Inhibition Of Time-domain Airborne Electromagnetic Emission Current And Design Of Switching Power Supply

In recent years, with the development of economy, the status of mineralresources is more and more important in our country. China is a vast country withcomplex geological structure, forests, lakes, swamps, and desert occupy a largeproportion, and they are resource-rich regions, but the ground geophysical explorationequipment cannot effectively detect those regions.Time-domain airborne electromagnetic method is a geologic method by aircraft,and the method by helicopter have the characteristics of fast, agile, which is widelyused in the detection of difficult terrain. Time-domain airborne electromagneticmethod system is composed of launch system and receiving system, and this paperstudies the two key technical problems in the launch system: emission currentovershoot inhibition and boost switching power supply.The paper introduces the technical indexes of airborne electromagnetic launchsystem at first, analyses the working principle of launch system, gives the overalldiagram of launch system, and puts forward the key technical problems which aresolved in this article.The paper analyzes the principle of the creation of the emission currentovershoot and the harm of it, and analyzes the principle acceleration resistancemethod, and raises the thought of designing a new method to inhibit current overshoot.Based on the analysis of the second order circuit working characteristic, the paperputs forward a new circuit. Through theoretical calculation and computer simulation,finally determines the specific value of the parameters of the circuit. With thecombination of the new circuit, the emission current overshoot inhibition system isdesigned, then gives the overall diagram of the system, then discusses the double limitcomparator, microcontroller programming of driving signal.Based on the strict requirement of the ripple noise of the switching power supplyin time-domain airborne electromagnetic method detection system, designs the boost switching power supply system which is based on VICOR power supply modules.The paper introduces the technical index of the power supply module, and putsforward the design of input-parallel output-series of seven pieces of power supplymodules. The single power module is designed at first, including the EMI filter circuitin front of power supply module, power supply module peripheral circuit, ripplesuppression circuit in the output of module, then designs the overall boost switchingpower supply system on the basis of it.After the accomplishment of the design of above two key technology problems,laboratory test is carried on. The emission current of the transmitter with the newdesign current overshoot inhibition circuit is tested, and then compared with the onewithout the current overshoot inhibition circuit and acceleration resistance method,the result shows that the current overshoot has been inhibited effectively, verifies thevalidity and feasibility of the theory design. The single power supply module is tested,observes the output voltage and ripples noise in the oscilloscope, calculates theefficiency by measuring the input-output voltage and input-output current. After thesuccess of the experiment on single power module, then the whole power supplysystem is tested, tests the output voltage ripples noise waveform under different loadwith the max output voltage, and calculates the working efficiency, the result is inconformity with the desired effect, which verifies the correctness and feasibility of thedesign. Finally, through theoretical analysis and the analysis of the actual test results,some suggestions are put forward.