User Manual Of EL7-EC** AC Servo
26
Rotational
velocity
Motor
Torque
0
V:Motor rotational velocity
0
Regenerative
torque
T
T
L
: Load torque
t
D
:Deceleration
time
Table 2-4 Steps to calculate capacity of regenerative resistor
Steps
Calculation
Symbol
Formula
1
Servo system regenerative
energy
E1
E1=(N+1)×J×V
2
/182
2
Depleted energy from loss of
load system during
acceleration
E
L
E
L
= (π/60) V×T
L
×tD
If loss is not determined, please assume E
L
= 0.
3
Depleted energy due to motor
coil resistance.
E
M
E
M
=(U
2
/R)×tD
R= coil resistance, U = operating voltage
If R is not determined, please assume E
M
= 0.
4
Energy stored by internal DC
capacitors
Ec
Please refer to table 2-5
5
Depleted energy due to
regenerative resistance
E
K
E
K
=E1-(EL+EM+EC),
If loss is ignored, EK=E1-EC
6
Required power rating of
regenerative resistor
Pr
Pr=E
K
/(0.5×T)
Internal capacitor capacity and rotor inertia
EL7-EC Drivers
Servo motor
Rotor Inertia
（
× 10
-4
kg.m
2
）
Max. regenerative energy
stored in capacitor Ec(J)
400W
ACM2-06004H2
0.58
13.47
750W
ACM2-08008H2
1.66
22.85
1000W
ACM8010M2
1.79
27.74
ACM13010M2
8.5
There are motors with low, medium and high inertia. Different motor models have
different rotor inertia. Please refer to product catalogue for more information on rotor
inertia.
