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Chapter 10 Adjustment
10–33
10-4-2 Deceleration control
Basically, this MDS-B-V14L servo driver carries out dynamic brake stopping when an emergency stop
occurs. However, if the deceleration stop function is validated, the motor will decelerate according to
the set time constant while maintaining the READY ON state. READY will turn OFF after the motor
stops, and the dynamic brakes will be activated.
<Features>
1. When the movable mass is large, deceleration and stop are possible in a short using the
dynamic brakes. (Stopping is possible with a basically normal acceleration/deceleration time
constant.)
(1) Setting the deceleration control time constant
The time to stopping from the rapid traverse rate (rapid: axis specification parameter) is set in the
deceleration control time constant (SV056: EMGt). A position loop step stop is carried out when 0
is set.
When linear (straight line) acceleration/deceleration is selected for the rapid traverse, the same
value as the acceleration/deceleration time constant (G0tL) becomes the standard value. When
another acceleration/deceleration pattern is selected, set the rapid traverse to linear
acceleration/deceleration. Adjust to the optimum acceleration/deceleration time constant, and set
that value as the standard value.
<Operation>
When an emergency stop occurs, the motor will decelerate at the same inclination from each
speed.
No. Abbrev. Parameter name Unit Explanation Setting range
SV055 EMGx Max. delay time for
emergency stop
Ms Normally, the same value as SV056 EMGt is set.
Set 0 when not using the deceleration stop function or drop
prevention function.
0 to 5000
(ms)
SV056 EMGt Deceleration control
time constant
Ms Set the time to stop from rapid traverse rate (rapid).
Set the same value as the rapid traverse acceleration/
deceleration time constant (G0tL) as a standard. Set 0 when
not using the deceleration stop function.
0 to 5000
(ms)
POINT
1. The deceleration will not be controlled when a servo alarm that uses the
dynamic brake stopping method occurs. Stopping is by the dynamic brake
method regardless of the parameter setting.
2. When a power failure occurs, the stopping method may change over to a
dynamic brake stop during deceleration control if the deceleration time constant
is set comparatively long. This is because of low bus voltage in the driver.
CAUTION
If the deceleration control time constant (EMGt) is set longer than the
acceleration/deceleration time constant, the overtravel point (stroke end point)
may be exceeded.
A collision may be caused on the machine end, so be careful.
RAPID
EMGt
Emergency stop occurrence
Constant inclination deceleration
Motor speed
Time
Motor brake control output (MBR)
Dynamic brakes
OFF
ON
OFF
ON