Belt conveyor soft starter and frequency converter is similar, also based on electronics and SCR, it fills the triangle starter and frequency converter in the functional practicality and price gap between the voltage control motor, motor can start smoothly, but also can be used for "soft" stop, With the advantages of high reliability, small maintenance, good motor protection and simple parameter setting, it fundamentally solves many drawbacks of traditional step-down starting equipment. With the rapid development of power electronics technology, AC soft starter has been widely used.
Principle of AC soft start of belt conveyor:
(1) The soft starter of belt conveyor is a motor control device which integrates soft start, soft stop, light load energy saving and various protection functions. It is mainly composed of three opposite thyristors and their electronic control circuit connected in series between the power supply and the controlled motor.
(2) The technical way to realize the soft starter of belt conveyor is SCR AC voltage regulation speed regulation. In order to obtain good speed regulation performance, the double closed-loop control system composed of speed closed-loop and current cut-off negative feedback closed-loop is adopted. The closed-loop control adopts PI adjustment mode.
(3) According to the requirements of multi-machine multi-point drive of the belt conveyor in coal mine, power balance technology is adopted. One soft starter is set as the main machine, and the speed is controlled by it, while the rest are set as slave machine. The current changes of the main machine are tracked to ensure that the output power is balanced.
(4) The start curve adopts the constant acceleration curve with "S" characteristic. In order to effectively overcome the static torque during the heavy load start, the control system can automatically start with "jump" mode according to the load condition