Modulation for Cascaded Multilevel Converters in PV Applications With High Input Power Imbalance

Cascaded multilevel inverters, such as the cascaded H-bridge (CHB) converter, are an attractive solution for multistring photovoltaic (PV) systems, because they enable direct connection to medium voltage grid and maximum power point tracking (MPPT) of multiple strings. As a challenge topology, operation with high imbalance in strings is constrained by overmodulation. This limitation analyzed sinusoidal modulation impact on demonstrated. For increasing operating range strings, discontinuous extended reduced losses proposed. The method terms imbalance, efficiency quality. In addition, validated experimental test bench.