Analysis and non-linear control of SEPIC dc-dc converter in photovoltaic systems

SEPIC dc-dc converter has multiple applications as a power conditioning system because it has a non-pulsating input current and its voltage ratio is both step-down and step-up. However, due to the non-linear characteristics of a SEPIC converter, a non-linear control is more suitable to attain better performance in voltage regulation. We designed a Sliding-Mode control and a passivity-based control for controlling both the output voltage of the SEPIC converter and the input voltage to reach the maximum power of a photovoltaic module. This paper presents the stability analysis and the design of the two non-linear controllers. The simulation results show a good performance of both controllers with fast transient responses and zero steady errors. However, the Sliding-Mode control shows less inductor current than the Passivity-Based control. These results confirm the good performance of non-linear control for a SEPIC converter in photovoltaic systems; we expect experimental validations in future work.