How to solve the problem of excessive temperature rise of the switch-mode power supply transformer
In practical applications, excessive temperature rise often occurs in two aspects: the MOS transistor of the power transformer and the design of the transformer itself. Today, we will start from these two aspects to see how to effectively solve the problem of excessive temperature rise in switching power transformers.
In practical applications, excessive temperature rise often occurs in two aspects: the MOS transistor of the power transformer and the design of the transformer itself. Today, we will start from these two aspects to see how to effectively solve the problem of excessive temperature rise in switching power transformers.
Firstly, from the perspective of the transformer itself, once there is a high temperature rise and overheating, it is mainly caused by four problems: copper loss, winding process issues, transformer iron loss, and transformer design power being too small. No load heating is caused by insulation failure of the transformer or high input voltage of the transformer. Insulation failure requires rewinding of the coil, and high input voltage requires reducing the input voltage or increasing the number of coils. If the voltage is normal and it heats up with a load, it means that the load on the power transformer is too high and needs to be changed in its load design.
In the design process of switching power transformers, the heating of MOS transistors is the most serious, and the problem of high temperature rise is caused by losses. The loss of MOS transistors consists of two parts: switching process loss and on state loss. To reduce on state loss, low on state resistance switching transistors can be used. Switching process loss is caused by the size of gate charge and switching time. To reduce switching process loss, devices with faster switching speed and shorter recovery time can be selected. But more importantly, by designing better control methods and buffering techniques to reduce losses, such as using soft switching technology, this loss can be greatly reduced.
In addition, there is also a possibility that the temperature rise of the power transformer itself may be too high, which is that the transformer itself has experienced aging. When the engineer checks the transformer itself and the MOS transistor and finds no abnormalities, it is necessary to make a comprehensive judgment based on the working time and service life of the transformer.
