Design Of The Explosion Protection Soft-Starter For Mining Based On STM32

There are many equipments such as belt conveyors,fans,water pumps used in coal mine underground working surfaces,most cases used AC asynchronous motors for dragging at present.However,if did not take any measures to start the drag motor directly,the impulsive current generated at the moment of starting is very severe,which will cause irreparable damage to the motor itself and the mechanical equipment.Therefore,adding a soft-starter between the power supply and the motor can limit the current,reduce damage to the equipment and cut down the impact on the grid voltage.In order to improve the starting characteristics of the motor and limit the adverse effects caused by excessive starting current,this thesis designs a mine soft-starter with STM32 series microcontroller as the main control core,the purpose is to limit the starting current to achieve soft start control.In response to the above problems and according to the design requirements,through analysis of several soft start solutions,decided that the system uses a three-phase thyristor voltage-regulating soft-start scheme.At the same time,the mathematical model of the AC asynchronous motor and the parameters that affect its starting performance are described.Then,in order to better control the inrush current during the starting process,the fuzzy PID control algorithm was introduced in detail,due to the limitations of the soft-start traditional current-limit starting method,fuzzy control technology was introduced into it,PID controller parameters are set in real time,realize the optimal treatment of motor starting current and time,and the fuzzy PID control algorithmIn was simulated by MATLAB/Simulink to make the output waveform more satisfactory.The control circuit and driving circuit are separated by optical fiber to reduce the EMI and improve the transmission speed of the signal.The thyristor drive circuit is composed of CPLD auxiliary control circuit and pulse transformer,which has a good effect in achieving reliable control of the thyristor.According to the actual needs of this subject,designed the software and hardware of the soft starter and debug the overall system,the hardware mainly includes the design of electrical main circuit,power supply circuit,detection circuit,thyristor trigger circuit,communication circuit,contactor control circuit and the explosion protection.The software mainly includes the design of the main program,system initialization program,fuzzy PID program,thyristor triggering program.The soft-starter designed in this thesis is easy to operate,small starting impact and strong practicability.