Generally you wouldn’t want a generator solely for the purpose of operating an air compressor, but rather one that is able to run other appliances in your workplace. Therefore going for a fixed size air co.
[pdf] Uses a dedicated variable frequency drive (VFD) for permanent magnet synchronous motors, enabling stepless speed regulation, constant pressure air supply, and soft start. This eliminates idle power consumption and enables intelligent air supply.
[pdf] Permanent magnet motors (PMMs), especially permanent magnet synchronous motors (PMSMs), have become a game-changer in air compressor systems. These motors use strong rare earth magnets, like neodymium-iron-boron (NdFeB), to make a steady magnetic field.
[pdf] 
