The design of communication switching power supply cooling technology must first meet the technical performance requirements of the industry. In order to be more adaptable to the special environmental use environment of the communication room, the cooling method is required to be adaptable to environmental temperature changes. At present, the commonly used cooling methods of rectifiers include natural cooling, pure fan cooling, a combination of natural cooling and fan cooling. Natural cooling has no mechanical failure, high reliability; no air flow, less dust, good for heat dissipation, and no noise. Pure fan cooling has light weight and low cost. The combination of fan and natural cooling technology has the characteristics of effectively reducing the volume and weight of the equipment, long service life of the fan, and strong ability to adapt to fan failure.

　　1, natural cooling

　　The natural cooling method is the traditional cooling method in the early days of the switching power supply. This method mainly relies on a large metal radiator for direct heat conduction heat dissipation. Q=KA△t (K heat transfer coefficient, A heat transfer area, △t temperature difference). When the output power of the rectifier increases, the temperature of its power components will rise, and the temperature difference of Δt will also increase. Therefore, when the heat exchange area of ​​the rectifier A is sufficient, its heat dissipation has no time lag, and the temperature difference of the power components is small. Thermal shock is small. But the main disadvantage of this method is the bulk and weight of the heat sink. The winding of the transformer is to reduce the temperature rise as much as possible to prevent the temperature rise from affecting its working performance, so the material selection margin is large, and the volume and weight of the transformer are also large. The material cost of the rectifier is high, and maintenance and replacement are inconvenient. Because of its low requirements for environmental cleanliness, there are still some applications for small-capacity communication power supplies in some small professional communication networks, such as electric power, petroleum, radio and television, military, water conservancy, national security, and public security.

　　2, fan cooling

　　 With the development of fan manufacturing technology, the working stability and service life of the fan have been greatly improved, and the average time between failures is 50,000 hours.

　　Using the fan to dissipate heat can reduce the bulky radiator, greatly improving the volume and weight of the rectifier, and greatly reducing the cost of raw materials. With the intensification of market competition and the decline of market prices, this technology has become the current main trend.

　　 The main disadvantage of this method is that the fan's mean time between failures is shorter than that of the rectifier's 100,000 hours. If the fan fails, the failure rate of the power supply will be greatly affected. Therefore, in order to ensure the service life of the fan, the rotation speed of the fan changes with the temperature change in the device. Its heat dissipation Q=Km△t (K heat transfer coefficient, m heat exchange air quality, △t temperature difference). m The quality of heat exchange air is related to the speed of the fan. When the output power of the rectifier increases, the temperature of its power components will rise, and the temperature of the power components will change until the rectifier can detect this change, and then increase the speed of the fan. In order to strengthen the heat dissipation, there is a great lag in time. If the load frequently changes suddenly, or the mains input fluctuates greatly, it will cause the power components to undergo rapid cooling and heating changes. The thermal stress and thermal shock caused by the sudden semiconductor temperature difference will cause stress cracks in different parts of the components. Make it invalid prematurely.

3. Combination of fan and natural cooling

　　 Due to changes in ambient temperature and load changes, the heat dissipation energy of the power supply during operation, the use of a combination of fans and natural cooling methods can quickly dissipate the heat energy. This method can reduce the area of ​​the 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 the change of 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 computer 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 easy 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 module fan is in a low-speed operation state.

　　 Under high load working conditions, the module heats up. The temperature of the module exceeds 55°C. The fan speed increases linearly with temperature changes. 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 rotations 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.

The communication switching power supply adopts a cooling method that combines fan and natural cooling, which can effectively reduce the internal working temperature of the rectifier when the ambient temperature is high, prolong the service life of the device, and can also work under the condition of low ambient temperature and low load. , The fan of the rectifier reduces the speed to work and prolongs the life of the fan. Using a radiator to dissipate heat, the device spacing and creepage distance can be relatively far, and under high humidity conditions, the safety performance is high. 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 communication switching power supply, reducing its operating temperature rise is a key technology. Adopt intelligent air cooling and self-cooling combination technology. It has technical advantages such as stronger environmental adaptability, long service life, reliability and stability.