Research And Development Control Technology In Towed 1500A Marine Controlled Source Electromagnetic Transmitter

Marine controlled source electromagnetic method is one of the effective means to detect submarine geological structure,submarine oil,gas hydrate and other targets.The transmitting system is an important part of marine controlled source electromagnetic detection.Its instrument performance directly determines the depth of detection and indirectly affects the imaging effect of submarine dielectric resistivity.Overseas Marine controlled source electromagnetic transmitting system has entered the mature application stage.Compared with international advanced equipment,the domestic transmitting system lags behind in some technical indicators.The purpose of this dissertation is to establish a stable and reliable high power artificial electromagnetic field source under the sea by studying the transmitting control technology.This paper focuses the control technology of the towed 1500 A marine controlled source electromagnetic system which is supported on the Research and Development of Deepwater Twin-boat Towed Marine Electromagnetic Exploration System of the national key research and development plan of the 13 th Five-Year Plan.The design improved the instrument performance and transmitting current from the transmitting current,state acquisition,data uploading,online programming and other aspects.The control technology is designed in four aspects: communication of the control system,inverter control,state acquisition and online programming.The communication unit uses fiber optic technology and network technology to achieve long distance continuous communication between deck equipment and underwater equipment.These technologies improve the anti-interference and scalability of communication circuits.Combined with software and hardware programming technology,the control system generates waveforms with controllable period and duty cycle to precisely control the H-bridges built by insulated gate bipolar transistor(Insulated Gate Bipolar Transistor,IGBT)power devices,thus achieving high-current transmitting.State acquisition unit not only acquires the attitude and the height above the seafloor of the transmitter carrier and the transmitting antenna,but also acquires the temperature,voltage and current of the inverter circuit.It ensures that the transmitting system can work stably and reliably.The online programming scheme is designed to realize the remote upgrade of the program of each microcontroller,which improves the efficiency of updating the program of the microcontroller.The transmitter designed with the towed 1500 A marine controllable source electromagnetic transmitting control technology has undergone several indoor tests and sea trials.The output current of outdoor tests has exceeded 1547 A.In the South China Sea test,the results show that the transmitting system can meet the long-time stable working requirements,with a frequency bandwidth of 0.01?10Hz and a maximum excitation current of 1988 A.And the data collection of each state is complete,stable and reliable.The practicality of the transmitting control technology developed in this paper has been proven.