Drive Tuning; Auto Tuning - Siemens 6SR41 series Product User Manual

Application and Operation

6.8 Drive Tuning

6.8 Drive Tuning
Section "Auto Tuning" describes the Auto Tuning feature provided by the NXG control and its
use in determining motor and control parameters. Section "Spinning Load" describes the
setup of the Spinning Load function. This feature is used by the drive control to detect motor
speed by scanning the output frequency over the operating range of the application.
6.8.1

Auto Tuning

The basic motor parameters can be divided into two categories: nameplate data and
equivalent circuit data. Nameplate data, as the name suggests, is readily available (such as
Motor Rated Voltage, Full Load Current, etc.). However, equivalent circuit data (such as
Stator Resistance, No-load Current, etc.) is available only from the motor manufacturer. If
this data is available, it can be entered into the NXG menu system. If this data is not
available, either default settings or Auto-tuning functions can be used.
Note
Auto Tuning is optional, but as stated above, it is recommended for applications in which
high performance is required.
Note
The correct equivalent circuit data is required only when good control performance, such as
high starting torque or very low speed operation, is desired.
When operating an induction motor, the drive control is capable of performing Auto-Tuning.
This feature allows the drive to estimate parameters of the motor equivalent circuit. There
are two stages of auto-tuning, each stage being selected individually. Apart from measuring
the motor equivalent circuit parameters during auto-tuning, the control uses the measured
motor parameters to adjust the control loops for the best possible control bandwidth (the
bandwidth for each control loop is fixed internally in software), and hence provides good
performance in demanding applications. Such a feature provides drive tuning without the
need for an extensive adjustment procedure. Although the auto-tuning feature can be used
with all induction motors, there are some limitations. Both stages of auto-tuning can be
performed with induction motors (OLVC or CLVC).
Only Stage 1 should be performed with Synchronous Motors (SMC or CSMC) or when
Output Filters are connected.
Note
In most general-purpose applications (such as pumps and fans), default data for the motor
equivalent circuit is sufficient and auto-tuning is not necessary.
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Operating Instructions, Version AE 12/2009, A5E01454341C
Product User Manual