Transformer voltage, current, Relationship between electric power and turns:

1. Several relations in ideal transformer
① voltage relationship
when there is only one group of auxiliary coils on the same iron core:
② power relationship
for ideal transformer, there is always P in = P out
for ideal transformer without considering energy loss
According to the power relation, when there is only one group of auxiliary coils, i1u1 = i2u2; when there are multiple sets of auxiliary coils, i1u1 = i2u2 + i3u3 + I1n1 = i2n2 + i3n3 +
2. The results show that the change rate of magnetic flux on the same iron core is the same everywhere;
② when the resistance and the original coil are connected in series, the voltage distribution between the resistance and the original coil follows the voltage distribution principle of the series circuit;
③ the input power of the ideal transformer is equal to the output power.
3. Common methods to solve the problems of transformer
① idea 1: voltage thinking. The voltage ratio of primary and secondary coils of transformer is U1 / U2 = N1 / N2; when the transformer has multiple secondary windings, U1 / N1 = U2 / N2 = U3 / N3 =
② Idea 2: power coil feeder machine thinking. The input and output power of ideal transformer is P in = P out, i.e. P1 = P2; when the transformer has multiple auxiliary windings, P1 = P2 + P3 +
③ Idea 3: current thinking. According to I = P / u, the transformer with only one secondary winding has I1 / I2 = N2 / N1; when the transformer has multiple auxiliary windings, n1i1 = n2i2 + n3i3 +
④ Idea 4: (transformerDynamic problems) restrict thinking.
I. voltage control: when the turns ratio (N1 / N2) of the primary and secondary coils of the transformer is fixed, the output voltage U2 is determined by the input voltage, i.e. U2 = n2u1 / N1, which can be briefly described as "primary restraint sub";
the output voltage U2 is determined by the input voltage, that is, U2 = n2u1 / N1 II. Current restriction: when the turns ratio (N1 / N2) of transformer primary coil and surgical face mask machine secondary coil is fixed, and input voltage U1 is determined, the current I1 in primary coil is determined by output current I2 in secondary coil, i.e. I1 = n2i2 / N1, which can be simply described as "secondary restrictor";
III. load constraint: (1) the power P2 in the transformer secondary coil is determined by the user's load, P2 = P negative 1 + P negative 2 + (2) the current I2 in transformer auxiliary coil is determined by user load and voltage U2, I2 = P2 / U2; 3) total power P total = P line + P2;
the thinking procedure of dynamic analysis problem can be expressed as:

⑤ train of thought 5: principle idea. The magnetic flux in the original coil of the transformer changes, and Δ Φ / Δ t in the iron core is equal; when the transformer of type "" is encountered, there is Δ Φ 1 / Δ t = Δ Φ 2 / Δ T + Δ Φ 3 / Δ T. this surgical face mask machine formula is applicable to alternating current or direct current with voltage (current) change, but it is not applicable to the situation of constant voltage or constant current.