The Development Of Airborne Electromagnetic Emission System Absorption Protection Circuit And Modular Power Supply

Helicopter-borne Time-domain Electromagnetic Method is a new type of rapid exploration system, which uses a helicopter as a carrier and can complete exploration in flight. Having the advantages of prospecting of speed, high sensitivity, strong resolution ability and efficient exploration, it has been widely used in mineral resources exploration, transgressive prospecting, environment evaluation, etc.Time-domain Helicopter-borne Airborne Electromagnetic Detection System consists of emission system,the receiving system,auxiliary system and data processing system. This paper studies the two technical problems in the emission system: the absorption and protection of IGBT technology transmitter bridge road and Low noise step-up switching power supply technology. This article first embarks from the technical indicators of Time-domain Helicopter-borne Airborne Electromagnetic Launch System,by referring to the related literature at home and abroad, the development scheme of passive lossless absorbing circuit and modular air electromagnetic switch power supply of electric isolation technique have been put forward.Analyzing the principle and the harms of the surge voltage IGBT and comparing with several common absorption protection circuit, the design of a new type of passive lossless absorption circuit is proposed. Through the theoretical calculation and simulation, the final design parameters are determined. The source of receiver’s electromagnetic interference was analyzed, the method of electromagnetic isolation to cut off the electrical noise propagation path is put forward, According to the specific requirements, combined with foreign advanced airborne electromagnetic detection equipment design experience, modular airborne electromagnetic switching power supply design which is based on the VICOR power module is finally proposed. First of all, a modular block diagram of the overall design of airborne electromagnetic switch power supply is drawn, including the overall design of the power module circuit, fault detection and protection circuit design, thermal design, etc. The design of input and output filter circuit in the whole design of single circuit power supply module is designed in detail and through the theoretical calculation and simulation, the final design parameters were determined.After the completion of the design of the two key technologies, laboratory tests are carried out. Passive lossless absorption circuit has been successfully applied to the transmitter, and the operating temperature of the instrument is decreased by 5; The filtering effect of the input and output filter circuit of the VICOR power supply module is tested. And the test results are analyzed by FFT analysis. By testing the output ripple coefficient reached 0.019 percent. EMI input filter circuit conducted interference between the power supply has been effectively attenuated. Multiple comparison analysis have been made between modular air electromagnetic switch power supply and old switch power supply,including laboratory measuring experiment and outdoor measuring experiments. Main test content includes the electromagnetic interference of receiver attenuation curve,contrast of late channel noise in profile and power efficiency. The test results are in accordance with what expected. The transmission of electrical noise is cut off and system electrical noise is reduced. The channel noise is obviously suppressed in the section of the profile map. Power efficiency has increased to more than 84%.At last, combined with several problems of field experiments, some suggestions are put forward.