Research On LCC Resonant Converter And Related Electromagnetic Field

Electrostatic precipitators are widely used in the field of air purification in home and industry.Its working efficiency is directly affected by the performance of dust removal power supply.As the heart of the switching power supply to supply power,the stray capacitance and leakage inductance of the high flrequency and high voltage transformer have greatly affected the overall performance of the converter.Mastering the influencing factors of these stray parameters and exploring the methods of controlling and utilizing these distributed parameters are directly related to the efficiency of electrostatic precipitators.The leakage inductance and the distributed capacitance of high frequency transformer have great influence on the circuit.This paper summarizes it and introduces the common methods to reduce the adverse effect of transformer stray parameters.Then the theoretical formula is deduced.ANSYS Maxwell simulation software,which is based on finite element principle,is used to model and analyze high frequency transformer.By using the control variable method,it is can be proved that both the current size and the core material have no effect on the leakage inductance of the transformer.And it is deduced that the saturation degree of the transformer core will not affect the leakage inductance as well.At the same time,with the increase of the frequency,the primary leakage inductance of the transformer decreases,but the reduction is very small.The effect of variation in the leakage inductance on the voltage transfer ratio is negligible,compared with the effect of frequency on the resonant cavity in the circuit,and then on the effect of the voltage transfer ratio.Similarly,the effect of air gap is negligible in this subject.The winding turns are the main factors affecting the leakage inductance of the transformer.So the most direct way to reduce the leakage inductance is to use the magnetic core with high permeability,as well as to increase the working frequency,and thus to reduce the number of winding's turns.The distribution parameters of high frequency transformer are simulated and calculated by three dimensional model.Compared with the experimental data,the error causes are analyzed.The rationality of the optimization model is proved,as well as the guiding significance of finite element simulation for the design of magnetic devices.The paper made a comparative analysis of several common switching power supply circuit topology.Finally,it is decided to use voltage doubling rectifier LCC resonant conversion circuit as the main circuit topology to make rational use of transformer distribution parameters and to reduce the equipment volume.At the same time,the frequency modulation control technology based on PI is introduced to solve the problems of time variability,nonlinearity and uncertainty of equivalent load and the uncertainty of circuit stray parameters,which makes the equipment work normally under complex working conditions,with realization of ZVS under CCM mode and improvement of working efficiency.The equivalent AC circuit is analyzed by the fundamental wave approximation method.And then this paper establishes mathematical model.The transmission characteristics of the converter are studied,and the circuit parameters are derived and calculated theoretically.The rationality of the parameter design is proved by a series of simulations.Finally,the prototype is made and verified by test.