孙淑琴,彭良玉,尚新磊,林 君,巨长磊.一种改善瞬变电磁发射电流波形的系统设计[J].电测与仪表,2017,54(3):. Sun Shuqin,Peng Liangyu,Shang Xinlei,Lin Jun,Ju Changlei.Design of a system for improving the wave of transmit current in transient electromagnetic method[J].Electrical Measurement & Instrumentation,2017,54(3):.
一种改善瞬变电磁发射电流波形的系统设计
Design of a system for improving the wave of transmit current in transient electromagnetic method
In order to reduce the transmit current off-time of the transient electromagnetic transmitter and ensure the transmit current off-edge’s linearity, restrain the current overshoot after shutting down, simplify the clamping voltage circuit, a simple transient electromagnetic transmitting system is designed. This paper puts forward a constant voltage clamping circuit which was combined by TVS tubes and capacitors,and the traditional way of a matching resistor in parallel with the across of the load is used in the circuit. By adjusting the voltage value of the TVS tube, shut-off time and off-edge’s linearity can be adjusted. Through matching the appropriate resistors across the load directly, that the pre-shutdown is in underdamped and the late of shutdown is in critically damped are ensured. It can effectively prevent the current from overshooting after shutting down and achieve the purpose of improving transmit current’s waveform under the premise of fast turn-off. The results show that the circuit structure of the system is simple , the system is stable and easy to implement. Three key indicators are significantly improved in the aspects of reducing the transmit current’s off-time, ensuring the transmit current’s off-edge’s linearity , restraining the current from overshooting after shutting down .
