Menu 3
Closed-loop
Parameter
structure
Keypad and
display
Parameter
x.00
Parameter
description format
Advanced parameter
descriptions
Macros
Serial comms
protocol
Electronic
nameplate
Performance RFC mode
64
Unidrive SP Advanced User Guide
www.controltechniques.com Issue Number: 10
This is the damping factor related to the response of the system to a torque transient, and so if the damping factor is unity the response to a load
torque transient is critically damped. The step response of the speed controller gives approximately 10% overshoot with unity damping factor.
This parameter is used to define the damping factor used for setting up the speed loop gain parameters automatically when Pr
3.17
= 1 or 2.
. 0
The hard speed reference is a reference value which does not pass through the ramp system (Menu 2). It is added to the normal post ramp speed
reference. Its value may be written from the keypad, via serial comms, from an analog input or from an encoder input. This parameter can also be
used by the position controller (Menu 13) as the speed reference input. The hard speed reference is selected when Pr
3.23
= 1.
0:
Closed-loop vector mode with position feedback
The drive uses the closed-loop vector algorithm with the selected position feedback.
1:
RFC mode - Closed-loop vector mode without position feedback
The drive uses the closed-loop vector algorithm and derives the position feedback internally.
2:
Closed-loop vector mode with no maximum speed limit
3:
RFC mode -
Closed-loop vector mode without position feedback with no maximum speed limit
In some applications using closed-loop vector control the maximum speed of the system is above the speed at which the encoder feedback frequency
is too high to be used by the drive. For these type of applications Pr
3.24
should be set to 2 for low speed operation and 3 for high speed operation. It
should be noted that the drive no longer checks that the maximum encoder frequency cannot be exceeded in closed-loop vector control, and so the
user must ensure that Pr
3.24
is set to 3 before the encoder frequency limit is reached.
If the drive encoder lines per rev (Pr
3.34
) is set to a value that is not a power of 2 and the drive encoder type (Pr
3.38
) is used to select any type of
SINCOS encoder this parameter is forced to zero. This is because the extra processing time required to support the feedback device would not allow
enough time for the closed-loop vector algorithm without position feedback to be executed. It should be noted that if the algorithm without position
feedback is active that the sample rate for 6 and 12kHz operation is reduced from 12kHz to 6kHz. Also operation at 4kHz, 8kHz or 16kHz is not
possible and if these frequencies are selected the actual switching frequency is switched down to the next lower frequency. Pr
5.37
displays the
actual switching frequency being used.
3.21
Damping factor
Drive modes
Closed-loop vector, Servo
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
1
Range
Closed-loop vector, Servo
0.0 to 10.0
Default
Closed-loop vector, Servo
1.0
Update rate
Background (1s) read
3.22
Hard speed reference
Drive modes
Closed-loop vector, Servo
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
1
1
Range
Closed-loop vector, Servo
±SPEED_FREQ_MAX rpm
Default
Closed-loop vector, Servo
0.0
Update rate
4ms read
3.23
Hard speed reference selector
Drive modes
Closed-loop vector, Servo
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Default
Closed-loop vector, Servo
0
Update rate
4ms read
3.24
Closed-loop vector mode
Drive modes
Closed-loop vector
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Range
Closed-loop vector
0 to 3
Default
Closed-loop vector
0
Update rate
Background read
Summary of Contents for unidrive sp
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