State feedback control for DC-photovoltaic systems

This paper proposes an alternative state feedback-based control strategy to a DC-DC converter applied to regulation purposes in photovoltaic (PV) systems. The PV generation voltage output level is determined through a maximum power point tracking (MPPT) algorithm. Moreover, the proposed control technique also provides a suitable duty-cycle for the switching of the DC-DC converter to improve its dynamics with regards the reference voltage generation, provided by the MPPT algorithm. The control technique relies on a state-space equations description of the PV generator connected to the converter. The controller gains are designed by building a proper characteristic polynomial which takes into account the conditions for system controllability using Ackermann formulation. Moreover in order to experimentally verify the converter system control dynamics, a switched load has been applied and controlled to set constant the converter output voltage. This control for this load secure it a mean value of resistance through a PWM period during the experiment. The proposed method is tested by means of computational simulations in Matlab/Simulink environment. In addition, an experimental apparatus has been mounted to emulate the simulated results and to corroborate the technique efficacy.