Menu 2
Commander SK Advanced User Guide
49
Issue Number: 9 www.controltechniques.com
Although the range for scaling purposes is ±550 Hz, the actual parameter value can be increased beyond this range by the current limit controller (up
to 20 % > than the maximum frequency).
This is shown on the drive’s display when Pr
23
is set to Fr (default).
0:
OFF Ramp hold disabled
1:
On
Ramp hold enabled
If this bit is set the ramp will be held. If S ramp is enabled the acceleration will ramp towards zero causing the ramp output to curve towards a constant
speed. If a drive stop is demanded the ramp hold function is disabled.
This parameter has 4 settings as follows:
0:
Fast ramp
1:
Standard ramp with normal motor voltage
2:
Standard ramp with high motor voltage
3:
Fast ramp with high motor volts
The acceleration ramp is not affected by the ramp mode, and the ramp output will rise at the programmed acceleration rate (subject to the current
limits programmed).
Fast Ramp
In modes 0 and 3, the output of the ramp will fall at the programmed deceleration rate (subject to the current limits programmed). The DC Bus voltage
controller is not active in these modes.
Standard Ramp
In modes 1 & 2, the voltage rising to the standard ramp level (Pr
2.08
) causes a proportional controller to operate, the output of which changes the
demanded current in the motor. As the controller regulates the bus voltage, the motor decelerates at a faster and faster rate as it approaches zero
speed. When the motor deceleration rate reaches the programmed deceleration rate the controller ceases to operate and the drive continues to
decelerate at the programmed rate. If the standard ramp voltage (Pr
2.08
) is set lower than the nominal DC bus level the drive will not decelerate but
will coast to rest.
The current demand is fed to the frequency changing current controller and therefore the gain parameters, Pr
4.13
and Pr
4.14
must be set up for
optimum control.
Standard ramp can increase output frequency by 20% during deceleration.
2.01
Post ramp reference {83}
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
1
1
1
Range
±550 Hz
Update rate
21ms
2.02
Unused parameter
2.03
Ramp hold
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Default
OFF(0)
Update rate
128ms
2.04
Ramp mode select {30}
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Range
0 to 3
Default
1
Update rate
Background
NOTE
Содержание 2202
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