Design And Research Of Rotary Magnetic Nonlinear Piezoelectric Energy Harvester

Devices such as wireless sensors and portable electronic products are widely used in various application fields.Most traditional wireless sensors and portable electronic products are powered by batteries.Battery power supply has short service life and hard to maintenance or replacement,and cannot meet the long-term stable operation applications in remote areas.Harvesting vibration energy from surrounding environment can be an effective alternative.The piezoelectric energy harvesting method has outstanding advantages,such as simple structure and high efficiency,which has been applied in many fields.A rotary type piezoelectric energy harvester was proposed in this project,in which the nonlinear effect of external magnetic field excitation is applied to improve the energy harvesting efficiency.The rotating magnetic field was generated during the rotation of the harvester proposed above,which can be used to excite the piezoelectric cantilever to vibrate.The vibrating piezoelectric cantilever can convert the vibration energy into electrical energy for harvesting.The nonlinear mathematical model of the piezoelectric cantilever beam is established based on the nonlinear 2-D Euler-Bernoulli beam theory.The nonlinear dynamic equation of the cantilever was derived based on Hamiltonian principle and discretized by the Galerkin method.A dimensionless nonlinear ordinary differential equation was set up.The magnetic potential energy and magnetic force equations between rotating magnets are established based on the electromagnetic theory,and numerically simulated in MATLAB.The steady-state response of the piezoelectric cantilever beam is analyzed through harmonic balance method.The relationship of performance of the harvester and operation conditions,such as excitation conditions,nonlinear parameters,electromechanical coupling terms,load,resistance and the number of magnets was simulated and studied.An energy harvester performance test experimental platform was set up.The experimental results show that when the number of rotating magnets is one and the speed is 370rpm,the optimal impedance value of the nonlinear piezoelectric energy harvester is 90kΩ,and the output power is as high as 7.05mW.In operation condition of two rotating magnets and 210rpm rotation,the best matching impedance is 90kΩ,and the output power is as high as 6.99mW.The average charging power is 72.27 μW,213.44 μW,322.21μW,and 357.99μW separately during the changing of a capacitance in 10s by four different type harvesters with one rotating magnet attached.The average charging power is 82.60 μW,426.90 μW,483.32μW,and 536.98 μW separately for four different type harvesters with two rotaing magnet attached during charging a capacitance.The performance of harvester was validated both theoretically and experimentally,which has higher harvesting efficiency compared to traditional rotating harvester,which can provides a possible battery-free power supply for fault diagnosis and health detection sensor node in rotating machinery.