Dynamic Brake Operation - Mitsubishi Electric MR-J5 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
equation (10.2) to calculate the approximate coasting distance to a stop. The dynamic brake time constant τ varies with the
servo motor and machine operation speeds.
Page 105 Dynamic brake time constant
A working part generally has a friction force. Therefore, actual coasting distance will be shorter than the maximum coasting
distance calculated with the following equation.
ON
EM1 (Forced stop 1)
OFF
Machine speed
V J
0
L = • t + τ 1 +
max e
60 J
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 internal relay delay time of about 10 ms.
5 CHARACTERISTICS
104
5.3 Dynamic brake characteristics
Dynamic brake
time constant τ
V
0
t
e
L
∙ ∙ ∙ (10.2)
M
-4
Time
2
kg•m ]
-4 2
kg•m ]