On Bounding the Junction Temperature by Means of Optimal Modulation with Relaxed Properties

Abstract

This paper presents the computation of three-level optimized pulse patterns (OPPs) that can keep the junction temperature bounded. Adding a thermal constraint, however, compromises the output current quality. To tackle this issue, OPPs with relaxed symmetry properties and multipolar switch positions are allowed. As a result, the harmonics remain low and close to those of conventional OPPs, as demonstrated by the presented results. Nevertheless, by relaxing the OPP properties, the computation time increases drastically. To exploit the benefits of the proposed OPPs, an efficient computation method is developed to keep the computation time modest. This is done by employing the concept of virtual switching angles that encapsulate the OPP switching transitions and the switching angles.