Abstract: In order to solve the chattering problem of sliding mode control, a three-phase voltage inverter based on
improved sliding mode variable structure is designed for photovoltaic grid-connected control system. The existence
of the switching function is deduced by using the sliding mode switching function, the obtained sliding mode
switching function is “expanded冶, and the incremental distance is obtained through adaptive control to stabilize the
output voltage, the total harmonic distortion is reduced, and the sliding mode control of the chattering problem is
solved. The theory analyzes the transient performance of sliding mode variable structure control strategy
contrastively in the Matlab platform. The result indicates that the output voltage improved is more stable, the total
harmonic distortion is reduced to below 0.62% and the problem of chattering in sliding mode control is solved.

Key words: photovoltaic grid-connected, sliding mode control, chattering problem, total harmonic distortion