DSP-based controller application in battery storage of photovoltaic system

Abstract

Photovoltaic power systems normally use maximum power point tracking (MPPT) to continuously deliver the highest possible power to the load when changes in insolation and temperature occur. This overcomes the problem of mismatch between the solar cells and the given load. The solar array is normally treated as a voltage source, but it is treated as a current source in this paper. A simple method of tracking the maximum power point (MPP) and forcing the PV power system to operate near this point is also presented. The effect of the negative impedance of power converters on the MPPT process is also considered. As to the system equivalent circuit model, the principle of energy conservation is used to develop large- and small-signal models and the transfer function. By using this model, the drawbacks of the state-space-averaging method can be overcome. A TI320C25 digital signal processor (DSP) was used to implement the proposed MPPT controller; simulations and experimental results show its excellent performance.