YASKAWA SGDH User Manual page 573

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