【正文】 Festival. In this day, girls will throw a sewing needle into a bowl full of water 。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 28 with his elder brother 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。 ll wait in the line for one hour to get a ticket, and another two hours at the site, to only see a tiny bit of the place due to the crowds. Last year, 428 million tourists traveled in China over the weeklong holiday in October. Traveling during this period is a matter that needs thorough preparation. If you are short on time to plan the uping Golden Week it may not be a bad idea to avoid some of the most crowded places for now. There is always a place so fascinating that everyone yearns for. Arxan is a place like this. The beauty of Arxan is everlasting regardless of the changing of four seasons. Bestowed by nature, its spectacular seasonal landscape and mountains are just beyond word. Arxan is a crucial destination for the remended travelling route, China Inner Mongolia Arxan — Hailar — Manzhouli. It is also the joint of the four prairies across the SinoMongolian border, where people gravitate towards the exotic atmosphere mixed with Chinese, Russian, and Mongolia elements. As a historic site for the Yitian Battle, Arxan still embodies the spirit of Genghis Khan. Walking into Arxan, you will be amazed by a kaleidoscope of geous colors all the year round the Spring azaleas blooming red in the snow, the Summer sea wavering blue in the breeze, the Autumn leaves painted in yellow covering volcanic traces, and the Winter woods shining white on the vast alpine snowscape. Hinggan League Arxan city is situated in the far eastern area of Inner Mongolia Autonomous Region. Its full name Haren Arxan means hot holy water in the Mongolian language. Arxan is a tourism city in the northern frontier with a blend of large forest, grand prairies, vast snowfield, heaven lake cluster, thermium, as well as volcanic cluster. It is a rare and unique ecotourism base filled with healthy sunshine, clean air and unspoiled green. Nestled close to the country39?；叵胝麄€(gè)論文的寫作過程，雖有不易，卻讓我除卻浮躁，經(jīng)歷了思考和啟示，也更加深切地體會(huì)了科研的艱難與不易，因此倍感珍惜。同時(shí)也感謝這篇論文所涉及到的各位學(xué)者。本論文從選題到完成，幾易其稿，每一步都是在26 徐老師的指導(dǎo)下完成的，傾注了大量的心血，在此向我的指導(dǎo)教師徐坤老師表示深切的謝意與祝福！ 本論文的完成也離不開物理與電子工程系其他各位老師、同學(xué)和朋友的關(guān)心與幫助。四年來，徐老師淵博的專業(yè)知識(shí)，嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度，精益求精的工作作風(fēng)，誨人不倦的高尚師德，樸實(shí)無華、平易近人的人格魅力對(duì)我影響深遠(yuǎn)。值此畢業(yè)論文完成之際，我謹(jǐn)向所有關(guān)心、愛護(hù)、幫助我的人們表示最誠摯 的感謝與最美好的祝愿。 參考文獻(xiàn) [1] 唐蘇亞 .我國(guó)電動(dòng)自行車產(chǎn)業(yè)的發(fā)展現(xiàn)狀 [J].電機(jī)技術(shù) ,2021(2): 3943. [2] 顧軍民 .基于 MSP430的電動(dòng)車穩(wěn)壓充電器研制 [D].江蘇 :江蘇大學(xué) ,2021. [3] 顧銘 .無刷直流電機(jī)控制系統(tǒng)設(shè)計(jì) [D].大連 :大連理工大學(xué) ,2021. [4] 萬文斌 ,劉瑞芳 .