Dynamic Brake Characteristics - Mitsubishi Electric Melservo-J3 Series MR-J3-B Instruction Manual

13. SERVO AMPLIFIERS WITH A LARGE CAPACITY (30k TO 55kW)

13.8.3 Dynamic brake characteristics

Fig. 13.2 shows the pattern in which the servo motor comes to a stop when the dynamic brake is operated. Use
Equation 13.1 to calculate an approximate coasting distance to a stop. The dynamic brake time constant
varies with the servo motor and machine operation speeds. (Refer to Fig. 13.3. Please contact us for the servo
motor not indicated.)
⎧
⎛
Vo
τ ⎜
⋅ ⎨ + +
t 1
L =
e
max
⎝
⎩
60
L : Maximum coasting distance ·········································································································· [mm]
max
V : Machine rapid feed rate ······························································································ [mm/min][in/min]
0
J : Servo motor inertial moment ······················································································ [kg cm
M
J : Load inertia moment converted into equivalent value on servo motor shaft ·············· [kg cm
L
: Brake time constant ·························································································································· [s]
t : Delay time of control section ············································································································ [s]
e
For 7kW or less servo, there is internal relay delay time of about 30ms. For 11k to 22kW servo, there
is delay time of about 100ms caused by a delay of the external relay and a delay of the magnetic
contactor built in the external dynamic brake.
40
35
30
25
20
15
10
5
0
0 200 400
Speed [r/min]
ON
Forced stop (EM1)
OFF
Machine speed
Fig 13.2 Dynamic Brake Operation Diagram
⎫
⎞
J
L
⎟
⎬
··················································································································· (13.1)
⎠
⎭
J
M
HA-LP30K1
HA-LP37K1
600 800 1000 1200
HA-LP1000r/min series
Time constant
V
0
t
e
40
35
30
25
20
15
10
5
0
0 200
13 - 67
Time
400 600 800 1000 1200
Speed [r/min]
2 2
][oz in ]
2 2
][oz in ]
HA-LP25K14
HA-LP30K14
HA-LP37K14