Research And Design Of Mining Electric Locomotive Speed Control System Of DC Chopper

As a dedicated transport of mine,mining electric locomotives are the necessary equipments of mine automation and high volume production,which can increase mining capacity and economic benefits.Nowadays most electric locomotives use the string resistance for speed modulation,the drawback is that the dramatic current have a greater impact on the gears of electric locomotives and DC motors,the mechanical contact are easily burned,lots of power consumed in the series resistance,heat generated by the resistance is a major risk mine safety management.Therefore it is necessary to change the existing mining electric locomotive speed modulation,strengthening stable operation of electric locomotives and the protection functions is the reliable guarantee to improve safe operation of electric locomotives.The paper briefly describes the common speed control mode of DC motor and chopper principle,and develops a DC chopper speed control system which has perfect functions such as stable operation and stepless speed regulation.Analysising the dual closed-loop control on the speed and current of the DC chopper speed control system.Making a comparison between fuzzy control and PI control.Aiming at solving the problems caused by the optical encoder on the weak anti-jamming and increased cost etc,a speed estimation of electric locomotive is proposed which is based on the extend Kalman filter algorithm.Simulation results show that speed observer has small speed error and short response time,and fuzzy control has the characteristics of fast response,small over and strong robustness etc.The thesis gives a detailed introduction on the hardware and the software design of speed control system based on ATmega644.Hardware circuit design includes main circuit(Buck),driving circuit and protection circuit of the IGBT,power protection circuit,DC signals isolated sample circuit and AVR auxiliary processing circuit etc.Software process design section includes the main program,interrupt program and signal sampling program etc.The manufactured speed control system of DC chopping has passed the local test in the well of coal mine and laboratory,which realizes stepless speed regulation and saves energy.The system has some economical and practical value.