YASKAWA SGD7S 020 Series, Product Manual

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8.2 Coasting Distance when Stopping with the Dynamic Brake
8-3
8
Appendices
8.2 Coasting Distance when Stopping with the Dynamic Brake
When stopping with the dynamic brake, the motor continues to rotate due to inertia until the
motor’s energy has been completely expended.
The travel distance during this period is called the coasting distance.
The coasting distance must be confirmed on the actual equipment, but you can use the follow-
ing formula to calculate an approximate value.
For Rotary Servomotors
The above formula is based on the following conditions.
• θ
[deg]: Coasting distance (mechanical angle)
•
J
[kgm
2
]: Moment of inertia (Motor moment of i Load moment of inertia)
•
R
D
[
Ω
]: Selected dynamic brake resistance
•
N
m0
[min
-1
]: Motor speed just before stopping with the dynamic brake
•
α
,
β
: Coasting distance coefficients
*1
•
Z
m
: Characteristic impedance
*2
*1.
Refer to the following section for details on the coasting distance coefficient.
8.3.1 Coasting Distance Coefficients on page 8-4
*2.
Refer to the following section for details on the characteristic impedance.
8.3.2 Characteristic Impedance on page 8-6
For Linear Servomotors
The above formula is based on the following conditions.
•
L
m
[m]: Coasting distance
•
M
[kg]: Conveying weight (Moving Coil mass + Load weight)
•
R
D
[
Ω
]: Selected dynamic brake resistance
•
V
m0
[m/s]: Motor speed just before stopping with the dynamic brake
•
α
,
β
: Coasting distance coefficients
*1
•
Z
m
: Characteristic impedance
*2
*1.
Refer to the following section for details on the coasting distance coefficient.
8.3.1 Coasting Distance Coefficients on page 8-4
*2.
Refer to the following section for details on the characteristic impedance.
8.3.2 Characteristic Impedance on page 8-6
WARNING

The calculated value of the coasting distance is a guideline. There may be error between the
calculated value and the actual coasting distance. Always evaluate the dynamic brake oper-
ation on the actual equipment or machine to confirm that there are no problems with the
coasting distance.
There is a risk of machine damage or injury.
R
D
+ Z
m
1
{
N
3
m0
}
[deg]
(
R
D
+ Z
m
)
N
m0
+
=
J
L
m
=
M
R
D
+ Z
m
1
{
v
3
m0
}
[m]
(
R
D
+ Z
m
)
v
m0
+