# What is the role of transformer coils? How to calculate transformer coils

What is the role of transformer coils? How to calculate transformer coils

The transformer is divided into two types: mutual inductance transformer and autotransformer. A varying current is passed through the primary coil to produce a varying magnetic field, and the secondary coil induces a varying current in the changing magnetic field. The ratio of the primary coil to the secondary coil determines the transformer ratio. In the whole process, the coil converts electric energy to magnetic energy and then to electric energy, and changes the magnitude of voltage and current.

Transformer principle

A transformer is a device that converts alternating voltage, current, and impedance. When an alternating current is passed through the primary coil, an alternating magnetic flux is generated in the core (or core) to induce a voltage (or current) in the secondary coil. The transformer consists of a core (or 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 other winding is called the secondary coil. In the generator, whether the coil moves through the fixed coil through the magnetic field or the magnetic field, the potential can be induced in the coil. In both cases, the value of the magnetic flux is constant, but the number of magnetic fluxes intersecting the coil is Change, this is the principle of mutual induction. A transformer is a device that uses electromagnetic mutual inductance to transform voltage, current, and impedance.

Satons transformers mainly use the principle of electromagnetic induction to work. Specifically: when the alternating current voltage U1 is applied to the primary side of the transformer, and the current flowing through the primary winding is I1, the current will generate an alternating magnetic flux in the iron core, so that the primary winding and the secondary winding are electromagnetically connected, according to the principle of electromagnetic induction. The alternating magnetic flux passes through the two windings to induce an electromotive force, the magnitude of which is proportional to the number of turns of the winding and the maximum value of the main magnetic flux. The voltage on the side with a large number of winding turns is high, and the side with a small number of winding turns The voltage is low. When the secondary side of the transformer is open, that is, when the transformer is unloaded, the secondary terminal voltage is proportional to the number of turns of the secondary winding, that is, U1/U2=N1/N2, but the primary and secondary frequencies are consistent, thus Achieve a change in voltage.

transformer China function

A transformer is a stationary electrical device. It is a device that converts a certain level of AC voltage and current into another level of voltage and current of the same frequency according to the principle of electromagnetic induction. Function: Transform AC voltage, exchange AC current and transform impedance.

How to calculate the transformer coil

First, calculate the power of the transformer Transformer power = output voltage X output current

For example, a transformer with an output voltage of 30V and a current of 10A is required according to the circuit requirements, 30V X 10A = 300W.

Second, calculate the core cross-sectional area of the transformer

Transformer power X 1.44 = Y , Y open root X 1.06 = core cross-sectional area

For example: 300W X 1.44 = 432, 432 roots X 1.06 = 22.00 square centimeters = 2200 square millimeters (core cross-sectional area)

Third, calculate the transformer core stack thickness

After iron core stacking = core cross-sectional area / 矽 steel sheet tongue width

For example: 2200 mm 2 / 40 mm = 55 mm (stack thickness), the core size of the core 40 is 55 mm. There is a problem here. Some people will ask why you can use 40 pieces of silicon steel to teach you an experience value. Stack thickness / tongue width = (1.0 ∽ 1.6), less than 1.0 with a small size 矽 steel sheet, larger than 1.6 with a larger size of 矽 steel sheet. What are the specifications of the silicon steel sheet? You can check it online and you will know.

Fourth, the choice of skeleton

The iron core is E40 X 55, then the skeleton is E40 X 55, just have the skeleton of this specification. If it is not, choose a thicker stack. Amateurs do it themselves.

Fifth, calculate the number of turns

45 / core cross-sectional area (cm 2 ) X 220V = primary turns, primary turns / 220 X secondary voltage = secondary turns

For example: 45 / 22 X 220 = 450 匝 (primary number of turns), 450 / 220 X 30V = 61.36 (take integer 62 匝)

Sixth, calculate the winding diameter of the enameled wire

Current (open root) X 0.7 = wire diameter

For example: secondary current 10A (opening) X 0.7 = 2.21 (copper wire with diameter 2.21), primary current = 300W / 220V (opening) X 0.7 = 0.81 (primary wire diameter)

Note: The power design of the transformer and the calculation of the wire diameter of the enameled wire are also closely related to the circuit. Different circuit designs will be different.