Composite Sliding Mode Control of a Permanent Magnet Direct-Driven System For a Mining Scraper Conveyor

A composite sliding mode control based on the load characteristic of the permanent magnet direct-driven system is presented for a mining scraper conveyor. First, the mathematical model of a permanent magnet synchronous motor is established based on the coordinate transformation theory. Subsequently, the soft switching sliding mode observer (SS-SMO) is designed to observe the change of load torque in real time. The composite sliding mode speed controller of PMSM is designed on the basis of non-singular terminal sliding mode control, in which the observed load torque is used for feed-forward compensation. The chain characteristics of a scraper conveyor are described by the Kelvin-Vogit model, and the dynamic model of the overall scraper conveyor system is established with the distinct element method. Next, according to the coupling relationship between the permanent magnet direct-driven system and the scraper conveyor, the electromechanical coupling simulation model is established using the MATLAB/Simulink module. The simulation results demonstrate that the composite sliding mode controller of the permanent magnet direct-driven system can achieve smooth starting of the scraper conveyor, and the effectiveness of the designed controller is illustrated by comparing the controller with the related reference. In addition, the designed SS-SMO can estimate the load torque precisely, enhance system robustness and suppress the chattering of the control system caused by the load change.