矿井电磁波能量安全性研究

Safety study of electromagnetic wave energy in coal mine

为了评价矿井射频设备电磁波能量对瓦斯的安全性,提出了井下存在的两种电磁波能量耦合方式:磁耦合共振和电磁波辐射谐振能量耦合.基于磁耦共振模型,分析了磁耦共振方式的最大能量传输效率.针对远场辐射,结合低衰减度传输线模型,从电大型和电小型两方面研究了井下金属结构作为电磁波接收天线可以向负载输送的最大功率.得出了不同能量耦合方式下射频源和耦合结构间的安全距离公式.结果表明:磁耦共振方式能量传输效率随线圈半径和导体半径增加而提高,但变化率与收发线圈间距有关;固定线圈和导体半径,效率随线圈间距的增大而降低.对于电磁辐射能量,安全距离随工作频率先增大后降低.结合井下实际,磁耦共振方式的安全距离为2m,电磁波远场辐射能量的安全距离为25m.

In order to evaluate the safety of electromagnetic wave energy on gas, this study pro- posed the two types of electromagnetic wave energy coupling, namely coupled magnetic reso- nance and electromagnetic radiation resonance. The maximum energy transmission efficiency was studied on the basis of coupled magnetic resonance model. For electromagnetic far field ra- diation, the maximum power dissipated in load from metal structure which acts as electrically- small or electrically-large receiving antenna was investigated by combining low attenuation transmission line model. In addition, this study presented the safety distance formulas between RF sources and the coupling structures for different coupling types. The results show that the energy transmission efficiency of coupled magnetic resonance increases with an increase in the radius of coil and wire. But the change rate of efficiency is related to the distance between the sending and receiving coil. When we fix the radius of coil and wire, the efficiency reduces as the distance between coils increases. For the electromagnetic radiation energy, as the working frequency increases, the safety distance climbs up to the peak and then declines. Combining the feature of mine, the safety distance is 2 meters for coupled magnetic resonance, and 25 meters for electromagnetic radiation energy.