A maximum power point tracking technique for single-phase PV systems with reduced DC-link capacitor

Electrolytic capacitors used in photovoltaic (PV) power conditioning units (PCU) for power decoupling purposes are unreliable. Film capacitors can be adopted instead of electrolytic capacitors if the energy storage requirement of the PCU is reduced, since they offer better reliability and have a longer lifetime. The energy storing capacitor size reduction can be facilitated by allowing DC-link voltage to have a specified amount of ripple. However, a high DC-link voltage ripple imposes a double-line frequency ripple in the PV voltage and current. This leads to oscillations in the extracted panel power and thereby results in power loss. In view of this, this paper develops a locus line based maximum power point tracking (MPPT) control algorithm to mitigate this power loss. The proposed digital control algorithm was simulated in MATLAB Simulink and also implemented in a laboratory prototype using TMS320F28035 processor.