Siemens SINAMICS G115D Operating Instructions Manual page 301

Function description
The three variables that the converter can directly set, which define efficiency of an
asynchronous motor, are speed, torque and flux.
However, in all applications, speed and torque are specified by the driven machine. As a
consequence, the remaining variable for the efficiency optimization is the flux.
The converter has two different methods of optimizing the efficiency.
Efficiency optimization, method 2
Generally, energy efficiency optimization method 2 achieves a better efficiency than
method 1.
We recommend that you set method 2.
Based on its thermal motor model, the converter continually determines - for the actual
operating point of the motor - the interdependency between efficiency and flux. The
converter then sets the flux to achieve the optimum efficiency.
SINAMICS G115D distributed drive
Operating Instructions, 12/2020, FW V4.7 SP13, A5E48681219B-002
Advanced commissioning
6.26 Efficiency optimization
299