Yaskawa FSP Amplifier - Manual (Page 342)

FSP Amplifier User’s Manual Appendix C: Specifications for Peripheral Devices
C-11
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:
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
E
S
=
( )
182
N x J J
2
M M L
+
Where: N
M
= Motor speed
J
L
= Load Inertia
J
M
= Motor Inertia
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
E
L
=
60
π
(N
M
x τ
L
x t
D
)
Where: τ
L
= Motor torque
3
Calculate the energy lost
(E
M
)
from servomotor winding
resistance.
t
D
= s = deceleration stopping
time
E
M
= Joules = J
E
M
= ( Value from the
“Servomotor Winding
Resistance Loss” graph below)
x t
D
4
Calculate the servo amplifier
energy (E
C
) that can be
absorbed.
E
C
= Joules = J
E
C
= Value from the
“Absorbable Servo Amplifier
Energy” graph below.
5
Find the energy consumed
by the regenerative resistor
(E
K
).
E
K
= E
S
=E
L
=E
M
= E
C
=
Joules = J
E
K
= E
S
— ( E
L
+E
M
+ E
C
)
6
Calculate the required
regenerative resistor
capacity (W
K
).
W
K
= W
E
K
= Joules = J
T = s
W
K
=
T x 2 . 0
E
K
Where: T = Time
*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%.