DPWM Strategy for CHB Multilevel Converters in EV Charging Stations Considering Reliability of Power Semiconductors and Capacitors

The Cascaded H-Bridge (CHB) converter offers advantages in reliability, power quality, and efficiency over non-modular topologies. However, variations in electrical and thermal parameters within individual cells can lead to uneven lifetimes, causing disproportionate degradation of capacitors and power semiconductors. This necessitates individual lifetime management to enhance system reliability and lower maintenance costs. Active thermal management has been explored to reduce thermal stresses and improve power semiconductor reliability, yet the reliability of DC-link capacitors is often overlooked. This paper examines the impact of different modulation schemes on the reliability of DC-link capacitors and power semiconductors in CHB converters. It then proposes an optimal modulation strategy for managing component reliability and validates it through experiments.