Research On Electromechanical Coupling Model Of Permanent Magnet Direct Drive System Of Scraper Conveyor

As a key mechanical equipment of fully mechanized working face,the performance of scraper conveyor directly determines the efficiency and cost of underground coal mining.The driving system of scraper conveyor is the primary condition for its stable and efficient operation.Asynchronous motor is generally used as the power of the drive system,and the output of low speed and high torque is realized by the reducer.The existence of the reducer could cause the drive system to be inefficient,high maintenance and prone to failure.This paper designed a drive system of permanent magnet synchronous motor directly drive the scraper conveyor,established the electromechanical coupling model of permanent magnet direct drive system of scraper conveyor and researched the dynamic characteristics.The results could provide theoretical and technical foundation for improving transmission efficiency and reliability of scraper conveyer and development of permanent magnetic driving technology for mine equipment.The following parts had been done in this paper:First,through the analysis of the running resistance of the scraper conveyor with an annual transport capacity of 15,000,000 tons,the power and speed of permanent magnet synchronous motor and the capacity of inverter were calculated,and the strength of the scraper chain was checked.The permanent magnetic drive system of the scraper conveyor could realize the stepless speed regulating at rated speed,meanwhile the transmission system could be shorten,and the failure rate could be reduced,and the efficiency could be improved.Next,according to the working condition,i_d=0 vector control strategy of permanent magnet synchronous motor was chosen.Three kind of coordinate transformations,SVPWM modulation were researched and studied in detail,and the model of PMSM vector control system was built in the MATLAB/Simulink.Then,through dynamic analysis of scraper conveyor,the simulation model was established in the MATLAB/Simulink,and the electromechanical coupling model of permanent magnet direct drive system of scraper conveyor was obtained consequently.Based on the electromechanical coupling model,the dynamic change of the output speed,torque,and three-phase current of permanent magnet synchronous motor and chain speed,acceleration and displacement of scraper conveyor were simulated analysis under typical working condition such as no-load startup,full load,random load,polygon effect.The analysis showed that the PMSM driving system had larger shocks when it start,and the system could quickly response to each load excitation when it worked.The change regulation of chain speed,acceleration and displacement of scraper conveyor were basically consistent,which were a brief overdue process at the beginning,and then stable.All the waves were whitin the reasonable range.Lastly,the experiment platform of small power PMSM direct drive was established,and the simulation load characteristic curve was used as the mechanical load torque characteristic curve of the scraper conveyor loaded by the magnetic powder dynamometer.And the simulation driving test of the permanent magnet synchronous motor drive system of scraper conveyor was carried out.The results showed that the change trend of the characteristic curve of the permanent magnet synchronous motor obtained by the experiment was basically consistent with the characteristic curve of the permanent magnet synchronous motor obtained by the simulation.The rationality and correctness of the electromechanical coupling model of the permanent magnet direct drive system of the scraper conveyor was verified.