Technosoft iMOTIONCUBE BX-CAN Technical Reference page 35

the maximum nominal supply voltage. This setting will activate the chopping resistor earlier, before reaching dangerous
voltages – when the over-voltage protection will stop the drive. Of course, U
over-voltage protection threshold.
Remark: This option can be combined with an external capacitor whose value is not enough to absorb the entire
regenerative energy E but can help reducing the chopping resistor size.
M
Chopping resistor selection
The chopping resistor value must be chosen to respect the following conditions:
1. to limit the maximum current below the drive peak current I
2. to sustain the required braking power:
where C is the capacitance on the motor supply (external), i.e:
3. to limit the average current below the drive nominal current I
where t is the time interval between 2 voltage increase cycles in case of repetitive moves.
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4. to be rated for an average power
Remarks:
U U
>
MAX CHOP
1. If
×
I 2
PEAK
or C – the external capacitor on the motor supply
×
P t
CR d
2. If
×
2
t I
CYCLE NOM
interval between braking cycles must be increased
WARNING!
 Technosoft 2019
E
M
=
P
CR
R
P
=
CR
P
AV
t
CYCLE
2
the braking power P
P
CR
2
U
>
CHOP
either the braking power must be reduced (see Remark 1) or t
×
2 P
CR
THE CHOPPING RESISTOR MAY HAVE HOT SURFACES DURING
OPERATION.
= 0.9A
PEAK
U
R >
MAX
CR
I
PEAK
1
− −
2
C ( U U
MAX CHOP
2
t
d
2
U
<
CHOP
R
×
CR
2 P
CR
=0.9A
NOM
×
P t
>
CR d
×
CR
2
t I
CYCLE NOM
×
t
d
and a peak power
must be reduced by increasing either t
CR
35
must always be less than U
CHOP
2
)
2
U
=
MAX
P
PEAK
R
CR
– the time to decelerate
d
iMOTIONCUBE Technical Reference
– the
MAX
– the time
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