Siemens SINAMICS G130 Engineering Manual page 16

Fundamental Principles and System Description
Engineering Information
With introduction of firmware version V2.3 and simultaneous modification of the CIB board hardware (interface
module between the Control Unit and power unit), pulse-edge modulation has been available as a standard feature
on the following SINAMICS units in vector control mode since autumn 2005:
•
SINAMICS G130* Chassis
•
SINAMICS G150* Cabinets
•
SINAMICS S150* Cabinets
•
SINAMICS S120* Motor Modules / chassis format
•
SINAMICS S120* Motor Modules / Cabinet Modules format
At low output frequencies and low depth of modulation, i.e. at low output voltage, these products utilize the space
vector modulation SVM option and switch automatically over to pulse-edge modulation PEM if the depth of
modulation required at higher output frequencies is so high that it can no longer be provided by space vector
modulation (output voltage > 92 % of input voltage).
In principle it would be possible to reach an output voltage of over 92% through overmodulation of the space vector
modulation (SVM). However, through doing this, the harmonics spectrum in the motor current would increase
considerably, which would lead to higher torque ripples and noticeabley higher motor losses. Therefore, SINAMICS
units operating in the vector control mode use pulse-edge modulation with optimised pulse patterns in order to
achieve optimum drive behaviour with regard to torque ripples and motor losses.
* Exceptions:
•
Parallel converters on which two or more power units operating in parallel are supplying one motor with a
common winding system. Under these conditions pulse-edge modulation cannot be selected.
If either a Basic or Smart Infeed is used to supply the inverter, the following formulas apply for the DC link
voltage at full load: V
DCLink
edge modulation is limited to 92 % of the line input voltage.
If an Active Infeed is used to supply the inverter, the following formula applies to the DC link voltage because the
Active Infeed utilizes a step-up converter function: V
This means that the maximum output voltage even without pulse-edge modulation can correspond to 100 % of
the line input voltage or higher if the parameters of ratio V
Active Infeed. This is described in the section "SINAMICS Infeeds and their properties", subsection "Active
Infeed".
•
Converters with output-side sine-wave filter. Pulse-edge modulation cannot be selected under these conditions.
If either a Basic or Smart Infeed is used to supply the inverter, the following formulas apply for the DC link
voltage at full load: V
limited to 85 % of the line input voltage for units with a supply voltage of 380 V to 480 V 3AC and to 83 % for
units with a supply voltage of 500 V to 600 V 3AC.
If an Active Infeed is used to supply the inverter, the following formula applies to the DC link voltage because the
Active Infeed utilizes a step-up converter function: V
This means that the maximum output voltage even without pulse-edge modulation can correspond to 100 % of
the line input voltage or higher if the parameters of ratio V
Active Infeed. This is described in the section "SINAMICS Infeeds and their properties", subsection "Active
Infeeds".
Note:
•
Pulse-edge modulation PEM is only available in vector control mode. In servo control mode, the converters
always operate with space vector modulation (SVM). The reason for this is the slight lower dynamic performance
of the drive when it is operating with pulse-edge modulation. This can be accepted in almost all vector control
applications, but not in high-dynamic servo control applications.
•
With the introduction of Firmware version V2.5 SP1 and the simultaneous changing of the hardware, pulse-edge
modulation is available as standard also for Booksize units since autumn 2007.
SINAMICS Engineering Manual – May 2008
16/396
© Siemens AG
≈ 1.32 • V
resp. 1.30
Line
≈ 1.32 • V
resp. V
DCLink Line
• V . Therefore the maximum output voltage without pulse-
Line
> 1.42 • V (factory setting: V
DCLink Line
/ V are set to sufficiently high values on the
DCLink Line
= 1.30 • V . In this case, the maximum output voltage is
DCLink Line
> 1.42 • V (factory setting: V
DCLink Line
/ V are set to sufficiently high values on the
DCLink Line
= 1.5 • V ).
DCLink Line
= 1.5 • V ).
DCLink Line