A Novel Modulation Strategy for HERIC Active Clamping Topology With Reduced Leakage Current and Reactive Power Capability to the Grid

One of the most promising renewable energy sources is photovoltaic (PV) solar power. Off-grid solar systems are far less common than grid-tied solar systems. Transformers are not used in transformerless grid-tied applications, which lowers the overall system cost and weight. When there is no galvanic separation between an AC grid and PV in a transformerless system, a leakage current with a high peak and root mean square (RMS) value flows throughout the system that disrupts safety matters. Furthermore, future grid-tied systems need to ensure reactive power injection to control voltage. In this paper, the authors have presented a new modulation method for HERIC active clamping topology to lower leakage current’s peak value and RMS value and introduce the reactive power injection capability to the grid. The open loop simulations and experiments have proven the leakage current suppression ability of the proposed modulation. The closed loop simulations and experiments have confirmed the reactive power injection capabilities of the grid by applying the proposed modulation with model predictive control (MPC). Finally, a comparison table related to similar topologies and modulations has been provided.