Not sure what 'app' you are using.
Do you have the specs on the core you are thinking about using?
Also, snubbers are usually used to catch the fast rising back emf from the primary as a transistor turns off. The reverse diode of the other transistor will catch part of it but that depends on goo coupling which is not as tight when there is leakage inductance. The snubbers protect the transistors.

If you click expand on my previous comment it should bring up the pictures with the appropriate information.
Kind regards ,
Rick

 

Hi,

Do those mosfets have internal reverse diodes? Those should be included.

Also, usually some kind of snubbers are employed to snub out the fast back emf.

Of course the transistors have built-in diodes. The coupling coefficient between the two halves of the primary winding I took 0.995. Since this winding is wound with two wires folded together, the coefficient can be higher.
Maybe you are right and you need to add a snubber. I will try to do a simulation of this on Monday.

 

Of course the transistors have built-in diodes. The coupling coefficient between the two halves of the primary winding I took 0.995. Since this winding is wound with two wires folded together, the coefficient can be higher.
Maybe you are right and you need to add a snubber. I will try to do a simulation of this on Monday.

Hello,

The reverse diode on the 'off' transistor takes effect when the 'on' transistor just starts to turn off. The effectiveness of this diode to clamp the high voltage spike on the transistor just turning off depend on the coupling but there could be some back emf that does not couple fast enough and so we get some high voltage spike across the collector emitter. The only way to get rid of this is with a snubber of some kind. The snubber will use a high speed diode that will conduct into a decent size capacitance and that will store some of the energy which later is either dissipated in a power resistor and/or partially recycled back into the DC buss. We could get lucky i guess but it doesnt look like that here.

 

If you click expand on my previous comment it should bring up the pictures with the appropriate information.
Kind regards ,
Rick

Well then do you have a core picked out? If so maybe you could display the specifications or data sheet.

 

Well then do you have a core picked out? If so maybe you could display the specifications or data sheet.

Couldn't find the data sheet but here is the basics.PC40

• Product Name: EE35 Vertical Ferrite Core Transformer Bobbin 6+6Pin
• Type: EE35 ; Pin spacing: 5mm/0.2''; Row spacing: 19.7mm/0.7"; Ferrite core Size: 34 x 10 x 13.5mm/1.3" x 0.4" x 0.5"(L*W*T); Bobbin size: 38 x 24 x 32.5mm/1.4" x 0.9" x 1.4"(L*W*H).

 

Couldn't find the data sheet but here is the basics.PC40

• Product Name: EE35 Vertical Ferrite Core Transformer Bobbin 6+6Pin
• Type: EE35 ; Pin spacing: 5mm/0.2''; Row spacing: 19.7mm/0.7"; Ferrite core Size: 34 x 10 x 13.5mm/1.3" x 0.4" x 0.5"(L*W*T); Bobbin size: 38 x 24 x 32.5mm/1.4" x 0.9" x 1.4"(L*W*H).

View attachment 236626

HI,

Ok then the area is the area of the center leg, which is C*D which is 95 square mm which is roughly 1 square centimeter.
I could not find any other data though so you'll have to experiment a little. Winding some turns, look for saturation at the required frequency. Once you know the turns, calculate if you have enough window area for the total number of turns including winding factor and tape and all that.