Disturbance Observer Based Fuzzy Sliding Mode Control of PV Grid Connected Inverter

In this paper, a disturbance observer-based fuzzy sliding mode control (DOBFSMC) strategy is proposed for a single-phase PV grid-connected inverter. In the fact that the uncertainties caused by the inverter component parameter variations and the changes of climatic conditions may seriously affect the control performance of the inverter, a disturbance observer is designed to estimate these disturbances in real time and a sliding mode controller designed with the output information of the disturbance observer is employed to control the output voltage of the DC-AC inverter, and a fuzzy system is used to approximate the upper bound of the observation error between the actual disturbance and its observation value in order to improve the performance of the control system. The inverter has strong robustness since the disturbances can be adaptively compensated, and the chattering is greatly reduced since the switching gain can be very small as the upper bound of observation error is estimated by the fuzzy system. Finally, simulation results verify the effectiveness of the proposed method and demonstrate it can work reliably under different conditions.