Sliding mode control for improving the performance of PV inverter with MPPT — A comparison between SM and PI control

In this paper, we propose the use of sliding mode (SM) control to improve the maximum power point tracking (MPPT) performance of a two-stage single-phase inverter (comprising a first-stage DC/DC boost converter and a second-stage full-bridge inverter) in photovoltaic (PV) systems. To underscore the benefits of SM control, the MPPT performance of the PV system under the SM control is compared to that of an optimally-tuned proportional-integral (PI) control under the same PV system setup. To ease the comparison, a methodology of quantifying the measurements, which provides a clear graphical indication of the quality of the tracking, is proposed as a general platform to examine the performance. Experimental results show that the SM control can guarantee a better tracking accuracy over a larger operating range than the PI control when the weather conditions are changed dynamically throughout the course of a day. Additional comparisons based on the proposed methodology further supports that the SM control can improve the MPPT accuracy of the PV system, thus increasing the overall amount of energy harvested.