Siemens SINAMICS S120 Function Manual page 264

Vector control
5.15 Efficiency optimization
Simple efficiency optimization (method 1)
For p1580 = 100%, the flux in the motor under no-load operating conditions is reduced to
half of the setpoint (reference flux) (p1570/2). As soon as load is connected to the drive, the
setpoint (reference) flux increases linearly with the load and, reaching the setpoint set in
p1570 at approx. r0077 = r0331 · p1570.
Figure 5-21
In the field-weakening range, the final value is reduced by the actual degree of field
weakening. The smoothing time (p1582) should be set to approx. 100 to 200 ms. Flux
differentiation (see also p1401.1) is automatically deactivated internally following
magnetization.
Figure 5-22
264
Efficiency tuning
Basic efficiency optimization
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Drive functions