Bosch rexroth MCL, Project Planning Manual

Page: 135 / 206

● either an interruption-free power supply or
● additional DC bus capacities (capacitors), and /or
● mechanical braking facilities
must be provided.
Determining the required addition‐
al DC bus capacity
Additional capacities in the DC bus represent an additional energy store that
can supply the brake energy required in the event of a power outage.
The control voltage must be available even at a power failure for
the time of braking! If needed, buffer the control voltage supply or
feed the control voltage from the DC intermediate circuit if possi‐
ble!
The additional capacity required for a deactivation upon a mains failure can
be determined as follows:
C
add
Required additional DC bus capacitor in mF
m Moved mass in kg
v
max
Maximum velocity in m/s
U
DCmax
Maximum DC bus voltage in V
U
DCmin
Minimum DC bus voltage in V
F
max
Maximum braking force of the motor in N
k
FN
Motor constant (force constant) in N/A
R
12
Winding resistance at 20 °C
F
R
Friction force in N
Fig. 9-30: Determining the required additional DC bus capacitor
Prerequisites:
- final velocity = 0
- velocity-independent friction
- constant deceleration
- winding temperature 135 °C
The maximum possible DC bus capacity of the employed power
supply module must be taken into account when additional ca‐
pacities are used in the DC bus. Do not initiate a DC voltage
short-circuit when additional capacitors are employed.
MCL Ironless Linear Motors 127/197
Application and construction instructions
R911330592_Edition 06 Bosch Rexroth AG