Switch power supply cooling fan | power thermal requirements and the thermal method
Switching power supply cooling fan.
When the switching power supply works, a large amount of heat will be generated. If these heat can not be discharged in time to cool down the temperature of the switching power supply, it will affect its normal work and even damage the switching power supply in severe cases.
In order to improve the reliability of switching power supply, heat dissipation design is an essential part.
If the temperature rising in the switching power supply is too high, the temperature sensitive semiconductor devices, electrolytic capacitors and other components will fail.
When the temperature exceeds a certain value, the failure rate increases exponentially.
Although there are many reasons for the failure of electronic equipment, high temperature is the most important factor (the other factors in order of importance are vibration, humidity, dust), and the influence of temperature on electronic equipment is up to 60%.
Statistical data show that the reliability of electronic components decreases by 10% when the temperature increases by 2℃;
The life at 50℃ is only 1/6 of that at 25℃.
Besides the electrical stress, temperature is the most important factor affecting the reliability of switching power supply.
Temperature is one of the most important factors affecting the reliability of high frequency switching power supply with high power heating devices.
The thermal design of switching power supply generally includes two aspects: one is how to control the heat of the heating source;
The other is how to send out the heat generated by the heating source, so that the temperature rise of the switching power supply is controlled within the allowed range, in order to ensure the reliability of the switching power supply.
In order to dissipate the heat of the heating device as soon as possible, the heat dissipation design of the switching power supply is generally considered from the following aspects: radiator, cooling fan, metal PCB, insulating thermal conductive sheet, etc.
In the actual design, it is necessary to apply the above methods to the design of power supply according to the requirements of customers and products themselves and the best cost-efficiency ratio.
In the actual design process of switching power supply, usually adopt natural air cooling and cooling fan forced air cooling two forms.
Natural air-cooled heat sink should be installed with the heat sink blade vertically upward. If possible, several vents can be drilled around the heat sink installation position on the PCB to facilitate air convection.
The cooling mode of the cooling fan of the switching power supply is forced air cooling, which uses the fan to force air convection. Therefore, the design of the air duct should also make the axial direction of the heat sink blade consistent with the direction of the exhaust of the fan. In order to have a good ventilation effect, the more heat dissipation devices should be closer to the cooling fan.
Due to the change of ambient temperature and load, the dissipative heat energy of the power supply can be dissipated faster by the combination of natural air cooling and forced air cooling of the cooling fan.
This method not only increases the heat dissipation of the fan, but also reduces the heat sink area, so that the power components can work in a relatively stable temperature field, and the service life will not be affected by the change of external conditions.
In this way, it not only overcomes the shortcomings of the cooling delay of the power elements in the pure fan cooling pair, but also avoids the low service life of the fan affecting the overall reliability of the rectifier.
Especially in the case that the ambient temperature of the machine room is very unstable, the combination of air cooling and self-cooling cooling technology has better cooling performance.
The material cost of this type of rectifier is between pure fan cooling and natural cooling, low weight and easy maintenance.
Especially when the intelligent air cooling and self-cooling technology is used, the module temperature rise is small and the module cooling fan is running at a low speed when the rectifier is working at a low load.
When the module temperature rises above 55 ° C, the fan speed increases linearly with the temperature.
Fan fault detection. After a fan fault occurs, the current output is limited and a fault alarm is generated.
Because the number of fan runs is related to the load size, the service life of the fan is longer than that of the pure air cooling, and its reliability is greatly improved.
Many industries use of switching power supply by using a cooling fan and natural cooling, the cooling system of the combination of both to the environment under the condition of high temperature, effectively reduce the internal working temperature of the rectifier, prolong the service life of device, and under the condition of low temperature and low load, the fan to reduce the speed of the rectifier, prolong the service life of fan.
Using radiator heat dissipation, the device spacing and creepage distance can be relatively far, in the case of high humidity, high safety performance.
The small size and light weight of the rectifier make maintenance easier.
In order to ensure the reliable and stable operation of the rectifier of switching power supply, reducing its working temperature rise is a key technology.
The combination of intelligent air cooling and self-cooling technology, with more adaptability to the environment, long service life, reliable stability and other technical advantages.
Sinda Thermal is a professional and experienced heat sink manufacturer, we own a team of thermal experts and many precise facilities and equipment, we are providing the heat sinks to the global customers. Please contact us freely if you have any thermal requirements.
