Fast-scale and slow-scale instabilities of photovoltaic inverter

This paper investigates the dynamical behavior of a full bridge DC-AC inverter controlled by fixed frequency pulse-width modulation which is widely used in photovoltaic (PV) generation system. The main results are illustrated with the aid of numerical simulations obtained from an accurate non-linear time varying model of the system derived without making any quasi-static approximation. Based on bifurcation diagram, discrete-time waveforms, sampled waveforms and the phase portrait, it is seen that the system occurs fast-scale and slow-scale instabilities with the change of the controller parameters and PV input voltage.