New MPPT algorithm for photovoltaic systems connected to NPC converters and optimized for large variations of solar radiation

This paper proposes a new MPPT algorithm (`maximum power point tracker') for photovoltaic panels (`PV') with NPC converters (`neutral point clamped'). One of the characteristic of this proposal is that it is not necessary to modify the voltage references in order to know the state of the MPP (`maximum power point'). The fundamentals are based on the use of the existing ripple in the NP (`neutral point') in the NPC converters. Given that the form of the ripple is known, it is possible to determine the power that is supplied by each maximum and minimum of the voltage ripple. The execution period of the algorithm does not depend on the time constant of the DC-bus, rather the frequency of the voltage ripple, which in the NPC converter is three-time the frequency of the grid.