Push-Pull SMPS spikes recuperation

[IVX]

I just wondered is this approach patented, or does exist any other reason to not use it? Why so simple trick still not popular? L1;L2 are primary power winding, L2;L3 aux winding about same turns and 1/10 of primary power copper.

[Eva]

I think this approach is not routinely used due to complexity. In general, if a low enough leakage inductance is achieved in the transformer, no additional clamping is required.

Note that if the output is regulated, output inductors will tend to "short" the transformer after primary side switch turn-off, which leaves some headroom for leakage inductance spikes without exceeding two times the supply voltage on the drains. This is true for forward converters too.

[carampsguru]

Hello,
it works pretty well as long as it is designed properly and the parasitic inductances are minimized(SMD components and good PCB layout).Adds complexity,but i think it is worth it.Don't know if it is patented.

[star882]

If the output voltage is always significantly higher than the input voltage, no isolation is needed, and it is acceptable to have input voltage (minus a few diode drops) on the output when it is off, a much simpler energy recovery circuit can be used. Simply connect two rectifiers from the MOSFET drains to a capacitor to ground. Then connect the low side of the secondary rectifier to the capacitor.

[IVX]

star882, I'm not sure if I understand correctly, but of course GND isolation is preferable, without it I like to use boost topology as most effective and compact.

carampsguru, why Kicker still don't use it?