Research On Key Technologies Of Piezoelectric Self-Powered Wireless Sensor Node

With the rapid development of science and technology,the complexity of mechanical equipment has become higher and higher,which puts forward higher and higher requirements for the reliability of mechanical equipment.Therefore,the health status of mechanical equipment must be monitored in real time to avoid the system evolving to fault state.Establishing a wireless sensor network with full-state networked monitoring function is an effective way to solve this problem.Wireless sensor nodes are the basic components of wireless sensor networks.For the condition monitoring of mechanical vibration environment,a piezoelectric self-powered wireless sensor node was proposed in this thesis.The key factors that restrict the lifetime of piezoelectric self-powered wireless sensor nodes are energy constraints and hardware faults caused by vibration.In order to solve the above problems,this thesis studied the performance of a piezoelectric ceramic plate in the symmetric fixation mode(PCPSFM),analyzed the energy collection circuit,and designed a permanent magnet passive vibration isolator.The specific work done in this paper is as follows.(a)Without changing the structure of the piezoelectric ceramic plate(PCP),PCPSFM was proposed.The mechanical and electrical properties of PCPSFM were studied by ANSYS simulation and experiment verification.The results are as follows.Compared with the traditional fixation mode of cantilever beam,the maximum allowable vibration acceleration of the PCPSFM is increased by more than a factor of five,the maximum open circuit voltage of the PCPSFM is increased by more than 4.5 V,the maximum average power of the PCPSFM is increased by more than a factor of four,and the electromechanical coupling coefficient is increased by more than 15%.(b)Traditional research methods of energy collection circuits and their shortcomings were analyzed.The requirements of energy supply in practical engineering applications were put forward.The equivalent circuit of the PCP was simplified,and the factors affecting the energy collection speed of the energy collection circuit were comprehensively considered according to the actual working conditions.From the point of view of charge and energy,a more suitable energy collection circuit was selected by theoretical calculation.The correctness of the theoretical calculation was verified by charging speed measurement experiment.In addition,the voltage stabilizing circuit and energy draining circuit were designed.(c)The kinematics model of the ordinary forced vibration isolator was established and the limitation of it for vibration acceleration suppression was analyzed.The magnetomechanical model of the permanent magnet was established and verified by COMSOL.The influence of various parameters on magnetic stiffness of the permanent magnet pair in vertical direction was studied.The design and parameter optimization of the permanent magnet passive vibration isolator were completed based on these parameters.The theoretical analysis of vibration acceleration suppression effect was carried out by establishing the Simulink simulation model of the permanent magnet passive vibration isolator.In addition,the correctness of theoretical calculation was verified by experiments.The result is as follows.Compared with the ordinary forced vibration isolator,the permanent magnet passive vibration isolator can further reduce the vibration acceleration by more than 15%.