【正文】
區(qū),因而它可以提高控制系統(tǒng)的可靠性,減少電路的復(fù)雜程度。圖中HIN和LIN為逆變橋中同一橋臂上下兩個(gè)功率MOS的驅(qū)動(dòng)脈沖信號(hào)輸入端。驅(qū)動(dòng)電路接線圖如圖37所示,懸浮電源VB可以從電源VCC通過(guò)二極管DIODE對(duì)電容C7充電自舉獲得(因?yàn)閷?duì)于橋式電路,每一路驅(qū)動(dòng)都必須獨(dú)立的直流電源)其二極管必須是快恢復(fù)二極管其耐壓值必須超過(guò)主電路直流輸入電壓,電容C7的電容值的選取決定于開關(guān)頻率及MOSFET輸入電容充放電的要求等。H0和L0是兩路驅(qū)動(dòng)信號(hào)輸出端,驅(qū)動(dòng)同一橋臂的MOSFET,IR2110的自舉電容選擇不好,容易造成芯片損壞或不能正常工作。才能夠正常工作,一般來(lái)說(shuō),SPWM的開關(guān)頻率較高,應(yīng)采用小容量電容,以提高充電電壓,否則在有限的時(shí)間內(nèi)無(wú)法達(dá)到自舉電壓,實(shí)驗(yàn)表明采用33μF的自舉電容時(shí),驅(qū)動(dòng)電路的工作狀態(tài)良好。本文采用的是電流互感器的方法來(lái)測(cè)量電流的,采用電流互感器測(cè)量電流。LM311接成電壓比較器的形式,5V基準(zhǔn)電壓通過(guò)R1R18組成的分壓電路分壓后接入電壓比較器的同相端,作為給定基準(zhǔn)電壓,來(lái)自霍爾電流傳感器的逆變器輸入電流信號(hào)經(jīng)濾波電路后與基準(zhǔn)電壓進(jìn)行較,正常工作時(shí)電壓比較器輸出高電平。圖38 過(guò)流保護(hù)第4章 系統(tǒng)仿真 系統(tǒng)仿真以下圖41為SPWM信號(hào)產(chǎn)生電路,電路通過(guò)對(duì)三角波的調(diào)制得到SPWM波形。 圖41 SPWM信號(hào)仿真電路 下圖42為仿真SPWM信號(hào)部分圖,正弦波作為調(diào)制波,SPWM波作為載波,可以采用模擬電路構(gòu)成三角載波和正弦調(diào)制波發(fā)生電路,用比較器來(lái)確定他們的交點(diǎn),在交點(diǎn)時(shí)刻來(lái)控制開關(guān)管通斷,可以生成SPWM波。圖47 20HZ時(shí)波形圖48 30HZ時(shí)輸出波形圖49 40HZ時(shí)輸出波形圖410 50HZ波形圖411 仿真產(chǎn)生波形 結(jié) 論自從電子設(shè)備特別是計(jì)算機(jī)問(wèn)世以來(lái),電源持續(xù)供應(yīng)問(wèn)題一直是人們十分關(guān)心的問(wèn)題。因?yàn)檫@些設(shè)備的電源一旦出現(xiàn)不穩(wěn)定或者消失,就將造成非常大的損失,甚至無(wú)可挽回的損失。通過(guò)逆變電路加濾波電路可實(shí)現(xiàn)DC12VAC220V電流,實(shí)現(xiàn)車載電源(DC12V)通過(guò)電流轉(zhuǎn)變能驅(qū)動(dòng)家用電器(AC220V),有非常強(qiáng)的實(shí)用性,整流電路中加裝蓄電池,可實(shí)現(xiàn)對(duì)蓄電池的充電過(guò)程,通過(guò)單片機(jī)的控制可實(shí)現(xiàn)斷電時(shí)對(duì)整體線路放電,實(shí)現(xiàn)停電續(xù)流過(guò)程。理論與實(shí)際結(jié)合,在實(shí)際運(yùn)用中融匯平時(shí)的理論積累,加深對(duì)平時(shí)理論的理解,也使理論知識(shí)有了實(shí)用價(jià)值,這次的畢業(yè)設(shè)計(jì)讓我明白其實(shí)平時(shí)覺(jué)得飄渺的,感覺(jué)離我們很遠(yuǎn)的理論知識(shí),其實(shí)就在我們身邊,只是這其中需要媒介將其聯(lián)通,將知識(shí)運(yùn)用于生活中,電氣學(xué)科其實(shí)也是離生活比較近的學(xué)科,小至手機(jī)充電,大至點(diǎn)亮世界,生活中無(wú)時(shí)無(wú)刻都活動(dòng)著電子,是社會(huì)的基礎(chǔ)學(xué)科,也是發(fā)展的尖端學(xué)科,在這個(gè)電氣研發(fā)的黃金時(shí)代,日新月異、連綿不斷的快速發(fā)展帶給了工業(yè)和社會(huì),難以形容、無(wú)法想像的巨大改變。參考文獻(xiàn)[1]沙占有,王彥朋,[M].北京:電子工業(yè)出版社,2004.[3][J].天津理工大學(xué)學(xué)報(bào),2009,25(4)[4]陳江輝,謝運(yùn)祥,[J].電氣應(yīng)用,2006,25(9)[6][J].電氣應(yīng)用,2008,27(13)[9]張?zhí)毂?謝運(yùn)祥,[J].通信電源技術(shù),2008,25(4) 基于DSP的UPS輸出電壓鎖相設(shè)計(jì)[J] 2003電工技術(shù)雜志.[11] 張勁松基于DSP的全數(shù)字化單相在線式UPS的設(shè)計(jì)[J] 2001 電力電子技術(shù)[12] 張振宇 [14] 詹躍東 史揚(yáng) 單相UPS電源的鎖相同步電路設(shè)計(jì)[J]《電力電子技術(shù)》 2001 第4期[15] 祁豐 用于UPS的兩級(jí)式蓄電池充電器設(shè)計(jì)[J]《電力電子技術(shù)》 2007 第8期 [16] 肖化 胡廣莉 智能化交流不間斷電源UPS設(shè)計(jì)[J]《電力電子技術(shù)》 1997 第2期 [17] 詹躍東 單相高頻化UPS中DC/DC、AC/DC與DC/AC的設(shè)計(jì)[J]《電力電子技術(shù)》 2000 第1期[18] 孫哲 劉華毅 一種基于單片機(jī)的在線式UPS的設(shè)計(jì)[J]《儀器儀表學(xué)報(bào)》 2006 第1期 [19] 李建國(guó) 凌立剛 李小鵬 UPS遠(yuǎn)程監(jiān)控系統(tǒng)的設(shè)計(jì)與實(shí)現(xiàn)[J]《電氣應(yīng)用》 2008 第2期 [20][22][A].四直轄市照明科技論壇、長(zhǎng)三角照明科技論壇暨上海市照明學(xué)會(huì)2008年年會(huì)論文集[C].2008.g an employment tribunal claimEmployment tribunals sort out disagreements between employers and employees.You may need to make a claim to an employment tribunal if:t agree with the disciplinary action your employer has taken against youDismissal.You can make a claim to an employment tribunal, even if you haven39。