REXROTH IndraDrive C - Page 262

15-4 Calculations Rexroth IndraDrive
DOK-INDRV*-SYSTEM*****-PR02-EN-P
If several main drives are operated at one DC bus, the simultaneously
required DC bus continuous powers must be added:
25,1*)P...PP(P
mHan2mHa1mHaZWHa
+++=
P
ZWHa
: DC bus continuous power for main drives [kW]
P
mHa1
... P
mHan
: mechanical continuous power for main drives [kW]
1,25: constant for motor and controller efficiency
Fig. 15-10: DC bus continuous power for main drives
Chokes and additional capacitors have to be selected according to the
actually required DC bus continuous power. It is determined by the
nominal power of the mains drives.
Note: When selecting the drive controllers, make sure that their
maximum DC bus continuous power will not restrict the short-
time operation power of the main drives.
When main and servo drives are operated at a drive controller, the
required DC bus continuous powers must be added.
At a typical NC machine tool, the required DC bus continuous power will
be primarily defined by the main drive. Accordingly, the following equation
is to be used for such applications:
25130
21
,*)]P...PP(*,P[P
mSenmSemSemHaZWD
+++=
0,3: experimental value for standard machine tools
1,25: constant for motor and controller efficiency
P
ZWD
: DC bus continuous power [kW]
P
mSe1
...P
mSen
: mechanical continuous power for servo drives [kW]
P
mHa
: nominal power for main drive (shaft output) [kW]
Fig. 15-11: DC bus continuous power for main and servo drives at NC machine
tools
∑∑
≤ devicesZWD,oninstallatiZWD, PP
PZWD,installation: generated DC bus continuous power of the installation
P
ZWD,devices: allowed DC bus continuous power of the devices
Fig. 15-12: Supply condition: DC bus continuous power
DC Bus Peak Power
The drive controller or combination of drive controllers has to produce DC
bus peak power for example when several axes of a machine tool
simultaneously accelerate to rapid traverse rate after a tool change,
approaching the workpiece.
CAUTION
Damage due to supply unit overload!
⇒ To avoid damage to the drive controller the sum of
peak powers of all drives mustn't exceed the DC bus
peak power of the supplying drive controller (central
supply).
DC Bus Continuous Power for
Main Drives
CD Bus Continuous Power for
Main and Servo Drives