T
treez
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Full Bridge SMPS ….why so much better than "identical" 2 Transistor Forward?
Hello,
The attached shows two LTspice simulations (schematics also included). One is a Full Bridge SMPS, the other is a Two Transistor Forward converter. They both are in DCM, currentmode, and at 100khz = F(sw) , pout=100W.
The transformer turns ratio, on-time and output inductor are the same for each converter. The primary and secondary currents are the same also. The transformer leakage inductances are the same, so are the RC snubbers across the secondary diodes.
Also, vout, vin and pout are the same for each converter.
However, the Full Bridge SMPS suffers far less overvoltage ringing than the Two Transistor Forward converter on its secondary diodes. (600V versus 1000V) Also, the total dissipation in the secondary-side snubber resistors is far less with the Full Bridge SMPS than the Two Transistor Forward. (0.6W total versus 1.8W total ).
Why is this?
Hello,
The attached shows two LTspice simulations (schematics also included). One is a Full Bridge SMPS, the other is a Two Transistor Forward converter. They both are in DCM, currentmode, and at 100khz = F(sw) , pout=100W.
The transformer turns ratio, on-time and output inductor are the same for each converter. The primary and secondary currents are the same also. The transformer leakage inductances are the same, so are the RC snubbers across the secondary diodes.
Also, vout, vin and pout are the same for each converter.
However, the Full Bridge SMPS suffers far less overvoltage ringing than the Two Transistor Forward converter on its secondary diodes. (600V versus 1000V) Also, the total dissipation in the secondary-side snubber resistors is far less with the Full Bridge SMPS than the Two Transistor Forward. (0.6W total versus 1.8W total ).
Why is this?