In this article, we look at various types of cooling methods used in a power supply.
Conduction Cooling
: This is defined as the transfer of heat from one hot part to another cooler part by direct contact. For example, many DC-DC converters have a flat surface that is designed to mount directly to an external heat sink or cold plate that will conduct the heat away from the power device by direct contact, thereby cooling it.
Conduction is the most widely used method of heat transfer. All power supplies use internal heat-sinks to help conduct the heat away from the hot devices. Unfortunately using heat-sink adds on weight and size to a power supply.
Convection Cooling
: This involves the transfer of heat from a power device by the action of the natural air flow surrounding and contacting the device. Many power devices are rated for natural convection cooling as long as the air surrounding the unit remains within a limited temperature range that is cooler than the device. The advantage of this method of cooling is that no electromechanical fans are required. Another type of convection cooling requires forced-air-flow via fans or blowers across the power device. Many power supplies come with a build-in fan to provide this forced air type of convection cooling.
Other types of power supplies specify the amount of air flow that must pass through or around the device (in cubic-feet-per-minute) in order for the supply to provide its maximum rated output power.
Fans can also be mounted on the front of the power supply or at the rear. For front mounted fan, air is blowing from front to rear. For rear mounted, the hot air is being sucked from the fan instead. Some power devices with heat sinks depend on convection cooling (with or without forced air) to assist in transferring the heat away from the power devices to the cooler air.
PULS standard din rail power supplies are convection cooled.