Dynamic Brake Characteristics - Mitsubishi Electric MR-J3-10B Instruction Manual

10. CHARACTERISTICS

10.3 Dynamic brake characteristics

Fig. 10.3 shows the pattern in which the servo motor comes to a stop when the dynamic brake is operated.
Use Equation 10.2 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. 10.4)
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V
0
L
max
60
L : Maximum coasting distance .................................................................................................... [mm][in]
max
Vo : Machine rapid feedrate ...............................................................................................[mm/min][in/min]
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 11kW 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.
25
20
15
10
5
0
60
50
40
30
20
10
0
ON
Forced stop(EM1)
OFF
Machine speed
Fig. 10.3 Dynamic brake operation diagram
J
L
....................................................................................................................... (10.2)
t
1
e
J
M
73 23
13
0 1000 2000 3000 4000 5000 6000
Speed [r/min]
HF-MP series
51
81
121
0 500 1000 1500
Speed [r/min]
HF-SP1000r/min series
Fig. 10.4 Dynamic brake time constant
V
0
t
e
43
053
201
2000
10 - 4
Time constant
Time
25
73
20
23
15
10
053
13
5
43
0
0 1000 2000 3000 4000 5000 6000
Speed [r/min]
HF-KP series
120
100
80
60
352
102
702
40
20
502
0
0 500 1000 1500 2000 2500 3000
Speed [r/min]
HF-SP2000r/min series
2 2
][oz in ]
2 2
][oz in ]
52
202
152