Power Density Optimization of 48V/12V DC-DC Converters Considering Several Topologies and Semiconductor Technologies

The aim to reduce the weight and volume of equipment is driving the evolution of embedded power electronic architectures. This trend has given rise to the adoption of a 48V on-board network. Advanced topologies such as switched capacitor DC-DC converters, combined with the integration of Wide Bandgap (WBG) semiconductors, represent a promising direction for the development of 48V systems. This paper presents a comparison methodology, based on a power density optimization of 48V-to-12V, 1KW output power converter. This method employs volume optimization as a critical metric for comparison. 4-Level Flying Capacitors Multilevel (FCML) and 3:1 Hybrid Dickson topologies are compared to a conventional 2-Level Buck converter across three semiconductor technologies: Lateral and Vertical Silicon MOSFET, and High Electron Mobility Transistor (HEMT) Gallium Nitride (GaN). Considering models of power semiconductor losses, volume of passive components and heat sinks, this approach facilitates a balanced comparison to identify the most compact topology/technology combination. First results give as an optimal solution a 3:1 Hybrid Dickson topology using HEMT GaN technology, which achieves superior efficiency and a higher power density.