Danfoss MCO 305, Design Manual, Page: 192 / 242

MCO 305 Design Guide
__ Parameter Reference __
¾ default setting [ ] value for use in communication via serial communication port
192
MG.33.L4.02 – VLT
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32-82 Ramp Type
RAMPTYPE
Option
¾ Linear [0]
S-ramp [1]
Movements with limited jerk [2]
Function
This parameter defines the ramp type: trapeze,
sinusoidal, or limited jerk. These ramp type are
relevant for all movements (POSA, POSR, CVEL,
and MOTOR STOP), but not with SYNCx.
Ramp type 0: trapeze
Ramp type 1: S- ramp
Ramp type 2: limited jerk
Movements with limited jerk start with acceleration
zero and increase acceleration by maximum Jerk
until the maximum acceleration which is defined by
par. 32-81
Shortest Ramp is reached. Then the
movement continues with maximum acceleration.
At the end the acceleration will be decreased by
maximum jerk until acceleration is zero again. The
maximum jerk is calculated by the internal
parameter Jerk Duration JERKMIN.
Function of JERKMIN
JERKMIN defines the minimum time in [ms] re-
quired before reaching the maximum acceleration.
There are four different JERKMIN options, see
“Limited Jerk” in chapter „Functions and
Examples”: JERKMIN, JERKMIN2, JERKMIN3,
JERKMIN4.
The maximum Jerk used with par. 32-82 Ramp
Type = 2 is calculated by JERKMIN using following
formulas:
Ramp Shortest 81 - 32 Par.
Velocity Maximum
on Accelerati Max.
JERKMIN Duration Jerk Par.
on Accelerati Maximum
Jerk Maximum
Note, that par. 32-81 Shortest Ramp and Jerk
Duration are time values in milliseconds.
Calculation sample:
Par. 32-80 VELMAX = 3000 [RPM]
Par. 32-01 ENCODER = 500 counts/rev [PPR]
Par. 32-81 RAMPMIN = 500 ms
Parrameter JERKMIN = 200 ms
This results in:
VELMAX = 3000 * 500 *
60
4
= 100,000 qc/s
= 100 qc/ms
MaxAcc = 200,000 qc/s
2
= 0.2 qc/ms
2
MaxJerk = 1,000,000 qc/s
3
= 0.001 qc/ms
3
NB!:
A changed setting of Jerk Duration is
executed after the next movement
command (POSA, POSR, CVEL, or MOTOR
STOP) and used for the calculation of the
acceleration. Thus it is possible in NOWAIT ON
mode with a repeated POSA command to adapt
during a movement online (i.e. without stop) the
movement to new definition.
NB!:
If JERKMIN2, JERKMIN3 and/or JERKMIN4
is set to “0” this will default to the same
value as JERKMIN.