| The health monitoring of high-speed train travel system is crucial to ensure the safety and reliability of high-speed train operation.The health monitoring of the travel system is inseparable from the data collection of the wireless network-based sensor nodes,data acceptance and fault diagnosis of the host computer,while the normal operation of the electrical devices of the sensor nodes is inseparable from an efficient and stable power supply.Due to the harsh working environment of bogies,the unavailability and fragility of cables and the need for periodic maintenance of batteries,it is of great significance to introduce vibration energy harvesters to convert the vibration energy in high-speed rail bogies into electrical energy for the underlying sensor nodes.However,the vibration energy harvesting method has the problems of narrow operating band,low output power and mismatch with working conditions.Therefore,how to design a vibration energy harvester with high output power to match the frequency band of the steering surface vibration condition is the difficulty and innovation point of this paper.In view of the above problems and the practical application scenarios of bogies,the main work of this paper is as follows:1.Through combing the related literature,the output efficiency and corresponding working conditions of the existing energy harvesters are summarized.The field research and vibration data collection of high-speed train bogies are also conducted to summarize and analyze the vibration conditions and installation locations of vibration energy harvestersduring high-speed train operation.The vibration conditions include vibration energy band distribution and vibration acceleration magnitude.2.The structure and effectiveness of existing vibration energy harvesters are compared,and the methods and advantages of the nonlinear behavior introduction are summarized.Based on the coupling of spring force,gravity and magnetism,an innovative bistable vibration energy harvester structure is proposed;and for the dynamic magnet structure,an innovative spherical-cylindrical coupled dynamic magnet structure is proposed,which maintains the advantage of spherical magnet in friction damping compared with a single cylindrical magnet or spherical magnet,but is higher than spherical magnet in effectiveness.3.The bistable energy harvester structure is analyzed and modeled.Firstly,the potential energy of the energy harvester is analyzed and the potential barrier between the bistable states is analyzed.Further,the magnetic fields of the spherical and cylindrical magnets were modeled under a double coil distribution to derive the electromechanical coupling coefficients with displacement.The force analysis of the dynamic magnet structure is performed to analyze the magnetic attraction force,spring force,gravity force and friction force respectively.Finally,a set of differential equations for the coupling of dynamics and electromagnetism is formed.4.The model is codified in MATLAB and the dynamic output response is obtained by the Rung-Kuta method.The dynamic output response contains swept and fixed frequency results.The parameters of the harvester are adjusted to compare the dynamic output response results to achieve the overall optimization goal.The optimized parameters are assembled into a prototype.The experimental platform is built and the experimental results of the prototype are compared with the model data to verify the validity of the model.5.The harvester was analyzed for the application of high-speed train bogie health monitoring,and the peripheral processing circuit was built.The energy consumption of the powered energy harvester and the powered sensing node were matched.The prototype and experimental results presented in this paper verify the validity of the theoretical model.The energy harvester with a spherical-cylindrical coupled motion magnet has an operating bandwidth of 9.5-45.1 Hz at 2 g and an output power of 18.2 mW at 40 Hz and 1200 Ω load.Compared with the conventional energy harvester with cylindrical and spherical motion magnets,the basal excitation is lower and the normalized output power is higher.Therefore,this energy harvester is more suitable for train monitoring scenarios. |
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