abstract
- IEEEIn this paper, a solution to mitigate the leakage-ground currents in a grid-tied H-bridge neutral-point clamped inverter is presented. This solution consists in splitting the LC filter capacitor and connecting each capacitor to a DC-link terminal. The proposal is referred to as the DC-link-tied LC output filter. Out of this hardware modification, it is not necessary to increase the number of switches nor design a new modulation scheme. Furthermore, a formal analysis is provided based on the common-mode model describing the role of this particular connection of the output LC filter on the minimization of the leakage-ground current. In addition, a closed loop control strategy has been implemented to allow testing the prototype connected to the electrical grid. The mitigation of the leakage-ground currents has been evaluated under this condition as well. To validate the proposed circuit modification, numerical simulations and experimental tests have been performed in a 1 kW laboratory prototype of the H-bridge neutral-point clamped inverter with the DC-link-tied LC filter solution.