Aliasing Suppression based on Sliding Goertzel DFT of Multisampling for Grid-tied Inverter with LCL Filter

In high-power LCL grid-tied inverter, low switching frequency under limitation of switching loss would cause low bandwidth, and multisampling is one of effective solutions. However, the aliasing introduced by multisampling would weaken the advantages of multisampling in reducing delay under the aliasing suppression of conventional digital filters. This paper proposes an antialiasing filtering method without any delay. This method uses sliding Goertzel DFT to detect all switching sideband harmonics at the known frequency to offset current ripple in the multi-sampled signal in real time, so as to achieve the purpose of eliminating multi sampling aliasing. Since this method directly subtracts the switching current ripple from the multi sampled signal, it would not bring any delay. Finally, the simulation verifies the effectiveness of the proposed antialiasing scheme and improving the dynamic response ability under multisampling.