Dynamic Brake Operation - Mitsubishi Electric Melservo-Jet MR-JET Series User Manual

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 (5.2) to calculate the approximate coasting distance to a stop. The dynamic brake time constant  varies with the
servo motor and machine operation speeds.
Page 50 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.
ON
EM1 (Forced stop 1)
OFF
V
0
Machine speed
V J
0 L
L = • t + τ 1 + ∙ ∙ ∙ (5.2)
max e
60 J
M
L : Maximum coasting distance [mm]
max
V : Machine's fast feed speed [mm/min]
0
J : Moment of inertia of the servo motor [× 10
M
J : Load moment of inertia converted into equivalent value on servo motor shaft [× 10
L
τ: Dynamic brake time constant [s]
t : Delay time of control section [s]
e
There is an internal relay delay time of about 10 ms.
Dynamic brake
time constant τ
Time
t
e
-4 2
kg•m ]
-4 2
kg•m ]
5 CHARACTERISTICS
5.3 Dynamic brake characteristics
5
49