Working principle of transformer

The working principle of transformers is mainly based on the principle of electromagnetic induction. It is an important equipment used in power systems to transform AC voltage, current, and impedance.

The following is a detailed explanation of the working principle of transformers:

01 Basic Principles

Transformers utilize the phenomenon of electromagnetic induction by winding two or more mutually insulated windings (i.e. coils) around the iron core (or magnetic core) to achieve the transmission of electrical energy and voltage conversion. When one of the windings (called the primary or secondary coil) is connected to an AC power source, an alternating magnetic flux is generated in the iron core. This alternating magnetic flux passes through another or more windings (called the secondary or secondary coil), inducing an electromotive force in the secondary winding and achieving voltage conversion.

02 Specific Process

When the primary winding is connected to an AC power source, current flows in the winding, and according to Ampere's loop law, alternating magnetic flux is generated in the iron core. This magnetic flux varies over time, and its frequency of change is the same as the frequency of the primary current.

When alternating magnetic flux passes through the secondary winding, according to Faraday's law of electromagnetic induction, an electromotive force will be induced in the secondary winding. The magnitude of this electromotive force is directly proportional to the primary voltage, the number of turns of the secondary winding, and the rate of change of magnetic flux.

Due to the fact that the number of turns of the secondary winding can be different from that of the primary winding, the induced electromotive force (i.e. secondary voltage) can be higher or lower than the primary voltage, thereby achieving voltage boost or buck conversion.

When the secondary winding is connected to the load, the secondary current begins to flow, which also generates its own magnetic flux. However, due to the constant applied voltage, the main magnetic flux tends to remain unchanged. In order to maintain magnetic flux balance, the primary current will increase accordingly to generate sufficient magnetomotive force to counteract the magnetic flux effect generated by the secondary current. In this way, energy transfer is achieved between the primary and secondary edges through electromagnetic induction.

03 Features and Applications

Although transformers may experience certain losses during energy transmission, such as copper and iron losses, their overall efficiency is relatively high, especially during high-power transmission.

By changing the turns ratio of the winding, different voltage levels can be flexibly transformed to meet the needs of various electrical equipment.

Transformers also have good electrical isolation function, which can effectively isolate the electrical systems on the primary and secondary sides, preventing the spread of faults and the risk of electric shock.

Transformers have a wide range of applications in the power system, including power generation, transmission, distribution, and consumption. Meanwhile, it also plays an important role in fields such as industrial automation, transportation, and communication.