MODEL AND HARVEST CHARACTERISTIC RESEARCH OF PIEZOELECTRIC ENERGY HARVESTER USED IN COAL MINE

About the problem of difficult electricity supply for wireless monitoring node of exploiting coal machine,a piezoelectric energy harvester is used to convert the vibration energy into electricity,the research of energy harvest characteristic has scientific significance.Using experimental and data fitting method to establish restoring force model,using magnetization current method to establish magnetic force model,using the Lagrange function to establish dynamic model,using RecurDyn to extract the exploiting direction acceleration of roller and swing arm,the dynamic model is solved by using Runge Kutta method,analyzing energy harvest characteristic at different magnetic distances,conducting experimental research.The results show that it is subjected to exploiting direction acceleration of front roller,after roller,front swing arm and after swing arm,at the magnetic distance with great energy harvest characteristic,the voltage gradually decreases,the voltage increases entirely when the hardness of the coal seam increases,when exploiting f4 coal seam,the energy harvest characteristic are great at magnetic distances of 12 mm,16 mm,12 mm and 12 mm, the effective voltage values are 5.107 V,4.224 V,0.998 V and 0.882 V,when exploiting the f6 coal seam, the energy harvest characteristic are entirely great at magnetic distance of 16 mm,the effective voltage values are 7.298 V,6.747 V,1.592 V and1.397 V,the voltage increases when adding magnetic force.Through experimental research, it was found that it is subjected to exploiting direction acceleration of front roller when exploiting f4,f6 seam,the voltage increases when the hardness of coal seam increases at a magnetic distance with great energy harvest characteristic,the energy harvest characteristic are great at magnetic distances of 12 mm and 16 mm,the effective voltage values are 3.340 V and 4.959 V,the voltage increases when adding magnetic force,verifing the correctness of theoretical result.The research provides a theoretical basis for improving the voltage,providing idea for self electricity supply of wireless monitoring node.