fig. 6.</p><p>　　Fig. 6. Volta

89、ge–current and power–current characteristics of PEMFC</p><p>　　5.2. Intelligent control strategy tests</p><p>　　The proposed intelligent control strategy has been implemented in the PEMFC test s

90、ystem. When the utility grid power is interrupted, the intelligent controller directs the battery to supply the UPS hybrid system and starts up the PEMFC stack, as illustrated in Fig. 7. After the voltage of the PEMFC st

91、ack is stable, the intelligent controller switches the power source from the battery to the PEMFC, as demonstrated in Fig. 8. </p><p>　　Fig. 7. Start-up performance of PEMFC Fig. 8 Switching of UPS power

92、 source from</p><p>　　battery to PEMFC</p><p>　　5.3. UPS hybrid system tests</p><p>　　The performance of the proposed UPS hybrid system is evaluated by building an experimental set-

93、up with the following specifications: the input voltage of utility grid = 160–275V ac, output voltage frequency = 50±5% Hz, PEMFC/battery-rated voltage = 36V dc, input power of load = 286W. The experimental load is

94、a Dell computer (HP-U2106F3, 213 W) and a monitor (E772p, 73 W). Moreover, a lamp box is used as the supplementary load. Figs. 9 show the input voltage and output voltage of the UPS when the</p><p>　　Fig. 9

95、Transitional waveform when utility grid power recovers</p><p>　　6. Conclusions</p><p>　　The design considerations and architecture for an intelligent network UPS system with back-up PEMFC and ba

96、ttery power source have been presented. An UPS hybrid system architecture is developed and includes a PEMFC generating system and its data-acquisition devices, an ac–dc rectifier, ac–dc charger, dc–ac inverter, dc–dc con