Transformer is a device that uses electromagnetic induction principle to transform AC voltage. Its main components include primary coil, secondary coil and iron core.
In the electronics profession, you can often see the shadow of the transformer, the most common is used in the power supply as a conversion voltage, isolation.
In short, the voltage ratio of the primary and secondary coils is equal to the turns ratio of the primary and secondary coils. Therefore, if you want to output different voltages, you can change the turns ratio of the coils.
According to the different working frequencies of transformers, they can generally be divided into low-frequency transformers and high-frequency transformers. For example, in daily life, the frequency of power frequency alternating current is 50Hz. We call transformers working at this frequency low-frequency transformers; The working frequency of high-frequency transformer can reach tens of kHz to hundreds of kHz.
The volume of high-frequency transformer is much smaller than that of low-frequency transformer with the same output power
The transformer is a relatively large component in the power circuit. If you want to make the volume smaller while ensuring the output power, you need to use a high-frequency transformer. Therefore, high-frequency transformers are used in switching power supplies.
The working principle of high frequency transformer and low frequency transformer is the same, both of which are based on the principle of electromagnetic induction. However, in terms of materials, their “cores” use different materials.
The iron core of low-frequency transformer is generally stacked with many silicon steel sheets, while the iron core of high-frequency transformer is composed of high-frequency magnetic materials (such as ferrite). (Therefore, the iron core of high-frequency transformer is generally called the magnetic core)
In DC stabilized voltage power supply circuit, low-frequency transformer transmits sine wave signal.
In switching power supply circuit, high-frequency transformer transmits high-frequency pulse square wave signal.
At rated power, the ratio between the output power and the input power of the transformer is called the efficiency of the transformer. When the output power of the transformer is equal to the input power, the efficiency is 100%. In fact, such a transformer does not exist, because the copper loss and iron loss exist, the transformer will have certain losses.
What is copper loss?
Because the transformer coil has a certain resistance, when the current passes through the coil, part of the energy will become heat. Because the transformer coil is wound with copper wire, this loss is also called copper loss.
What is iron loss?
The iron loss of transformer mainly includes two aspects: hysteresis loss and eddy current loss; Hysteresis loss refers to that when alternating current passes through the coil, magnetic lines of force will be generated to pass through the iron core, and molecules inside the iron core will rub against each other to generate heat, thus consuming part of electrical energy; Because the magnetic line of force passes through the iron core, the iron core will also generate induced current. Because the current is swirling, it is also called eddy current, and eddy current loss will also consume some electric energy.
Post time: Dec-27-2022
