Effect of Cooling Methods on the Operating Temperature of Switching Power Supplies
The heat dissipation of switch mode power supplies generally adopts two methods: direct conduction and convective conduction. Direct heat conduction is the transfer of thermal energy along an object from the high temperature end to the low temperature end, and its heat conduction ability is stable. Convective conduction is the process in which a liquid or gas undergoes rotational motion to make its temperature more uniform. Due to the involvement of dynamic processes in convective conduction, the cooling process is relatively rapid.
Installing the heating element on a metal heat sink, by squeezing the hot surface, can achieve energy transfer of varying heights of energy bodies. The energy that can be radiated out by a large area of heat sink is not much. The heat conduction method of switch mode power supply is called natural cooling, which has a longer delay time for heat dissipation. The heat transfer capacity Q=KA △ t (K heat transfer coefficient, A heat transfer area, △ t temperature difference). If the indoor ambient temperature is high, the of △ t will be small, and the heat dissipation performance of this heat transfer method will greatly decrease.
Adding a fan to the switching power supply can quickly dissipate the accumulated heat from energy conversion outside the power supply. The continuous air supply from the fan to the heat sink can be regarded as convective energy transfer. It is called fan cooling, which has a short and long delay time for heat dissipation. The heat dissipation Q=Km △ t (K heat transfer coefficient, m heat exchange air quality, △ t temperature difference). Once the fan slows down or stops running, the m value will rapidly decrease, and the accumulated heat in the power supply will be difficult to dissipate. This will greatly increase the aging rate of electronic components such as capacitors and transformers in the switching power supply and affect the stability of their output quality, ultimately leading to component burnout and equipment failure.
