DIGIVEX Little Drive Servoamplifier
17
PVD 3530 GB 01/2005
2. ENERGY DISSIPATION
The energy a module has to dissipate is broken down into:
Energy generated by braking.
Energy from rectifier and power bridge losses.
2.1 Braking Energy Dissipation
2.1.1 Calculating the power to be dissipated in the braking resistor
The permanent and pulse power levels given in the table below are limited by the characteristics
of the "breaking" resistors.
When the application includes intensive cycles or long-duration decelerations, the mean power to
be dissipated by each axis must be calculated.
P in Watts =
J
2
N
9.55
2
⎛
⎝⎜
⎞
⎠⎟
.f
J : Moment of inertia of the servomotor and the related load in kgm².
N : Angular speed of motor shaft at start of braking, in rpm.
f : repeat frequency of braking cycles in s
-1
.
This formula is for the least favourable case. For a mechanism with substantial friction or with low
reverse output, the power to be dissipated may be greatly reduced.
.
The power to be dissipated by the axis must not exceed the permanent power admissible by the
resistor. Duration and repetition must not exceed the ratings in table
§ 2.1.3
.
2.1.2 Braking energy dissipation
Dissipation of breaking energy is carried out through a resistor (or 2 resistors depending on the
calibre) situated in the module.
This manual was downloaded on www.sdsdrives.com
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