Research On Switch Control Strategy Of Medium-frequency Electrostatic Precipitator Power Supply

The main source of air pollution in China is coal combustion,which produces a large amount of dust-containing waste gas.In all kinds of dust removal methods,electrostatic dust removal technology is an important means.In order to adapt to the increasingly stringent emission standards,the upgrading of electrostatic dust removal technology is imperative.The medium-frequency electrostatic precipitator power supply is an ideal scheme to replace the industrial frequency power supply due to the advantages of good dust removal effect and relatively easy upgrade and transformation.At present,there are two main aspects,which need to be further improved,of the performance of medium-frequency power supply.On the one hand,it is to enable the medium-frequency power supply to provide the maximum output power while reducing the number of spark flashover occurrences On the other hand,the rapid recovery of load voltage and current after the spark of the medium-frequency power supply is improved.Based on the above background,the control strategy of the main circuit of the mediumfrequency electrostatic precipitator power supply is proposed,and verified experimentally by the power supply prototype.This thesis details the working principle of the medium-frequency electrostatic precipitator power supply.The voltage and current characteristics of the period are analyzed,and the mathematical model is established.Theoretical derivation and simulation are made for the constant current control method of medium-frequency power supply.A constant frequency current hysteresis loop control strategy based on triangular wave superposition is proposed to improve the output power of the medium-frequency power supply during stable state.The traditional three-segment spark control of medium-frequency power supply is modified to improve the current recovery ability of the medium-frequency power supply after spark.Based on the proposed control strategy,a collaborative control framework between DSP and CPLD is designed.The circuit overcurrent detection and IGBT protection circuit are designed,and the main control program design of medium-frequency power supply is completed.At last,the feasibility and effectiveness of the control strategy are verified on the prototype.