Introduction to the principle of transformer.

The transformer consists of an iron core (or magnetic core) and a coil, which has two or more windings, of which the winding connected to the power supply is called the primary coil, and the rest is called the secondary coil. It can change AC voltage, current and impedance. A simple core transformer consists of an iron core made of a soft magnetic material and two coils with different turns on the iron core. The role of the iron core is to strengthen the magnetic coupling between the two coils. In order to reduce the eddy current and hysteresis loss in the iron, the core is made of painted silicon steel sheet laminated; There is no electrical connection between the two coils, which are wound by insulated copper (or aluminum) wire.

One coil connected to the AC power supply is called the primary coil (or primary coil), and the other coil connected to the electrical appliance is called the secondary coil (or secondary coil). The actual transformer is very complex, there is inevitably copper loss (coil resistance heating), iron loss (core heating) and magnetic leakage (magnetic induction line closed by air), etc., the ideal transformer is established under the conditions of: ignore the leakage flux, ignore the resistance of the primary and secondary coils, ignore the loss of the core, ignore the no-load current (the current in the primary coil of the secondary open circuit). For example, when a power transformer is running at full load (rated power output of the secondary coil), it is close to the ideal transformer situation.