Yaskawa Sigma II Series Servo System - Manual (Page 176)

Sigma II User’s Manual Chapter 5: Parameter Settings and Functions
5-90
Regenerative Energy Calculation Method
This section shows the procedure for calculating the regenerative resistor capacity
when acceleration and deceleration operation is as shown in the following diagram.
Calculation Procedure
The procedure for calculating the capacity is as follows:
Note: 1. The “0.2” in the equation for calculating W
K
is the value for when the regenerative resistor’s
utilized load ratio is 20%.
Step Procedure
Units
[in. (mm)]
Equation
1
Find the rotational energy of the
servo system (E
S
).
E
S
= [Joules] = [J]=
[ oz-in-s
2 (kg-m 2 -s 2 )]
J
L
= J
M
= J
N
M
= rpm
2
Find the energy consumed by
load system loss (E
L
) during the
deceleration period (t
D
).
τ
L
= oz-in (N-m)
E
L
= Joules = J
N
M
= rpm
t
D
= s
3
Calculate the energy lost (E
M
)
from servomotor winding
resistance.
t
D
= s = deceleration
stopping time
E
M
= Joules = J
4
Calculate the servo amplifier
energy (E
C
) that can be
absorbed.
E
C
= Joules = J
5
Find the energy consumed by
the regenerative resistor (E
K
).
E
K
= E
S
=E
L
=E
M
= E
C
=
Joules = J
6
Calculate the required regener-
ative resistor capacity (W
K
).
W
K
= W
E
K
= Joules = J
T = s
Rotation speed
Motor torque
tD
0
0
Regenerative
torque
T
N
M
: Motor rotation speed
T
L
: Load torque
E
S
=
( J
L
+ J
M
) × N
M
2
182
Where: N
M
= Motor speed
J
L
= Load Inertia
J
M
= Motor Inertia
E
L
=
π
60
N
M
× τ
L
× t
D
( )
Where: τ
L
= Motor torque
E
M
= ( Value from the “Servomotor
Winding Resistance Loss” graph
below) × t
D
E
C
= Value from the “Absorbable
Servo Amplifier Energy” graph
below.
E
K
= E
S
— E
L
+E
M
+ E
C
( )
W
K
=
E
K
0.2 × T
Where: T = Time