Research On Controller Of Multiloop Vacuum Electromagnetic Starter Used In Coal Mine

Vacuum electromagnetic starter used in coal mine is one of the most important electronic equipment, by which the safety of power supply system and production of coal mine is directly influenced. Thereby, it is of great importance to develop high-performance vacuum electromagnetic starter. The purpose of this project is to develop the controller of multiloop vacuum electromagnetic starter used in coal mine, the function of which is to achieve combination control and protections of high capacity motors. The content of this thesis is as follows:1) The advantage of 3.3KV power supply used underground coal mine is analyzed, and the content and meaning of motor protection underground coal mine is presented, besides, the development and present status of vacuum electromagnetic starter used in coal mine are introduced.2) Mathematical model of the heat accumulated and dissipating of motors to protect overload fault is built.The method of using software to simulate temperature rise curve is introduced. The principle of homopolar power is used to select the loop which is grounding fault on the bases of ananlyzing the characterics of grounding current. Analysis together with respective protection methods of overvoltage and under-voltage fault is presented.3) According to the working conditions, the control method of vacuum electromagnetic starter is presented, the overall plan is made. The controller is based on 4 pieces of PIC18F single chip processor, which is in master-slave mode , the function of combination control of motors(less than 6 motors), grounding fault detection, earth-fault lock-out, overload protection, display of working conditions in real-time are realizd.4) The hardware and software design of system is completed. The hardware design includ signal conditioning circuit, earth-fault lock-out circuit, emergency stop and lock circuit, keypad design, monitor of principal voltage and so on. According to the idea of modular design, the software design of main control board and auxiliary board is developped using PIC C language. Besides, anti-interference techniques both in hardware design and software design based on analysis of the characteristic of interference source is used, which greatly improve the reliability of the system.5) Experiment related to system design is done under the plantform of development board, debugger ICD2 and MPLAB IDE, including the configuration of MPLAB, voltage sample experiment, storaging and accessing parameters for site to EEPROM in PIC and I2C device 24C01, the algorithm of AC signal RMS, the usage of I/O module, timing module and interrupting module and so on.The purpose of this paper is to develop vacuum starter used in bad conditions under mine. The product is developed using single chip processor. It is featured of real-time, high reliability, friendly human-machine interface and easy to maintain. The idea of design has some instructive meaning to the development of similar products.