Parameter 02.007 Maximum Rate Of Change Of Acceleration
Short description Defines the maximum rate of change of acceleration used by the ramp system
Mode Open‑Loop
Minimum 0.0 Maximum 300.0
Default 3.1 Units
Type 32 Bit User Save Update Rate Background read
Display Format Standard Decimal Places 1
Coding RW
A rate of change of acceleration ramp (S ramp) can be applied by different methods depending on the value of S Ramp Set-up Mode (02.041). If
S Ramp Set-up Mode (02.041) = 0 then the maximum rate of change of acceleration in both directions, accelerating away from or towards zero, is
defined by Maximum Rate Of Change Of Acceleration (02.007).
The general equations are given below for a linear ramp and S ramp where
Δw is the required change of frequency or speed
a
Max
is the maximum allowed acceleration in units of frequency/s or speed/s
J
Max
is the maximum rate of change of acceleration (i.e. jerk) in units of frequency/s
2
or speed/s
2
The time for a linear ramp to give a change of frequency or speed Δw is
T
Linear
= Δw / a
Max
If an S ramp is used w
B
is the change of frequency or speed as the acceleration changes from zero to aMax, i.e. the S shaped part of the frequency or
speed change.
w
B
= a
Max
2
/ 2J
Max
If the required frequency or speed change is less than 2wB, i.e. Δw < 2wB, then the acceleration never reaches its limit and the ramp does not contain a
linear ramp section and the time for the ramp is given by
T
SRamp1
= 2 √(Δw / J
Max
)
Otherwise
T
SRamp2
= (Δw / a
Max
) + (a
Max
/ J
Max
)
The following is an example based on the default parameter values for Open-loop mode. The diagram below shows a change of frequency from 0Hz to
50Hz with the ramp rate set to 5.0s/100Hz and Maximum Rate Of Change Of Acceleration (02.007) set to its default value of 3.1s
2
/100Hz.
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