Why aren't all full bridge converters done as Phase shift full bridge's instead?

Hello,
Why aren’t all Full Bridge converters implemented as Phase Shift Full Bridge converters instead?
I mean, control IC’s to manage the phase shift full bridge switching are very commonplace and cheap now.
And the Phase Shift Full Bridge has one huge difference compared to all other resonant converters…that is, the Phase Shift Full Bridge doesn’t work badly if one completely mismanages the resonant element sizing. (for the Phase Shift Full Bridge converter, the resonant element is the leakage inductance in the transformer). Even if you get far too little leakage inductance, it does no harm, but will just hard-switch like a normal full bridge, so there’s absolutely nothing lost when compared to a normal full bridge.

So why is anyone still using the Plain old Full Bridge topology now?

I mean, one of the problems with a Plain old Full Bridge topology is that when the bottom transistor of a leg turns on, the top transistor is often spuriously turned on due to charging currents in its internal device capacitances……..this is unlikely to ever happen in a Phase Shift Full Bridge converter, since there’s always going to be some transformer leakage, and so generally the device capacitance of the top fet is virtually certain to have already charged up by the time the bottom fet turns on, thus alleviating the spurious shoot-through problem.


You just can’t loose with a Phase Shift Full Bridge converter, so why is anyone still using the Plain old Full Bridge topology?

-OK I think I have found the answer now...its as follows...Do you agree?
...I am disillusioned with the Phase Shift Full Bridge converter. Please tell me I am wrong to be?

I find that if there is too much current referred to the primary from the secondary during the intervals where the output inductor is discharging, then you do not achieve zero voltage switch-ON of the primary side FETs.
Thus you have more chance of achieving zero voltage FET switch-ON if you have a low NS/NP value for your transformer, and your load is lighter.

If you cannot achieve zero voltage FET switch-ON of the primary side FETs, then you can solve this by increasing the leakage inductance in the transformer (or by adding an extra auxiliary inductor in series with the primary).
-However, if you do add such ‘extra leakage inductance’, then you end up with more dissipation in the secondary side RC snubber resistors.

So I am wondering, whether the Phase Shift Full Bridge converter is really that good after all?
Why do the semico’s not give these downsides in their PWM controller IC datasheets?

It appears to me that the Phase Shift Full Bridge converter is really only suited for very high ratio step-down applications, whose load current is not too high?

The attached LTspice simulation demonstrates the problems.