A sliding mode control method based on improved reaching law for superbuck converter in photovoltaic system

Abstract

Due to the influence of input voltage fluctuation, output load mutation, inductance and capacitance parameter perturbations, the DC bus voltage of photovoltaic power generation system will fluctuate accordingly. In order to maintain the stability of the bus voltage, a PID-type sliding mode control based on the improved reaching law is proposed. Using the saturation function sat(s), an improved fast reaching law is constructed to weaken the inherent chattering effect of sliding mode control, the finite time reachability property of the reaching law is verified, and the disturbance stability bound of closed-loop sliding mode control system in the presence of bounded disturbance is derived. Compared with PID control method and sliding mode control method based on power reaching law and exponential reaching law, the results show that the proposed control method weakens the influence of chattering, improves the dynamic response speed of the system by about 23% in the start-up stage. At the same time, the proposed control method has good dynamic performance and global robustness when subjected to external disturbances.