Boost-buck inverter variable structure control for grid-connected photovoltaic systems with sensorless MPPT

The present work describes the analysis, modeling and control of a transformerless boost-buck power inverter used as a DC-AC power conditioning stage for grid-connected photovoltaic (PV) systems. The power conditioning system's control scheme includes a variable structure controller to assure output unity power factor and a sensorless maximum power point tracking (MPPT) algorithm to optimize the PV energy extraction. To maximize the steady-state input-output energy transfer ratio a discrete linear controller is designed from a large-signal sampled data model of the system. The achievement of the DC-AC conversion at unity power factor and the efficient PVs energy extraction are validated with simulation results.