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Study Of Vibration-based Energy Harvesters For Healthmonitoring Of Coal Mining Equipment

Posted on:2019-08-29Degree:MasterType:Thesis
Country:ChinaCandidate:J H LinFull Text:PDF
GTID:2371330545973301Subject:Mechanical engineering
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Coal industry is the main energy supply in the process of rapid economic development in China.With the increasing improvement of the mechanization and automation of the coal mining equipment,the hidden risks in the production process have gradually attracted the attention of the government.In order to reduce the accidents,health monitoring of coal mining equipment is necessary.Due to the rotation of the coal mining equipment,cable installation is not available for health monitoring system because of the wire winding problems.Therefore,wireless sensor node(WSN)is used to monitor the status of coal mining equipment.In this paper,intends to use energy harvesting technology and design vibration-based energy harvesters(VEHs)have been developed for powering the WSN in the harsh and complex vibrational environment.There is a broad frequency range in the working environment of coal mining equipment,for example,the low frequency vibration can be observed when the reel of the hoist is working,and the higher frequency occurs when the shearer is cutting with the coal seam,etc.In this paper,two types of VEH have been developed for different working frequency.A stator magnet and a rotor magnet which can attract each other were used in the rotary VEH,which can obtain a considerable output.The rotary VEH is suitable for low frequency vibration environments around 0-10 Hz.And then based on Faraday's law of electromagnetic induction,a cantilever structure was utilized in VEH.A high power output was obtained because of the nonlinear vibration phenomena.The VEH is suitable for the vibration environments with a higher frequency around 10-30 Hz.At last,based on the VEH,a selfpowered WSN system was built up for realizing the intermittent monitoring of the node.The main contents of this paper are listed as follows:(1)For the low frequency around 0-10 Hz,a rotary electromagnetic VEH was designed in this paper.A rotor magnet is able to rotate around the centre stator magnet with less surface friction.The rotating magnet right above the wound coils introduces the change of magnetic flux,resulting in the induced current in the coils.Then based on the conjunction of triboelectrification and electrostatic induction,a triboelectric nanogenerator(TENG)was combined on the rotary VEH,and the output voltage was improved.At a frequency of 8 Hz and an amplitude of 4 mm,the power density of the electromagnetic part is 0.29 m W/cm3,and the triboelectric part is 0.76 m W/cm3.Test results show that the rotary VEH is very sensitive to low frequency vibration environments.(2)For a higher frequency range from 10 Hz to 30 Hz,an electromagnetic cantilever generator was presented.At the resonant frequency,cantilever will drive the magnets to vibrate,resulting in the induced voltage in the fixed coils.High–permeability magnetic materials were applied to enhance the magnetic flux in the coil,and caused the nonlinear vibration phenomena to improve the output power of the VEH.At a resonant frequency of 26 Hz,the peak-to-peak voltage can reach up to 4 V,the maximum output power reaches up to 500 m W,which is able to meet the demand.(3)A self-powered WSN system is built up based on the VEH,power management module and WSN.The applied sensor is MPU-6050,which can collect temperature and acceleration signals.Under the external stimulation,the VEH is managed to power WSN to transmit the data wirelessly and intermittently.
Keywords/Search Tags:Vibration-based energy harvester, Rotation type, Cantilever type, Selfpowered wireless sensor node
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