【作者】 杨洋；

【导师】 杨桢；

【作者基本信息】 辽宁工程技术大学 ， 电气工程， 2021， 硕士

【摘要】 随着煤矿朝着智能化、精准化方向发展,要求井下各种通讯以及传感器设备需要安全、快速、可靠,这就对井下电磁环境提出了更高的要求。然而通过实地测量发现,变频调速系统产生的电磁干扰往往超过了国家标准的限值,因此对其干扰特性的研究有十分重要的意义。本文首先通过对变频调速系统的运行状况进行分析,得到了IGBT开断的原理。然后对电磁干扰的产生机理从传导和辐射两个方面分别进行了研究,介绍了干扰产生的原因以及传播路径。最后采用矩量法和天线理论相结合的方式,参考实际变频调速系统的几何结构,在电磁仿真软件FEKO中搭建了矿用变频调速系统天线模型,以此来计算调速系统最大可能出现的辐射干扰情况。模型的计算结果从近场和远场两个方面进行了分析。对于近场,变频器机壳将高场强限制在了内部,起到了很好的屏蔽作用,机壳0.5m以外场强均符合限值要求;出线电缆对于变频调速系统的整体辐射起到了主要作用,场强辐射均是以线缆为中心向四周扩散减小。对于远场,辐射波瓣的方向与频率密切相关,低频时向X、Y轴水平方向均匀分布,高频时主要朝进出线电缆与Z轴相夹45°方向传播。结合计算结果以及干扰机理的分析,对共模传导电磁干扰提出了两种增大共模阻抗的抑制方式;通过计算对比理想屏蔽、编织网屏蔽以及不屏蔽下的干扰情况,证明了编织网屏蔽对于线缆辐射抑制的有效性。在相关测量标准的规定下,分别测量了半载与满载运行状态下典型位置处0.1～30MHz频段辐射场强的大小,30～1000MHz频段调速系统整体辐射场强,以及0.15～30MHz频段传导干扰的情况。测量结果表明:(1)天线模型的计算结果与测量结果拟合程度高,天线模型有效;(2)半载下,变频器正面各位置场强分布较为一致,出线电缆接线端总体场强要大于进线端的,整流器与逆变器散热片安装处的场强分布曲线几乎一致,综合各位置点的场强分布来看,高场强均分布在低于1MHz频点;(3)满载下,各典型位置处场强分布趋势与半载下的较为一致,幅值上均高于半载下的;(4)高频段整体辐射除个别频点因环境噪声的原因幅值略高于限值外其余大部分频点均符合规定限值;(5)电源侧传导电磁干扰1MHz以下多个频点超过限值,最大幅值出现在0.2～0.3MHz频段,达到了133d BμV/m。该论文有图63幅,表9个,参考文献54篇。更多还原

【Abstract】 With the development of coal mines in the direction of intelligence and precision,various underground communications and sensor equipment are required to be safe,fast,and reliable,which puts forward higher requirements for the underground electromagnetic environment.However,it is found through field measurement that the electromagnetic interference generated by the variable frequency speed regulation system often exceeds the limit of the national standard,so the research on its interference characteristics is of great significance.This article first analyzes the operating conditions of the variable frequency speed regulation system,and obtains the principle of IGBT switching.Then,the mechanism of electromagnetic interference is studied from two aspects of conduction and radiation,and the cause of interference and the propagation path are introduced.Finally,the method of combining the method of moment and antenna theory,referring to the geometric structure of the actual variable frequency speed control system,builds an antenna model of the mine variable frequency speed control system in the electromagnetic simulation software FEKO to calculate the maximum possible occurrence of the speed control system Radiated interference situation.The calculation results of the model are analyzed from two aspects: the near field and the far field.For the near field,the enclosure of the frequency converter limits the high field strength inside,which plays a good shielding effect.The field strength outside the enclosure of 0.5m meets the limit requirements;the outgoing cable plays a role in the overall radiation of the frequency conversion speed control system.The main function is that the field strength radiation is reduced by spreading around the cable as the center.For the far field,the direction of the radiation lobe is closely related to the frequency.At low frequencies,it is evenly distributed in the horizontal direction of the X and Y axes.At high frequencies,it mainly propagates in the direction of 45°between the incoming and outgoing cables and the Z axis.Combining the calculation results and the analysis of the interference mechanism,two ways to suppress the common mode conducted electromagnetic interference are proposed to increase the common mode impedance;the calculation and comparison of the interference conditions under ideal shielding,braided mesh shielding and unshielded proves the braided mesh shielding For the effectiveness of cable radiation suppression.Under the regulations of the relevant measurement standards,the radiated field strength of the 0.1-30 MHz frequency band,the overall radiated field strength of the speed control system in the 30-1000 MHz frequency band,and the conducted interference in the 0.15-30 MHz frequency band at the typical position under half-load and full-load operation are respectively measured.Case.The measurement results show that:(1)The calculation results of the antenna model and the measurement results have a high degree of fit,and the antenna model is effective;(2)Under half load,the field strength distribution at the front of the inverter is relatively consistent,and the overall field strength of the outlet cable terminal is important.The field strength distribution curve at the installation place of the rectifier and the inverter heat sink is almost the same if it is larger than the inlet end.From the comprehensive field strength distribution of each position,the high field strength is distributed at the frequency below 1MHz;(3)Under full load,The distribution trend of the field strength at each typical location is more consistent with that under half load,and the amplitude is higher than that under half load;(4)The overall radiation in the high frequency band is slightly higher than the limit due to environmental noise at individual frequency points.Most of the other frequency points outside the value meet the specified limit;(5)The conducted electromagnetic interference on the power supply side exceeds the limit at multiple frequency points below 1MHz,and the maximum amplitude appears in the 0.2-0.3MHz frequency band,reaching 133 d BμV/m.The paper has 63 figures,9 tables,and 54 references.更多还原