T
treez
Guest
Hello,
We are doing a Current mode, DCM Full Bridge SMPS,
VIN=390VDC (PFC output) ;
VOUT=400VDC max;
Pout=100W max ;
Application=100W LED lamp
(V(LED) = 340-400VDC at 250mA);
F(sw) = 100KHz
Dimmable down to 10W.
Mains isolation
We have chosen to do the Full Bridge as a DCM Full Bridge.
The reason for DCM is because CCM Full bridge’s suffer the problem where the bottom/top FET in a ‘leg’ gets spuriously turned ON when the top/bottom FET in the same leg turns ON..resulting in momentary ‘shoot-through’ current.
This can be avoided in a DCM Full Bridge because the turn-on of a DCM full bridge can be heavily damped (slowed) so that this spurious effect does not happen. Heavily damping the turn-on in a DCM full bridge does not incur heavy switching losses because turn-on involves zero current.
Do you agree that this is the best plan?
LTspice Simulation of DCM , Current mode Full Bridge SMPS provided.
We are doing a Current mode, DCM Full Bridge SMPS,
VIN=390VDC (PFC output) ;
VOUT=400VDC max;
Pout=100W max ;
Application=100W LED lamp
(V(LED) = 340-400VDC at 250mA);
F(sw) = 100KHz
Dimmable down to 10W.
Mains isolation
We have chosen to do the Full Bridge as a DCM Full Bridge.
The reason for DCM is because CCM Full bridge’s suffer the problem where the bottom/top FET in a ‘leg’ gets spuriously turned ON when the top/bottom FET in the same leg turns ON..resulting in momentary ‘shoot-through’ current.
This can be avoided in a DCM Full Bridge because the turn-on of a DCM full bridge can be heavily damped (slowed) so that this spurious effect does not happen. Heavily damping the turn-on in a DCM full bridge does not incur heavy switching losses because turn-on involves zero current.
Do you agree that this is the best plan?
LTspice Simulation of DCM , Current mode Full Bridge SMPS provided.