Implementation of an EMI active filter in grid-tied PV micro-inverter controller and stability verification

This paper presents a novel technique to suppress Common-mode EMI using digital active EMI filter (DAEF). The DAEF control technique is concurrently implemented with a digital controller of a grid-tied photovoltaic (PV) micro-inverter. A brief description of the micro-inverter architecture and its inverter circuit is illustrated. The inverter stability is investigated using the overall transfer function. The experimental results validate the feasibility of the proposed technique. Compared with the conventional passive EMI filter, the proposed embedded DAEF can significantly reduce the size, cost and space of the overall power inverter PCB without while improving the overall efficiency of the micro-inverter.