Investigation And Realization Of Key Technologies On High Power Supply Of Dielectric Barrier Discharge Ozone Generation

Ozone is one of the strongest oxidizing and bleaching agents without residues that could be harmful to the environment. For this reason, ozone has been used for a variety of applications , such as bleaching, deodorization and disinfection of water and industrial waste water. Ozone has beeing played the key roles in the quality raise of water and the development of the nature environment. However, ozone is highly unstable, readily reverting to the benign form oxygen, and therefore the ozone gas cannot be easily stored, consequently it is normally generated at point of use.The most common method of ozone generation is the dielectric barrier discharge, named as DBD method, in that a single phase AC power supply is applied on the metallic electrodes of the DBD type ozone generator, to produce an AC corona discharge in a gap bounded by electrodes and containing at least one solid dielectric barrier. Obviously, the DBD type ozone generator and AC power supply are two key components in the DBD method.Having been conducted a thorough study on a great number of references and existing technologies developed and studied by others all over the world, a whole and systematical research on the inductive phase-shift PWM controlled load series resonant DBD type power supply of ozonier with resonant pole capacitors has been developed, including three key technologies such as the electrical characteristics of ozone generator, the phase-shift control properties and the MOSFET soft switching techniques of inverter. These researches and studies have very important roles in both theories and applications.The main achievements obtained by this dissertation are:The working processes of the series resonant DBD type ozone generating power supply are systematically analized firstly, which powered by an inverter being controlled by phase-shift PWM control method. Three kinds of working conditions and five main characteristics are obtained;Secondly, by analyzing the time-domain electric waveforms of the power supply under the resonant discharging condition, the peak voltage expression of dielectric layer and the matching conditions as well as optimum matching ranges of electric parameters for ozonier to discharge stably arc obtained;Meantime, the phase-shift control properties of the power supply is also developed and studied, as well as the phase-shift control ranges are obtained for main electricparameters to be controlled under various operation conditions;Then, by means of analyzing the time-domain electric waveforms of the ozone generator, two new fundamental wave equivalent models of ozone generator are developed, one for generator powered by sinusoidal current, the other for generator powered by sinusoidal voltage. In the first equivalent model, gas gap of the generator is equivalent to a series circuit, which consists of two nonlinear fundamental wave equivalent elements -resistor Rg and capacitor Cg\ varing with the sinusoidalcurrent peak value. In the second , the generator is equivalent to a parallel circuit, which also consists of two nonlinear fundamental wave equivalent elements -resistor Re and capacitor Ce varing with the sinusoidal voltage peak, value;Utilizing the electric charges accumulated and devolving on the dielectric surface, the popular discharge power formula and the characters of ozone generator are developed. The limit of the assumption that voltage drop between the two electrodes are sinusoidal wave is out of use ,so that the popular discharge power formula is suitable for any kinds of pwer supply possessing non-sine-shaped voltage drop between the two electrodes. The discharge power formula of the series resonant power supply has been induced in detail so as to verify the effectiveness of the popular one;Based on the fundamental wave equivalent models proposed above, the electrical properties of generator are studied in detail and the matching conditions as well as the optimum matching ranges of electrical parameters for ozonier to discharge stably are achieved also, the popular discharge power expression can be directly obtained by the energy consumption of the equivalent fundamental wave resistor Re or Rg;Conseqently, a kind of time-domain design method and a kind of fundamental wave equivalent model design method for the series resonant medium-high freqency power supply are developed, and a kind of fundamental wave equivalent model design method for parallel compensating power freqency application is also developed;Finally, the operating modes of the power supply are analyzed in considerable detail. Conseqently, the important characteristics of the operating modes are induced. Then the ZVS ZCS soft switching techniques of the ozone generating inverter using MOSFET as the main switchs are studied, and a new kind of equivalent circuit describing the Turn-Off transients of the MOSFET is put forvvords in the same time. Based on the equivalent circuit, the soft-switching characteristics and a simple design method of the pole capacitors is also developed. Using this method, the reasonable value of the capacitors can be easily selected which makes the power supply not only has a higher power factor .but also possesses with a wider ranges which ensure theMOSFET ZVS and ZCS soft switching.Some design examples and their simulation results hav been completed, it is obvious that the results have confirmed the effectiveness and suitabilities of the theories and desin methods developed by this paper.