Inverter generator
An inverter generator converts its alternator’s raw output to DC and re-synthesizes clean AC electronically, producing low-distortion power at any engine speed. The result is quieter operation, better fuel economy at partial load, and output safe for sensitive electronics.
Because the AC waveform is synthesized rather than tied to engine RPM, the engine can throttle down when demand is light — the source of both the fuel savings and the low noise. Conventional generators must hold ~3600 RPM constantly to keep 60 Hz output.
The trade-offs are price per watt and size at the top end: most inverter models are under 8 kW. For laptops, CPAP machines, and modern furnace controls, the low total harmonic distortion is the deciding feature.