| Optical fiber electrostatic voltmeter has good application prospect in high voltage measurement and electrostatic voltage protection detection,which has advantages of small volume,light weight,high precision,wide frequency response,large dynamic range and strong anti-interference ability and the ability of electrostatic voltage measurement basing on great input impedance(>1015Ω).The high-response sensitivity of the fiber Fabry Perot(F-P)high voltage sensor is developed on the basic of serpentine beam structure of silicon membrane which is prepared basing on the Micro Electro-Mechanical System(MEMS)processing technique.The deflection of sensing unit is analyzed by the theory of small deflection and the theory of material mechanics.On the basic of these theory,the mathematical model of F-P electrostatic sensor is established.Then,straight beam structure and serpentine structure of F-P sensing diaphragm beam is designed on the basic of the mechanics finite element analysis method,the calculation of intrinsic mode and forced vibration response sensitivity of different structure.Then high voltage sensor is assembled by high and low voltage electrode,insulated jacket and F-P interferometer,which is made up with the help of MEMS technology high sensitivity silicon strain and optical tail fiber.High and low voltage electrode and insulated jacket structure of sensor are desined basing on the theory of electrical insulation design and the electric field simulation with COMSOL software.The strength of electric field between high and low electrodes is analyzed on the basic of electrostatic theory.The high voltage sensing measurement experiment is finished with the help of demodulation system which is constructed by DFB laser.Experimental result shows that the F-P voltage sensor can measure 3-10 kV AC voltage,the measurement basic error is smaller than 3.90%,the basic error level islevel 5.0,the sensitivity is better than 7.32mV/kV.In view of the shortcomings of the range of F-P voltage sensor,it is optimized with SF6.The optimized F-P voltage sensor can measure 4-24.1kV AC voltage,the measurement basic error level is smaller than 1.00%,the basic error level is level 1.0,the sensitivity is better than10.00 m V/kV.With the increase of the applied voltage,the sensitivity of optical fiber sensor and the accuracy is more and more better.Compared with F-P electrostatic voltage sensor,the optimized F-P electrostatic voltage sensor’s range elevated nearly2.4 times,the basic error decreased by 74.4%,the sensitivity increased by 36.6%.Compared with the current F-P electrostatic voltage sensor,the optimized F-P electrostatic voltage sensor basic error level decreased by 20.2%,the basic error level increase three levels,the volume size reduced by 5/6,the weight reduced by 5/6.The desired effect of design is achieved. |
