Design, modeling and software implementation of a current-perturbed maximum power point tracking control in a DC-DC boost converter for grid-connected solar photovoltaic applications

In this paper, a control scheme for tracking maximum power point for a solar photovoltaic (PV) panel feeding power to the three phase grid through an intermediate boost converter followed by a grid-tie PWM inverter stage is presented. The intermediate DC to DC boost converter small signal model is derived considering the fact that its output behaves as a constant DC voltage power sink. The selection criteria for the inductor value for continuous current mode operation and the capacitor at the PV panel output are discussed at length. A separate controller, in addition to the maximum power point tracking (MPPT) controller, is designed for the boost converter based on its derived model to set the current value for maximum power point tracking and presented. A method is also described here for choosing the sampling instances for getting average inductor current in a cycle corresponding for MPPT without using a filter. The analytical findings and simulation results are well agreeing.