High-frequency transformers are the most important component of switching power supplies. There are many topologies in switching power supplies. For example, in a half-bridge power conversion circuit, two switching transistors alternately conduct to generate a 100kHz high-frequency pulse wave, which is then transformed by a high-frequency transformer to output AC power. The ratio of the number of turns in each winding of the high-frequency transformer determines the output voltage.
In a typical half-bridge transformer circuit, the most prominent components are three high-frequency transformers: the main transformer, the drive transformer, and the auxiliary transformer (standby transformer). Each type of transformer has its own national standards. For example, for the main transformer, for power supplies above 200W, the core diameter (height) must not be less than 35mm. For the auxiliary transformer, when the power supply does not exceed 300W, a core diameter of 16mm is sufficient.
