This is the Fardriver inverter ND72850, that controls the main motor.
Fardriver is a very popular inverter due to its easy setup and still has a lot of advanced function.
It has an App where you can setup all parameters.
On youtube there are a lot of videos showing how it works.

This forum on facebook is also very helpful if you have any questions:
https://www.facebook.com/groups/fardriver

Motor and Inverter is availiable as a kit on aliexpress.com