Loss-Constrained Optimized Pulse Patterns for Three-Level Converters with Robustness to Power Factor Variations

This paper presents the computation of three-level optimized pulse patterns (OPPs) that limit the converter losses and are robust to power factor variations. By constraining the switching and conduction losses in the optimization process the trade-off between converter losses and current harmonic distortions can be improved. Moreover, to increase the solution space of the loss-constrained OPP problem, and thus have more degrees of freedom when establishing the Pareto optimal solutions, the symmetry properties of conventional OPPs are relaxed. Additionally, by constraining the losses not only for a specific power factor but for a range of them, the variation of the losses is small when varying the power factor. As a result, the converter efficiency is improved over a wide range of operating points, as shown with the presented results.