Winding method of high frequency transformer in high frequency inverter

There are two things to note when making it:

First, each winding should be made of multiple strands of thin copper wire and wound together. Do not use a single thick copper wire because high frequency alternating current has a skin effect. The so-called skin effect, simply means that the high-frequency alternating current only travels along the surface of the wire, and the inside of the wire does not run current (actually, the closer to the wire, the weaker the current, the closer the current is to the wire surface). The use of multiple strands of thin copper wire and wound together is actually to increase the surface area of ​​the wire, so that the wire can be used more effectively. For example, the primary 3T+3T, if you use a single enameled wire with a diameter of 2.50mm, the cross-sectional area of ​​the wire is 4.9 square millimeters, and if the enameled wire with a diameter of 0.41mm (single cross-sectional area 0.132 square mm) is 38, the total The cross-sectional area also meets the requirements. However, the second method has a much larger surface area of ​​the wire (the surface area of ​​the first method wire is: single wire cross section circumference × number of strands × total winding length = 2.5 × 3.14 × 1 × L = 7.85L, the second type The surface area of ​​the method wire is: the circumference of the single-strand wire section × the number of strands × the total length of the winding = 0.41 × 3.14 × 38 × L = 48.92L, the latter is the former 48.92L / 7.85L = 6.2 times), the effective use of the wire Higher, the current is smoother, and because the thin wires are softer, they are better wound. The secondary 75T high voltage winding can be wound with 3~5 wires.

Second, the high-frequency transformer in the high-frequency inverter is preferably stratified and segmented. The main purpose of this winding method is to reduce the high-frequency leakage inductance and reduce the distributed capacitance. For example, the winding method of the above transformer has two layers in the primary and three layers in the third. specifically is:

1 around the first section of the secondary high voltage winding. Connect the lead wire (head), first use 5 and wrap around the secondary high voltage winding 25T, do not cut the wire, and then wrap a layer of insulating paper (insulation paper should be thin, cover one layer, otherwise it will be used several times as follows) Insulating paper, it is possible to not accommodate the entire wire package), ready to wrap around half of the primary low-voltage winding.

2 is half of the primary low voltage winding. Reserve the lead line (head), pay attention to the reservation, because the back should be unified and then connected to the lead line, the following primary use of the word "reserved" is the same. Use 19 and wrap around 3T, reserve the center tap, and then wrap around 3T, reserve the lead line (tail), and cut the line. There is also a technique here in the specific operation, that is, due to the large number of shares, the 19-strand line is not convenient at one time, and the torque tension is also large, so it can be divided into several times, as here can be divided into three times, each time using the line 6 To 7 shares, this can be even more even. Note that the head, middle, and tail of the three times are placed together and the winding direction is the same. Then a layer of insulating paper is wrapped and ready to be wound around the second section of the secondary high voltage winding.

3 around the second section of the secondary high voltage winding. Turn over the secondary high-voltage winding wire that has not been cut before (be careful not to touch the front primary winding wire, if necessary, separated by insulating paper), and then wrap around 25T. Note that the winding direction is the same as the first segment in the front. The line is still not cut. A layer of insulating paper is also wrapped around the other half of the primary low voltage winding.

4 around the other half of the primary low voltage winding. Then follow the same method as step 2 to wind the primary low-voltage winding. Note that the winding is the same as the previous half. The same line is cut, covered with a layer of insulating paper, ready to wrap around the third section of the secondary high voltage winding.

5 around the third section of the secondary high voltage winding. Then follow the method indicated in step 3 to bypass the remaining secondary high voltage winding 25T, and still note that the winding direction is the same as the previous two sections. Connect the lead wire (tail) and cut the wire. At this point, all windings are wound up.

6 merge the primary low voltage windings. The first low-voltage winding, which is wound twice in the front, is connected to the head, the center tap is connected to the center tap, and the tail and tail are connected in parallel (so that the winding turns are still 3T+3T, and the total parallel line is 38). After the lead wire is connected, the three leading ends of the head, the middle and the tail of the primary low voltage winding are obtained. Finally, a layer of insulating tape is wrapped, and the wire package is completed.