基于C8051F040单片机软起动控制系统的研制

发布时间：2018-06-22 13:18

本文选题：软起动 + 晶闸管　；参考：《太原理工大学》2014年硕士论文

【摘要】：本文的研究内容是太原市科技局大学生创新创业项目“刮板输送机驱动系统”(项目编号：110148032)的重要组成部分。三相异步电机具有结构简单、稳定性高、易于维护、产品廉价等诸多优点而被广泛应用于国民生产生活的各个方面,但是三相异步电机在直接起动时,起动电流大、对电网冲击严重,严重影响设备的安全运行。针对上述问题,开发可以降低电机起动电流,减小对电网冲击的三相异步电动机软起动控制系统,具有重要现实意义。本文以一台3kW三相异步电机作为研究对象,晶闸管为主功率元件,C8051F040单片机为主控芯片,开发了一套三相异步电动机软起动控制系统,并且进行了实验验证。实验结果显示该系统能够有效降低三相异步电动机的起动电流,减小对电网的冲击,达到了三相异步电动机软起动的目的。本文主要研究内容如下：经过阅读大量文献,总结了三相异步电动机软起动控制系统的国内外研究现状,阐述了三相异步电动机软起动技术的传统状况,列举了传统软起动方法,介绍了现代基于晶闸管软起动的控制方法和工作原理。经过比较选择了用三组双向反并联晶闸管组成的三相全控桥作为主回路方案。研究了离散变频起动原理,分析了既可以降低起动电流又不降低起动转矩的方法,讨论了谐波对电机转矩的影响、最优频段的选取、最小频段的确定、触发方式的选择以及功率因数角的控制等,阐述了频段切换注意事项及谐波抑制方法等。对主功率元件和主控芯片型号进行选型,设计并开发了硬件电路,包括电压同步信号检测电路、电流检测电路、晶闸管驱动电路、控制芯片最小系统电路、人机交互电路等。经过测试表明系统性能稳定、精度高,符合设计要求。采用模块化编程方法,编写了软起动控制系统程序,软件包括主程序、初始化程序、信号采集程序、晶闸管触发程序、多种起动方式子程序、人机交互子程序等。经过实验调试,软件执行时间短、实时性好。建立了三相异步电动机软起动控制系统平台,对其进行软硬件联合调试,空载情况下,测试了电压同步信号波形、电压电流相位差波形图、触发脉冲相位波形图等,结果显示均能较高精度的满足系统要求,实时性高,可靠性好。搭建了磁粉制动器加载平台,对三相异步电动机进行加载实验,比较了软起动电流波形和直接起动电流波形,在一定负载下电机起动电流远远小于直接起动电流,达到了软起动限制起动电流的目的。
[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.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM343

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