Mitigation of zero-crossing transients in H5 transformerless photovoltaic inverters using RC snubber integration

Transformerless photovoltaic (PV) inverters are widely used in residential and commercial applications due to their reduced size, weight, and cost. However, the absence of galvanic isolation introduces leakage current through the parasitic PV-to-ground capacitance (Cp). The H5 topology mitigates this issue by maintaining the common-mode voltage (CMV) at half of the direct current (DC)-link voltage. Nevertheless, transient leakage current spikes still occur at zero-crossing instants due to high dv/dt switching events that excite device and parasitic capacitances. This paper proposes a snubber-integrated H5 inverter in which resistor–capacitor (RC) snubber circuits are incorporated as a hardware-based solution to suppress zero-crossing transients without modifying the original topology or modulation scheme. Experimental results show that both the conventional and modified inverters preserve a three-level output waveform and stable CMV characteristics. However, the inclusion of RC snubbers significantly reduces the root-mean-square (RMS) leakage current from 2.2 mA to 0.91 mA. These results demonstrate that RC snubber integration provides a simple and effective approach for mitigating zero-crossing leakage current while maintaining the inherent advantages of the H5 inverter.