Calculation method of power transformer
Tools/raw materials
Calculator, silicon Steel sheet specification table, transformer skeleton specification table, enameled wire specification table, silicon steel sheet material 470 or 600 IE type
Steps/Methods
1. Calculate the power of the transformer
Transformer power = output voltage >
30V Y root X 1.06 = core cross-sectional area
Transformer power 300W X 1.44 = 432, 432 root = 2200 square millimeters (core cross-sectional area)
3. Calculate the transformer core stack thickness
Core cross-sectional area (square millimeters) / silicon steel Tongue width (mm) = iron core stack thickness
2200 square millimeters / 40 mm = 55 mm (stack thickness). The iron core specifications use silicon steel sheets with a tongue width of 40, and the stack thickness is 55 mm.
There is a question here. Some people will ask why 40 silicon steel sheets are used. Let me teach you an experience value.
Lamination thickness / tongue width = (1.0∽1.6), 55mm / 40mm =1.375.
If it is less than 1.0, use a silicon steel sheet with a smaller specification, which means that the window of the silicon steel sheet is too large and cannot be wound around; if it is larger than 1.6, use a silicon steel sheet with a size that is larger than that, which means that the window of the silicon steel sheet is too small and cannot be wound around. For specific specifications, please refer to the silicon steel sheet specification table.
4. Selection of skeleton
The cross-sectional area of the iron core is E40 There is a frame of this size. If it is not available, you can choose one with a larger thickness. If it is inconvenient for amateurs to buy a skeleton, then make one yourself.
5. Calculate the number of primary turns of the coil
45 / Iron core cross-sectional area (square centimeters) >
(45/22 square centimeters) X 220 = 450 turns (enter the number of primary turns)
6. Calculate the number of secondary turns of the coil
(Number of input primary turns/220) X output voltage = Number of output secondary turns
(450/220) X 30V = 61.36 (takes 62 turns)
7. Calculating winding wiring wire diameter
current (open root) x 0.7 = wire diameter
Output current 10A (open root) X 0.7 = 2.21 (output 30V wire diameter),
Input current = (300W transformer power/220V input voltage) open root (Input 220V wire diameter)
8. Calculation results
Silicon steel sheet specification E40mm, stack thickness 55mm; transformer frame specification E40 X 55; input coil The number of turns is 450 turns and the wire diameter is 0.81 copper enameled wire; the output coil has 62 turns and the wire diameter is 2.21 copper enameled wire.
Notes
This is mainly for electronics amateurs. The calculation method of the transformer is only suitable for small power power transformers, which are made of EI cores. At the same time, the circuit requirements are different, and the design requirements for the transformer are also different. Please treat them differently. High-power transformers have different materials, different winding processes, different transformer structures, and of course different design methods. We will not introduce them in detail here.
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