38
DMM Technology Corp.
DYN4 AC Servo Drive Instruction Manual
REV. ZM7-A10A
CT1
█
Acceleration / Deceleration
Soft Start
In Speed Servo Mode, the
Max Acceleration
parameter in the servo drive can be used to soft start/stop the
servo motor. If the analog speed command is sent as a step reference, it is often desirable to ramp up/
down this command to smooth motor motion. Without soft start, the servo motor can accelerate/decelerate
instantaneously. Soft start creates a smooth s-curve motion with conistent acceleration/deceleration.
The relation to physical acceleration / deceleration time is measured as the rise time from 10% of the tar
-
get speed to 90% of the target speed.
Rise from 10% to 90% time = 59.98/(
Max Acceleration
)
2
seconds
Physical acceleration time = 1.2 * 59.98/(
Max Acceleration
)
2
seconds
Rough Motion
Smooth Motion!
Max Acceleration
█
Torque Filter Constant
TrqCons is a first order low-pass filter used to smooth torque delivery to improve stability
and accuracy of servo motor speed. The bigger value means wider frequency range of that
filter. That filter can be expressed as:
a / ( S + a), here a = 26*TrqCons ; if TrqCons = 100, then a = 2600.
The filter is used to make the torque sent to the servo torque loop more smooth especially
for heavier loads when bigger SpeedGain settings are used. If a very quick response servo
with small load is desirable, TrqCons
can be increased up to 127 to ensure stability and fast
dynamic following.
The Torque Filter Constant parameter should only be used in speed and torque servo mode.
Leave this parameter at “127” in position servo mode.
