- 170 - Aries Hardware Installation Guide
Energy Dissipated in Load
The load dissipates energy through friction losses, viscous damping, and
other motor/load related losses. These losses are known as load losses. If
some of the parameters are not known, the energy dissipated in the load (
E
L
)
can conservatively be assumed zero (0).
This can be derived from the force required during the constant velocity
portion of the move profile, either measured or calculated.
D
L
t
v
F
E
⋅
⋅
=
2
1
Where
E
L
=
energy dissipated by the load (Joules) – load losses
F
=
force at constant velocity in Newtons (
N
)
v
=
velocity in meters per second (m/s)
t
D
=
deceleration time (Seconds)
Energy to Dissipate in the External Power-Dump Resistor
To stop a motor, kinetic and potential energy must go somewhere. Through
the previous calculations, you have determined the total kinetic and potential
energy, and the energy lost to various paths.
From the total kinetic and potential energy, subtract the energy dissipated
through the drive capacitors, motor windings, and load loss. If the copper
losses (EW) or load losses (EL) are not easily determined, you can
conservatively assume they are zero (0).
The resulting sum represents the power for dissipation in an external power
dump resistor.
L
W
C
P
K
R
E
E
E
E
E
E
−
−
−
+
=
Where
ER
= energy to be dissipated in the external resistor (Joules)
EK
=
rotational kinetic energy (Joules)
EP
=
potential energy (Joules)
EC
= energy that can be absorbed by the drive capacitors (Joules)
EW
= energy dissipated in the motor windings (Joules) – copper losses
EL
=
energy dissipated by the load (Joules) – load losses
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