High-stability Ultraviolet LED Light Source System For Water Disinfection

Since the use of mercury lamp will cause serious damage to the environment,the related products are gradually restricted and eliminated.Ultraviolet light emitting diode(UV-LED)is gradually replacing mercury lamp as a hot research area in the field of water disinfection because of its wavelength diversity,environmental friendliness and easy integration.According to the experimental setup and evaluation methods in the published work,insufficient accuracy of radiation dose control is the problem to UVLED light sources.The accuracy is determined by the stability of irradiance and the accuracy of irradiation time.The temperature stability and driving current stability of UV-LED panel are the main factors affecting the stability of iradiance.In addition to the low irradiance stability,most of the existing light source systems are expensive,bulky,and have low flexibility.In this paper,a high stability UV-LED light source system for water disinfection was designed.Modular design was used in the hardware design,including six main circuit modules:UV-LED panel module,MCU control module,temperature control module,current source module,power module and human-computer interaction module.The temperature control module was used to solve the problem of irradiance decreasing in the process of irradiation.The current source module was controlled by the program,which realized the precise control of irradiation time.The software design included the program running on the MCU and a MATLAB GUI program.The system realized the temperature control by running the increment PID algorithm on STM32,realized the precise control of irradiation time by using a timer in the MCU.Experiment data showed that the system basically eliminated the error caused by insufficient time control accuracy;the noise current of the current source was the key factor which limits the performance of the system when the temperature is controlled.The core performance indexes of the system are listed as follows:1.A program-controlled current source was designed and realized,the output range was 0-400 mA,the output current noise was in 59 ?A,the maximum absolute error of current was 51 ?A.2.A temperature control circuit based on PID algorithm was designed and realized.The temperature fluctuation range was 0.02?(peak-to-peak)at steady state temperature of 25?.3.During the irradiation time within 120 s,the optical power of 265 nm UV-LED panel fluctuated within 3%,the optical power of 280 nm UV-LED panel fluctuated within 1%.In order to evaluate the inactivation efficiency of the 265 and 280 nm UV-LED,the system was used in irradiation experiments which chose E coli as the model microbe.Reliable results were got and were published on the authoritative journal in the field of water disinfection,which proved the reliability and practicability of the system.The system was an equipment for the specific application field of UV water disinfection,which solved the problem of uncontrollable error of irradiation dose.The system greatly increased the tolerance of experiment design and UV-LED devices selection,the system had the advantages of small size,low cost and good human-computer interaction experience.