switching transformer

[MacIntoshCZ]

Added poly caps near reset diodes, parralel to 300V
Still get hot

 

[MacIntoshCZ]

I just calculated that with 300V 50khz 50% duty cycle i am at 165mT
0.000024*150k = 3,6W

 

[MacIntoshCZ]

Maybe primary inductance was not big enough to reset core fully. With 1 forward topoly core doest get hot i think
First transformer has Lmag 1,5mH
Eq from presentation : 300/(0,5/(0,1/50000)) = 1,2mH ???
It should be rrght

https://www.onsemi.cn/pub/Collateral/TND378-D.PDF

 

[ronsimpson]

Some/much of the ringing is from the long wires to the transformer.
Copper loss: It looks like the winding area is not full. Your outside winding is two wires and you might have room for 3 wires.
Core loss: You can try increasing the turns. This will decrease the volts/turn.

 

[MacIntoshCZ]

Some/much of the ringing is from the long wires to the transformer.
Copper loss: It looks like the winding area is not full. Your outside winding is two wires and you might have room for 3 wires.
Core loss: You can try increasing the turns. This will decrease the volts/turn.

I Will try to rewind IT.

 

[MacIntoshCZ]

I rewound transformer.
39 turn primary 3x 0,3mm diamater wire
16 turn secondary 6x 0,3mm d. wire
It still gets hot.