Danfoss MCO 305 Design Manual page 52

MCO 305 Design Guide
__ Functions and Examples __
The chart below shows a stopping movement that begins from a negative velocity and a very high decelera-
tion. (It is a deceleration because the speed is slowing down.) However, because the initial deceleration is
so high, the motor is unable to stop without overshooting 0 velocity and 'coming back'.
So the curve starts with a deceleration ramp-down
segment (using JERKMIN4) to slow the deceleration
as much as possible before reaching 0 velocity. At
0 velocity, the 'deceleration' becomes an
'acceleration' because the direction has changed.
Hence, the curve continues by ramping-down the
acceleration (using JERKMIN2) until it gets to 0
acceleration. The motor is now at a constant
positive velocity and so the curve will finish in the
normal way with a deceleration ramp-up segment
(using JERKMIN3), a constant deceleration
segment (very short in this example), and a
deceleration ramp-down segment to 0 velocity
(using JERKMIN4).
Changing to a Constant Velocity
This chart shows a movement that begins from a
positive constant velocity and increases its speed
to a higher positive constant velocity. This curve
consists of an acceleration ramp-up segment (using
JERKMIN), followed by a constant acceleration
segment (at maximum acceleration), and finally an
acceleration ramp-down segment to constant
velocity (using JERKMIN2). Note that the decelera-
tion JERKMIN3 and JERKMIN4 values are not used
because there is never any deceleration.
Next chart shows a movement that begins from a
high positive constant velocity and decreases its
speed to a lower positive constant velocity. This
curve consists of a deceleration ramp-up segment
(using JERKMIN3), followed by a constant
deceleration segment (at maximum deceleration),
and finally a deceleration ramp-down segment to
constant velocity (using JERKMIN4). Note that the
acceleration JERKMIN and JERKMIN2 values are not
used because there is never any acceleration.
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