Development Of Grounded Source Electromagnetic Emission System Based On Cascade Multi-level Inverter Technology

At present,in the field of grounded source electromagnetic exploration,generally a large current is entered to the earth through the grounding resistance to stimulate the electromagnetic field changes.Due to that different terrain grounding resistance is not the same,so the current under the same voltage is not the same.To ensure that under different geological structures the current can meet the detection requirements,maximizing the transmission system output voltage is needed.1.In order to determine the technical requirements of high-power transmission system,the H-bridge inverter technology,IGBT cascade technology,and multi-level inverter technology used in the existing transmitter has been fully analyzed,based on the understanding of the principle of electromagnetic prospecting.And the existing equipment were tested,the status of the instrument and the develop direction were known.2.In order to meet the demand of high power for electromagnetic detection,combined with the characteristics of multi-level inverter with simple control strategy and high output voltage in power electronic technology,a multi-level inverter scheme is proposed.The multi-level inverter and H-bridge inverter were compared in the technical indexes such as the emission voltage,the waveform spectrum,the falling edge and switch-off time.On this basis,the technical scheme of cascade five-level emission is determined.The principle of each process of the program was analyzed.At the same time,the whole system is systematically simulated.3.Aiming at the technical scheme of cascade five-level emission,this paper puts forward the technical index of the system according to the demand of electromagnetic detection.At the same time control circuit and drive circuit were designed for the scheme.The control circuit and the driving circuit were tested to achieve effective control for the the whole system.4.The voltage and current output of the five-level cascade system are tested in the laboratory.The rise and fall of the output voltage and current are observed and analyzed.In the field experiment,the five-level emission system and the JDD-100 transmitter with H-bridge topology were compared to verify the ability of the system to improve the output current.At the same time,when the five-level transmitter works independently,the consistency of the positive and negative current and the consistency of the continuous output of the current are tested to verify the reliability of the work.