Danfoss MCO 305 Design Manual page 54

MCO 305 Design Guide
__ Functions and Examples __
Next chart shows a typical 'short' movement where
maximum velocity cannot be reached. In this case,
the curve ramps-up the acceleration (using
JERKMIN) for as long as possible. This may or may
not reach maximum acceleration, depending on
how far away the target position is. There will then
be an acceleration ramp-down (using JERKMIN2),
followed immediately by a deceleration ramp-up
(using JERKMIN3). Again, depending on the target
position, there may or may not be a constant
deceleration segment. The curve ends with a
deceleration ramp-down to 0 velocity at the target
position.
The chart below shows an example where the motor is initially moving in the "wrong" direction and must
turn around and 'go back' to the target position. Since it must "turn around", the curve starts with a
deceleration ramp-up segment (using JERKMIN3) to maximum deceleration.
This will slow the speed down until it turns around. Deceleration continues at maximum deceleration until 0
velocity is reached and the direction reverses. At exactly this point, the motor is now 'speeding up'" but in
the other direction.
From this point, the curve is similar to a normal
movement to a target position, except that the
whole curve is inverted because the direction has
changed. The curve will have an acceleration ramp-
up segment (going backwards), it may or may not
have a constant acceleration segment, it will have
an acceleration ramp-down segment, it may or
may not have a constant velocity segment, it will
have a deceleration ramp-up segment, it may or
may not have a constant deceleration segment,
and finally it will have a deceleration ramp-down to
the target position.
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