High power density battery chargers with fast-charging utilizing heat storage

While wide bandgap semiconductor technology, such as gallium nitride, has considerably enhanced power density in mobile battery charger applications, the development of smaller, cost- and resource-effective systems is hindered by thermal constraints arising from miniaturized components and compact housings. This work proposes a transient thermal management system that dynamically adjusts converter output power according to thermal boundaries, utilizing latent and sensible heat storage to enable an initial boosted performance. An analytical and numerical sensitivity analysis of power density limits was conducted to evaluate the impact of thermal and electrical boundary conditions. A 40 W hardware prototype of a quasi-resonant flyback converter with transient thermal management was realized using epoxy resin and phase change material filling. The findings show a 40% higher effective power density when charging a conventional 50 Wh laptop battery, all within the same thermal boundaries as common operation at constant output power, with a power density measurement accuracy of 5.2%. The system was implemented using PI controller for inner component and surface temperature control. This novel approach to fast-charging highlights the optimization potential of current systems through converter heat storage utilization and provides valuable insights, including analytical and numerical models, for developing chargers capable of overcoming thermal barriers.