Frequency Slaving Demand; Zero Speed Threshold; At Speed Lower Limit; At Speed Upper Limit - Control Techniques unidrive sp Advanced User's Manual

Menu 3 Parameter Keypad and
Open-loop structure display
3.01

Frequency slaving demand

Drive modes Open-loop
Bit SP
Coding
Range Open-loop
Update rate 4ms write
The slave frequency demand is only relevant if the drive is operating in frequency slaving mode, in other modes this parameter reads as 0.0. The
value shown in slaving mode is the fundamental drive output frequency. Frequency slaving mode is used to lock the fundamental frequency produced
by the drive with an external frequency applied to the main drive encoder input. This could be used for example to keep the shafts of two synchronous
machines in lock, by feeding the frequency slaving output from the master drive into the encoder input of the slave drive. Alternatively the two
machines could be operated so that the shafts rotate with an exact ratio, i.e. as though the shafts were connected by gears (see Pr 3.14 and Pr 3.15
on page 47).
The source for frequency slaving mode may be quadrature A/B encoder signals or Frequency and Direction. With the latter care must be taken to
ensure that the D set-up time (10µs) is observed or pulses may be lost. The frequency slaving input must be selected as F and D or quadrature to
match the source mode. The input mode is selected by Pr 3.38 which defines the encoder type. The default for source and destination drives is
quadrature A/B mode, unlike previous products which used F and D only.
The drive will not count pulses while it is disabled (this parameter will show 0.0), but will maintain lock once enabled even if the direction of rotation
reverses. In frequency slaving mode the drive current limits are not active, however, the drive peak limit is active and will try and limit the drive current
to the magnitude limit by modifying the output voltage away from the defined V to F (Voltage to Frequency) characteristic. If synchronous machines
are used and the current required exceeds the drive magnitude limit the slave machine will pole slip.
3.05

Zero speed threshold

Drive modes Open-loop, Closed-loop vector, Servo
Bit SP
Coding
Range Open-loop
Default Open-loop
Update rate Background read
If the post ramp reference (Pr 2.01) is at or below the level defined by this parameter in either direction the Zero speed flag (Pr 10.03) is 1, otherwise
the flag is 0.
3.06

At speed lower limit

Drive modes Open-loop, Closed-loop vector, Servo
Bit SP
Coding
Range Open-loop
Default Open-loop
Update rate Background read
3.07

At speed upper limit

Drive modes Open-loop, Closed-loop vector, Servo
Bit SP
Coding
Range Open-loop
Default Open-loop
Update rate Background read
46
Parameter Parameter
x.00 description format
FI DE Txt VM DP ND RA NC NV
1 1 1
±1000.0 Hz
FI DE Txt VM DP ND RA NC NV
1
0.0 to 20.0 Hz
1.0
FI DE Txt VM DP ND RA NC NV
1
0.0 to 3,000.0 Hz
1.0
FI DE Txt VM DP ND RA NC NV
1
0.0 to 3,000.0 Hz
1.0
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Advanced parameter
Macros
descriptions
PT US RW BU
1 1
PT US RW BU
1 1
PT US RW BU
1 1
PT US RW BU
1 1
Serial comms Electronic
Performance
protocol nameplate
PS
PS
1
PS
1
PS
1
Unidrive SP Advanced User Guide
Issue Number: 7
Feature look-
up table