Research On High Power Supply Of Ozone Generation Powered By Serial Load Resonant Inverter

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 being played more and more important role in the development of the nature environment .However, ozone is unstable in normal temperature and readily turns into oxygen, which leads to that ozone is hard to be stored and transport. So it must be generated at point of use. Now, there are a lot of methods to generate ozone, such as ultraviolet radiation irradiation method, electro-analysis method, radiation method, DBD (Dielectric Barrier Discharge) method and so on. In these methods, DBD method has a lot of merits, such as low energy dissipation, higher yield of single equipment, being easy to generate ozone in working field. So DBD method is widely adopted in industrial ozone produce.At present, the square wave formed by serial inverter is directly applied to ozone generator and the control system is open loop control in most ozone equipment manufacturer, so there exist low working frequency, big switch loss, big switch stress and difficultly increasing the output discharge power in the power supply for ozone generator.Aim at these questions, a full bridge serial load resonant DBD type power supply of ozone generator has been studied, including the formulas describing the main electric characteristics vs. system parameters are deduced, the MOSFET soft switching technique of inverter is developed and the multifunctional control system is composed. These researches and studies have important roles in both theories and applications.The main achievements obtained by this dissertation are:(1) At present, the design of power supply for ozone generator mostly depends on the experience and approximate equivalent impedance gotten from the working current and working voltage analysis. So these design methods can't describe the working process of DBD circuit. To solver the question, a method of modes analysis is adopted by combining the on-off conditions of the power switch and the states of discharge or not discharge in DBD circuit.(2)There are not relevant documents and references about the performance analysis of DBD type ozone generator powered by serial load resonant inverter. In order to solver the questions, the expresses and regulating characteristics of main electric parameters are deduced under the PFR(Power Factor Regulation) capacitive load control, the PFR inductive load control and PSC(Phase Shifting Control) inductive load control . These researches are validated by experiments. The conclusions can make the designer to choose reasonable control scheme according to actual needs.(3) In order to avoid the analysis difficulties of DBD circuit in time domain method, a new fundamental wave analysis method of DBD circuit is presented since the current of inverter is closed to sinusoidal wave. Based on the fundamental wave analysis method, the formulas describing the main electric characteristics vs. system parameters are achieved. The errors between the calculation results, the simulation results and the experiment results are less than 8%. Compared with the time domain method, the fundamental analysis is more concise, and has engineering value. And a kind of power supply design method of DBD circuit is presented based on the fundamental wave analysis, the design method is a high performance design method validated by experiments.(4) After synthesis of the existing methods, a general frequency track method of PFR capacitive control, PFR inductive control and PSC inductive control is achieved Based on the general frequency track realizing ways, a new control system is present, which consist of power lag relay controller, peak voltage of DBD circuit regulator and inverter power factor angle regulator. Simulation results show that the new control system not only can regulate the discharge power in the optimum discharge voltage but also solver the over-voltage of DBD circuit, so the performance of the new control system is better than the other control system, such as PDM (Pulse Density Modulation) etc al.(5) For the reason of secrecy and convenient to debug, a new control system based on CPLD/FPGA chip is built. Since a power electronic circuit is essentially a discrete event system, a model method of its control system is presented base on the FSM (Finite State Machine) theory. With this control model, the PFR capacitive control, PFR inductive control and PSC inductive control can be realized in a same set of hardware. Experiments prove that the control model can be applied in most power electronic circuits.(6) The ZVS (Zero Voltage Switching) techniques of ozone generating inverter using MOSFET as the power switches are studied, and a new kind of equivalent circuit describing the turn-off transients of the MOSFET is presented according to the actual process of MOSFET. Based on this equivalent circuit, the soft-switching characteristics are studied and a design method is put forwards. The conclusions are proved by simulations.(7)By the analysis and design method in the paper, a 1kgO3/h ozone generator powered by serial load resonant inverter is built. The experiments results show the power supply can satisfied the design requirements. The ozone generator has been running in a factory located in PanYu, Guangdong Province. It works reliably, and obtains the user'praise.