Dead-space Protection and Energy Attenuation during Large-power Electromagnetic Transmission in Subsurface

摘要

According to the fact that there are shallow detection depth,low precision and resolution,weak anti-interference ability of solid mineral resources exploration technology,it is important to develop earth resistivity imaging techniques and instruments of high power pit (well) which processes independent intellectual property.That is helpful to efficiently enhance the detection accuracy and depth for mineral resources,and to meet the national need of exploring the "blind" and deep resources.Through internal switching device of transmitter,the transmission frequency of excitation field source can be changed so that the detection resolution can be improved and the information in different exploration depth can be reflected.In the process of underground large current launch,because of the turn-off time,the dead time to protect electromechanical circuit cannot set too small.As to the high frequency,too long dead time can contribute to the reduction of turn-on time,which leads to power waveform distortion and has an effect on spectrum characteristics,bringing the energy loss and low efficiency.In this paper,varied models on the dead time length are simulated theoretically using Matlab software.In calculation process,the proportion range of the dead time to the positive power time is given quantitatively,which changes the situation that set the dead time based on the experience in the past.According to the stimulation calculation,the conclusion,which accords with the requirements of the large power electromagnetic transmitting devices,can provide the theory reference for the developing the subsequent geophysical instruments.