【正文】 he humble guy sitting in front of me. He just simply said ,”well, I caught sight of this flower and thought that it’s beautiful and you may like it”. I wonder why I was moved because of these simple words and present. Maybe it is the sincerity and the true self that impress me. I thanked him and some colleagues walked past my desk would appreciate the beautiful flower and they noticed that something romance happened there. Then later on, there were some little surprises once in a while. Once, there was something wrong with my drawer and I had plained about it unconsciously. And he fixed it for me. Then the other day, he placed several pink diamond roses beside the flower with a piece of paper saying” I love you more than I can say! Diamond stands for marriage, rose stand for love. I hope you are mine, bee my wife. You are the only girl who I really want to spend the rest of my life to stand by.” Although there were some grammar errors but I got what he meant. He meant so clear and so direct. And actually, I accepted him some days earlier.。這次實(shí) 踐是對(duì)自己大學(xué)四年所學(xué)的一次大檢閱，使我明白自己知識(shí)還很淺薄，雖然馬上要畢業(yè)了，但是自己的求學(xué)之路還很長(zhǎng)，以后更應(yīng)該在工作中學(xué)習(xí)，努力使自己 成為一個(gè)可以參與工作能獨(dú)立完成設(shè)計(jì)的人。 西安理工大學(xué)本科生畢業(yè)設(shè)計(jì)（論文 ） 第 17 頁 數(shù)字抖 動(dòng)的 FPGA實(shí)現(xiàn) 目前，主要是通過查表方式實(shí)現(xiàn)數(shù)字“抖動(dòng)”。因此純粹的延遲式 DPWM 并沒有太多的應(yīng)用空間。 數(shù)字 PWM（ DPWM）的高精度已成為目前的研究熱點(diǎn)，也是數(shù)字控制開關(guān)電源中急需解決的一個(gè)問題。電路的穩(wěn)定運(yùn)行狀態(tài)在一個(gè)周期內(nèi)可分為 4 個(gè)運(yùn)行階段。但是隨著開關(guān)頻率的 提高，功率開關(guān)管損耗在電源運(yùn)行中所占的比例也將增加，使得效率有所降低。 從電源技術(shù)要求來看，要實(shí)現(xiàn)脈沖電源波形穩(wěn)定、參數(shù)調(diào)節(jié)范圍寬，必定使 電路復(fù)雜化、造價(jià)提高、可靠性降低。出現(xiàn)了許多新型的脈沖電源和新的發(fā)展趨勢(shì)。這些問題的出現(xiàn)便隨之出現(xiàn)了高頻化的脈沖電源的研究。（參考《倍頻式 700KHZ 高頻大功率感應(yīng)加熱電源的研究》）其主電路拓?fù)鋱D如下所示： 本論文的主電路拓?fù)浼磪⒖忌鲜鐾負(fù)涞牡刃負(fù)鋱D，利用分時(shí)復(fù)合控制功率策略。在電鍍過程中，被 鍍件附近有 個(gè)極化區(qū)域，該區(qū)域的離子濃度隨著通電時(shí)間的延長(zhǎng)，離子濃度也隨著降低，被 鍍件上金屬離子的沉積速度減慢，如果在此時(shí)將電源停電，致使離子濃度恢復(fù)加 快，再施加電源，必將提高金屬離子的沉積速度，并且也可解決不規(guī)則形狀被鍍 件的均鍍問題。 實(shí)現(xiàn)高精度的 PWM波是通過研究數(shù)字“抖動(dòng)”的基本原理，以 FPGA為載體在 基于計(jì)數(shù)方式的數(shù)字 PWM上使用數(shù)字“抖動(dòng)”來提高 DPWM的精度，精度達(dá)到 500ps。通過合理的設(shè)計(jì)可以使輸出電流紋波幅值接近于或等于零 ,實(shí)現(xiàn)零紋波輸出。 田 晨：大功率脈沖變換器高頻化技術(shù)研究 第 14 頁 第 3 章 高精度 PWM 波的產(chǎn)生 數(shù)字開關(guān)電源已逐漸成為一個(gè)發(fā)展趨勢(shì)。