 ATTENTION: The program is intended only for calculating the forward converter transformer under the condition that the output choke (inductor) operates in continuous current mode. For this case, the magnetic core of the transformer operates in bipolar mode and it is possible to use double amplitude of induction. To ensure continuous current mode when disconnecting the load, it is necessary to load additionally the output in the converter circuit itself and increase the inductance of the output inductor. In the case when operation in the mode of discontinuous currents is allowed, the developer must take special measures to exclude core saturation and ensure a margin of induction amplitude.


	On some entry fields and on some calculation results that need comments, the tooltips are placed.
The content of these tips actually repeats the help points.

	1. Main work in the program takes place in the "Optimization" group.
Automatic calculation is used when choosing a different core or when changing any initial data (outside the "Optimization" group) to obtain a starting point for optimizing the transformer winding data. 	
	2. In the "Optimization" group, when changing values using the arrows, the start of optimization begins automatically. But if the new value is entered "manually", then optimization should be started with this button.
	3. The controllers UC3844 and the like with a operating time of not more than 50% should be used or push-pull controllers, but use only one output.
	4. The fill factor of the window characterizes how much of the core window the copper of all windings will occupy.
	5. The current density depends on the cooling conditions and on the dimensions of the core.
For free cooling, choose 4-6 A / mm2. 
During ventilation, the current density can be selected more, up to 8 - 10 A / mm2.
Large current densities correspond to small cores. 
For forced cooling, the permissible current density depends on the intensity of cooling.	
	6.  If stabilization of the output voltage is selected, the first output is the leading one. And it must be assigned to the output with the highest consumption. The remaining outputs are counted according to the first one.
	7. At the minimum, nominal and maximum output voltages, the tooltips with voltage amplitudes on the secondary windings are placed, respectively, at the minimum, nominal and maximum supply voltages.
	8. If stabilization operation is selected, then the minimum and maximum output voltages are absent and, accordingly, are not shown.

RECOMMENDED OPERATION PROCEDURE:

	1. Decide on the power of the converter. Set the possible limits of the input power supply of the converter, taking into account fluctuations in the line. User can select AC or DC input voltage.
	2. Set the winding sequence of the primary winding.
	3. Set the output voltages and currents, the voltage drop across the rectifier diodes. The program provides up to three outputs.
	4. Decide on the availability of the demagnetizing coil. Excess winding degrades performance of the transformer.  Special circuitry decisions are adopted often to exclude the demagnetization winding. To determine correct the diameter of the demagnetizing winding, you need to specify a knowingly small diameter (the minimum diameter according to the table of diameters is 0.063 mm), then the program itself will increase the diameter to the required one. If the diameter is set larger than required, the program does not take any action. If winding is not required (for example, an oblique half-bridge), set "0". Then the installation of the demagnetizing winding is not calculated by the program.
	
	5. Set the limit value of the pulse fill factor (cannot be more than 0.5). For the case with no PWM stabilization, the maximum pulse fill factor is determined by the controller used. For example, 0.45 for UC3844. If PWM stabilization is used in the circuit, then a real, much smaller value can be indicated, which, with a working PWM circuit, will not be exceeded for a long time. A lower fill factor will reduce the size of the transformer.

	6. Set the channel resistance of the open power switch (used for field transistors) of the converter or the voltage drop across it (used for bipolar transistors or IGBT).

	7. Set the window fill factor. It characterizes the filling of a torus hole with a wire. If it is practically not possible to wind through the estimated number of turns, the duty cycle should be reduced and the calculation repeated. And vice versa, if it is possible to lay the windings with a higher fill factor, it is possible to use a smaller and cheaper core.
	
	8. Set the current density. It determines the diameter of the wire. Low values reduce losses in the winding, but increase size of the core because these windings cannot be placed on a small core. High density values increase winding loss and overall overheating. But at the same time, it is often possible to use a smaller size of the core. Usually for a specific task there is an optimum. Therefore, it is recommended to perform a series of calculations, changing the set density value by step. Say, from 3 to 10 in steps of 1. For some density value from the interval, a reasonable overheating will occur at a minimum size. Further, when specifying the calculations in the “Optimization” group, it is possible  to change the diameters of the winding wires in an optimal way, evaluating the total overheating, i.e. use a different current density in each winding.

	9. Set the limit ambient temperature.	
	10. Set the number of cores in the package. Sometimes it is required to use several cores to increase power or for other tasks (for example, use two small cores instead of a large size).
	11. Set the expected transformer temperature. The maximum temperature is 120 degrees C. The user can set lower values of the expected temperature if high temperature of the transformer is not desirable for some reason. When calculating the project, the program will not exceed this set value.
	12. Set the maximum Rac / Rdc. With a small value of this ratio, the program will use a large number of wires in parallel to reduce the skin effect. This is not always optimal for design reasons and for reasons of minimizing dimensions. With a large value, the minimum value of the wires in the winding will be obtained, but at the same time, it is possible that the use of the wire will be suboptimal due to the skin effect. In particular, it is possible to simulate the use of special high-frequency stranded wires with insulation of each core. To do this, set the number of cores and the diameter of the cores in the Optimization group. The use of a rectangular wire profile is not provided in the program. Alternatively, you can recalculate the total cross-sectional area of the wire into the cross-sectional area of the wire of a rectangular profile (busbar).	
	13. Press the button "Automatic selection of the core and its calculation". The program will select the core from a given series and give the calculated results.
	14. Designing a transformer is a complex task with many variables. Each user has their own optimum criteria. For one, this is the price and size, for the other - maximum efficiency, for the third - minimum leakage inductance and parasitic parameters (in order to reduce electromagnetic interference and reduce damping elements of high-frequency emissions - dampers), for the fourth - minimal overheating, for the fifth - manufacturability and minimum labor and so on. And more often it is a combination of criteria. Therefore, the result of the calculation can be considered only the initial stage of the project. The main work is performed by the user in the "Optimization" group. The user can select a smaller or larger size of the core (or specify the exact size), change the diameters of the wires of the windings, the number of wires in the windings, the number of turns of the primary winding. By consciously changing this data, and observing the change in individual optimization criteria, you can significantly improve the project according to your requirements.	
	15. The completed project can be saved to disk for later download.
	16. Final verification and refinement of the project are carried out by practical testing in a real scheme.

	You can send the errors noticed, your questions, comments and suggestions to edf01@yandex.ru