Electromagnetic interference‐based comparative study between transformerless H5 and optimised H5 grid‐connected photovoltaic inverters

Abstract

In this study, a comparative study between two single-phase transformerless gridconnected photovoltaic (PV) inverters, namely H5 and optimised H5 (oH5), is carried out based on conducted electromagnetic interference (EMI) performance. For this purpose, a high-frequency (HF) model of the grid-connected inverters is proposed and simulated using Simulation Program with Integrated Circuit Emphasis (SPICE)-based circuit simulation software. Moreover, an experimental setup is developed to measure the conducted emissions. The obtained results show an EMI advantage of the oH5 inverter at low frequencies but not at HF frequencies. Therefore, a mitigation method is proposed to optimise the oH5 topology in the HF range. It consists in using only one Resistor-Capacitor (RC) snubber circuit connected in parallel with the inverter's extra switch. The obtained results show that the oH5 inverter with only one RC snubber circuit provides lower conducted EMI than the H5 in a wider frequency range without worsening the efficiency. The proposed EMI mitigation method can therefore be considered as an adequate and preferred solution for the transformerless grid-connected oH5 PV inverter.