An improved control method to reduce harmonic level for a single phase grid-connected flyback micro-inverter of a small scale solar PV

Abstract

One of an attractive solution for PV ac-module is flyback-type micro inverter since it has a number of advantages include simple control, stable current injection and potentially low-priced technique. But, it has high voltage ripple in the DC-link that may cause high harmonic distortion. Hence, a smooth DC voltage is required in order to maintain the total harmonic distortion within standard level. DC link voltage can be smoothened by using capacitor. However, the size of this capacitor is large and hence affects the weight and size of the inverter package. This paper proposes a control method to reduce harmonic level for flyback-type micro-inverter. MPPT (maximum power point tracker) technique used in this study is perturb & observe because it is the simplest online MPPT method with high efficiency. Several experiments are carried out to examine the effectiveness of the proposed method. The results show that the proposed method can reduce the harmonic level significantly and can be used as an alternative solution.