| The electric excavator is a large shovel equipment which is used to dig hard rocks andores in opencast site of mine, cement industry and water conservancy construction. At present,magnetic amplifiers control,the generating units thyristor excitation control and electronicexcitation adjustment control are widely adopted by DC speed control part of mining electricexcavator in our country, its electrical system has many disadvantages, such as backwardtechnology, large noise,inconvenient operation,low dynamic efficiency,high cost and so on.Along with the development of computer technology, microelectronics technology, moderncontrol theory, the DC motor control starts to shift from analogue control to digital, and theintelligent motor control is gradually realized. The topic of this research work is to realizedigital control of mine electric excavator, a set of all-digital DC speed controller of mineelectric excavator based on ARM-linux is designed by using Samsung S3C2440A microcontroller as the core, embedded control technology is used into the DC speed control field.Thesis is mainly completed as the following aspects:The structure and the working principle of the DC speed control system for mine electricexcavator were analyzed and the overall scheme of the system was designed; Based on thetheory of automatic control, tool boxes of Matlab’s Simulink, SimPowerSystems andsimulation method facing electrical principle of the system’s structure, the double closed loopDC speed control system of mining electric excavator was simulated, and analysis andcomparison were made. The simulation model and simulation waveform of mine electricexcavator DC speed control system based on Simulink were given, correctness of the settingsof regulator’s parameter and the simulation model were verified from the simulation results.Based on algorithm of digital PID control and programming method of Matlab, theparameters of double closed loop of digital PID controller were designed, from step responseand obtained parameters can obviously find that the obtained controller parameters based onprogramming method of Matlab were consistent with simulation method based on Simulink,which can powerfully evidence the selective rationality of the control system parameters.The structure and the working principle of DC speed control system were analyzed atfirst,then in order to overcome the disadvantages which existed in traditional electroniccontrol system of electro-excavator, core board utu2440-F based on S3C2440A was adoptedto design a digital control DC speed regulating device for electro-excavator,12isolated andamplified pulse signal were exported by speed control circuit of DC motor to control theconduction,deadline of12thyristors and to change the value of armature voltage. Based onthe analysis of hardware resources which the core board already had, hardware and softwaredesign of detection circuit and triggering pulse circuit were focused on.Software platform of the system development was build, mainly configurated andtailored the embedded Linux operating system for the DC speed control of mine electricexcavator, then transplanted the embedded system into hardware expand board which wasmade for the subject; The design of driver and the application of upper stratum which realizedthe related function of the control system were completed. The main ideas and key code of the12road triggering pulse program were given by the paper. According to the requirements ofthe system, in order to directly watch the running state of electric monitor through the userinterface for mine excavator, and finally achieved the functions of dynamic display ofreal-time monitoring information, overrun alarm, data curve analysis and so on,thedevelopment of user interface based on Qt/Embedded was primarily discussed in the paper. Finally, when the design of software and hardware were completed, the experimentalresearch and online function test were done for DC speed digital control system of mineelectric excavator. Test results show that each function index of the system can basically meetrequirements of the design, the control performance and stability of the system wereperforming well, the system had better practicability and great applied value. |
