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# Low Frequency Transformer Transformer Core

Oct 18, 2017

Low Frequency Transformer Transformer core

Calculation of low - frequency transformers

Tongue 32MM, thick 34MM, E width 96MM, asked the power, the primary 220, the number of turns, the number of thick lines, the secondary 51V double group, the maximum power to use more thick lines, mouth refers to the EI-type transformer core Cross-sectional area refers to the middle of the E-piece that cross (inserted into the middle of the transformer skeleton in the middle of the width) that is, the width of the iron core and inserted into the transformer side of the total thickness of all E films that stack the product of the most simple means Transformer skeleton in the middle of the area of the square, the transformer core cross-sectional area refers to the coil covered part: tongue width × stack thickness = cross-sectional area, unit: C

The first calculation method:

(2) Calculate the transformer power according to the cross section of the silicon steel sheet: P = S / K ^ 2 = (9.79 / 1.25) ^ 2 = 61.34 (1) Transformer silicon steel sheet Section: 3.2CM * 3.4CM * 0.9 = 9.792CM ^ W = 4.5 * 10 ^ 5 / BmS = 4.5 * 10 ^ 5 / (10000 * 9.79) = 4.6 turns / V (4) Primary coil turns (4) (5) Primary coil current: 60W / 220V = 0.273A (6) Primary coil diameter: d = 0.715 Root number 0.273 = 0.37 (MM) (7) Secondary coil turns: 2 * (51 * 4.6 * 1.03) = 2 * 242 (turns) (1.03 is depressor, two-stage 51V = 2 * 242 turns) (8) Secondary coil current: 60W / (2 * 51V) = 0.59A (9) Secondary wire diameter: d = 0.715 Root number 0.59 = 0.55 (MM)

The second calculation method:

E-shaped core to the middle tongue for the calculation of the width of the tongue. Calculate the formula: Output power: P2 = UI Taking into account the loss of the transformer, the primary power: P1 = P2 / η (where η = 0.7 ~ 0.9, the general power to take a large value) per volt turns calculation formula: (B = silicon steel sheet permeability, generally 8000 ~ 12000 Gauss, good silicon steel sheet selection value, and vice versa to take a small value. S = iron core tongue Of the area, the unit is the square CM) such as the quality of silicon steel can generally choose 10000 Gauss, then can be simplified as: N = 45 / S Calculate the number of secondary winding turns, consider the transformer leakage inductance and wire copper loss, to increase 5% margin. No need to add the primary level. By the current seeking diameter: I = P / U (I = A, P = W, U = V) to the diameter of each square MM ≈ 2.5 ~ 2.6A selected. The third method of calculation

It is important to note that the cross-sectional area of the transformer is the cross-sectional area of the coil-enclosed position. If your core area (the coil is covered) is 32 * 34 = 1088mm2 = 10.88cm2 I do not have time to calculate it. For example, if you have a core section = 3.5 ╳ 1.6 = 5.6 square centimeters per minute of the number of turns per volts = 55 / core section For example, your core section = 3.5 ╳ 1.6 = 5.6 square centimeters Therefore, the number of turns per revolution = 55 / 5.6 = 9.8 turns 2, seeking coil turns primary coil n1 = 220 ╳ 9.8 = 2156 turn secondary coil n2 = 8 ╳9.8 ╳ 1.0 = 82.32 desirable for 82 turns secondary coil turns Calculate the 1.05 is to consider the load when the pressure drop 3, find the wire diameter you do not specify how much power you need to output the number of low? Here I assume 8V. Current 2 amps. Transformer output capacity = 8 ╳ 2 = 16 V input capacity of the transformer = transformer output capacity / 0.8 = 20 VA Primary winding current I1 = 20/220 = 0.09 Ann wire diameter d = 0.8√I Primary coil wire diameter d1 = 0.8√I1 = 0.8√0.09 = 0.24 mm Secondary coil wire diameter d2 = 0.8√I2 = 0.8√2 = 1.13 mm.