Transformers or transformers are passive electrical components used for the conversion of alternating voltages and for potential separation. They consist of two coils, the primary coil and the secondary coil, which are closely coupled to each other via a magnetic field.
According to the transformation principle, an induction field is generated in the primary coil of the transformer, which produces an alternating voltage of the same frequency in the secondary coil by induction. For better magnetic field transfer, the primary coil and the secondary coil are coupled together via a ferrite or iron core.
The voltage transformation from the primary coil to the secondary coil is done in the ratio of the coil turns and is called transformation ratio or turns ratio. If the turns ratio is 1:1, then the primary coil has exactly as many turns as the secondary coil, and the secondary voltage in this case is exactly as large as the primary voltage. If the ratio is 2:1, then the secondary voltage is only half as large as the primary voltage.
In addition to the classic transformers with a primary and secondary winding, there is also the autotransformer principle, which works with only one primary winding. With this principle, the different voltages are generated by voltage taps. However, an autotransformer or autotransformer has no galvanic isolation. Another principle, that of mechanical coupling, is used by the piezo transformer, which makes use of the piezo effect. With this technology, power densities of 50 W/ cc can be achieved. This enormously compact design, which allows transformers to be manufactured with overall heights of less than 1 mm, is of particular interest for mobile devices and for DC/DC converters. The mechanically operating piezo transformers also have the advantage that they do not generate any interference radiation.
Transformers are used to transform AC voltages, such as converting the mains voltage into various lower level AC voltages. Autotransformers are used in audio technology in crossovers, because they have a relatively uniform impedance curve; for example, in 100 V technology.