Muhammed Ramees, M.M.K.P.Ahmad, M.W.2026-02-032025IEEE Transactions on Industrial Electronics, 2025, 72, 8, pp. 8633-86452780046https://doi.org/10.1109/TIE.2025.3528481https://idr.nitk.ac.in/handle/123456789/20490Transformerless inverters are widely used to integrate the photovoltaic (PV) source into the distributed generation system. Within the converter, an open-circuit (OC) switch fault may lead to the partial or total failure of the converter. To address this issue, a new technique for detecting and localizing OC switch faults based on pole-to-pole voltage (voltage measured across the inverter output terminals) is proposed. The proposed variables for fault detection and localization (FDL) are continuously generated with every sampled pole-to-pole voltage and are compared with threshold values which are immune to parameter variation. As a result, OC is detected and located within a switching cycle for the ac side bypass switches. For localizing the OC fault in the H-bridge, the converter is reconfigured once the fault in the H-bridge switch is detected using pole-topole voltage. The input voltage required for the maximum power point tracking (MPPT) is estimated from the voltage measured with the new sensor arrangement for pole-to-pole voltage measurement. This makes the number of sensors the same as in a conventional converter. The viability and effectiveness of this approach are demonstrated through simulation studies on the highly efficient and reliable inverter concept (HERIC) inverter, a popular transformerless inverter topology. Additionally, a laboratory prototype is developed to validate the practical applicability of the method. © 1982-2012 IEEE.Bridge circuitsDirected graphsDistributed power generationElectronic circuit trackingFault detectionStructural health monitoringCircuit switchFault detection and localizationH-bridgesMaximum Power Point TrackingOpen-circuit faultOpen-circuitsPole voltagesSwitch faultsTransformerless inverters