A digital predictive controller for a SEPIC-based battery charger in photovoltaic power systems

This paper presents the optimal controller design for an improved battery charger structure which can be supplied from a photovoltaic power system. The transfer characteristic of the presented converter is the same as a buck/boost converter. Therefore, even in extreme conditions, the presented converter has the ability to extract the maximum power from the photovoltaic power system and charge the battery efficiently. Other advantages of the presented converter such as continuous smooth input current also make it suitable for photovoltaic generation systems. The presented converter consists of two charging modes which develop the efficiency of charging; pulsating output current and constant voltage. A predictive controller is designed for the presented converter which assures the optimal operation of the system. The controller chooses the best operating conditions for the photovoltaic power system. Simulation results are provided to validate the proper operation of the controller.