Switching power transformer is a power transformer with switch tube. In the circuit, in addition to the voltage conversion function of ordinary transformer, it also has the functions of insulation isolation and power transmission. It is generally used in switching power supply and other occasions involving high-frequency circuits.
The main heating components in switching power supply are semiconductor switching tube, power diode, high-frequency transformer, filter inductor, etc. Different devices have different methods of controlling calorific value. Power tube is one of the devices with large calorific value in high-frequency switching power supply. Reducing its calorific value can not only improve the reliability of power tube, but also improve the reliability of switching power supply and improve the mean time between failures.
The heat output of the switch tube is caused by the loss. The loss of the switch tube is composed of switching process loss and on state loss. To reduce the on state loss, the on state loss can be reduced by selecting the switch tube with low on state resistance; Switching process loss is caused by 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, the loss can be reduced by designing better control mode and buffer technology. For example, the loss can be greatly reduced by using soft switching technology. Reduce the heating capacity of power diodes. Generally, there will be no better control technology to reduce the loss of AC rectifier and buffer diodes. The loss can be reduced by selecting high-quality diodes. For the rectifier on the secondary side of the transformer, the synchronous rectifier technology with higher efficiency can be selected to reduce the loss. For the loss caused by high-frequency magnetic materials, the skin effect should be avoided as far as possible. The influence caused by the skin effect can be solved by winding multiple strands of fine enamelled wires together
