Sairaj Dhople with adviser P. L. Chapman
Maximum power point tracking (MPPT) algorithms control power-electronic circuits employed in photovoltaic (PV) energy systems to maximize the energy harvested over different ambient conditions. Irrespective of the algorithm utilized, there are likely to be operating conditions under which MPPT can not be realized. This phenomenon is termed tracking ineffectiveness.
Tracking ineffectiveness is explored in the context of a boost converter and a generalized constant voltage (VCOM), current or resistive load, as illustrated in Figure 21. Simulation results demonstrate the infeasibility of MPPT when loads violate limits that are derived based on the operational constraints of the boost converter. For instance, consider Figure 22 that depicts the minimum and maximum allowed output voltages (VCOM-MIN and VCOM-MAX, respectively) over a wide spectrum of ambient conditions for a representative boost converter such that MPPT is always feasible and the converter operates in continuous current conduction mode (CCM). The maximum allowed output voltage is based on the desire of operating in CCM; increasing the switching frequency, f, is noted to relax this bound. This analysis provides a systematic tool to improve the performance of MPPT applied to a wide range of PV applications.
This research is supported by the Grainger Center for Electric Machinery and Electromechanics.