The Experimental Research Of Suppress Electric Bearing Current Based On Carbon Nanotube Field Emission

High frequency common mode signal,produced by the zero-sequence circuit of power electronic drive circuit,will stimulate the parasitic impedance in the equipment,which will store electric common mode energy.However,the parasitic powers will arbitrary release in stator and rotor of the rotating machinery,which can lead sliding interface of bearing and gear to ionization thermal corrosion.And bearing electrical corrosion caused by bearing failure has become one of the prime reasons for motor drive and generation system failure.As a quasi-one-dimensional nanomaterial,the carbon nanotubes are chemically stable,difficult to react with other substances,light weight and the hexagonal structure is perfectly connected.Coupled with its structural features,such as high mechanical strength and good toughness,and excellent electrical properties,it shows good field emission performance.In order to reduce the intensity of the emission field,several carbon nanotube fibers was used to form a cluster of electric energy emitting electrodes.The tip effect of the end of carbon nanotubes has a low opening voltage,which realizes the space power transmission condition of large distance and non-mechanical contact.It will results in the two ends of the bearing oil gap are short connected by the electrode in the space,that can eliminate the parasitic powers between the two relative moving parts.Based on the research and explore the mechanism of the carbon nanotubes field emission,which perhaps to set up a new basic theory and experimental research method of space power transmission,that is a wireless transmission mode,and it has important theoretical significance and engineering application prospect.Firstly,this paper introduces the classification of electron emission,the metal field electron emission theory and influence factors are given emphatically.Based on the Fowler-Nordheim theory improved F-N formula and combined with the quality of the emitter parameters,the carbon nanotubes equivalent calculation model is presented.On this basis,the field emission mechanism and electric field enhancement effect of carbon nanotubes are demonstrated.Secondly,based on the equivalent calculation model of carbon nanotubes in the second chapter,simulate the effect of different length-diameter ratio and distance for the single carbon nanotube in CST,and concluded that the influences of the carbon nanotube tip electric potential distribution density,field emission and current density respectively.At the same time,a carbon nanotube field emission experiment platform was constructed to conduct field emission experiments on the TNF300 carbon nanotubes under non-vacuum conditions,and the voltage and current values of carbon nano-materials under different distances were obtained.After the data is processed,the field emission characteristic curve is plotted and the results of different distances are compared and analyzed.Finally,the aligned carbon nanotubes are introduced and the schematic diagram of carbon nanotube fiber electrode is given.Analogy the advantages and disadvantages of the diode and the triode field emission structure,establish a tertiary structural model for aligned carbon nanotubes,and focuses on the optimum grid mesh,get maximum field emission current for anode,grid mesh size exist a peak of the best relationship.