Efficiency Optimization - Siemens SINAMICS G120D Operating Instructions Manual

8.24

Efficiency optimization

Overview
The efficiency optimization reduces the motor losses as far as possible.
Active efficiency optimization has the following advantages:
• Lower energy costs
• Lower motor temperature rise
• Lower motor noise levels
Active efficiency optimization has the following disadvantage:
• Longer acceleration times and more significant speed dips during torque surges.
The disadvantage is only relevant when the motor must satisfy high requirements relating to the
dynamic performance. Even when efficiency optimization is active, the converter closed-loop
motor control prevents the motor from stalling.
Requirement
Efficiency optimization functions under the following preconditions:
• Operation with an induction motor
• Vector control is set in the converter.
Function description
Figure 8-64
The three variables that the converter can directly set, which define efficiency of an induction
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.
Converter with the control units CU240D-2
Operating Instructions, 10/2020, FW V4.7 SP13, A5E34262100B AH
Efficiency optimization by changing the motor flux
Advanced commissioning
8.24 Efficiency optimization
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