Current converter with two-loop maximum power tracking control for solar arrays

Conventional maximum power point tracking (MPPT) controllers only use one loop tracking. The fast changes of atmospheric conditions result in power loss in the tracking process. In this paper, two-loop MPPT of solar array using a current converter is presented. The solar array is treated as a current source tnodel instead of the traditional voltage source. A current converter operating in MPPT mode under different insolations and temperatures is designed for a solar power system. The principle of energy conservation is used to develop the small-signal model and transfer function for the solar power system. Using principle of energy conservation, the drawback of state-space-averaging method can be overcome. A digital PI compensator is used to implement the proposed MPPT control in real-time, and the effect of the floating operation by the fixed-point processor is also considered. Simulations and experimental results are presented to demonstrate better performance for the proposed system.