Switching power supply cooling fan | Brief description of power supply cooling requirements and cooling methods
Switching power supply cooling fan. The switching power supply will produce a lot of heat when it is working. If the heat cannot be discharged in time and the temperature rise of the switching power supply can be reduced, it will affect its normal operation, and even damage the switching power supply in severe cases. In order to improve the reliability of the switching power supply, heat dissipation design is an essential and important link. Excessive temperature rise inside the switching power supply will cause the failure of temperature-sensitive semiconductor devices, electrolytic capacitors and other components. 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 (other factors are vibration, humidity, and dust in order of importance), and the influence of temperature on electronic equipment is as high as %. Statistics show that the reliability of electronic components will decrease by% every time the temperature of electronic components rises by ℃; when the temperature rises ℃, the life span is only that of the temperature rise ℃. In addition to electrical stress, temperature is the most important factor affecting the reliability of switching power supplies. For high-frequency switching power supplies with high-power heating devices, temperature is one of the most important factors affecting its reliability. The thermal design of the switching power supply generally includes two aspects: one is how to control the heat generation of the heating source; the other is how to dissipate the heat generated by the heating source, so that the temperature rise of the switching power supply is controlled within the allowable range to ensure the switching power supply Reliability. 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 heat conduction sheet, etc. In actual design, it is necessary to comprehensively apply the above-mentioned methods to the design of the power supply according to the requirements of customers and the product itself and the best cost-effectiveness ratio. In the actual design process of the switching power supply, two forms of natural air cooling and forced air cooling by a radiating fan are usually adopted. When installing the natural air-cooled heat sink, the blades of the heat sink should be placed vertically upwards. If possible, several vent holes can be drilled around the mounting position of the heat sink on the pcb to facilitate air convection. The heat dissipation method of the switching power supply cooling fan is forced air cooling, and the fan is used to force air convection. Therefore, in the design of the air duct, the axial direction of the heat sink blade should be consistent with the air extraction direction of the fan. In order to have a good ventilation effect, the more The more heat-dissipating devices should be closer to the cooling fan. Due to changes in ambient temperature and load changes, the heat dissipation energy of the power supply during operation, the use of natural air cooling combined with forced air cooling by the cooling fan can quickly dissipate the heat energy. This method can reduce the area of u200bu200bthe radiator while increasing the heat dissipation of the fan, so that the power components work in a relatively stable temperature field, and the service life will not be affected by changes in external conditions. This not only overcomes the shortcomings of pure fan cooling of the power element heat dissipation adjustment lag, but also avoids the low service life of the fan from affecting the overall reliability of the rectifier. Especially when the ambient temperature of the machine room is very unstable, the cooling technology that combines air cooling and self-cooling has better cooling performance. The material cost of the rectifier in this way is between pure fan cooling and natural cooling, low weight and convenient maintenance. Especially when using intelligent air cooling and self-cooling technology, the rectifier can be operated under low load conditions, the temperature rise of the module is small, and the cooling fan of the module is in a low-speed operation state. Under high load working conditions, the module heats up, and the temperature of the module exceeds ℃, and the fan speed increases linearly with the temperature change. Fan failure is detected in place, after fan failure, fan failure current limit output, and fault alarm at the same time. Since the number of fan operations is related to the size of the load, the service life of the fan is longer than that of pure air cooling, and its reliability is greatly improved. Switching power supplies used in many industries use a cooling method that combines cooling fans and natural cooling, which can effectively reduce the internal working temperature of the rectifier when the ambient temperature is high, and prolong the service life of the components. When it is low, the fan of the rectifier will work at a reduced speed to prolong the service life of the fan. Using a radiator to dissipate heat, the device spacing and creepage distance can be relatively far, and the safety performance is high in the case of high humidity. The rectifier is small in size and light in weight, making maintenance work easy. In order to ensure the reliable and stable operation of the rectifier of the switching power supply, reducing its operating temperature rise is a key technology. Using the combination of intelligent air cooling and self-cooling technology, it has technical advantages such as stronger environmental adaptability, long service life, reliability and stability.