Technosoft 2018
40
iPOS4808 VX Technical Reference
Power Supply Connection
3.4.11.1 Supply Connection
Figure 3.25. Supply connection
3.4.11.2 Recommendations for Supply Wiring
Always provide a nearby capacitor on the motor supply lines. The capacitor should be located within
10cm of the iPOS4808 edge connector, max. 20cm. The minimum recommended capacitance is
330µF for iPOS4808, always rated at the appropriate voltage.
Use short, thick wires between the iPOS4808 and the motor power supply. Connect power supply
wires to all the indicated pins. If the wires are longer than 2 meters, use twisted wires for the supply
and ground return. For wires longer than 20 meters, add a capacitor of at least 2,2
00μF (rated at
an appropriate voltage) right on the terminals of the iPOS4808.
3.4.11.3 Recommendations to limit over-voltage during braking
During abrupt motion brakes or reversals the regenerative energy is injected into the motor power
supply. This may cause an increase of the motor supply voltage (depending on the power supply
characteristics). If the voltage bypasses 53V, the drive over-voltage protection is triggered and the
drive power stage is disabled. In order to avoid this situation you have 2 options:
Option 1. Add a capacitor on the motor supply
big enough to absorb the overall energy flowing
back to the supply. The capacitor must be rated to a voltage equal or bigger than the maximum
expected over-voltage and can be sized with the formula:
2
2
2
NOM
MAX
M
U
U
E
C
−
×
≥
where:
U
MAX
= 53V is the over-voltage protection limit
U
NOM
is the nominal motor supply voltage
E
M
= the overall energy flowing back to the supply in Joules. In case of a rotary motor
and load, E
M
can be computed with the formula:
F
M
d
d
Ph
2
M
final
initial
L
M
2
M
L
M
M
T
2
t
t
R
3I
)
h
-
)g(h
m
(m
)
J
(J
2
1
E
ϖ
ϖ
−
−
+
+
+
=
Kinetic energy
Copper losses Friction losses
Potential energy
