Yaskawa FSP Amplifier - Manual (Page 143)

FSP Amplifier User’s Manual Chapter 5: Parameter Settings and Functions
5-76
„ 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
Note: The “0.2” in the equation for calculating W K is the value for when the regenerative resistor’s utilized load
ratio is 20%.