Effect of temperature on the performance and life of the communication switching power supply unit
The main component of the communication switching power supply is the high-frequency switching rectifier, which is gradually developed and matured along with the development of power electronics theory and technology and power electronic devices. The power consumption of rectifiers with soft switching technology becomes smaller, the temperature is lower, the volume and weight are reduced substantially, and the overall quality and reliability are continuously improved. However, whenever the ambient temperature rises by 10°C, the life of the main power components decreases by 50 per cent. The reasons for such a rapid decline in life are all due to temperature changes. Fatigue failure caused by a variety of micro- and macro-mechanical stress concentration, ferromagnetic materials and other components operating under the continuous action of alternating stress, will sprout many types of micro-internal defects. Therefore, to ensure the effective heat dissipation of the equipment is a necessary condition to ensure the reliability and life of the equipment.
The relationship between operating temperature and the reliability and life of power electronic components
Power supply is a power conversion equipment, in the conversion process itself needs to consume some electrical energy, and these electrical energy is converted into heat release. The stability and aging rate 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 generation, the thermal cycling of multiple materials with different coefficients of expansion in relation to each other can cause very significant stresses, and may even lead to instantaneous fracture and failure of the components. If a power element is operated under abnormal temperature conditions for a long period of time, fatigue will be induced that will lead to fracture. The existence of thermal fatigue life in semiconductors requires that they should be operated in a relatively stable and low temperature range.
At the same time, rapid hot and cold changes can temporarily create semiconductor temperature differences, which can generate thermal stresses and thermal shocks. The components are subjected to thermal-mechanical stresses, which, when the temperature difference is too large, lead to stress cracks in the different material parts of the components. Make the component premature failure. This also requires that the power components should work in a relatively stable operating temperature range, reduce the rapid changes in temperature, in order to eliminate the impact of thermal stress impact, to ensure that the components of long-term reliable work.
Working temperature on the transformer insulation capacity
Transformer primary winding energised, the magnetic flux generated by the coil in the core flow, due to the core itself is a conductor, perpendicular to the plane of the magnetic lines of force will produce induced potential, in the cross-section of the core to form a closed loop and produce current, known as "eddy current". This "eddy current" makes the transformer loss increase, and make the transformer core heating transformer temperature rise increases. The loss generated by the "eddy current" is called "iron loss". In addition to wind the transformer using copper wire, these copper wires exist resistance, the current flows through the resistance will consume a certain amount of power, this part of the loss into heat and consumption, said this loss is "copper loss". So iron loss and copper loss is the main reason for the temperature rise of the transformer work.
