Electric Turbo!

I see ZERO advantage, and what you have essentially done here is turn the exhaust powered turbo into a belt drive blower, just like a paxton. WHY? Because the ALTERNATOR is belt drive and it now has to supply the power to spool up the supercharger. And it takes a LOT of power to run a blower.
I understand where you are coming from... I see it as a NOS like device. Where you add boost ONLY when you want. 98% of the time it would not be used. If it was hooked up to a LI battery, like a jump starter battery, (lots of current flow for a short amount of time, but a lot of time between to recharge the batteries) the batteries could be recharged with a low current source.