三相功率因数校正及其数字控制系统的研究

发布时间：2018-11-21 08:15

【摘要】：三电平电力变换装置凭借其较低的元器件应力,较高的功率密度等优势在大功率电流变换场合得到了广泛应用。三电平特有的结构决定了其与传统两电平电流变换设备在控制、分析等方面的差异。本文以三电平维也纳AC/DC为研究对象,以功率因数校正为基本目标,在对数学模型进行构建的基础上,对结构特点、校正原理以及性能表现等进行了分析。对提高功率因数方法的分析从两方面展开,一方面,对传统的以相为控制单位的控制方式进行了阐述,另一方面,以空间矢量控制方式进行了分析,并提出了改进的三电平空间矢量合成技术,该技术利用几何投影方式实现三电平矢量合成向两电平矢量合成转换,并通过对三相电流极性的实时采集确定参考矢量的坐标位置。和传统的空间矢量合成校正方式相比,一方面能充分利用现有的传统两电平合成方法,另一方面使得复杂的矢量合成更易理解和掌握。除了对单台设备功率因数校正技术分析外,本文还从设备网侧以及直流输出侧两个角度对多台设备并列运行的情况进行了数学建模与分析,通过构建网侧并联设备的整体数学模型,使得关于设备间的环流路径、设备间的相互影响等的分析过程更为简化。同时,揭示了零序分量在设备并列运行过程中的关键作用,阐述了三电平AC/DC设备直流侧电压均衡控制与零序电流抑制间的联系;以戴维南等效原理构建的直流输出侧整体数学模型,从直流侧的角度揭示了设备间并列运行时,直流输出电压对环流产生的促进作用。同时,引入了虚拟电阻思想。借助虚拟电阻,根据直流侧环流的变化情况,实时的对直流输出电压进行调整。仿真结果表明,上述方法能够有效实现功率因数校正与控制,且实现对环流的抑制。本文从三电平整流设备的结构、数学模型出发,针对功率因数校正及其控制、单机独立运行以及多设备并列运行问题进行了系统、详细的理论分析与验证。
[Abstract]:Three-level power converter is widely used in high-power current conversion field due to its advantages of low component stress and high power density. The unique structure of three-level determines the difference between three-level current conversion equipment and traditional two-level current conversion equipment in control, analysis and so on. In this paper, the three-level Vienna AC/DC is taken as the research object and the power factor correction as the basic goal. Based on the construction of the mathematical model, the structural characteristics, correction principle and performance are analyzed. The method of improving power factor is analyzed from two aspects. On the one hand, the traditional control mode with phase as the control unit is expounded, on the other hand, the space vector control method is analyzed. An improved three-level space vector synthesis technique is proposed, which uses geometric projection to realize the conversion from three-level vector synthesis to two-level vector synthesis. The coordinate position of the reference vector is determined by the real-time acquisition of three-phase current polarity. Compared with the traditional space vector synthesis correction method, on the one hand, it can make full use of the traditional two-level synthesis method, on the other hand, it makes the complex vector synthesis easier to understand and master. In addition to the analysis of power factor correction technology for single equipment, the mathematical modeling and analysis of the parallel operation of multiple devices are carried out from the two angles of the equipment network side and the DC output side. By constructing the overall mathematical model of the parallel equipment on the network side, the analysis process of the circulation path between the devices and the interaction between the devices is more simplified. At the same time, the key role of zero sequence component in the parallel operation of the equipment is revealed, and the relationship between DC side voltage equalization control and zero sequence current suppression of three-level AC/DC equipment is discussed. The integral mathematical model of DC output side based on Davinan's equivalence principle is used to reveal the effect of DC output voltage on the circulation when the equipment is running side by side in parallel. At the same time, the idea of virtual resistance is introduced. With the help of virtual resistor, the DC output voltage is adjusted in real time according to the variation of DC side circulation. The simulation results show that the proposed method can effectively realize power factor correction and control and suppress the circulation. Starting from the structure and mathematical model of three-level rectifier equipment, this paper presents a detailed theoretical analysis and verification of power factor correction and its control, independent operation of single machine and parallel operation of multi-equipment.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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