Soft Start Of Belt Conveyor

Belt conveyor is now the most important bulk material handling equipment. He widely used in electric power,metallurgical,chemical,and other fields. Starting control and output power control problem is two important issues in the study of the belt conveyor. In recent years, the development of belt conveyor mainly concentrated in the development of the belt conveyor controllable soft drive.With the development of power electronics technology, power electronic soft-starter of induction motor has also been developing rapidly. Because of its reliable operation,easy to maintain,cheaper prices,and other characteristics,power electronic soft-starter has the trend to replace traditional starter equipments. Therefore this study focuses on electronic soft starter.In this paper,the mathematical formula of the motor starter's model is derived and the paper describes mainly the relationship between the variables of the voltage, current, torque. Using the Matlab/simulink,it proved that although the asynchronous motor soft-starter can solve the current problem but at the same time produce smaller torque.In order to improve the shortcomings of the traditional soft-starter technology, the paper presents a discrete frequency voltage control method (DFVC). Without changing main circuit of the traditional soft-starter,the method changes thyristor triggered moment to include or exclude half cycle of AC power. By this way,voltage frequencies switch from 16.67Hz to50Hz and electromagnetic torque of the induction motor is increased. For all the frequencies,in order to obtain maximum positive torque,the system is properly unbalanced and the most positive sequence of three phases is achieved. The paper explains the theory applied the proposed strategy with mathematic langue. Then the simulation is derived and DFVC is proved to have good starting torque and current performance compared to traditional soft-start method.