Study On Special Switching Power Supply Techniques And Their Applications In Wastewater Treatment

Today, the environmental protection has been drawing more and more attention on people in the world with the environmental pollution continually becoming worse. Particularly, the bright development of special power supply and its wide applications in environmental protection is valuable to pay more attention. The study on the technology of switching power supply and its application in wastewater treatment was investigated in the paper. The research was carried out in the methods such as theoretical modeling, identification of model parameters, software simulation and experiment validation. And some valuable research results were obtained.A switching power supply that can output any arbitrary voltage waveforms was designed and made for wastewater treatment. The output voltage parameters such as amplitude, frequency and duty ratio can be variable in a wide range with programmable digital adjustment. The full-bridge converter was controlled with the PID strategy based on the feedback of voltage output. The real-time SPWM generation algorithm using a combination of look-up and interpolation base on DSP was proposed for digital altering frequency.The load characteristics of wastewater treatment by electrocoagulation with DC power supply was investigated. The theoretical model describing the relation between electrolysis voltage and the other variables of an electrocoagulation process was established, the model parameters being determined using least squares identification. Moreover, the experiments were performed to validate the established model. The load characteristics of clearing wastewater by electrocoagulation with the pulse power supply was also analyzed. The double layer capacitor effect is significant. Using bipolar electrodes and adding electrolysis separators can reduce the value of the load capacitor.The wastwate treatment experiments were conducted using the diverse voltage ouput with the disngned special power supply. The experiments demonstrated that the removal of color and chemical oxygen demand (COD) and decolorization percentage is satisfying using pulse voltage waveform. Moreover, the applications of pulse voltage waveform in the wastewater result in less power and electrode consumption than DC voltage, which reduces the cost. The cyclic reversed-polarity square voltage not only saves power and electrode consumption but also preventes from electrode passivation and scaling on the surface of electrode resulting in steady quality of purified water. So the cyclic reversed-polarity square voltage could be applied in thewastewater treatment. The effects of pulse voltage waveform on physical and chemical water treatment processes include double layer capacitor effect, mass transport, absorption and deabsorption on the surface of electrode.The applications of bionics in power electronics were firstly proposed as a new research subject. Some inspiration or new ideas on the technology of power electronics can be drew from nature. Based on redundancy, a multilevel converter topology with self-repair ability was proposed. The multilevel topology has fault-tolerant ability in case of switch failures as well as self-voltage balancing ability without any additional control or neutral-point balancing circuit. Under the inspiration drew from hierarchical architecture and control strategy of the human biological system, a overview of bionic power electronic system characterized by hierarchical architecture and autonomous decentralized control was proposed, which was made up of autonomous power electronics building cells. The proposed power electronic system has a promising prospect and paves the way towards future Plug and Play power electronic system for with many significant advantages.