【正文】
重慶科技學(xué)院高等教育自學(xué)考試本科畢業(yè)論文 中文摘要高等教育自學(xué)考試本科畢業(yè)論文基于PLC的三相異步電機(jī)變頻調(diào)速系統(tǒng)的設(shè)計(jì)高等教育自學(xué)考試本科畢業(yè)論文 基于PLC的三相異步電機(jī)變頻調(diào)速系統(tǒng)的設(shè)計(jì)摘 要隨著科技的進(jìn)步,電機(jī)的運(yùn)用已經(jīng)深入到各行各業(yè)的各個(gè)領(lǐng)域。而現(xiàn)今也是一個(gè)資源高度消耗造成能源匱乏的時(shí)代,在這個(gè)時(shí)候考慮如何讓其在高可靠性的同時(shí)又有效的節(jié)約能源耗費(fèi)提高自身的效率,這不僅可以使企業(yè)的生產(chǎn)成本降低,而且對于社會的可持續(xù)發(fā)展有著重要的意義。本文所討論的是利用PLC控制的三相異步電機(jī)變頻調(diào)速的基本原理與實(shí)現(xiàn)方法。三相異步電機(jī)一般的調(diào)速方法有:降壓調(diào)速,轉(zhuǎn)子回路串電阻調(diào)速,變極調(diào)速,串極調(diào)速,變頻調(diào)速等。但是這些調(diào)速方法都有著各自的缺點(diǎn),降壓調(diào)速的調(diào)速范圍很小,沒有多大的實(shí)用價(jià)值;轉(zhuǎn)子回路串電阻調(diào)速不利于空載或輕載調(diào)速,效率低,經(jīng)濟(jì)性差;變極調(diào)速調(diào)速的平滑性差;串極調(diào)速的控制設(shè)備復(fù)雜,成本高,控制困難。所以調(diào)速性能至少需從兩方面考慮。第一,應(yīng)從節(jié)能和提高效率的角度考慮,應(yīng)將損耗在轉(zhuǎn)子附加電阻上的能量吸收,轉(zhuǎn)化成別的有用的能量或反饋到電網(wǎng),以提高傳動系統(tǒng)的效率。第二,應(yīng)從高性能調(diào)速要求考慮,應(yīng)用控制理論,將其組成閉環(huán)調(diào)速控制系統(tǒng),滿足調(diào)速精度、動態(tài)響應(yīng)等各項(xiàng)指標(biāo)的要求。綜上所述,利用PLC控制的變頻調(diào)速系統(tǒng),是使三相異步電動機(jī)實(shí)現(xiàn)高性能高效率調(diào)速的有效辦法。通過改變定子繞組的供電頻率f來實(shí)現(xiàn),當(dāng)轉(zhuǎn)差率s一定時(shí),電動機(jī)的轉(zhuǎn)速n基本上正比于f。很明顯,只要有輸出頻率可以平滑調(diào)節(jié)的變頻電源,就能平滑的調(diào)節(jié)異步電動機(jī)的轉(zhuǎn)速。關(guān)鍵詞:變頻調(diào)速,PLC,異步電機(jī)II重慶科技學(xué)院高等教育自學(xué)考試本科畢業(yè)論文 英文摘要The threephase asynchronous motor variable frequency speed regulation system based on PLC designAbstractHuman being is seriously threatened by exhausting mineral fuel, such as coal and fossil oil. As a kind of new type of energy sources, solar energy has the advantages of unlimited reserves, existing everywhere,using clean and economical .But it also has disadvantages ,such as low density,intermission,change of space distributing and so on. These make that the current series of solar energy equipment for the utilization of solar energy is not high. In order to keep the energy exchange part to plumb up the solar beam,it must track the movement of solar. In this paper, the solar tracking system of the mechanical part and control system part are designed.Mechanical structure mainly includes the main spindle, stepping motors, gears and gear ring, and so on. When the sun39。s rays has a deviation, small gear are rotated by stepper motor according to the control signal from MCU. And the large gear and main spindle is rotated by small gear in order to track to achieve the level direction. At the same time, another small gear is rotated by another stepper motor according to the control the large gear and the solar panels are rotated by the small gear in order to track to achieve the vertical direction. Solar is tracked by the two stepper motors together. Control system mainly includes the sensors part, stepper motor, MCU system and the corresponding external circuit, and so on. Photoelectric detection system is used to track solar. Sensors use photosensitive resistance. The two same photosensitive resistances were placed in east and west direction of the bottom edge .When the two photosensitive resistances received different light at the same time, the signal from parison circuit is sent to MCU in order to rotate stepping motors.Keywords: Frequency control, PLC, asynchronous motorII重慶科技學(xué)院高等教育自學(xué)考試本科畢業(yè)論文 目錄目 錄中文摘要 I英文摘要 II1 緒 論 1 本課題的背景及意義 1 1 2 22 PLC的運(yùn)用和發(fā)展 4 4 PLC的特點(diǎn)與應(yīng)用 4 PLC的工作原理 53 三相異步電機(jī)及其數(shù)學(xué)模型 6 6 6 6 8 9(簡稱轉(zhuǎn)矩) 9 10 114 變頻器及變頻調(diào)速原理 13 13 13 14 15 V/F控制原理 165 變頻調(diào)速系統(tǒng)總體設(shè)計(jì) 17 17 186 結(jié) 論 21致 謝 22參考文獻(xiàn) 23IV重慶科技學(xué)院高等教育自學(xué)考試本科畢業(yè)論文 1 緒論1 緒 論 本課題的背景及意義 隨著電力電子技術(shù)的發(fā)展,以及各種新型控制器件和先進(jìn)控制方法在電機(jī)調(diào)速系統(tǒng)中的應(yīng)用,三相異步電機(jī)控制精度得到極大提高。為了滿足高性能和節(jié)能環(huán)保的要求,三相異步電機(jī)以其特有的調(diào)速優(yōu)點(diǎn),正逐步取代直流調(diào)速。電機(jī)的