cupoftea
Advanced Member level 5
Do you agree that of all the topologies, the Half Bridge SMPS gives the most ripple current stress to its immediately local input capacitors?
Please allow me to explain…
Consider, if you will, a 750W offline Half Bridge (after a 400Vout PFC) where there are say two 6u8 Film caps in the rail splitting capacitor leg of the Half Bridge……upstream of this, say there is a 220uF electrolytic capacitor bank………now consider a 750W Full Bridge, with the same two 6u8 film capacitors (this time in pllel) near to the bridge, and then the same 220uF electrolytic cap bank upstream of that……Now, the Full Bridge will take a significant portion of its ripple current from the electrolytic capacitor bank, and the two pllel’d 6u8 film caps near to the full bridge will be somewhat spared……however, in the case of the Half Bridge…even though the same ‘lytic cap bank exists upstream, the two 6u8 film caps acting as rail splitters will take the full ripple current of the Half Bridge…as such, the stress on these film capacitors is far greater in the case of the Half Bridge…would you agree?
LTspice if a Half Bridge attached.
Please allow me to explain…
Consider, if you will, a 750W offline Half Bridge (after a 400Vout PFC) where there are say two 6u8 Film caps in the rail splitting capacitor leg of the Half Bridge……upstream of this, say there is a 220uF electrolytic capacitor bank………now consider a 750W Full Bridge, with the same two 6u8 film capacitors (this time in pllel) near to the bridge, and then the same 220uF electrolytic cap bank upstream of that……Now, the Full Bridge will take a significant portion of its ripple current from the electrolytic capacitor bank, and the two pllel’d 6u8 film caps near to the full bridge will be somewhat spared……however, in the case of the Half Bridge…even though the same ‘lytic cap bank exists upstream, the two 6u8 film caps acting as rail splitters will take the full ripple current of the Half Bridge…as such, the stress on these film capacitors is far greater in the case of the Half Bridge…would you agree?
LTspice if a Half Bridge attached.