A Passive Damping Design Method of Three-phase Asymmetric-LCL Power filter for Grid-Tied Voltage Source Inverter

In order to suppress the harmonics at both the switching and double switching frequencies in the grid current, many power supply filters (such as LCL-T filter, LCL-2T filter and Asymmetric-LCL (A-LCL)) were proposed for grid-tied voltage source inverter. Compared with these high order power filters, A-LCL power filter has the smallest total inductance, when the parameter shifts are fully addressed. However, due to the inherent resonance of A-LCL filter, it is necessary to add damping strategy. Passive damping method is attractive but how to place the damping resistance and set the value is a problem. This paper introduces a passive damping design scheme for A-LCL filter. The passive method is verified through simulations on a 380V/6kW/50Hz three-phase A-LCL grid-connected voltage source inverter.