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Introduction to the principle of high frequency transformer


As the name implies, high-frequency transformer is a power electronic instrument that changes the voltage. It is a device that uses Faraday law of electromagnetic induction to change AC voltage, mainly composed of primary coil, ferrite core, secondary coil, etc. It can realize the matching conversion of input and output current, voltage and impedance, as well as the physical isolation of the primary level. According to the different primary voltage, it can be divided into step-down high-frequency transformer, step-up high-frequency transformer and isolation high-frequency transformer.

The frequency of electricity used in our daily life is 50Hz, which is called low-frequency alternating current. If the high-frequency transformer works at this frequency, we call it high-frequency transformer low-frequency high-frequency transformer, also called power frequency high-frequency transformer. The high-frequency transformer has large volume and low efficiency. The iron core is stacked with mutually insulated silicon steel sheets, and the primary coil is wound with enamelled wire. The primary voltage is proportional to their turns.

In addition, some high-frequency transformers work in dozens of hundreds of kilohertz settings, and this high-frequency transformer becomes a high-frequency transformer. High frequency transformers generally use magnetic cores instead of iron cores. High frequency transformer has small volume, few turns of primary coil and high efficiency.

The working frequency of high-frequency transformer is generally tens to hundreds of kilohertz. High frequency transformer adopts magnetic core, and the main component of magnetic core is manganese zinc ferrite. This material has low eddy current, low loss and high efficiency at high frequencies. The low frequency working frequency of the high frequency transformer is 50Hz. High frequency transformer core is a kind of soft metal magnetic material. Thin silicon steel sheet can greatly reduce eddy current loss, but the loss is still greater than that of high-frequency transformer core.

The high-frequency transformer with the same output power is much smaller than the low-frequency high-frequency transformer, and its heating capacity is low. So at present, many power adapters of consumer electronics and network products are switching power supplies, and the internal high-frequency transformer is the most important component of switching power supplies. The basic principle is to convert the input alternating current into DC, and then convert it into high frequency through triode or FET. Through high-frequency transformer transformation, the output is rectified again, and other control parts are added to stabilize the output DC voltage.

In short, the similarities between high-frequency and low-frequency high-frequency transformers are based on the principle of electromagnetic induction. The difference is that the low frequency and high frequency transformers are metal cores made of silicon steel sheets, and the high frequency transformers are whole pieces made of manganese zinc ferrite and other materials.

Post time: Jan-05-2023