How does the power transformer work? Many electronic component manufacturers are confused!

Today, Nanfang Electrical Components Factory introduces the working principle of power transformer!

What is a power transformer?

Regarding the power transformer, it is a special transformer with a common set of coils for output and input. Step-up and step-down are implemented with different taps. The portion of the tap voltage that is smaller than the common inductor is reduced. The tap voltage is higher than that of the common coil. The working principle of the power transformer is to use the principle of electromagnetic induction. The alternating current we use generates a magnetic field through coil N, and there is a coil M next to coil N. Because the magnetic field generated by coil N is not constant, it changes accordingly according to the change in current. The change of the magnetic field causes a corresponding current to be generated in the coil M, and the frequency of the coil M will change the frequency of the coil M according to the different turns ratio of the coil N and the coil M. Of course, many power transformers are now becoming single coils (called autotransformers), and the principles are basically the same.

Working principle, function and loss of power transformer:

An autotransformer is a transformer with only one winding. When used as a step-down transformer, a part of the turns are drawn from the windings as secondary windings. When used as a step-up transformer, the applied voltage is only applied to the windings-part of the turns on. Generally, the part of the winding that belongs to both primary and secondary is called the common winding, and the rest of the autotransformer is called the series winding. Compared with ordinary transformers, the autotransformer with the same capacity is not only small in size but also highly efficient. The larger the capacity, the higher the voltage. This advantage is even more prominent. Therefore, with the development of the power system, the improvement of the voltage level and the increase of the transmission capacity, the self-sustaining transformer is widely used due to its large capacity, small loss and low cost.

Third, the function of the power transformer:

In addition to the small size of power transformers, there is no clear dividing line between power transformers and electronic transformers. Generally, the power supply of a 60Hz power network is very large. It may cover a capacity as large as half a continent. The power limitation of electronic devices is usually limited by the ability to rectify, amplify, and other components of the system. Some of them are those that amplify power. However, compared with the power generation capacity of power systems, it still belongs to the scope of small power. Transformers are commonly used in various electronic equipment for the following reasons: to provide various voltage levels to ensure the normal operation of the system; to provide electrical isolation for parts operating at different potentials in the system; to provide high impedance for AC currents, but low impedance for DC; Maintain or modify the waveform and frequency response at different potentials.

The basic principle is the principle of electromagnetic induction. Take a single-phase dual-winding transformer as an example to explain the basic working principle :: When a voltage ú1 is added to the primary winding, a current í1 flows, and an alternating magnetic flux is generated in the core. These magnetic fluxes are called main magnetic fluxes.

The windings respectively induce potentials é1 and é2. The formula of the induced potential is: E = 4.44fN? M where: E--effective value of induced potential f--frequency N--number of turns? M--peak of the main magnetic flux due to the secondary winding Unlike the number of primary winding turns, the magnitudes of the induced potentials E1 and E2 are also different.

When the internal impedance voltage drop is omitted, the voltages ú1 and ú2 are different in magnitude. When the secondary side of the transformer is unloaded, only the main flux current (í0) flows on the primary side. This current is called the exciting current. When the load current í2 flows through the secondary load, it also occurs in the iron core.

Magnetic flux, trying to change the main magnetic flux, but when the voltage is constant, the main magnetic flux is constant. There will be two parts of current flowing on the primary side, one is the exciting current í0 and the other is used to balance í2, so this part The current changes as í2 changes. When the current is multiplied by the number of turns, it is the magnetic potential.

Fourth, the heat source of the power transformer:

The main heat sources of power transformers are "copper loss" and "iron loss". These two phenomena also make the power transformer lose more power. Therefore, the temperature rise of the transformer is mainly caused by iron loss and copper loss. Because the power transformer has iron loss and copper loss, its output power is always less than the input power. Therefore, we introduce an efficiency parameter to describe this, η = output power / input power.

The above are some answers from Changzhou Nanfang Electrical Component Factory engineers on the working principle of power transformers! Understanding every detail factor is important! Hope to be able to help inductor manufacturers.