Siemens SINAMICS S120 - Partial Load Efficiency of S150 Converters

Fundamental Principles and System Description
Engineering Information
SINAMICS Engineering Manual – November 2015
Ó Siemens AG
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1.14.2.7 Partial load efficiency of S150 converters
The charts below show the partial-load efficiency of SINAMICS S150 converters for constant-torque drives. The
calculations are based on a typical efficiency at full load of 96 %. The efficiency is represented in two different ways.
In one chart, the efficiency is shown as a function of the output frequency with the output current as a parameter, and
in the second chart, as a function of the output current with the output frequency as a parameter.
Figure 1a) shows the characteristic curve of the efficiency for constant-torque drives as a function of the output
frequency ratio f
Out
/f
Out-rated
which is proportional to the motor speed ratio n/n
rated
. The parameter for the family of
curves is the output current ratio I
Out
/I
Out-rated
which is proportional to the motor torque ratio M/M
rated
.
Figure 1a)
Efficiency of SINAMICS S150 converters in constant-torque drives
as a function of the output frequency ratio in %
Figure 1b) shows the characteristic curve of the efficiency for constant-torque drives as a function of the output
current ratio I
Out
/I
Out-rated
which is proportional to the motor torque ratio M/M
rated
. The parameter for the family of
curves is the output frequency ratio f
Out
/f
Out-rated
which is proportional to the motor speed ratio n/n
rated
.
Figure 1b)
Efficiency of SINAMICS S150 converters in constant-torque drives
as a function of the output current ratio in %