Influence of cooling method on the operating temperature of switching power supply
The heat dissipation of switching power supply generally adopts direct conduction and convective conduction in two ways, direct heat conduction is the transfer of heat energy along the object from the end of the high temperature to the end of the low temperature, and its heat conduction ability is stable. Convective conduction is a liquid or gas through the rotary movement, so that the temperature tends to be uniform process. Because convection conduction involves a kinetic process, cooling is more smooth and rapid.
Mounting the hair element on a metal heat sink enables the transfer of energy by squeezing the hot surface to achieve a high and low energy body, and not much energy can be radiated out by relying on the large area of the heat sink. This type of heat transfer in switching power supplies is called natural cooling, which has a long delay time for heat dissipation. Heat transfer Q = KA △ t (K heat transfer coefficient, A heat transfer area, △ t temperature difference), if the indoor ambient temperature is high, △ t of the small, then this heat transfer method of heat dissipation performance will be greatly reduced.
In the switching power supply to increase the fan will energy conversion in the accumulation of heat quickly discharged outside the power supply. The continuous air supply from the fan to the heat sink can then be regarded as convective transfer of energy. Known as fan cooling, this type of heat dissipation has a short and long delay time. Heat dissipation Q = Km △ t (K heat transfer coefficient, m heat transfer air mass, △ t temperature difference), once the fan speed reduction, stopping, m value will be rapidly reduced, power supply in the accumulation of heat will be very difficult to dissipate, which will greatly increase the switching power supply capacitance, transformer, and other electronic components within the aging speed and affect the stability of the quality of the output, and ultimately lead to components burned out, equipment failure.
