Research On Electromagnetic Emission Mechanism And Characteristics Of Mining Frequency Conversion Governors

With the rapid development of power electronics and high-speed and high-power switching elements,mining frequency conversion governors have been widely applied.In the meantime,the automation and the Intellectualization of the mining equipment is promoting;intelligent equipment such as Io T equipment,monitoring system and wireless communication system is used massively under the shaft.Due to its rapid-response characteristics,the electromagnetic interference that frequency conversion governors generated directly affect the safe operation of the equipment and the mining production system.Electromagnetic emission,conducted and radiated emission consisted,is an important assessment for the access inspection of mining products safety approval and certification.The electromagnetic emission test of the mining frequency conversion governors must be carried out under the load that can represent its emission characteristics.Focusing on the problem of typical working state of its electromagnetic emission is uncertain,by analyzing the basic structure principle of mining frequency conversion governors,IGBT switching characteristics,and the analysis of the amplitude-frequency characteristic of the generated voltage pulse,electromagnetic interference coupling phenomenon,differential and common mode interference propagation path.The thesis proposed that the voltage change rate du_ce/dt,current change rate di_c/dt,differential and common mode interference and their propagation loops are only related to the inherent parameters of the frequency conversion governors,the influence of the load is minimum;under asynchronous modulation of mining frequency conversion control,the electromagnetic emission of the governors have no correlation with the output working frequency;under synchronous modulation of the mine frequency conversion control,the electromagnetic emission of the governors have a positive correlation with the carrier frequency and output working frequency of the governors.In order to verify the influence of different load conditions and carrier frequencies on the electromagnetic emission characteristics of mining frequency conversion governors,according to the electromagnetic emission test requirements,a semi-anechoic testing system with motor loading capacity and electromagnetic emission signal analyzing function was constructed,both the synchronous modulation and differential power asynchronous modulation of two-quadrant and four-quadrant frequency conversion governors are selected and verified.Through analysis and experimental verification,the thesis proved that the influence of the load on driving motor on the electromagnetic emission of mining frequency conversion governors was negligible;the amplitude-frequency characteristics of the electromagnetic emission generated by IGBT increase with the increase of its carrier frequency,which was IGBT switching frequency.