Application Research Of 3.3kV High Voltage Inverter In Remote Drive Of Mining Scraper

Scraper conveyor is an important transportation equipment in coal mine,which is driven by frequency conversion and has excellent start-up performance and speed regulation performance.With the development of intelligent and intensive coal mining technology,frequency converter is widely used in long-distance drive scraper.In the actual production,the motor is frequently damaged by the long-distance drive of the frequency converter,which affects the normal operation of the scraper machine,reduces the production efficiency of the coal mine,and brings great problems to the application of the frequency converter in the scraper machine,which needs to be solved urgently.In this paper,firstly,the mechanism of motor damage caused by long-distance drive of frequency converter is analyzed in detail.According to the transmission line theory,the transmission cable distribution parameter model is established,and the single-phase equivalent circuit among frequency converter,transmission cable and motor is established.Because the characteristic impedance of transmission cable and load motor do not match,the output pulse wave of frequency converter is in the long cable transmission process The phenomenon of voltage reflection occurs in,which leads to the over-voltage and harmonic aggravation at the motor end.The influence of PWM wave rise time,cable length,topological structure and transmission cable parameters on the over-voltage and harmonics at the motor end is studied by simulation circuit model.According to the results of mechanism analysis,two kinds of measures are put forward to prevent the over-voltage and harmonic of the motor,one is to suppress the harmonic by adding the AC reactor on the input side of the rectifier,the other is to suppress the over-voltage and harmonic of the motor by adding the output filter on the inverter side.The inductance and capacitance parameters of incoming AC reactor and output filter are calculated in detail,and the selection table of output filter reactor L and C parameters suitable to the length of transmission cable is derived.The simulation circuit model of three-phase long-distance drive is established,and the suppression effect before and after taking measures is compared and analyzed by computer simulation.The improved 3.3kV frequency converter drives the scraper motor in the coal mine transportation,the operation data and curve meet the expected design requirements,the motor performance is stable,meet the coal mine production needs.The correctness of the research results is verified in practical application.