How the transformer is transformer
And then come to:
U1 / U2 = N1 / N2
In the case of no-load current, I1 / I2 = -N2 / N1, that is, the original and secondary coil current RMS value is inversely proportional to the number of turns, and the phase difference π.
And then available
I1 / I2 = N2 / N1
Ideal transformer original, vice coil power equal P1 = P2. Indicating that the ideal transformer itself without power loss. The actual transformer always has the loss, its efficiency is η = P2 / P1. Power transformers are highly efficient and up to 90%.
Transformer is the use of electromagnetic induction principle made of static appliances. When the transformer's original coil connected to the AC power supply, the core will produce alternating magnetic flux, alternating magnetic flux with φ said. The original, the secondary coil φ is the same, φ is also a simple harmonic function, the table for the φ = φmsinωt. By Faraday's law of electromagnetic induction, we can see that the induced electromotive force in the original and secondary coils is e1 = -N1dφ / dt, e2 = -N2dφ / dt. Where N1, N2 is the original, the number of turns of the secondary coil. U1 = j1n1, U2 = E2 = -jN2ωΦ, and the complex value is U1 = -I1 = jN1ωΦ, U2 = E2 = -jN2ωΦ, and the complex value is U1 = Let k = N1 / N2, said the variable ratio of the transformer. U1 / U2 = -N1 / N2 = -k, that is, the ratio of the original value of the transformer and the secondary coil voltage, is equal to its turns ratio and the difference between the original and the secondary coil voltage is π.
The role of the core is to strengthen the magnetic coupling between the two coils. In order to reduce the iron in the eddy current and hysteresis loss, the core from the painted silicon steel sheet laminated; between the two coils there is no electrical connection, the coil by the insulated copper wire (or aluminum) A coil connected to the AC power supply is called the primary coil (or the original coil), and the other coil is called the secondary coil (or secondary coil). The actual transformer is very complicated, inevitably there is copper loss (coil resistance heating), iron loss (core fever) and magnetic flux leakage (by air closed magnetic induction line), etc., in order to simplify the discussion here only describes the ideal transformer. The ideal transformer is set up under the condition that the leakage flux is ignored and the resistance of the original and secondary coils is ignored. The loss of the core is ignored and the no-load current is ignored (the current in the secondary coil turns the original coil). For example, when the power transformer is running at full load (the secondary coil output rated power) is close to the ideal transformer situation.
Transformer (Transformer) is the use of electromagnetic induction to change the principle of AC voltage.
Transformer consists of iron core (or core) and coil, the coil has two or more than the winding, which connected to the power supply winding called the primary coil, the rest of the winding called secondary coil. It can transform AC voltage, current and impedance. The simplest core transformer consists of a core made of soft magnetic material and a coil of two turns on the core, as shown in the figure.
