F. . Bouchafaa, A. . Chouder, and S. . Boukhalfa, “Stability of input voltages of a three-level inverter NPC fed by photovoltaic sources”, J. Ren. Energies, vol. 15, no. 3, pp. 501–512, Sep. 2012, doi: 10.54966/jreen.v15i3.339.