基于直流無刷電機(jī)的電動(dòng)車智能驅(qū)動(dòng)系統(tǒng)設(shè)計(jì) [J].儀表技術(shù) ,2021(3): 79. [5] 姜書政 ,王桂海 .基于 AT89S52單片機(jī)的電機(jī)控制系統(tǒng)設(shè)計(jì) [J].現(xiàn)代電子技術(shù) ,2021,33(7): 3840. 25 [6] 魏昌洲 .基于 DSP的交流變頻調(diào)速系統(tǒng)研究 [D].南京 :南京航空航天大學(xué) ,2021. [7] 郭崇軍 ,李琦 ,洪權(quán) ,許強(qiáng) .基于 C8051的無刷直流電機(jī)控制系統(tǒng) [J].機(jī)電工程 ,2021,24(9): 3638. [8] 駱?gòu)?.基于 AVR 單片機(jī)的電動(dòng)自行車控制系統(tǒng)研究 [D].大連 :大連理工大學(xué) ,2021. [9] 葛榮 ,張邦武 .電動(dòng)自行車控制器的設(shè)計(jì)與實(shí)現(xiàn) [J].南通職業(yè)大學(xué)學(xué)報(bào) ,2021,19(2): 3539. [10] 吳俊卿 ,張浩然 ,范宇龍 .基于 PIC16F877 的電動(dòng)自行車控制器的設(shè)計(jì) [J].電子器件 ,2021,33(5): 642645. [11] 范化明 ,盧文科 ,張健 .基于 ATmega88 單片機(jī)的新型電動(dòng)車控制器的設(shè)計(jì) [J].電子測(cè)量技術(shù) ,2021,32(11): 8084. [12] 汪飛鵬 .直流無刷電機(jī)電動(dòng)自行車控制器的硬件設(shè)計(jì) [J].中國(guó)科技博覽 ,2021(11): 6868. [13] 廖承喜 .基于 ATmega48單片機(jī)的電動(dòng)自行車控制器的設(shè)計(jì) [D].湖南 :湖南大學(xué) ,2021. [14] 賈桂麗 ,高延濱 ,初德進(jìn) .基于 ST7FMC 的電動(dòng)自行車用無刷直流電機(jī)控制器 [J].應(yīng)用科技 ,2021,35(1): 6164. [15] 黃燦水 ,林榮文 ,林珍 .無刷直流電動(dòng)機(jī)控制器設(shè)計(jì) [J].福建能源開發(fā)與節(jié)約 ,2021 (1): 4547. [16] 林義民 .基于無刷直流電機(jī)的電 動(dòng)自行車控制器的研究 [D].廣西 :桂林理工大學(xué) ,2021. [17] 李虹霖 .電動(dòng)自行車控制保護(hù)系統(tǒng) [D].四川 :四川大學(xué) ,2021. [18] 康世斌 .自行車低成本直流無刷電機(jī)控制器研究 [D].上海 :同濟(jì)大學(xué) ,2021. 致 謝 歲月如梭，轉(zhuǎn)眼間四年的大學(xué)生活即將結(jié)束，站在畢業(yè)的門檻上，回首往昔，奮斗和辛勞成為絲絲的記憶，甜美與歡笑也都?jí)m埃落定。閉環(huán)控制的理論及方法已非常成熟，但是測(cè)速電機(jī)的成本卻影響了閉環(huán)方法在直流無刷電機(jī)控制器上的應(yīng)用，而以反電動(dòng)勢(shì)檢測(cè)法為主的低成本速度檢測(cè)方法目前尚在性能上與測(cè)速電機(jī)方法有較大差異。將直流無刷電機(jī)控制器全數(shù)字化，是比較有 前景的研究方向。數(shù)字化設(shè)計(jì)具有參數(shù)修改方便、減小系統(tǒng)對(duì)器件性能依賴、提高工作效率和便于實(shí)現(xiàn)多種功能等優(yōu)點(diǎn)。 （ 2） 系統(tǒng)全數(shù)字化設(shè)計(jì)。力矩的抖動(dòng)對(duì)電動(dòng)車的使用者會(huì)產(chǎn)生一定程度的不適感，不利于提高用戶對(duì)產(chǎn)品的人性化的需求。 由于時(shí)間以及水平有限， 本 設(shè)計(jì) 提出的解決方案， 也 存在一些 缺點(diǎn) 和 未 深入 分析探討 的地方。 針對(duì)原有直流無刷電機(jī)控制器電流采樣的快速性、準(zhǔn)確性問題， 設(shè)計(jì)出合理的電流采樣保持電路。增加了多種保護(hù)功能，使電動(dòng)車的可靠性大大提高，而且更加人性化。 5. 展望 本 設(shè)計(jì) 對(duì)電動(dòng)自行車用無刷直流電動(dòng)機(jī)控制器的各個(gè)方面進(jìn)行了 分析 探討 ，經(jīng)過分24 析驗(yàn)證能夠較好地解決目前直流無刷電動(dòng)機(jī)控制器存在的一些問題 。 綜上所述， 該設(shè)計(jì)方案具有實(shí)際可行性，達(dá)到了預(yù)期要求，運(yùn)行平穩(wěn)可靠。 圖 19 堵轉(zhuǎn)保護(hù)相電流波形 通過波形圖可以看出，在電機(jī)發(fā)生堵轉(zhuǎn)時(shí)，相電流迅速增大，此時(shí)保護(hù)程序啟動(dòng)，使輸出 PWM 波占空比迅速減小，從而相電流減小，保護(hù)電機(jī)不至于損毀。 23 圖 18 柔性電子剎車效果圖 電動(dòng)機(jī)在正常運(yùn)行中，受到外力不能正常 運(yùn)轉(zhuǎn)或者電子換相異常，會(huì)導(dǎo)致相電流迅速增大，對(duì)電機(jī)造成不可修復(fù)的損傷。在沒有使用機(jī)械剎車的情況下只使用柔性電子剎車，如圖 18 所示為柔性電子剎車效果圖。結(jié)果與預(yù)期目標(biāo)符合?？梢钥闯鲭妱?dòng)車剛啟動(dòng)轉(zhuǎn)速較低時(shí)，電機(jī)轉(zhuǎn)矩迅速增大。當(dāng)軟啟動(dòng)結(jié)束， PWM 波形正常。如圖 16所示為 PWM 波形。 4. 結(jié)果與分析 本設(shè)計(jì)從理論分析、硬件電路設(shè)計(jì)、軟件設(shè)計(jì)和系統(tǒng)總體調(diào)試等方面考慮， 逐步實(shí)現(xiàn)了控制器所要完成的各項(xiàng)功能。在調(diào)試過程中，能夠很容易找到錯(cuò)誤位置。當(dāng)系統(tǒng)受到外界突發(fā)干擾時(shí)，軟