Research On A Half Bridge LCC Resonant Converter For Electrostatic Precipitators

In the recent years,with the rapid development of industrialization,fog and haze pollution is becoming more and more serious.In the implementation of related policies and wide application of high frequency power supply for electrostatic precipitator,dust emission of heavy industry is greatly reduced.However,due to the cost of the power supply for electrostatic precipitator applied in heavy industry,it's difficult to promote it in light industry.Namely,it's impossible to greatly reduce the total dust emission.Therefore,it's of certain value to research on medium and small power supply for electrostatic precipitator.First of all,the merits and shortcomings of LC series and LC parallel resonant converter are pointed out through graphic analysis and comparison,thus selecting half bridge LCC resonant converter as the main structure of power supply for electrostatic precipitator.According to the characteristics of various working modes of LCC resonant converter,the continuous current mode with the resonant tank perceptual is selected.A detailed analysis of the working principle of the various modes of the above mode is completed.At the same time,mathematical expression of key parameters of circuit under each mode is derived by mathematical derivation method.But these expressions are too complicated to calculate and optimize parameters in engineering.So the fundamental wave analysis method is applied to deduce steady state model of the half bridge LCC resonant circuit in the chapter third.And then the constant voltage and constant current characteristics are analyzed.On the basis of the constant current characteristics,better range of the quality factor and the ratio of parallel capacitor and series capacitor is optimized through analysis and comparison.Moreover,the result lays theoretical foundation for the optimization of circuit parameters.Secondly,the thesis shows the main design steps for the high frequency and high voltage transformer,which is the key part of the power supply.Contraposing the specificity of ESP(electrostatic precipitator),the paper optimizes the insulation structure,heat dissipation of the transformer and the control of leakage inductance and stray capacitance based on the structure of common transformer.And the thesis has designed the structure of transformer with the rectifier integrating into the transformer.Finally,we built a sample.On account of the range of parameter optimization of constant current characteristic,the thesis obtains the main resonance parameter.The thesis verifies the approximate constant current characteristic under the open loop system by Saber software.The trial and error method which is often used in the engineering application has the shortcoming of a waste of time to design the controller.The small signal model of the half bridge LCC resonant converter under PWM control is established based on extended describing function method.In addition,analytical expression of control-to-output current transfer function is derived.At the same time,the bode plot of control-to-output current function is gained through Simplis simulation software,thus validating the validity and the correctness of the small signal model.The design method is considered to be valuable for theoretical guiding.In the end,we complete the close loop of ESP.The related simulation has proved the constant current characteristic of the power supply for electrostatic precipitator.And it can solve the spark breakdown which usually takes place under the control of constant voltage.Importantly,the design of control loop will improve the stability and dynamic response speed of the system.