15
Calculations
15.1
Determining the Appropriate Drive Controller
15.1.1
Introduction
Supply for the drive system Rexroth IndraDrive takes place by means of com‐
pact HCS converters or HMV supply units. According to the drive task, design
of drive controller and operating conditions, chokes, additional capacitors,
braking resistors, transformers, etc., may be required.
The drive controller or supply unit has to supply the DC bus continuous pow‐
er and for acceleration the DC bus peak power. With regenerative operation,
they must be able to absorb the continuous recovery power and peak recov‐
ery power.
Before the drive controller or supply unit and the additional components can
be selected, the motors and drive controllers to be used must be defined.
To ensure correct sizing of the drive system, you should do the calculations
in the order described in the following chapters.
15.1.2
DC Bus Continuous Power
The DC bus continuous power is calculated from the mechanical power, tak‐
ing the following aspects into consideration:
●
Motor and controller efficiency
●
Simultaneity Factors
Mechanical Power
P
m
Mechanical power
M
Torque [Nm]
ω
Angular velocity [min
-1
]
n
Motor speed [min
-1
]
Fig.15-1:
Mechanical Power
Mechanical Continuous Power for
Servo Drives
To calculate the mechanical continuous power of a servo drive, you need the
effective motor torque and the average motor speed.
The effective motor torque can be taken from the servo drive calculation. The
average motor speed is determined as follows:
Average Motor Speed
For servo drive tasks at common NC machine tools, the average motor
speed is approx. 25% of the rapid traverse speed. In some cases, however,
this rough estimation is not sufficient. An exact calculation of the average mo‐
tor speed is required.
Average Speed With Run-Up and
Braking Times not Taken Into Ac‐
count
If the period during which the motor is run at constant speed is significantly
greater than the run-up and braking time, the following applies:
DOK-INDRV*-SYSTEM*****-PR06-EN-P
Rexroth IndraDrive Drive Systems with HMV01/02 HMS01/02, HMD01, HCS02/03
Bosch Rexroth AG
247/309
Calculations
