Implementation and control of distributed maximum power point tracking in solar photovoltaic applications

Maximum power point tracking (MPPT) is an important feature in solar photovoltaic (PV) systems as it increases the energy yield from such systems by optimizing their operating point. Current state-of-the-art solutions perform MPPT for a whole system, a string of panels or an individual panel within a PV system. This results in a loss of energy when the optimal operating point varies among different units. In this thesis, the implementation of MPPT on the sub-panel level is presented. This enables increased energy output under mismatched conditions (e.g. due to partial shading) across the system. Three centrally controlled dc-dc buck converters with series connected outputs are implemented and tested. As the maximum power point (MPP) of panel sections may vary, the proposed multiphase converters operate under asymmetric conditions. Therefore, a control technique to minimize the output current ripple under these conditions is mathematically derived and verified through simulations and experimental measurements