Research On Traction Converter Of The Mine Electric Locomotive

Mine electric locomotive is a type of rail transit vehicles,mainly used for miningenterprises,and undertake the underground alleys or ground transportation over longdistances.Mine electric locomotive has a special working environment,which would offendeal with complex condition,such as overloading,climbing and load disturbances,So electriclocomotive should have a large enough starting torque,in addition,the voltage fluctuation ofsupply network is also an important factor which influence the working performance of thelocomotive.But the speed control system of existing mine electric locomotive is mainly dcchopper and resistance regulation system in china,and resistance regulation system accountsfor about80%,which caused a lot of energy waste,while abroad,AC speed regulationtechnology has been widely applied to mine electric locomotive yet,which performance wellon energy saving.Traction converter is the core part of mine electric locomotive which realize operationcontrol,The traction converter and its control strategy are studied in this paper considered theparticularity of electric locomotive.Traction converter realize electrical energy transformationwhich composed of two parts:rectifier and inverter,Traditional rectifier has manyquestions,such as low power factor、serious distortion of net side current and a large numberof harmonic and reactive power injection to grid,Considered this,we chose PWM rectifierscheme in this paper,the control strategy are studied with double closed-loop structure ofvoltage and current,both inside and outside ring controller was designed,the simulationmodel was built and simulation studies were completed;Considered the special workingcondition of mine electric locomotive,the VVVF control scheme based on maximum torqueoutput is studied combined with V/F control and slip frequency control,compensationmeasures of the network was taken,the simulation model was built and simulation studieswere completed,In order to reduce the cost,main circuit of inverter was designed by IGBTmodule of small capacity in parallel mode,control system was designed based ondsPIC33F,and the control program was written.Finally a traction inverter prototype with capacity of300kVA was develop,and theexperimental platform was built.lots of experiments on traction inverter under different frequency have been done, output voltage and current waveforms of the inverter werecollected and analized,and the starting and braking process were observed.Experimentalresults show that the VVVF control scheme based on maximum torque output proposed inthis paper can output the maximum starting torque,and has excellent performance especiallyin dealing with overloading starting and load mutation,meanwhie it also has a goodadaptability to voltage fluctuation of network.