Nearly all the brushless motors on bikes are 3-phase BLDC.
In this forum, there is a list of sticky threads that have quite a bit of info on ebike motors and controllers, how they work, etc. I'd recommend those as a first reading.
There is also a wiki, linked in threads at the top of every forum, that has some of the same info and more.
There's also dozens (hundreds) of motor and controller modification and repair threads with more detail on specific ones.
https://endless-sphere.com/forums/searc ... mit=Search
finds a number of posts that mention VFD, don't know if any of them cover the info you're after.