A high-reliability PV system by replacing electrolytic capacitors with film capacitors

Electrolytic capacitors are considered a vulnerable link in PV systems. In order to enhance the system reliability and lifespan, this paper investigates a PV system without electrolytic capacitors. First, the system structure is introduced. Then, the system control architecture based on the system structure of a bidirectional-DC/DC connecting to the dc-bus is proposed. Five control loops are illustrated for current ripple absorbing. Furthermore, an alternative control solution is proposed to eliminate four current sensors for reducing system costs. Meanwhile, a DC-bus voltage over-limit control block is added. Additionally, another alternative solution is proposed where a blocking unit is added. The blocking unit is activated only when the dc-bus voltage is over the limits to increase system efficiency. Finally, experimental results are provided to verify the theory.