User manual of EL8-EC***F AC Servo
47
Theoretical selection of regenerative resistor
Without external loading torque, the need for an external regenerative resistor can be
determined as the flow chart below
Start
Determine the
duration of motion
cycle T (s)
Determine motor max.
rotational velocity
V(rpm)
Determine motor load-
inertia ratio(N)
Calculate
regenerative energy
E1(J)
Determine energy
stored by capacitor
Ec
（
J
）
E1(J)>Ec
（
J
）
?
External
resistor needed
Calculate required
regenerative resistor
power rating Pr
Pb>Pa?
Use external
regenerative resistor
Please consider external
factor(s) when using external
regenerative resistor
Use internal
regenerative resistor
End
No external
resistor needed
T is the time for velocity to reach
max. velocity from 0 rpm and
decelerates back to 0rpm
Can be monitored on the front panel
Can be determined through inertia
measuring function
E1=(N+1)×Eo Eo=J×V^2/182
J: Motor unloaded rotational inertia
V: Motor rotational velocity
N: motor load-inertia ratio
Use table 2-5 to determine the maximum
regenerative energy stored by the capacitors
- - - - - - - - - Pr=
((E1-Ec)/T)
0.5
Y
N
Y
N
