Performance Of D₁₅Mode Piezoelectric Energy Harvesters With Double-mass Structure And Rotating Magnetic Structure

Energy harvesting from ambition vibration source into electrical has become a hot research topic due to its potential to application in wireless electronic sensing devices and MEMS.Piezoelectric energy harvester has been studied extensively because of its outstanding advantages of simple configuration and easy minimization,no environmental pollution,and no electromagnetic interference.The higher piezoelectric coefficient of a piezoelectric ceramic used in piezoelectric energy harvester,the greater its performance in energy harvesting.Actually,the piezoelectric coefficient of many piezoelectric materials are usually large in the order of d15>d33>d31,such as PMN-PT crystal,PZT-51,PZT-4,PZT-5H,PZT-7A,PZT-6B.Therefore,it is of potential application value for the research of d15 piezoelectric energy harvester in the field of energy harvesting.Secondly,the double-mass structure has been reported to help improve the energy harvesting performance of the d31 and d33 mode piezoelectric energy harvester.A d15 mode piezoelectric energy harvester with rotary magnetic structure can be applied to the self-powered demand of wheel and its bearing health monitoring system in rail transit.In a word,it is of academic value and application prospect to study the d15 mode piezoelectric energy harvester with double-mass structure and rotary magnetic structure.The main contents of this thesis are given as follows.(1)A PZT-51 piezoelectric material with a higher d15 coefficient is chosen to fabricate a d15 mode piezoelectric energy harvester with double-mass structure.The cantilever beam vibration experiment and the finite element ANSYS model are used to analyze the output peak voltage and output power of the piezoelectric energy harvester under different load resistances and frequencies.The effect of the position of the mass on the energy harvesting performance is also discussed.The maximum peak voltage and output power are 6.8 V and 77.1 ?LW under the load resistance RL of 300 k? and resonant frequency of 140 Hz,respectively.For natural environment at vibration frequencies of 120 to 150 Hz,It is an effective way to capture more external vibration energy into electricity by adjust the position of double-mass.(2)A traditional d15 mode piezoelectric energy harvester with single mass is designed and fabricated.The peak output voltage is discussed by finite element ANSYS mode and cantilever beam vibration experiment to compare with the double-mass structure.The d15 mode piezoelectric energy harvester with double-mass structure has better energy performance in low frequency environment.(3)Aim at meeting the self-powered demand of rail transit wheel and its bearing monitoring system,a d15 mode piezoelectric energy harvester with rotating magnetic structure was designed and fabricated.The effects of rotation speed,load resistance,and magnetic field intensity on the peak voltage and output power are discussed.The maximum peak voltage and output power of the piezoelectric energy harvester are 5.08 V and 43.01 ?W at the rotation speed of 690 r/min and load resistance of 300 k?.