Electric Motor-drive type/setup recommendations needed. I need 90,000 rpm at the output shaft @ a power of 30kW.?
The turbo's compressor impeller can spin that fast because it is fairly small in diameter and made from lightweight, high-strength materials.

Motors, by their nature, need magnetics, so that restricts the armature material choices somewhat. As a result, a motor suitable for that kind of RPM would have to have a long, skinny armature to withstand the forces at high RPM. And if you look at the KERS motor-generators used for turbos on F1 cars, that's exactly what they look like.

Here's an example of a 'hybrid' turbo from Magnetti Marelli:


Link: http://speed.academy/future-boost-hybrid-turbochargers-and-thermal-energy-recovery-systems/2/

Being a hybrid system, this is a bit different than what you're asking. Nevertheless the design challenge is the same: developing a motor armature that can spin at turbo speeds with enough armature coil flux capacity to handle 30KW and not fry itself in the process.

There's another possibility: use a gearbox to step up the turbo speed from the motor. This relaxes some constraints on the armature, at the expense of some losses in the gears.

That said, real (not hokey bolt-on) electric superchargers are coming to production cars. More here: https://www.garrettmotion.com/electric-hybrid/garrett-e-turbo/

These will tend to show up on hybrid cars. Why? Hybrids have high-voltage high-current power available - a big advantage for high-powered motors, like the 40HP motor you propose.