appealedFurther help.Employment tribunals are less formal than some other courts, but it is still a legal process and you will need to give evidence under an oath or affirmation.Most people find making a claim to an employment tribunal challenging. If you are thinking about making a claim to an employment tribunal, you should get help straight away from one of the organisations listed underdamagesbased agreement. In England and Wales, your solicitor can39。if you win the case.If you are thinking about signing up for re clear about the terms of the agreement. It might be best to get advice from an experienced adviser, for example, at a Citizens Advice Bureau. nearest CAB.For more information about making a claim to an employment tribunal, sees antiracism taskforce, is in London for the Football Association39。s Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport.For me it39。opened disciplinary proceedings against CSKACity39。s governing body, has also ordered an immediate investigation into the referee39。s plaint. In a statement the Russian side added: We found no racist insults from fans of CSKA.Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of different life became the appearance of the same day?;蛟S是愧疚于自己似乎把轉(zhuǎn)瞬即逝的很多個(gè)不同的日子過(guò)成了同一天的樣子;或許是追溯過(guò)去,對(duì)自己那些近乎偏執(zhí)的怪異信念的醒悟,這些天以來(lái),思緒一直很凌亂,在腦海中不斷糾纏。二十年的人生軌跡深深淺淺,突然就感覺(jué)到有些事情,非做不可了。 Junior high school, thought to have a crush on just means that the real growth, but over the past three years later, his writing of alumni in peace, suddenly found that isn39。 Then in high school, think don39。t remember his appearance. 童年時(shí),覺(jué)得壓歲錢和新衣服是過(guò)年必備,但是隨著年齡的推進(jìn),會(huì)越來(lái)越發(fā)現(xiàn),那些東西根本就可有可無(wú);初中時(shí),以為要有一場(chǎng)暗戀才意味著真正的成長(zhǎng),但三年過(guò)去后,自己心平氣和的寫同學(xué)錄的時(shí)候,突然就發(fā)現(xiàn)是不是真正的成長(zhǎng)了,好像并沒(méi)有那么重要了;然后到了高中,覺(jué)得非要吐露出自己的心聲才能為高中生涯里的懵懂情愫劃上一個(gè)句點(diǎn),但畢業(yè)晚會(huì)的時(shí)候最終還是被梗塞在了咽喉,后來(lái)再次站在他曾經(jīng)揮汗如雨的球場(chǎng),看著他投過(guò)籃球的球框時(shí),突然間發(fā)現(xiàn)自己已經(jīng)想不起他的容顏。A person39。想要的,不想要的,界限明確,好像沒(méi)有什么可以撼動(dòng)自己。嫌惡過(guò)自己的怯懦,最終卻發(fā)現(xiàn)有很多緣分,有很多錯(cuò)過(guò),好像冥冥之中真的已經(jīng)注定。At the moment, the sky is dark, the air is fresh factor after just rained. Suddenly thought of blue plaid shirt。 From the corner at the beginning of deep friendship。t start planning... Those years, those days of do, finally, like youth, will end in our life. 此刻,天空是陰暗的,空氣里有著剛下過(guò)雨之后的清新因子。Baumgartner the disappointing news: Mission aborted. r plays an important role in this mission. Starting at the ground, conditions have to be very calm winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our daytoday weather lives. It will climb higher than the tip of Mount Everest ( miles/ kilometers), drifting even higher than the cruising altitude of mercial airliners ( miles/ kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The supersonic descent could happen as early as Sunda.The weatheThe balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth bees the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he39。s not needed. Instead, he plans to deploy his 270squarefoot (25squaremeter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it w