Research And Design Of Multi-Frequency Quasi-Resonant Inverter For Ozone Generator

Ozone is highly unstable, readily reverting to the benign form oxygen, the most common method of ozone generation is the dielectric barrier discharge, named as DBD method. As the relative circuits and electrical parameters of the ozoniner have defined, the power supply of ozonier becomes the key point of the efficiency of the DBD method.The main power switches of the topologies of the inverter in nowadays may cause switching losses more or less during the operation, especially at high operating frequency, which extremely affect then improving of the circuit's operating efficiency and the switching frequency.After analyzing of the methods of improving the discharge efficiency of ozonier, a multi-frequency quasi-resonant inverter power supply for ozone generator was presented by transplanting the topology of the dual-frequency quasi-resonant inverter which used for induction heating. The math models of the each modes of the power supply were deduced after researched the operating theories and modes carefully in time area in half period. Base on the topology structure, modes and math models, the calculate formulas of the main parameters and adjusting characteristics were obtained.For the significant character of multi-frequency inverter without continuous current circuit and the ozonier feedback based, a pulse density modulation and pulse width modulation hybrid based control scheme was proposed. The appropriate control strategy was emerged after analyse the power in the period of PDM regulation. This PDM power control strategy with additional PWM scheme reduced the distinction of power regulation when PDM and PWM changing in different power density. Furthermore, then rising time of the current when the next discharge period starts was shorten.Otherwise, this thesis has researched and designed a control system for the inverter of multi-frequency quasi-resonant ozonier base on CPLD EPM7128SLC84. Then make the creation of the digital phase loop locked as well PDM pulse into reality and the phase-shift adjusting. The hardware circuits of the each function modules about the power control system then were put forward, particularly the circuit around CPLD, zero crossing detection, IGBT driving circuits and protection circuits.Via the research of designing and emulating of the real example of the ozone generator, the rationality and feasibility of the research results were proved to be correct.