Method for obtaining three-gear rotating speed of variable-rotating-speed energy-saving air compressor

The invention provides a three-gear rotating speed obtaining method for a variable-rotating-speed energy-saving air compressor, which comprises the following steps: determining a total power rotating speed range and a 100% volume flow range of a unit during full-load operation according to the limitation of the total power of the whole variable-rotating-speed energy-saving air compressor; according to the relation between the volume flow and the rotating speed, a first rotating speed range corresponding to the 100% volume flow range is determined, a second rotating speed range corresponding to the 70% volume flow range is also determined, and a third rotating speed range corresponding to the 40% volume flow range is determined; determining a reference rotating speed range according to the total power rotating speed range and the first rotating speed range; selecting a reference rotating speed value in a reference rotating speed range according to a set step length, and obtaining a corresponding second rotatin