基于at89s51單片機(jī)觸發(fā)的直流升壓斬波電路研究-預(yù)覽頁(yè)
【正文】 a斬波電路。隨電子技術(shù)的發(fā)展，近年來(lái)已發(fā)展各種集成式控制芯片，這種芯片只需外接少量元器件就可以工作，這不但簡(jiǎn)化設(shè)計(jì)，還大幅度的減少元器件數(shù)量、連線和焊點(diǎn)。圖1 升壓斬波電路原理圖分析升壓斬波電路的工作原理時(shí)，首先假設(shè)電路中電感值極大，電容C值極大。當(dāng)V處于斷態(tài)E和L共同向電容C充電并向負(fù)載R提供能量。不過(guò)，在電容C值足夠大時(shí)，誤差很小，基本可以忽略。AT89S51是一個(gè)低功耗，高性能8位單片機(jī)，片內(nèi)含4K Bytes ISP的可反復(fù)擦寫1000次的Flash只讀程序存儲(chǔ)器，器件采用ATMEL公司的高密度、非易失性存儲(chǔ)技術(shù)制造，兼容標(biāo)準(zhǔn)MCS51指令系統(tǒng)及80C51引腳結(jié)構(gòu)，芯片內(nèi)集成了通用8位中央處理器和ISP Flash存儲(chǔ)單元，AT89S51在眾多嵌入式控制應(yīng)用系統(tǒng)中得到廣泛應(yīng)用。圖22 AT89S51單片機(jī)PWM輸出電路圖 總體硬件組成框圖圖23 總體硬件組成框圖系統(tǒng)框圖如圖23所示，系統(tǒng)主要由五大模塊組成即時(shí)鐘電路、LED顯示、復(fù)位電路、按鍵電路和示波器顯示。圖24 AT89S51單片機(jī)構(gòu)成的最小應(yīng)用系統(tǒng) LED顯示電路 如圖25所示，由于外電路不需要占用很多的I/O口，因此在本設(shè)計(jì)中數(shù)碼管與AT89S51的P0口和P2口直接相連，采用靜態(tài)顯示的方法，具有亮度高等優(yōu)點(diǎn)。 圖27 主程序流程圖 定時(shí)中斷子程序 定時(shí)器中斷子程序中有定時(shí)器0和定時(shí)器1中斷，定時(shí)器0控制占空比變化步進(jìn)為1，如圖28；定時(shí)器1控制占空比變化步進(jìn)為5，如圖29。只要有一臺(tái)計(jì)算機(jī)就可以對(duì)不同的控制系統(tǒng)進(jìn)行仿真和研究，而且進(jìn)行一次仿真實(shí)驗(yàn)研究的準(zhǔn)備工作也比較簡(jiǎn)單，主要是控制系統(tǒng)的建模、控制方式的確立和計(jì)算機(jī)編程。它為用戶提供了一個(gè)圖形化得用戶界面（GUI）。 當(dāng)負(fù)載不變?yōu)?00，頻率1KHz，占空比從5%到95%以等百分比遞增時(shí)，輸出電壓，與輸入電壓和電路參數(shù)之間的關(guān)系。 (2) 在選取元器件型號(hào)和參數(shù)時(shí)，缺少實(shí)際經(jīng)驗(yàn)難以找到合適的元件。 學(xué)到的知識(shí)： (1) 通過(guò)這次課程設(shè)計(jì)我夯實(shí)了電力電子和單片機(jī)的基礎(chǔ)知識(shí)。相信我在未來(lái)的學(xué)習(xí)與生活中，能牢記此次課程設(shè)計(jì)的教訓(xùn)，吸取此次課程設(shè)計(jì)的經(jīng)驗(yàn)，從而追求更高的目標(biāo)。三、設(shè)計(jì)計(jì)劃課程設(shè)計(jì)共一周內(nèi)完成。指 導(dǎo) 教師：劉春喜 張繼華 李國(guó)華教研室主任：李洪珠時(shí) 間：2013年 1 月 6 日 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:Dismissal.You can make a claim to an employment tribunal, even if you haven39。Further 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 underif you win the case.If you are thinking about signing up for nearest CAB.For more information about making a claim to an employment tribunal, sees 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。City39。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。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。 Then in high school, think don39。A person39。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。 From the corner at the beginning of deep friendship。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,
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