Siemens SINAMICS G130 Engineering Manual page 330

SINAMICS G150
Engineering Information
Motor with three electrically isolated winding systems and G150 converter with two Motor Modules
The following measures then need to be taken to balance the motor-side currents:
·
Current compensation control in the motor-side inverters.
·
Use of symmetrical power cabling between the two inverters and the motor (cables of identical type with the
same cross-section and length).
·
Decoupling measures at the inverter outputs.
By comparison with the first variant described above, this variant has, like the variant for motors with a common
winding system, the disadvantage that decoupling measures need to be implemented at the converter output in order
to limit potential circulating currents between the parallel-connected inverters. These decoupling measures slightly
reduce the quality of current balance between the inverters.
Adequate decoupling of the inverter outputs can be achieved either by installing cables of the specified minimum
length between the inverter outputs and the motor or, alternatively, by installing motor reactors at the inverter outputs
(option L08). Adequate decoupling is automatically afforded when dv/dt filters plus VPL (option L10) or dv/dt filters
compact plus VPL (option L07) are used. The required motor cable lengths for SINAMICS G150 parallel converters
can be found in the table in the following section.
The motor-side inverters can utilize both space vector modulation and pulse-edge modulation. Pulse-edge
modulation makes it possible to achieve a maximum output voltage which is almost equal to the value of the input
voltage (97 %). (For further details, please refer to chapter "Fundamental Principles and System Description",
sections "Maximum attainable output voltage with space vector modulation SVM" and "Maximum attainable output
voltage with pulse-edge modulation PEM".)
Despite the current-balancing measures described above, it is not possible to obtain an absolutely symmetrical
current distribution which means that the currents of the rectifier sections or inverter sections in a SINAMICS G150
parallel converter are 7.5 % lower than the currents of the individual rectifiers or inverters. Allowance is already made
for this reduction factor in the current values specified in catalog D 11 and in the table shown a few pages above in
this manual.
Parameter p7003 must be set to "0" during commissioning (single winding system).
Operation of G150 parallel converters at motors with one common winding system
The following measures must be taken to balance the motor-side currents:
·
Current compensation control in the motor-side inverters.
·
Use of symmetrical power cabling between the inverters and the motor (cables of identical type with the
same cross-section and length).
·
Decoupling measures at the inverter outputs.
Adequate decoupling of the inverter outputs can be achieved either by installing cables of the minimum required
length between the inverter outputs and the motor or, alternatively, by installing motor reactors at the inverter outputs
(option L08). Adequate decoupling is automatically afforded when dv/dt filters plus VPL (option L10) or dv/dt filters
compact plus VPL (option L07) are used.
SINAMICS Engineering Manual – November 2015
330/528
Ó Siemens AG