Study On Speed-adjusting System Of Compound Excited DC Motor

In the AnSteel removal project of the production line of 800 Structral Steel,because the machines are provided by the Soviet Union at the sixties of the last century,and to decrease the investment,the project group decide that remove the 800 Structral Steel Mill and its auxiliary machines to the new production line.Because the motors of the elevating table and the carry over table are compound exited motor,whose the power provided by DC busbar and started by DC contactor,so the motor's control system can not reused in the new production line.At the end,the project group decide that use DC Speed-adjusting device to start the motors.Our study has designed a DC Speed-adjusting device,which meet the technical requirement and work fine in the new production line.Our study has solved several problems at the designing process.(1)Check the equipment capacity.We will check the equipment capacity beforeremoving,to check the equipment can work fine in the new production line,becausesteel-rolling process and products program have changed.(2)Design the rectifier circuit for compound excited DC motor,which can let DC motorwork at four-quadrant operation.The compound excited DC motor have twowindings,which are series winding and shunt winding.If the motor powered by twoantiparallel three phase full bridge rectifier circuit,the motor can not work atfour-quadrant operation.Our study series a diode-bridge rectifier circuit at the directcurrent side of bridge rectifier circuit to sovle that program.(3)Design the control system for compound excited DC motor.Current-speed doubleclosed loop control system is wide application in industry,which has high controlaccuracy,advanced anti-jamming capability and fast responsibility.The originalequipments don't have encodes,so we cann't collect speed signal directly.Our studycompute the motor speed by armature voltage and current,which signal can collectdirectly.And,have deep study at control ideas,current adjuster,speed adjuster andtrigger circuit.(4)Construct network control system.The system let rectifier,PLC and PC worktogether by network,which can remote control and monitor motors.After testing,the DC Speed-adjusting System can meet the performance index.