Research On Electromagnetic Vibration Energy Harvester

With the rapid development of electronic technology,electronic products are moving toward the miniaturization,portability,wireless and long-lasting capability,power consumption is also decreasing,Wireless sensor networks are applied.In order to provide energy efficiently,extend their service life,reduce maintenance costs,energy harvesting technology came into being.In this paper,an electromagnetic vibration energy harvester based on radial magnetic field was designed based on the available literature both at home and abroad.By studying the equivalent magnetic charge theory of magnetization,the normalized dynamic model of the vibration energy harvester is established and the influence of system damping on the steady-state response and the relative vibration response of the vibrator are analyzed.According to the basic principle of electromechanical energy conversion,considering electromagnetic damping coupling,the system vibration response and output response are studied.The structural of the vibration energy harvester is designed.The scheme of energy harvesting circuit is also briefly introduced.The magnetic field of vibrator and dynamic response of load variation is also simulated by finite element method.The results were verified with the theoretical analysis.Finally,the prototype was tested.The stiffness of the springs was tested,and the total stiffness of the system was 28.41N/mm,and the natural frequency of the system was determined to be 32.52 Hz.The radial magnetic field of the permanent magnet vibrator was measured by Hall sensor.The vibration response and output characters with different load resistance were tested and analyzed.When the vibration source keeps a certain value,with the increase of the load resistance,the amplitude of the vibrator response and the output voltage tend to increase,but there is an upper limit on the output power and the total efficiency.The maximum output power is 74.37 mW at the load of 99.7?,and the maximum total output efficiency is 28.3% at the load of 47.2?.