Effect of temperature on performance and life of communication switching power supply
The main component of the communication switching power supply is the high-frequency switching rectifier, which has gradually matured with the development of power electronics theory and technology and power electronic devices. Rectifiers using soft switching technology have smaller power consumption, lower temperatures, significant reductions in volume and weight, and continuous improvement in overall quality and reliability. But every time the ambient temperature increases by 10°C, the life of the main power components is reduced by 50%. The reason for such a rapid decrease in life is due to temperature changes. Fatigue failure caused by the concentration of various micro and macro mechanical stresses, ferromagnetic materials and other parts will develop various types of micro internal defects under the continuous action of alternating stress during operation. Therefore, ensuring effective heat dissipation of the equipment is a necessary condition to ensure the reliability and life of the equipment.
Relationship between operating temperature and reliability and life of power electronic components
A power supply is an electrical energy conversion device that consumes some electrical energy during the conversion process, and this electrical energy is converted into heat and released. The working stability and aging speed of electronic components are closely related to the ambient temperature. Power electronic components are composed of a variety of semiconductor materials. Since the loss of power components during operation is dissipated by their own heat, the thermal cycle of multiple materials with different expansion coefficients will cause very significant stress, and may even lead to instantaneous fracture and component failure. If power components work under abnormal temperature conditions for a long time, fatigue will occur that will lead to fracture. Due to the thermal fatigue life of semiconductors, it is required that they should work in a relatively stable and low temperature range.
At the same time, rapid hot and cold changes will temporarily produce a temperature difference in the semiconductor, resulting in thermal stress and thermal shock. The components are subjected to thermal-mechanical stress. When the temperature difference is too large, stress cracks occur in different material parts of the component. causing premature component failure. This also requires that power components should work within a relatively stable operating temperature range to reduce rapid changes in temperature to eliminate the impact of thermal stress shock and ensure long-term reliable operation of the components.
Effect of operating temperature on the insulation capacity of transformer
After the primary winding of the transformer is energized, the magnetic flux generated by the coil flows in the iron core. Since the iron core itself is a conductor, an induced electric potential will be generated on a plane perpendicular to the magnetic lines of force, forming a closed loop on the cross section of the iron core and generating a current, which is called " vortex". This "eddy current" increases the loss of the transformer and increases the temperature rise of the transformer's core heating transformer. The loss caused by "eddy current" is called "iron loss". In addition, the copper wires used in the transformer must be wound. These copper wires have resistance. When the current flows through, the resistance will consume a certain amount of power. This part of the loss is converted into heat and is consumed. This loss is called "copper loss". Therefore, iron loss and copper loss are the main causes of temperature rise during transformer operation.
