Hysteresis Current Controlled H5 Inverter with Dual Clamping Diodes for Leakage Current Mitigation in Grid-Connected Transformer-Less PV Systems

This paper presents a comprehensive review of transformer-less PV inverter topologies combined with an original MATLAB/Simulink implementation and validation of the HCH5-D2 topology. The simulation confirmed the theoretical analysis with the following key results: constant CMV at 200 V (VDC/2) across all operating modes, grid current THD of 7.5% (improved over the base paper's 9.13%), unity power factor operation, and leakage current suppression to below 2 mA compared to 285 mA in H4 topology — a reduction of over 99%. A significant contribution of this work is the identification and analysis of the false-tripping problem as a critical practical challenge for transformer-less PV systems in India. As shown constant CMV maintains AC excitation and capacitive leakage current path under control and limit as per safety standards by avoiding false trip issue.   As per Indian atmospheric conditions this is a important property as parasitic capacitance  can increases due to moisture and rain. Sometimes system following standard may also fail to meet them. In further work study will be continue with – (i) improved simulation and results with additional adaptive HCC to meet varying conditions, (ii) analysis of leakage current in false tripping point of view, (iii) improvement in THD and for meeting with the standards.

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