3-43
3-3
Regenerative Energy Absorption
The Servo Drivers have internal regenerative energy absorption circuitry for absorbing
the regenerative energy produced during time such as Servomotor deceleration, and
thus preventing the DC voltage from increasing. An overcurrent error is generated, how-
ever, if the amount of regenerative energy from the Servomotor is too large. If this oc-
curs, measures must be taken to reduce the regenerative energy produced by changing
operating patterns, and so on, or to improve the regenerative energy absorption capac-
ity by connecting external regeneration resistance.
3-3-1 Regenerative Energy Calculation
H
Horizontal Axis
Servomotor
operation
Servomotor
output torque
Note
In the output torque graph, acceleration in the positive direction is shown as positive, and accel-
eration in the negative direction is shown as negative.
•
The regenerative energy values for E
g1
and E
g2
are derived from the following equations.
E
g1
=
1
2
⋅
2
π
60
⋅
N
1
⋅
T
D1
⋅
t
1
[J]
E
g2
=
1
2
⋅
2
π
60
⋅
N
2
⋅
T
D2
⋅
t
2
[J]
N
1
, N
2
: Rotation speed at beginning of deceleration [r/min]
T
D1
, T
D2
: Deceleration torque [N
S
m]
t
1
, t
2
: Deceleration time [s]
Note
There is some loss due to winding resistance, so the actual regenerative energy will be approxi-
mately 90% of the values derived from these equations.
System Design and Installation
Chapter 3
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