The High Voltage Electrostatic Precipitator Of Frequency Rectificaton Based On PWM Control

The existing demestic dust removal device commonly used is thyristor-controlledmode,due to the using of thyristor,this electrostatic precipitator (ESP) has some inherentdefects,such as slow system dynamic performance,high output voltage ripple,low dustcollection efficiency,and the supply power cutting off is not timely when sparkoccuring.Luckly high frequency power supply can well solve the aboveproblems.However,the complete eliminiation of the traditional thyristor-controlled powerwill bring to the large investment for the enterprise related,at the same time it means a kindof waste.Based on the above considerations,we determine to design a certain power supplyfrom the traditional thyristor-controlled power,we use IGBT bridge to replace the thyristormodule,meanwhile the original frequency transformer and the high voltage rectifier modulewill be remained.This certain power supply is called high voltage dust power of frequencyrectification based on PWM control by us.It has some advantages such as good systemdynamic performance and high dust collection efficiency.In addition,it significantly reducesinvestment of the enterprise,avoids the waste of completely the traditionathyristor-controlled power eliminated.Therefore,the research on this dust power has someimportant significance.In this paper,it presents the electrostatic precipitator power supply circuit structure,wedetermine to design a kind of prototype that can attain maxmum output power of56kW,maxmum output voltage of72kV.The two different working modes of circuit areanalyzed:CCM and DCM mode.and this paper presents that the output voltage feedforwardis unfavorable to system normal working when the circuit operates in the DCM mode.Howto select circuit parameters is analyzed in detail,The parameters of transformer is obtainedby experimental measurement.the selections of soft starting resistance and filteringinductance are analyzed,and explains that the leakage inductance of the transformer is usedas the filtering inductance in the practical system.The control of electrostatic precipitator power supply and the control of spark arediscussed.Protection on the circuit device is very important,this paper shows the two waysof protection:hardware protection and software protection.Analyzing the reasons oftransformer DC bias magnetic phenomena,and its suppression method is given.Consideringthe effect on the bias suppression loop when current loop using PI controller,the method that lag correction replaced with PI controller is proposed,and the steps of designing lagcorrection are given in detail.The dead time effect is analyzed and the method of dead timecompensation is proposed.According to the simulation experiment,the design of powercontrol is proved to be correct.Finally the methods of spark detecting and spark dealing aregiven in detail,meanwhile,the method how to realize optimal spark rate is proposed in thispaper.In the last part of the paper,it presents waveforms of magnetic bias regulatingexperiment,dead time compensation experiment. the experimental waveforms of powersteady-state operation and waveforms when spark occuring are also showed.these all provethat the performance of the prototype of power suuply is all-right.