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This example of calculation will allow you to get acquainted with the rWinding application features and its interface.
Calculation conditions: it is required to calculate the transformer for a single-stroke DC-DC Converter. Input voltage range 10-20 V, output voltage 15V, output current 2A.
Run the rewinding application and click the TRANSFORMER WIZARD button.
In the Transformer Wizard window, select the transformer core. Let's say the cores loaded by default do not fit us for some reason. Click the LOAD button.
Attention! The calculation is carried out in millimeters. If you have inches in the app settings, then change to millimeters.
On the screen that appears, select the file we are interested in to upload to the Transformer Wizard. As the name suggests this is ferrite, the dimensions in the file are in millimeters.
If the dimensions in the selected file are inches, the Transformer Wizard will convert them to millimeters.
You can see that the data from the selected file has been loaded.
Now select the core from the list. Let it be K12x8x3
Since the calculation is carried out for a single-stroke DC-DC Converter, then in the calculation type, choose Forward.
Specify the input voltage range from 10 V to 20 V.
Specify the required output voltage 15V and current 2A. Since we do not need other windings, we do not fill the W2 and W3 .
Change the maximum fill factor to 0.41. This value depends on the selected frequency, the switching speed of the transistor and diodes.
The value of the induction will leave 0.12 Tesla.
Let's determine the losses on the transformer and active elements. Set the voltage drop on the diode 0.5 V.
Before pressing the CALCULATE button, the primary and secondary windings are not defined.
After clicking the CALCULATE button, the Transformer Wizard calculates the turns of the primary and secondary windings.
In this case, you can estimate core losses at minimum and maximum input voltages.
Reduce the losses in the core, increasing the number of turns of the primary winding. Increase the number of turns of the primary winding to 13 in the graph Selection.
To recalculate the parameters of the transformer with a new number of turns of the primary winding, press the SELECT button.
After pressing the SELECT button, the secondary windings of the transformer are recalculated.
In this case, the losses in the transformer core are reduced.
The induction decreases with increasing turns of the primary winding.
This calculation will be considered satisfactory and click APPLY.
Now we have moved on to the calculation of the transformer windings. As you can see, the application highlighted in red the buttons for setting the parameters of the ring and windings 1 and 2. Let's start by setting the ring sizes. Press the CORE CHOICE button.
On the ring selection screen, the k12x8x3 core selected in the transformer Wizard is already preinstalled.
Since we selected a ferrite core without coating, it is necessary to perform its isolation. Enter the thickness of the core insulation 0.15 mm and press the CALC button.
As a result we calculate the size of the core with insulation:
the outer diameter D of
inner diameter d
the height h
Hit the SET button.
The indicator next to the CORE CHOICE button turned green, and the dimensions of the core are displayed to the right of the button. Now to calculate the primary winding, press the WINDING 1 button.
The winding calculation screen already contains the data transferred from the Transformer Wizard:
number of turns = 13
current = 3.395 A
number of windings simultaneously wound = 1 (for push-pull the number of windings would be 2)
the number of wires in Ext. wind = 1 (this is the recovery winding)
Select from the list of wire 0,180, specify the number of wires = 5. Tails - the length of the leads after winding. Will do tails on 20 mm. Click CALC button. We see that the wire was laid in 1 layer, and there is still free space in the inner layer for winding another 5 turns.
Also, the current density will be 26.68 A / mm2. In this case, the losses in the wire will be 0.3261 watts.
To reduce losses in the wire, change its diameter by 0.200. The number of wires will increase to 7. Press the CALC button. We see that the wire was laid in 2 layers, and there is still free space in the upper inner layer for another 10 turns.
The number of wires will increase to 11. Press the CALC button. The wire was laid in 2 layers, in the last inner (inner diameter) layer, the number of freely turns will be 1.
Press the winding SCHEME OF WINDING button. The inner diameter of the winding was laid in 2 layers. In the first layer, 7 turns were laid along the inner diameter, in the second - 6 turns. All 13 turns of the winding were laid in 1 layer on the outer diameter. Close the SCHEME OF WINDING window with the BACK button.
The current density is now 9.82 A / mm2. Losses in the wire 0.1243 W. Hit the SET button.
The indicator next to the WINDING 1 button turned green, and to the right of the button the dimensions of the transformer after winding the primary winding are displayed. Now to calculate the secondary winding, press the WINDING 2 button.
The winding calculation screen already contains the data transferred from the Transformer Wizard:
number of turns = 51
current = 2 A
number of windings simultaneously wound = 1 (for push-pull the number of windings would be 2)
the number of wires in Ext. wind. = 0
Select from the list of wire 0,180, specify the number of wires = 8, make the tails of 20 mm. Specify the thickness of the insulation 0.05 mm. Click CALC button. We see that the wire was laid in 5 layers along the inner diameter, in the last inner layer the coils took all the place, the number of freely turns = 0.
The current density is 9.82 A / mm2, losses in the wire 0.3657 W.
Click the SET button.
The indicator next to the WINDING 2 button turned green, and the dimensions of the transformer are displayed to the right of the button.
Greetings! The transformer calculation is finished. To view the winding data in a more convenient way, click the SUMMARY button.
On the SUMMARY screen, the arrow buttons are used to navigate. On the left side of the screen, Roman numerals indicate the windings, the letter C-the core. Here you can see such parameters as losses in the wire, the length of each winding wire, the mass of all wires, etc.
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