Study On Electronic Ballasting Techniques For UV Lamps Oriented To Biological Effects

In the field of sewage treatment, the method of using ultraviolet radiation to inactivate the microorganisms and degrade the organic matter is more and more popular on account of high efficiency for sewage treatment and causing no secondary pollution in recent years. However, the lack of necessary connection between the design of UV electronic ballast and the research of biological effects makes it hard for the biological effect research to guide the design of the ballast. Moreover, the design of ballast is mostly based on switching-mode power supply. As a result, the improper ballast parameters could decrease UV lamps' disinfection efficiency and lead to severe injury of filament, shorten the life of lamp and so on. Therefore, the design of electronic ballast and the relationship between electronic ballast parameters of UV lamp, UV irradiance and biological effects should be taken into consideration in this paper from various aspects.Firstly, in order to drive the UV lamps reliably, this paper mainly analyzes the topology and control methods of second stage of UV electrical ballasts. Main topology of proposed ballast is half-bridge LCC resonant circuit which can provide a high starting voltage and suitable steady working voltage when adopting reasonable parameters. The control strategy, including slip frequency starting control, transition process control and power closed loop control, helps to realize the soft start and constant power output of UV lamp.Secondly, considering the strong nonlinearity of UV lamp, many electrical parameters will change under different lamp operation status and is difficult to be derived by means of theoretical calculation, this paper builds the lamp network based on BP neutral network. By analyzing the working characteristic of UV lamp, the approximate equivalent circuit of UV lamp network is derived, what's more, it will be and trained and identified by BP neutral network in this paper. The successful trained BP neutral network model is capable to predict the operating parameters of UV lamp network as well.Lastly, after the electronic ballast being designed, experiments are conducted to study the relationship between electronic ballast parameters, irradiance and biological effects. In this paper, PFC bus voltage and steady-state power are used as variable factors to study the influence of the UV lamp operating parameters affected by different bus voltage and steady state power. Based on the experimental data collected and collated, the relationship between UV light irradiance and operating parameters can be obtained and summarize the impact of the irradiance affected by the filament current. Referring to the biological effects of ultraviolet light, atrazine is set as target organic. The degradation of organic was investigated carefully under different irradiance of UV lamp through experimental data, which was gathered by changing the lamp power and paralleled capacitance.