I wanted to confirm if the design for PSFB Transformer is same as that of Full Bridge DC-DC Transformer. Are there any references for the PSFB Transformer Design.
So if we estimate the calculate the primary and secondary currents then we will be able to design transformer. What about the volt-sec. Is there any good reference for the Transformer Design of PSFB
..yes , PSFB keeps a high circulating current which is needed to discharge and charge the vds caps of the pri fets so as to bring about zvs...especially zvs at lighter loads.
Hello, The Phase Shift Full Bridge (PSFB) converter is a hoax. –The LTspice simulation attached of a “plain” Full Bridge SMPS bears this out. PSFB claims to be able to reduce switching losses compared to the “plain” Full Bridge SMPS. However the PSFB does have Turn-OFF switching losses, just...
www.edaboard.com
It shows that a external leakage L is required...so really, consider sandwich winding the PSFB transformer since you will be likely using an external L(leak).
at higher powers ( at any power level ) simple primary over secondary winding increases leakage but also AC resistance of wire - leading to quite a lot of heating at higher frequencies and currents ...
..yes , PSFB keeps a high circulating current which is needed to discharge and charge the vds caps of the pri fets so as to bring about zvs...especially zvs at lighter loads.
Hello, The Phase Shift Full Bridge (PSFB) converter is a hoax. –The LTspice simulation attached of a “plain” Full Bridge SMPS bears this out. PSFB claims to be able to reduce switching losses compared to the “plain” Full Bridge SMPS. However the PSFB does have Turn-OFF switching losses, just...
www.edaboard.com
It shows that a external leakage L is required...so really, consider sandwich winding the PSFB transformer since you will be likely using an external L(leak).
Thanks for reply. But can you refer me to any design note for the transformer. In Full bridge the volt-sec is calculated based on switch on time. But in PSFB there is no concept of duty ratio, Then how do we obtain volt-sec in primary for design of Transformer.
For the transformer, you can think of it being like a full bridge, btu just design for the true rms current, which includes the circulating current.
The PSFB is like a full bridge in many ways...its just that the current is kept circulating at a high level so as to allow it to be high enough to discharge the vds caps to give zvs.
Ill get you a sim of a PSFB..
..and in there there is a phase shift full bridge folder in which there are some ltspice sims for you to play with if you want.
--- Updated ---
for a duty cycle you have an "On time" and OFF time right?
Well look at the sim, and you will see times when diagonally opposite fets are on together...that time is the ON time....the rest of the switching period is the OFF time.
For the transformer, you can think of it being like a full bridge, btu just design for the true rms current, which includes the circulating current.
The PSFB is like a full bridge in many ways...its just that the current is kept circulating at a high level so as to allow it to be high enough to discharge the vds caps to give zvs.
Ill get you a sim of a PSFB..
..and in there there is a phase shift full bridge folder in which there are some ltspice sims for you to play with if you want.
--- Updated ---
for a duty cycle you have an "On time" and OFF time right?
Well look at the sim, and you will see times when diagonally opposite fets are on together...that time is the ON time....the rest of the switching period is the OFF time.