Research On Control Method Of Cascaded DC Power Supply For Ground-to-air Electromagnetic Detection

As one of the main methods of geophysical detection,electromagnetic detection has played a vital role in the fields of mineral exploration,geological survey,and shallow target investigation.As a country with a large demand for minerals,China is imminent in the exploration and development of mineral resources.Therefore,the research and development of electromagnetic detection equipment has become an important direction in the field of geology and mineral resources.As the source of electromagnetic detection,the launch system provides the output current and voltage required for electromagnetic detection,which has an important influence on the effect of electromagnetic detection.In order to meet the requirements for the emission current in the steady state of electromagnetic detection,the emission power and voltage level need to be doubled,when the detection depth increases,the emitter distance increases,and the impedance between the emitter electrodes increases.Due to the limited withstand voltage of the semiconductor switching devices used in the DC power supply and the limited power of the single-stage DC power supply,a cascaded DC power supply is used.The input terminals of the same AC-DC converter are connected in parallel and the output terminals are connected in series,which can effectively increase the emission voltage level and meet the electromagnetic need for detection.This article takes the ground-to-air electromagnetic detection cascaded DC power supply control method as the research goal,and the main work includes:(1)Analyze the topology of the current mainstream electromagnetic detection transmitter DC power supply,aiming at the ground-to-air electromagnetic detection that needs electrical source transmitter system.In order to meet the needs of high-voltage and high-power output,the ground-to-air electromagnetic detection cascaded DC power supply topological structure and working principle need to be analyzed,and equivalent circuit model is established;(2)The control method of the cascaded DC power supply system can be improved,and the hardware circuit with the corresponding software control program are designed.The electromagnetic detection cascaded DC power supply constant current and voltage equalization output control method is studied to form a double closed-loop control system,which can effectively control the output current to keep constant,and can also ensure that the output voltage of the cascaded two-stage power supply is consistent.The control system model and the simulation model are establish in this paper.Adjusting the internal parameters of the controller is to reduce control errors.The open loop system,constant current control single closed loop system,and constant current voltage equalization control double closed loop system are simulated respectively.From the simulation results,it can be seen that the constant current voltage equalization control system can effectively control the output current to keep constant,which can make the two-level output voltage Maintain consistency and greatly reduce the system ripple.The sudden load simulation verifies the rapidity of the system.(3)The principle prototype is developed,and the inverter output voltage is adjusted by using DSP to control the duty cycle of the switching device of the inverter circuit,so as to achieve the purpose of controlling the output state of the DC power supply and keeping the output current of the transmitting system consistent with the preset value.The output current deviation is within0.5%;the output voltage of the two stages is controlled at the same time to keep the output voltage of the two stages consistent,and the deviation is within 0.5%,which meets the requirements of the ground-to-air electromagnetic detection and launch system.