Power Frequency EPS Based On High-frequency PWM Control

Electrostatic precipitator (ESP) is an important means to control air pollution,electros-tatic precipitator device used by most enterprises currently is thyristor-controlled system.With the continuous improvement of environmental protection requirements, wastedischarge requirements of the enterprise also increase. Traditional electrostatic precipitatordevice has been unable to meet the requirements, there is an urgent need for it to be replac-ed or renovated. Development of high frequency power supply is a major breakthrough, butthe replacement of the original electrostatic precipitator system by the high frequencypower supply completely means a big price for enterprises, also abandoning the originalelectrostatic precipitator system is a great waste of resources. Therefore, this paper presentsan economic, simple retrofit scheme: keep the step-up transformer and high voltage silicondiode bridge rectifier of original ESP system remain, only thyristor-controlled system willbe replaced by full-bridge inverter controlled by IGBT with power frequency output.Theapplication of high-frequency PWM control will obtain a good result without difference inhigh frequency power supply.This paper introduces the basic working principle of ESP，points out that when theresistance of dust is large, the system may work on the inductor current discontinuouscondition，and analyzes the adverse effects on the closed loop control system caused by thisphenomenon. In order to solve this problem, this paper proposes the pulse working mode.The best spark rate control is the key to the control of ESP, this paper analyses the bestspark rate control of ESP and the slow start process of system.DC magnetic bias will inevitably exist in power electronics device with transformeroperation, this paper analyzes the cause and suppression method of DC magnetic bias,introduces the suppression method based on DC bias current detection, and points out itsdefects. Finally, this paper proposes a method based on magnetic flux limiter and magneticreset,which is suitable for ESP system.Simulation test of the ESP system desgined by this paper has been taken first, and itachieved good results. Then the on-site operation test was conducted,the output and sparkcontrol have reached the expected goal.