变频供电交流电机轴电流问题的分析与抑制

发布时间：2018-12-11 02:25

【摘要】：随着电力电子技术及器件不断发展,变频驱动被广泛应用于新能源发电、高速列车牵引传动和许多交直流传动系统中。由于变频器的输出电压存在高频的共模电压,在电机杂散电容的耦合作用下,在电机轴上感应出轴电压,继而引发轴电流,造成轴承的电腐蚀,严重危害变频驱动系统的安全运行。因此,研究变频供电系统中的轴电流产生机理,提出有效地抑制方法,对提高系统运行的可靠性具有重要的意义。本文首先分析了轴电流的产生机理,介绍了轴电流的分类,测试方法以及抑制方案的研究现状,指出在目前分析中存在的问题。然后针对变频驱动系统共模电压的产生以及影响因素展开研究。建立了SVPWM变频驱动系统共模电压分析模型,采用MATLAB仿真分析了不同的IGBT死区时间、IGBT和二极管的管压降、IGBT下降沿时间对共模电压的影响。分析结果表明IGBT死区时间对共模电压的峰值和有效值影响不大,但是随着死区时间的增加,共模电压在载波频率处的分量幅值不断增加。IGBT和二极管的管压降、IGBT下降沿时间对共模电压则影响较小。针对变频驱动系统交流电机的共模电压、轴电压和轴电流进行了实验测试。考察了不同的死区时间、载波频率、调制波频率下共模电压的变化,实验结果与仿真结果一致。变频器的上述参数对轴电压和轴电流的影响也较小。研究分析了基于共模变压器的低通滤波器,给出RLC网络和共模变压器各元件的定值计算方法。利用变频器实验平台,证明低通滤波器对共模电压、轴电压的抑制作用。最后搭建了变频器-异步电机实验平台,介绍了变频器的硬件和软件设计。给出了共模电压、轴电压和轴电流的测量方案。
[Abstract]:With the continuous development of power electronics technology and devices, frequency conversion drive is widely used in new energy generation, high-speed train traction transmission and many AC / DC transmission systems. Because the output voltage of frequency converter has high frequency common-mode voltage, under the coupling action of stray capacitance of motor, the shaft voltage is induced on the motor shaft, and then the shaft current is induced, which results in the electric corrosion of the bearing. It seriously endangers the safe operation of frequency conversion drive system. Therefore, it is of great significance to study the mechanism of axial current generation in frequency conversion power supply system and to put forward effective suppression methods to improve the reliability of the system. In this paper, the generation mechanism of axial current is analyzed, the classification of axial current, the testing method and the research status of suppression scheme are introduced, and the existing problems in the analysis are pointed out. Then, the generation of common-mode voltage and its influencing factors are studied. A common-mode voltage analysis model of SVPWM variable-frequency drive system is established. The influence of different IGBT dead-time, IGBT and diode voltage drop and IGBT drop time on common-mode voltage is analyzed by MATLAB simulation. The results show that the dead time of IGBT has little effect on the peak and effective value of common-mode voltage, but with the increase of dead-time, the amplitude of common-mode voltage at carrier frequency increases continuously. The drop time of IGBT has little effect on common-mode voltage. The common mode voltage, shaft voltage and shaft current of AC motor in frequency conversion drive system are tested experimentally. The changes of common mode voltage at different dead-time, carrier frequency and modulation frequency are investigated. The experimental results are in agreement with the simulation results. The influence of the above parameters on the shaft voltage and current is also small. The low-pass filter based on common-mode transformer is studied and analyzed. The calculation method of RLC network and each component of common-mode transformer is given. The suppression effect of low pass filter on common-mode voltage and axis voltage is proved by using inverter experimental platform. Finally, the inverter-asynchronous motor experimental platform is built, and the hardware and software design of the inverter is introduced. The measurement scheme of common-mode voltage, axial voltage and axial current is given.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM34

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