為了解決系統(tǒng)對(duì) DPWM 精度要求與過高的技術(shù)頻率直接的矛盾，數(shù)字電源的先驅(qū)們?cè)O(shè)計(jì) 西安理工大學(xué)本科生畢業(yè)設(shè)計(jì)（論文 ） 第 15 頁 了幾種其他形式的 DPWM 結(jié)構(gòu) 2，延遲式 DPWM 不使用高頻時(shí)鐘的最直接的方法就是使用延遲線。圖 2示出數(shù)字“抖動(dòng)“示意圖。同時(shí)在這次畢業(yè)設(shè)計(jì)中遇到了很多的麻煩，最難的莫過于 FPGA的編程過程了，大量的新語言都需要自己去慢慢學(xué)習(xí)，最終在還是一點(diǎn)一點(diǎn)的攻克了下來。s time for the wild fruits to ripe. The picturesque Arxan in Autumn is indeed a fairyland only exists in a dream that satisfies all your fantasies. If it rains heavily on Saturday night, some elderly Chinese will say it is because Zhinu, or the Weaving Maid, is crying on the day she met her husband Niulang, or the Cowherd, on the Milky Way. Most Chinese remember being told this romantic tragedy when they were children on Qixi, or the Seventh Night Festival, which falls on the seventh day of the seventh lunar month, which is usually in early August. This year it falls on Saturday, August 2. Folklore Story As the story goes, once there was a cowherd, Niulang, who lived with his elder brother 西安理工大學(xué)本科生畢業(yè)設(shè)計(jì)（論文 ） 第 27 頁 and sisterinlaw. But she disliked and abused him, and the boy was forced to leave home with only an old cow for pany. The cow, however, was a former god who had violated imperial rules and was sent to earth in bovine form. One day the cow led Niulang to a lake where fairies took a bath on earth. Among them was Zhinu, the most beautiful fairy and a skilled seamstress. The two fell in love at first sight and were soon married. They had a son and daughter and their happy life was held up as an example for hundreds of years in China. Yet in the eyes of the Jade Emperor, the Supreme Deity in Taoism, marriage between a mortal and fairy was strictly forbidden. He ordered the heaven troop to catch Zhinu back. Niulang grew desperate when he discovered Zhinu had been taken back to heaven. Driven by Niulang39。 最后 ，感謝這篇論文所涉及到的各位學(xué)者教授，本論文引用了數(shù)位學(xué)者的研究文 獻(xiàn)， 如果沒有各位學(xué)者的研究成果的幫助和啟發(fā)，我將很難完成本篇論文的寫作。 程序 根據(jù)數(shù)字抖動(dòng)的實(shí)現(xiàn)框圖，如下： 田 晨：大功率脈沖變換器高頻化技術(shù)研究 第 18 頁 編譯相關(guān)程序?yàn)椋? 西安理工大學(xué)本科生畢業(yè)設(shè)計(jì)（論文 ） 第 19 頁 原理 田 晨：大功率脈沖變換器高頻化技術(shù)研究 第 20 頁 在 QuartusⅡ開發(fā)環(huán)境下設(shè)計(jì) 基于 QuarterII 的設(shè)計(jì)流程 西安理工大學(xué)本科生畢業(yè)設(shè)計(jì)（論文 ） 第 21 頁 模型搭建 田 晨：大功率脈沖變換器高頻化技術(shù)研究 第 22 頁 仿真過程及分析 西安理工大學(xué)本科生畢業(yè)設(shè)計(jì)（論文 ） 第 23 頁 第 4 章 總結(jié) 這 次畢業(yè)設(shè)計(jì)我做的大功率脈沖變換器的高頻化研究。在占空比低位信號(hào)選通的脈沖信 號(hào)通過高位比較器控制的與門后