Research On A Piezoelectric-Electromagnetic-Triboelectric Composite Energy Harvester Based On Human Movement

With the development of wireless communication and low-power embedded technology,smart wearable devices are gradually entering people’s daily lives.Traditional smart devices have the problem of short battery life to a certain extent,while can only be charged near the power source,and need long charging time,severely affects the user experience.In this work,a method of collecting mechanical energy generated by human motion is proposed,which provides a feasible method for solving the problem of short battery life of wearable devices.In order to achieve the purpose of harvesting the mechanical energy of human motion and supplying energy to low-power wearable devices,this paper proposes a new structure piezoelectric-electromagnetic-triboelectric hybrid energy harvester.A theoretical analysis of the generator system of each module is carried out.At the same time,a theoretical model of the movement process of the magnet in the period is established.A theoretical analysis of the piezoelectric-electromagnetic-triboelectric composite energy harvester is carried out,and given a simplified theoretical model of the movement of the magnet in the period.According to the model,the parameters of each energy collection module were optimized by finite element simulation.The materials and working modes of each energy harvesting module are analyzed,and the specific preparation process is given,a test platform was built to test the performance of the experimental prototype,experimental results show that: under the condition of horizontal movement,excitation frequency of 4Hz and movement displacement of 200 mm,the output voltage of the electromagnetic module reaches 9.4V,and the current reaches 21.4m A;the output voltage of the piezoelectric module reaches 95 V,and the current reaches 106?A;The output voltage reaches 150 V,and the current reaches 1.4?A.Under this condition,connect an external load to the test circuit to obtain the output power of each module: the optimal impedance of the electromagnetic module is 500?,and the maximum output power is 87.1m W;the optimal impedance of the piezoelectric module is 70k?,and the maximum power is 26.17 m W;the optimal impedance of the triboelectric module is 140M?,and the maximum power is 63?W.In order to match the irregular movement of human body,the application test experiment was carried out.The results show that output voltage of the triboelectric module gradually decreased with the increase of the angle,and the output voltage of the piezoelectric and electromagnetic modules gradually increased,the temperature sensor and the wireless sensor module can work for 14 s and 18 s respectively through the energy collection circuit and about 10 s charging,which proves that the energy harvester designed in this paper has practical application potential.Through the work of this article,a more in-depth study on the energy harvester that collects human movement has provided a further reference for collecting the mechanical energy of human movement.At the same time,the research of the composite energy harvester has certain practical application value,and it has practical significance for realizing the self-powered smart wearable device.