Sampling Time Modulation of a Photovoltaic Power Tracking Controller Based Upon Real-Time Monitoring of Converter Dynamics

The maximum power point tracking (MPPT) or flexible power point tracking (FPPT) of a photovoltaic (PV) array is typically performed by using a discrete-time control system. The sampling time of an MPPT/FPPT controller plays a crucial role in determining its transient performance. Performing the MPPT or FPPT control at a fixed sampling rate makes it necessary to set the respective sampling time to a large value so as to effectively deal with the worst case of converter transient. This, in turn, makes the power tracking continue for an unnecessarily longer time duration. The main objective of this article is to improve the speed of power tracking through a dynamic adjustment of the power tracker's sampling time. Although the same idea was already deployed in the literature, existing methodologies are essentially based upon tedious offline assessments of converter dynamics using the PV module information. In contrast, the proposed dynamic moment-based adaptive rate sampling (D-MARS) scheme modulates the sampling time of the power tracking controller by monitoring the actual state of converter dynamics through a moving variance calculation in real time. Detailed experimental studies are performed to verify the benefit of the proposed D-MARS scheme over the other sampling time modulation (STM) techniques.