Although very efficient, the electric three-phase induction motor has a very simple operation as the electric three-phase induction motor only repeats the grid frequency at which it is attached.
The frequency of the alternating current network is the amount of times this current switches per second and this change can be measured in Hertz 174695.
The oscillating voltage goes directly to the electric motor windings and they form a rotating field and the electric motor of three-phase induction follows this field. Thus, the higher the frequency, the faster the field happen and electric three-phase induction motor is able to rotate faster.
By placing a frequency inverter in the electric motor, this will cause the frequency of the network that feeds the electric motor of three-phase induction to be changed and this will cause the electric motor three-phase induction varies its speed very efficiently.