AC/DC power supply thermal management patent enables efficient design-in

TDK Corporation has announced that TDK-Lambda UK’s Power Supply Apparatus patent application has been approved for a grant by the UK Intellectual Property Office. The new thermal strategy covered by the patent enables power supplies that are flexible in their cooling needs, keep audible noise to a minimum, and are straightforward for customers to integrate into their systems.

“Thermal management is one of the main technical challenges to overcome in the design of any system,” explains Martin Coates, engineering director, TDK-Lambda UK. “Very often, there are hot spots within systems that require a disproportionately high airflow over them to keep component temperatures within acceptable limits. This, in turn, often leads to excessive audible noise from fan cooling and/or limitations in the system’s thermal performance.”

There are two specified techniques for overcoming the thermal management challenge. One method is to increase unit dimensions to provide for better airflow. Driving up efficiency is another technique, thereby minimising internal heat dissipation. Increasing unit size is often inappropriate, as units are seen as uncompetitive and overly large, making them difficult to incorporate into systems. Also, as power supply efficiencies increase, the law of diminishing returns applies, and incremental improvements become excessively expensive. Above all, these techniques come with an increased BOM cost.

The new thermal management strategy employed in manufacturing the CUS400M series of AC/DC power supplies, covered by the patent, overcomes these issues by using existing system metalwork for cooling. Through careful PCB design and thermally conductive plastics, the heat generated by the electronic components is spread and transferred into the system chassis. This signifies that a slower fan can deliver good thermal performance with substantially lower airflow, producing reduced audible noise.

Many medical and industrial applications need a peak output power for a few minutes but relatively low continuous quiescent output power. “The design methodology also means that the unit is more resilient to peak loading since the thermal time constant is substantially longer than traditional designs,” adds Coates. “This means that the internal component temperatures do not rise as rapidly for peak loading, decreasing the stress on the components and increasing the power supply lifetime. This enables us to offer the CUS400M series with a five-year warranty. In addition, the CUS400M can replace larger, more expensive convection cooled products that are rated continuously for the peak requirement, translating into a cost saving for the customer.”