Boost converter with combined control loop for a stand-alone photovoltaic battery charge system

The converter control scheme plays an important role in the performance of maximum power point tracking (MPPT) algorithms. In this paper, an input voltage control with double loop for a stand-alone photovoltaic system is designed and tested. The inner current control loop with high crossover frequency avoids perturbations in the load being propagated to the photovoltaic panel and thus deviating the operating point. Linearization of the photovoltaic panel and converter state-space modeling is performed. In order to achieve stable operation under all operating conditions, the photovoltaic panel is linearized at the maximum power point (MPP) and at the voltage and current source regions. A settling time under 1 ms is obtained which allows fast MPP tracking implementation.