Design techniques for thermal management in switch mode converters

Thermal management plays a pivotal role in achieving high power densities in converters. Improvement on thermal performance of critical components in printed-circuit board (PCB) assembled switch mode converters is achieved by using design techniques that extend across electromagnetic, geometrical, and thermal-integration technologies. For better use of the already available PCB material, three-dimensional component layout and flexible PCB technology are utilized to gain advantages. A theory to evaluate the thermal-management effectiveness of switch mode converters is introduced based on two new figures of merit, namely thermal-management loss density and thermal-design rating. These two figures of merit quantify the effective use of thermal-management material as well as the thermal performance of a converter design. The figure-of-merit criteria allow flexibility so that it can be adjusted to an appropriate design objective. Design objectives include achieving higher power densities or achieving good reliability. The thermal-management-effectiveness theory is applied here to thermally optimize a Flyback converter that has been geometrically integrated. The design technique to adjust the thermal-management effectiveness of integrated switch mode converters to achieve a set objective, by means of the introduced figures of merit, forms the core of the publication, validated by experimental measurements.