You can get a vfd from SZBIDOR, if you search Amazon. I have an 8 pole BT30 ATC spindle motor that hits 18k rpm, so it requires a 1200Hz output 3phase 220v supply and my power at the shop is only a single phase 220v source, this vfd does everything I need it to, provides massive torque (for a 3.5kw spindle) at low speeds, so milling any metal from hardened steels through soft alloys like aluminum all the way through high speed needs of plastics, this is quite a good vfd for what you are seeking.