The Belt Conveyor Vvvf Drive Systems Research

As belt conveyors are currently developing in the direction of long span, high power, high belt speed, high stability, the research on dynamic design and starting stability of belt conveyors has become a new subject. Adopting a reasonable starting way to reduce the dynamic load of belt conveyors is the main method to improve starting stability. Therefore, based on analyzing the dynamic characteristics of belt conveyors, this thesis studies a kind of soft starting device driven by variable-frequency motors after analyzing.Firstly, dynamic models of belt conveyors have been created in the paper, the effects of various starting plans on the starting characteristics of belt conveyors have been analyzed, and the best starting acceleration curve of belt conveyors has been identified. Besides, the method to adjust the power balance has been found out after a analysis of ideal and actual distribution of the driven power of each motor. Then combined with the specific requirements of a belt conveyor, a set of variable frequency soft starting system has been designed, including main circuit breaker, isolation transformer, the selection of the ACS 1000 transducer in variable frequency starting system, and the design of control unit, the design of speed control system as well as multi-motors power balance, etc. in variable frequency driving system. Finally, field trials have tested whether variable frequency driving system can meet the different demands for driving forces and speed changes during the starting process of belt conveyors, the changes of drive pulley output torque with load changes, system stability in the acceleration and deceleration phase and long-running stability of the system as well.The experimental results have showed that variable frequency soft-driving system can meet the requirements of driving force output changes during the starting process for large belt conveyors, extend the start-up time and greatly reduce the starting tension of the conveyor belts. Meanwhile, the use of variable frequency driving system can reduce the strength of the conveyor thereby reducing the cost of equipment investment. Moreover, variable frequency drive also has the advantages of low maintenance and energy saving.