Comparison and analysis of a novel passive damping for LCL filtered voltage source inverters

Compared with the traditional L and LC filter, a LCL-filter can achieve higher attenuation ability with even lower L and C values. LCL filter is more suitable for the three-phase grid-connected voltage source inverters (VSIs) in high power occasion, with its lower cost and better high-order harmonic attenuation. However, the LCL filter is a three order system, which is easy to produce resonance challenging the stability and power quality of VSIs. In order to suppress the resonance, many passive damping methods are proven as a robust stabilizing technique for LCL-filtered voltage source inverters. This paper proposes a novel passive damping LCL filters with a coupled inductor which can obtain the similar filtering performance with reduced power loss and greater harmonic attenuation. In this paper, comparison and analysis of the proposed and the conventional passive damping design are illustrated. The passive method is verified through simulation studies carried out on a three-phase grid-connected voltage source inverter. For verification, experimental testing has been performed with the results obtained matching the theoretical expectations closely.