High-frequency transformer is the most important component of switching power supply. There are many topologies in switching power supplies. For example, a half-bridge power conversion circuit, when working, two switching transistors are turned on in turn to generate a 100kHz high-frequency pulse wave, and then the high-frequency transformer is used to transform the voltage and output alternating current. The ratio of turns of each winding coil of the high-frequency transformer is determined. the output voltage. The most conspicuous in a typical half-bridge transformer circuit are three high-frequency transformers: main transformer, drive transformer and auxiliary transformer (standby transformer). Each transformer has its own measurement standard in national regulations, such as the main transformer, As long as it is a power supply above 200W, the core diameter (height) must not be less than 35mm. As for the auxiliary transformer, it is enough for the magnetic core diameter to reach 16mm when the power supply does not exceed 300W.
working principle
A transformer is a device that transforms AC voltage, current, and impedance. When an AC current passes through the primary coil, an AC magnetic flux is generated in the iron core (or magnetic core), which induces a voltage (or current) in the secondary coil.
The transformer consists of an iron core (or magnetic core) and a coil. The coil has two or more windings. The winding connected to the power supply is called the primary coil, and the remaining windings are called the secondary coil.
use
High-frequency transformer is a power transformer whose operating frequency exceeds intermediate frequency (10kHz). It is mainly used as a high-frequency switching power transformer in high-frequency switching power supplies, and is also used as a high-frequency inverter in high-frequency inverter power supplies and high-frequency inverter welding machines. power transformer. According to the working frequency, it can be divided into several grades: 10kHz-50kHz, 50kHz-100kHz, 100kHz-500kHz, 500kHz-1MHz, and above 1MHz. When the transmission power is relatively large, the power device generally adopts IGBT, because the IGBT has the off-current tailing phenomenon, so the operating frequency is relatively low; when the transmission power is relatively small, MOSFET can be used, and the operating frequency is relatively high.
