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02.07
05.01
The following applies for the storage capacity of the capacitor battery
when the power fails:
Formula:
Assumptions for the example:
Capacitance of the capacitor battery
Rated DC link voltage
Minimum DC link voltage
––> w = ½ S 20 S 10
For this voltage range, a 20 mF capacitor module can supply energy for
2375 Ws.
Notice
V
For voltages below 350 V, the switched–mode power supply for the electronics
shuts down.
The possible buffer time t
power P
t
Ü
Dynamic energy
The DC link capacitors should be considered as being a battery. The capaci-
tance and, thus, the storage capacity are increased as a result of the capacitor
module.
In order to evaluate the required capacitance for a specific requirement in a cer-
tain application, the energy flow must be determined.
The energy flow depends on the following:
S
S
S
S
S
In practice, often there is no precise data about the mechanical system. If the
mechanical system data is determined using rough calculations or estimated
values, then the capacitance of the DC link capacitors required can only be de-
termined during tests performed during the commissioning phase.
© Siemens AG 2012 All Rights Reserved
SIMODRIVE 611 Configuration Manual (PJU) – 02/2012 Edition
w = ½ S C S (V
F S ((600 V)
–3
must be y 350 V.
DClinkmin
is calculated as follows with the output DC link
Ü
:
DC link
= w / P
DC link
All moved masses and moments of inertia
Velocity, speed (and their change, acceleration, deceleration)
Efficiencies: Mechanical system, gear units, motors, inverters (driving/braking)
Back–up duration, buffering
DC link voltage and the permissible change, output value, upper/lower limit
value.
6 Infeed Modules
6.7 DC link options
2
2
– V
)
DC link n
DC link min
C = 20 mF
V
= 600 V
DClinkn
V
= 350 V
DClinkmin
2
2
– (350 V)
) = 2375 Ws
6
6-187
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