基于多模态控制的离散变频高转矩软起动技术研究

发布时间：2018-01-12 19:42

本文关键词：基于多模态控制的离散变频高转矩软起动技术研究　出处：《长沙理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：交流异步电机以结构简单、性能稳定、性价比高等突出特点,在工农业、国防以及家用电器设备中得到广泛的使用。与此同时,交流异步电机的配套控制设备也得到了快速发展。异步电机起动控制就是被关注的热点之一。从传统的降压起动控制,到新型的电机软起动控制,电机的降压起动从有级调压发展到无级调压,有效解决了在起动过程中的抖动和电流冲击问题。电机软起动设备中,电子式软起动器以其结构紧凑、控制方便、操作简单、重量轻等突出优点,在不需要调速的场合,得到了最广泛的应用。但是起动转矩比较小,一般只适用于轻载或者空载起动的场合。变频调速技术虽然能够完美解决电动机的起动问题,实现小电流高转矩的优良起动性能,但是其价格比较昂贵,一般适用于需要调速的场合,仅仅当成起动器来用是非常不经济的。所以研究具有重载起动功能的软起动器具有很大的实际意义。针对电子式软起动器起动转矩小的弊端,文章研究了一种具有高起动转矩的离散分级变频软起动技术。首先是根据相关文献,分析了离散分级变频的原理,得到了离散变频后三相的相序关系,并总结正序对称的分频等级以及分频方式。其次,通过傅立叶分析得到了各分频子频率下每相的初相角公式,并通过仿真验证了公式的正确性。然后,利用对称分量法分析出二分频和三分频两个不对称分频等级的最佳分频方式,根据正序分量最大原则,选择出初始频率和过渡频率。最后,根据离散分级变频的特点,首次将仿人人工智能控制中的多模态控制应用到分频控制中,并以各级子频率转速接近本级频率下电机的额定值和切换前后两个子频率等效电压的相位一致时间点为判据,构建频段切换特征模型,实现频段的自适应切换。使用Matlab/Simulink工具箱搭建仿真模型,验证了控制方案的有效性。仿真结果表明,文章提出的控制方案能够根据负载的不同自适应的调节电动机在各分频子频率下的运行时间,有效提高了离散分级变频软起技术的综合性能。这种具有自适应切换效果的高转矩软起动器的提出,对于需要重载起动或者恒负载起动而又不需要调速的工业场合具有重要的意义,而且能够促进晶闸管软起动器的智能化和多功能化发展。
[Abstract]:Ac asynchronous motor is widely used in industry, agriculture, national defense and household appliances because of its simple structure, stable performance and high cost performance. The auxiliary control equipment of AC asynchronous motor has also been developed rapidly. The starting control of asynchronous motor is one of the hotspots that has been paid close attention to, from the traditional step-down starting control to the new type of motor soft start control. The step-down starting of motor develops from stepwise voltage regulation to stepless voltage regulation, which effectively solves the problems of jitter and current shock during the starting process. In the soft starting equipment of motor, the electronic soft starter is compact in structure and convenient in control. Simple operation, light weight and other outstanding advantages, in the case of no need for speed regulation, has been the most widely used, but the starting torque is relatively small. Frequency conversion technology can solve the starting problem of motor perfectly and realize the excellent starting performance of low current and high torque, but its price is expensive. Generally applicable to the need to speed the occasion. It is very uneconomical to use only as a starter. So it is of great practical significance to study the soft starter with heavy load starting function. Aiming at the disadvantage of small starting torque of electronic soft starter. In this paper, a kind of soft start technology with high starting torque is studied. Firstly, according to the related literature, the principle of discrete stepwise frequency conversion is analyzed, and the phase sequence relation of three phase after discrete frequency conversion is obtained. And summed up the positive order symmetry frequency division level and frequency division mode. Secondly, through Fourier analysis, the formula of initial phase angle of each phase is obtained, and the correctness of the formula is verified by simulation. By using the symmetrical component method, the optimal frequency division mode of two asymmetrical frequency division levels is analyzed, and the initial frequency and the transition frequency are selected according to the principle of maximum order component. Finally. According to the characteristics of discrete hierarchical frequency conversion, the multimodal control in artificial intelligence control is applied to the frequency division control for the first time. The characteristic model of frequency band switching is constructed based on the rated motor speed of each subfrequency close to this frequency and the phase consistent time point of the equivalent voltage of two subfrequencies before and after switching. The Matlab/Simulink toolbox is used to build the simulation model, which verifies the effectiveness of the control scheme. The simulation results show that. The control scheme proposed in this paper can adaptively adjust the operating time of the motor at different frequency subfrequencies according to the load. The proposed high torque soft starter with adaptive switching effect can effectively improve the comprehensive performance of the discrete stage frequency conversion soft start technology. It is of great significance for the industrial situation which requires heavy load or constant load start and does not need speed regulation, and can promote the intelligent and multifunctional development of the thyristor soft starter.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM573

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