It is not enough only to compare the preset value (|Fs|*) and the real one (|Fs|) of the modulus of the stator flux, without considering a hysterezis.
The hysterezis limits the frequency of the changes of the controller's output and, consequently, the switching frequency of the inverter.
The value of the hysterezis must be correlated with the commutation speed of the inverter's semiconductors. It can be as small as possible (ideally zero), as the semiconductors are faster (figure 2).
Figure 2
