Research On Electronic Ballast Technology Of Ultraviolet Lamp Based On Photochemistry

In recent years,the disinfection technology of excimer ultraviolet lamp based on photochemical wavelength of 222 nm has aroused widespread concern in society.Compared with the traditional disinfection technology,this technology has high safety factor and less pollution,and has broad application prospects in the field of medical disinfection.Excimer ultraviolet lamp can use dielectric barrier discharge to excite the corresponding mixed gas in the lamp tube under the condition of high frequency and high pressure,generate the corresponding excimer and release photons at the same time when it transitions to the ground state in a short time,so as to generate ultraviolet rays with corresponding wavelengths,thus achieving the purpose of sterilization.At present,there have been many researches and designs on ordinary electronic ballasts for ultraviolet lamps used in daily life,but ordinary electronic ballasts for ultraviolet lamps can’t provide the high-frequency and high-voltage conditions required for low-power excimer ultraviolet lamps to work normally.Therefore,the research and design of electronic ballasts for low-power excimer ultraviolet lamps need to be deepened.Because the output characteristics and control strategy of electronic ballast determine the working state of excimer ultraviolet lamp,the research and design of electronic ballast with superior performance has a positive effect on the popularization of excimer ultraviolet lamp disinfection technology.In this paper,the topological circuit and control circuit of electronic ballast for excimer ultraviolet lamp based on photochemistry are studied,and an electronic ballast for excimer ultraviolet lamp with a maximum output power of 70 W and good output characteristics is designed and built to ensure that the excimer ultraviolet lamp can work normally and stably under the action of the electronic ballast.The main research content is as follows:(1)The principle of ultraviolet sterilization,the structure and working principle of ultraviolet lamp and the process of ultraviolet generation under dielectric barrier discharge are analyzed in detail.According to the working requirements of excimer ultraviolet lamp,the output characteristics of electronic ballast of excimer ultraviolet lamp are analyzed,and the common topological structures of electronic ballast of excimer ultraviolet lamp are compared and analyzed,and the topological structure adopted in this paper is determined according to the design objectives.(2)Based on the analysis of the working principles of the power factor correction circuit and LLC resonant circuit of electronic ballasts,the Boost circuit is determined as the power factor correction circuit of electronic ballasts,and the half bridge LLC resonant circuit is determined as the DC/AC circuit of electronic ballasts.The main circuit and control circuit of Boost type power factor correction circuit and half bridge LLC resonant circuit are designed,The main components such as switch tubes,magnetic components,and high-frequency transformers are selected,and the parameters and structure are designed.(3)In order to ensure the normal operation of the ultraviolet lamp,a reasonable control strategy is designed to ensure the stable voltage output of the electronic ballast.Firstly,in view of the difficulty in sampling the output high frequency and high voltage of the half-bridge LLC resonant circuit,a sampling scheme of adding auxiliary windings in the high frequency transformer is proposed.Secondly,taking the rectified and filtered voltage output of auxiliary winding as the controlled object,the small signal model of half-bridge LLC resonant circuit is established by frequency sweeping method,which realizes simple and accurate small signal modeling.Then,based on the established small signal model,by optimizing the zero-pole configuration,a single-pole network is proposed to compensate it,so as to realize the stability control and fast response of the output voltage.Finally,the proposed control strategy is realized by designing and building the corresponding controller hardware circuit.(4)The prototype of electronic ballast for 70 W excimer ultraviolet lamp is completed,and the key working waveforms of the prototype are tested.Combined with the working conditions of ultraviolet lamp,the feasibility of the designed hardware circuit and the proposed control strategy is verified.