Mitigation of Low Order Current Harmonics Arising from Dead Time in HERIC Inverters

Proportional-resonant and repetitive controllers are widely used for grid current control in single-phase grid-connected inverters. This paper presents a comparative study of the performance of these two controller types in mitigating low-order harmonics with a descriptive analysis of their design. Moreover, low-order harmonics arising from the dead time in single-phase highly efficient and reliable inverter concept (HERIC) are investigated. Then, a novel scheme based on the harmonic decoupling network and second-order generalized integrator is designed to extract the low-order harmonics from the grid current. These extracted components are subtracted from the reference current to efficiently attenuate the low-order components. Experimental studies show an efficient mitigation of the low-order harmonics with the proposed scheme.