Mitsubishi Electric Melservo-J5 MR-J5 Series - Dynamic Brake Operation

5 CHARACTERISTICS
5.3 Dynamic brake characteristics
125
5
Dynamic brake operation
Calculation of coasting distance
The following figure shows the pattern in which the servo motor comes to a stop when the dynamic brake is operated. Use the
equation (10.2) to calculate the approximate coasting distance to a stop. The dynamic brake time constant  varies with the
servo motor and machine operation speeds.
Page 126 Dynamic brake time constant
A working part generally has a friction force. Therefore, the actual coasting distance will be shorter than the maximum
coasting distance calculated with the following equation.
L
max
: Maximum coasting distance [mm]
V
0
: Machine's fast feed speed [mm/min]
J
M
: Moment of inertia of the servo motor [× 10
-4
kg•m
2
]
J
L
: Load moment of inertia converted into equivalent value on servo motor shaft [× 10
-4
kg•m
2
]
: Dynamic brake time constant [s]
t
e
: Delay time of control section [s]
There is an internal relay delay time of about 10 ms.
t
e
V
0
ON
OFF
EM1 (Forced stop 1)
Dynamic brake
time constant 
Machine speed
Time
J
M
t
e
+  1 +
J
L
60
V
0
L
max
=•    (10.2)