外磁场对直流接触器开断电弧特性影响的研究

发布时间：2018-03-26 18:41

本文选题：低压直流电弧　切入点：磁流体动力学　出处：《沈阳工业大学》2017年硕士论文

【摘要】：低压开关电器作为关键的配电设备之一,在开断过程中不可避免地将会产生电弧。电弧在毫秒级时间、毫米级空间内快速动态变化,从而影响电器的开断能力。电弧衍生机理和发展规律是国内外研究者们广泛关注的研究热点与难点,相比于交流电弧,由于直流电弧不存在电流自然过零点现象,其熄灭更加困难。合理设计接触器触头结构,使之产生磁场有利触头开断是公用技术。磁场对电弧作用形成磁吹有利于电弧熄灭已是不争的事实,因此探索外磁场及其变化对直流电弧的影响及有利电弧熄灭意义重大。本文以电磁场数值计算为基础,建立外磁场及直流电弧数学模型,通过数值仿真分析为直流接触器外加磁场装置结构设计提供指导和方案。通过对多种永磁材料的磁场分布进行对比仿真分析,研究结果表明三维磁场计算中的电弧模型由于电导率差异而产生磁场分布不均匀的现象,这为选择和设计合理的外加磁场发生装置提供了理论支撑。基于磁流体动力学(MHD)理论建立了综合电弧运动特性和电弧机理的空气电弧数学模型,分别对外磁场作用下电弧特性和电弧运动特性仿真分析,探究不同外磁场对直流电弧影响的共性机理,研究电弧在外磁场作用下运动特性的本质规律。通过外磁场对电弧特性的调控,为研究不同外磁场作用下电弧特性和电弧运动行为提供理论依据。为了进一步验证上述理论分析和仿真计算的正确性,搭建直流接触器电弧开断特性实验平台。利用高速摄像机对电弧开断过程进行图像采集并进行图像处理,根据实验图像及数据分析归纳出不同磁场作用下的电弧形态及变化规律,结合仿真分析结果,研究外磁场对直流感性负载产生电弧的反向运动现象,以及电弧的温度、气流场、受力及压强场等特性,结果表明:有外磁场作用电弧电压明显升高,熄弧时间减少,有利于电弧的熄灭;横向磁场作用可以缩短电弧随机运动时间,有助于电弧弧根运动,提高趋势性运动速度,增大电弧偏移量;径向磁场作用可使电弧温度和电导率降低,导致电弧的等效电阻增大。
[Abstract]:As one of the key distribution equipments, the low-voltage switchgear will inevitably produce arc during the process of switching off. The arc changes rapidly in millisecond time and millimeter space. The mechanism and development law of arc derivation are the focus and difficulty of researchers at home and abroad. Compared with AC arc, DC arc does not exist natural zero-crossing phenomenon. It is more difficult to extinguish the contactor. It is a common technology to design the contactor contact structure reasonably and make it produce magnetic field favorable to break the contact. It is an indisputable fact that the magnetic field forms a magnetic blow to the effect of the arc in favor of the arc extinguishing. Therefore, it is of great significance to explore the influence of external magnetic field and its changes on DC arc and the beneficial arc extinguishing. Based on the numerical calculation of electromagnetic field, the mathematical model of external magnetic field and DC arc is established in this paper. The numerical simulation analysis is used to provide guidance and scheme for the structure design of DC contactor's external magnetic field device, and the magnetic field distribution of various permanent magnetic materials is compared and analyzed by simulation. The results show that the arc model in 3D magnetic field calculation has the phenomenon of uneven magnetic field distribution due to the difference of conductivity. This provides a theoretical support for the selection and design of a reasonable external magnetic field generator. Based on the MHD theory, a mathematical model of air arc is established, which integrates the characteristics of arc motion and the arc mechanism. The common mechanism of the influence of different external magnetic fields on DC arc is explored by simulation and analysis of arc characteristics and arc motion characteristics under the action of external magnetic field, respectively. The essential law of arc motion characteristics under the action of external magnetic field is studied. It provides a theoretical basis for the study of arc characteristics and arc motion behavior under different external magnetic fields, and further verifies the correctness of the above theoretical analysis and simulation calculation. The experiment platform of arc breaking characteristics of DC contactor is set up. The high speed video camera is used to collect and process the image of the arc breaking process. According to the analysis of experimental images and data, the arc shape and variation law under different magnetic fields are summarized. Combining with the results of simulation analysis, the reverse motion phenomenon of arc produced by external magnetic field to DC inductive load, as well as the arc temperature and airflow field, are studied. The results show that the arc voltage increases obviously and the arc extinguishing time decreases with the external magnetic field, and the transverse magnetic field can shorten the arc random motion time, which is helpful to the arc root movement. The radial magnetic field can decrease the arc temperature and conductivity and increase the equivalent resistance of the arc.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM572.1

【参考文献】