LLC converter unsuitable for electric vehicle battery charger?

[treez]

The following article clearly states that electric vehicle battery chargers using LLC converters have a totally different design algorithm, that if not followed, results in failure of the battery charger. This algorithm is complex. Is this why electric vehicle battery chargers, when searched for on the internet, are almost never done as LLC’s, but instead as Phase shift full bridge’s?

“Optimal design of line level control resonant converters in plug-in hybrid electric vehicle battery chargers”

(ietdl.org)

**broken link removed**

Equation 17 of the article tells how the resonant capacitor value can be calculated to be safe with the LLC, but there is a parameter "alpha" in this equation, and the value of "alpha" is unknown. I appears to be a time interval shown on page 4 but is value is hard to calculate, do you know how to calculate alpha?

 

[Easy peasy]

It's just that PS-FB is very straight forward to design and no hidden control issues for dynamic loads and short circuits, also less parts, current mode control makes FS-FB bullet proof, a LOT more testing is required for LLC at high powers as sudden shorts put a LOT of current through the main switches...!