Corona Discharge Numerical Simulation And Discharge Detection Technology Based On GaN Ultraviolet Detector

With the rapid development of ultra-high voltage and ultra-high technology in China,the problem of corona discharge has become increasingly prominent,which has caused sustained damage to high-voltage electrical equipment and a lot of adverse effects on the environment.Therefore,the research of high-sensitivity detection technology of discharge is of great significance.From the microscopic point of view,discharge produces a large number of electrons as well as positive and negative ions;and the transition recombination process is accompanied by ultraviolet radiation.The non-contact detection of discharge can be realized by ultraviolet detection.At present,the ultraviolet imager used for discharge detection is expensive,and the vacuum ultraviolet detector has large volume,low sensitivity and high power supply voltage.Based on the principle of corona discharge,the development of discharge micro-particles and the generation of ultraviolet light are analyzed by numerical simulation.The ultraviolet detector and application circuit based on GaN,the third generation semiconductor material,are optimized and fabricated,and applied to the ultraviolet detection of discharge.The main work of this paper is as follows:Firstly,based on the hydrodynamic model,the numerical model of air discharge is established,and the rod-plate negative corona discharge model is solved by the finite element software COMSOL Multiphysics.The result shows that the discharge produces a large number of electrons as well as positive and negative ions,which develops forward to the anode in space,and the electrons and positive and negative ion clouds will distort the electric field.The ion produced by discharge is the source of exciting ultraviolet light and the theoretical basis of ultraviolet detection.Secondly,the generation,propagation and detection of corona discharge ultraviolet light in air are analyzed.During the period of discharge,ultraviolet light is mainly produced by atomic transition and ion recombination in plasma region.Besides,the spectrum is concentrated between 200 and 400 nm.Since GaN material has good photoelectric response to ultraviolet light,the working principle of metal-semiconductor-metal structure photodetector(GaN MSM-PD)is analyzed.Then,the principle of GaN MSM-PD is simulated and validated by Silvaco TCAD software;and the method of burying electrodes in GaN epitaxy layer to improve the responsiveness is proposed.Also,the feasibility is verified by simulation method.GaN MSM-PD with buried electrode structure was fabricated by Chongqing Key Laboratory of Photoelectric Functional Materials,and the photoelectric test was carried out.The result shows that the response speed of GaN MSM-PD is nanosecond,the suppression ratio is 10~5 orders of magnitude,the spectral response at 280 nm is 0.8A/W,and the ideal bias voltage is 3.7V.Finally,based on GaN MSM-PD,an application module and a prototype of detection device for discharge detection are designed.First,the circuit of current-voltage conversion and amplification is designed.And the n the application module of discharge ultraviolet detection with high response speed and sensitivity is made as well as the battery power supply is used to improve the convenience.Based on this module,the pin-to-plate discharge experiment is carried out.The result indicates that the module can detect the high-frequency optical pulse signal generated by the discharge well,and its performance is better than that of the traditional pulse current method.In order to achieve low-cost data acquisition,envelope detection module is used to reduce frequency,and a prototype of acquisition system based on FPGA is designed,which is suitable for field application of electrical equipment discharge detection.