Cottonwood
Roadster#433, Model S#S37
I seriously doubt there are 3 "sub-chargers" in each module. It's likely just 2 additional diodes in the front end (3 phase full wave bridge) before PFC.
The THD limits on the current waveforms and the very high power factor for the AC->DC conversion imply a design that is much more sophisticated than a diode bridge on the input. The Current THD and power factor limits that Europe imposes require very close to a resistive load or its simulation. To meet those requirements, my guess is that there are three sub modules as FlasherZ suggests, and that each submodule has a sophisticated voltage/current converter that simulates the draw of a resistive load.