Six‐element circuit for maximum power point tracking in photovoltaic‐motor systems with variable‐frequency drives

A low-cost circuit was developed for stable and efficient maximum power point (MPP) tracking in autonomous photovoltaic-motor systems with variable-frequency drives (VFDs). The circuit is made of two resistors, two capacitors, and two Zener diodes. Its input is the photovoltaic (PV) array voltage and its output feeds the proportional-integral-derivative (PID) controller usually integrated into the drive. The steady-state frequency–voltage oscillations induced by the circuit were treated in a simplified mathematical model, which was validated by widely characterizing a PV-powered centrifugal pump. General procedures for circuit and controller tuning were recommended based on model equations. The tracking circuit presented here is widely applicable to PV-motor system with VFDs, offering an efficient open-access technology of unique simplicity. Copyright © 2010 John Wiley & Sons, Ltd.