Reliability Evaluation Method And Experimental Verification Of Shearer Traction Inverter

The traction frequency converter,as one of the core equipment of the coal mining machine traction department,determines the overall production efficiency and coal output of the coal mining machine based on its own operational reliability.Affected by harsh working conditions,the reliability and stability of the traction frequency converter of the coal mining machine are challenged,and the high fault phenomenon greatly increases the operation and maintenance costs.The existing factory testing still relies mainly on threshold judgment,with a single testing method and low theoretical depth of inspection methods.It is of great practical significance to establish more effective and comprehensive reliability evaluation methods and test plans in order to improve the operational reliability of coal mining machines and reduce the failure rate of traction frequency converters.This article focuses on the IGBT module,control circuit,and frequency converter system of traction frequency converters,conducts research on reliability evaluation methods from components to systems,and designs and completes experimental verification work.The main research content includes:(1)Analyzing the research status of reliability evaluation methods and tests for traction frequency converters,based on the analysis of frequency converter fault types in a domestic coal mining equipment enterprise in the past three years,starting from the principle of frequency converters,the causes of each fault are summarized.Based on this and combined with reliability evaluation theory,the reliability evaluation direction for IGBT modules,control circuits,and frequency converter systems in this article is established.(2)Conduct reliability evaluation research on IGBT module of traction inverter based on life assessment.Based on the working characteristics and failure mechanism of IGBT modules,a loss calculation model for IGBT and FWD was established;A dedicated junction temperature simulation thermal network analysis model has been established based on the actual heat dissipation method and process of the IGBT module of the traction inverter;Substitute the actual operating data of the frequency converter into the electric heating simulation model of the inverter circuit built by PLECS software,and obtain the IGBT junction temperature data.A life evaluation method suitable for traction inverter IGBT has been established by applying the rain flow counting method to collect junction temperature data and combining the life model and Miner’s linear damage theorem to evaluate the life of IGBT.(3)Conduct research on the reliability evaluation of traction frequency converter control circuits with the main focus on electromagnetic immunity evaluation.Introduce the functions and relationships of each module in the control circuit,consider the system reliability,analyze the working principles of the tested frequency converter RS485 electrical communication bus and SP3485 chip,summarize the mechanism of electromagnetic interference,and propose an electromagnetic immunity evaluation method and test plan suitable for the control circuit,including: electrical fast transient group pulse,voltage sag/interruption The immunity evaluation scheme corresponding to the three types of electromagnetic interference under surges is proposed,and experiments are conducted to obtain the test data and evaluation results of the control circuit under various interference types and levels.(4)Conduct reliability evaluation research on traction frequency converter system,including the following four parts:(1)Whole machine temperature rise evaluation test:In response to the issue of not considering the impact of environmental temperature on temperature rise in existing temperature rise tests,a temperature rise relationship model between environmental temperature,heat dissipation plate,and IGBT was established through IPOsim and FLUENT simulations.The effectiveness of the model was verified through experiments,and a temperature rise test evaluation method was proposed,Improved the existing temperature rise test;(2)Reliability loading test of the whole machine: in view of the problem that the current Functional verification loading test can not truly reflect the working capacity of the inverter under the actual working condition load,carry out the reliability loading test research based on the load spectrum,focus on the analysis of the extraction and processing of the inverter load,propose a method for the preparation of the load spectrum and obtain the corresponding load spectrum,and give the reliability loading test scheme based on the load spectrum;(3)Whole machine electromagnetic immunity evaluation test: Establish an electromagnetic immunity evaluation method and test plan suitable for frequency converter systems based on the control circuit immunity evaluation method,and conduct tests to obtain corresponding evaluation results;(4)Harmonic suppression and reliability optimization: In order to improve the reliability of frequency converters and reduce the impact of harmonics,a LLCL filter and dedicated parameter design method suitable for four-quadrant traction frequency converters are proposed.Compared with traditional filters,this method has obvious advantages and further analyzes the impact of LLCL filters on the electromagnetic immunity of the entire frequency converter.