11 Appendix
11.1.3 Calculating the Required Capacity of Regenerative Resistors
11-10
(a) Calculation Procedure
The procedure for calculating the regenerative capacity is as follows:
Note: 1. The “0.2” in the equation for calculating W
K
is the value for when the regenerative resis-
tor’s utilized load ratio is 20%.
2. The units for the various symbols are as follows:
E
S
to E
K
:
Energy joules (J)
T
L
:
Load torque (N·m)
W
K
:
Regenerative resistor required capacity (W)
t
D
:
Deceleration stopping time (s)
J
: (
= J
M
+ J
L
)(
kg·m
2
)
T
:
Servomotor repeat operation period (s)
N
M
:
Servomotor rotation speed (min
-1
)
If the above calculation determines that the amount of regenerative power (Wk) processed by the built-in
resistor is not exceeded, then an external regenerative resistor is not required.
If the amount of regenerative power that can be processed by the built-in resistor is exceeded, then install an
external regenerative resistor for the capacity obtained from the above calculation.
If the energy consumed by load loss (in step 2 above) is unknown, then perform the calculation using E
L
= 0.
When the operation period in regeneration mode is continuous, add the following items to the above calcula-
tion procedure in order to find the required capacity (W) for the regenerative resistor.
• Energy for continuous regeneration mode operation period: E
G
(joules)
• Energy consumed by regenerative resistor: E
K
= E
S
- (E
L
+ E
M
+ E
C
) + E
G
• Required capacity of regenerative resistor: W
K
= E
K
/ (0.2
×
T)
Here, E
G
= (2
π
/60) N
MG
T
G
t
G
• t
G
:
Same operation period (s) as above
• T
G
:
Servomotor’s generated torque (N·m) in continuous regeneration mode operation period
• N
MG
:
Servomotor rotation speed (min
-1
) for same operation period as above
Step
Item
Symbol
Equation
1
Calculate the rotational energy of the servo-
motor.
E
S
E
S
= JN
M
2
/182
2
Calculate the energy consumed by load loss
during the deceleration period.
E
L
E
L
= (
π
/60) N
M
T
L
t
D
3
Calculate the energy lost from servomotor
winding resistance.
E
M
(Value calculated from “(b) Servo-
motor Winding Resistance Loss”
diagrams)
×
t
D
4
Calculate the SERVOPACK energy that can
be absorbed.
E
C
Calculate from “(3)
SERVOPACK’s Absorbable
Energy” diagrams.
5
Calculate the energy consumed by the regen-
erative resistor.
E
K
E
K
= E
S
−
(E
L
+E
M
+E
C
)
6
Calculate the required regenerative resistor
capacity (W).
W
K
W
K
= E
K
/ (0.2
×
T)
Summary of Contents for SGDH
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