Effect of Temperature on Performance and Life of Communication Switching Power Supplies

1. The relationship between working temperature and the reliability and life of power electronic components.

The power supply is an electric energy conversion device. During the conversion process, it needs to consume some electric energy, which 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 the power component during operation is dissipated by its own heat, the thermal cycle of multiple materials with different expansion coefficients will cause very significant stress, and may even cause instantaneous fracture and component failure. If the power component works under abnormal temperature conditions for a long time, it will cause fatigue that will lead to fracture. Since semiconductors have thermal fatigue life, this requires that they should work in a relatively stable and low temperature range. At the same time, rapid changes in temperature will temporarily produce a semiconductor temperature difference, which will produce thermal stress and thermal shock. Make the component bear thermal-mechanical stress. When the temperature difference is too large, stress cracks will occur in different material parts of the component. Make the component fail prematurely. This

also requires that the power component should work in a relatively stable operating temperature range, reduce the rapid change of temperature, eliminate the influence of thermal stress shock, and ensure the long-term and reliable operation of the component.

2. The influence of working temperature on the insulation capacity of the transformer

After the primary winding of the switching power supply 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 potential will be generated on the plane perpendicular to the magnetic field line, forming a closed loop on the cross section of the iron core and generating current, which is called "eddy current". This "eddy current" increases the loss of the transformer, and causes the iron core of the transformer to heat up and the temperature rise of the transformer to increase. The loss generated by the "eddy current" is called "iron loss". In addition, the copper wire used to wind the transformer has resistance. When the current flows through, this resistance will consume a certain amount of power. This part of the loss is converted into heat and consumed, which is called "copper loss". Therefore, iron loss and copper loss are the main reasons for the temperature rise of the transformer.

As the working temperature of the transformer rises, the coil will inevitably age. When its insulation performance decreases, the ability to resist the impact of the main power will be weakened. At this time, if there is a lightning strike or a main power surge, the high reverse voltage appearing in the primary of the transformer will break down the transformer, causing the switching power supply to fail. At the same time, there is also the risk of high voltage entering the communication main equipment in series, forming the main equipment damage.