本文選題：軟起動 + 晶閘管　； 參考：《太原理工大學(xué)》2014年碩士論文

【摘要】：本文的研究內(nèi)容是太原市科技局大學(xué)生創(chuàng)新創(chuàng)業(yè)項目“刮板輸送機驅(qū)動系統(tǒng)”(項目編號：110148032)的重要組成部分。三相異步電機具有結(jié)構(gòu)簡單、穩(wěn)定性高、易于維護、產(chǎn)品廉價等諸多優(yōu)點而被廣泛應(yīng)用于國民生產(chǎn)生活的各個方面,但是三相異步電機在直接起動時,起動電流大、對電網(wǎng)沖擊嚴重,嚴重影響設(shè)備的安全運行。針對上述問題,開發(fā)可以降低電機起動電流,減小對電網(wǎng)沖擊的三相異步電動機軟起動控制系統(tǒng),具有重要現(xiàn)實意義。 本文以一臺3kW三相異步電機作為研究對象,晶閘管為主功率元件,C8051F040單片機為主控芯片,開發(fā)了一套三相異步電動機軟起動控制系統(tǒng),并且進行了實驗驗證。實驗結(jié)果顯示該系統(tǒng)能夠有效降低三相異步電動機的起動電流,減小對電網(wǎng)的沖擊,達到了三相異步電動機軟起動的目的。本文主要研究內(nèi)容如下： 經(jīng)過閱讀大量文獻,總結(jié)了三相異步電動機軟起動控制系統(tǒng)的國內(nèi)外研究現(xiàn)狀,闡述了三相異步電動機軟起動技術(shù)的傳統(tǒng)狀況,列舉了傳統(tǒng)軟起動方法,介紹了現(xiàn)代基于晶閘管軟起動的控制方法和工作原理。經(jīng)過比較選擇了用三組雙向反并聯(lián)晶閘管組成的三相全控橋作為主回路方案。 研究了離散變頻起動原理,分析了既可以降低起動電流又不降低起動轉(zhuǎn)矩的方法,討論了諧波對電機轉(zhuǎn)矩的影響、最優(yōu)頻段的選取、最小頻段的確定、觸發(fā)方式的選擇以及功率因數(shù)角的控制等,闡述了頻段切換注意事項及諧波抑制方法等。 對主功率元件和主控芯片型號進行選型,設(shè)計并開發(fā)了硬件電路,包括電壓同步信號檢測電路、電流檢測電路、晶閘管驅(qū)動電路、控制芯片最小系統(tǒng)電路、人機交互電路等。經(jīng)過測試表明系統(tǒng)性能穩(wěn)定、精度高,符合設(shè)計要求。 采用模塊化編程方法,編寫了軟起動控制系統(tǒng)程序,軟件包括主程序、初始化程序、信號采集程序、晶閘管觸發(fā)程序、多種起動方式子程序、人機交互子程序等。經(jīng)過實驗調(diào)試,軟件執(zhí)行時間短、實時性好。 建立了三相異步電動機軟起動控制系統(tǒng)平臺,對其進行軟硬件聯(lián)合調(diào)試,空載情況下,測試了電壓同步信號波形、電壓電流相位差波形圖、觸發(fā)脈沖相位波形圖等,結(jié)果顯示均能較高精度的滿足系統(tǒng)要求,實時性高,可靠性好。 搭建了磁粉制動器加載平臺,對三相異步電動機進行加載實驗,比較了軟起動電流波形和直接起動電流波形,在一定負載下電機起動電流遠遠小于直接起動電流,達到了軟起動限制起動電流的目的。
[Abstract]:The research content of this paper is an important part of "scraper conveyor driving system" (item No.: 110148032). Three-phase asynchronous motor has many advantages such as simple structure, high stability, easy maintenance, cheap products and so on, so it is widely used in all aspects of life and production of Yu Guomin, but the starting current of three-phase asynchronous motor is large when it starts directly. The serious impact on the power grid seriously affects the safe operation of the equipment. In view of the above problems, it is of great practical significance to develop a three-phase asynchronous motor soft start control system which can reduce the starting current of the motor and reduce the impact on the power grid. In this paper, a 3kW three-phase asynchronous motor is taken as the research object, and the main power element of thyristor, C8051F040, is used as the main control chip. A set of soft start control system of three-phase asynchronous motor is developed and verified by experiment. The experimental results show that the system can effectively reduce the starting current of the three-phase asynchronous motor and reduce the impact on the power grid, and achieve the purpose of soft starting of the three-phase asynchronous motor. The main contents of this paper are as follows: after reading a large number of documents, this paper summarizes the domestic and international research status of three-phase asynchronous motor soft-start control system, and expounds the traditional status of three-phase asynchronous motor soft-start technology. This paper enumerates the traditional soft start method and introduces the modern control method and working principle based on thyristor soft start. Three-phase full-control bridge composed of three-way anti-parallel thyristors is chosen as the main circuit scheme. In this paper, the principle of discrete frequency conversion starting is studied, and the method of reducing the starting current and the starting torque is analyzed. The influence of harmonics on the torque of the motor, the selection of the optimal frequency band and the determination of the minimum frequency band are discussed. The selection of trigger mode and the control of power factor angle are discussed. The main power component and the main control chip are selected, and the hardware circuits are designed and developed, including voltage synchronous signal detection circuit, current detection circuit, thyristor drive circuit, control chip minimum system circuit, human-computer interaction circuit and so on. The test results show that the system has stable performance, high precision and meets the design requirements. The software includes main program, initialization program, signal acquisition program, thyristor trigger program, multi-starting mode subprogram, man-machine interaction subroutine and so on. After the experiment debugging, the software execution time is short and the real-time is good. The soft start control system platform of three-phase asynchronous motor is established, and the software and hardware joint debugging is carried out. Under the condition of no load, the voltage synchronous signal waveform, voltage and current phase difference waveform diagram, trigger pulse phase waveform diagram and so on are tested. The results show that the system can meet the requirements of high accuracy, high real-time and good reliability. The loading platform of magnetic powder brake is built, and the loading experiment of three-phase asynchronous motor is carried out. The soft start current waveform and direct starting current waveform are compared. The starting current of the motor is much smaller than the direct starting current under a certain load. The aim of limiting the starting current by soft start is achieved.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM343

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