Menu 5
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x.00
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Performance RFC mode
122
Unidrive SP Advanced User Guide
www.controltechniques.com Issue Number: 10
Open-loop
Setting this bit enables dynamic V to f mode which is intended for applications where power loss should be kept to a minimum under low load
conditions. The rated frequency used to derive the voltage to frequency characteristic of the drive is varied with load:
if |active current| < 0.7 x rated active current
motor rated frequency = Pr
5.06
x (2 - (active current / (0.7 x rated active current)))
else if |active current|
≥
0.7 x rated active current
motor rated frequency = Pr
5.06
Although the rated frequency varies the value shown as Pr
5.06
does not vary from that set by the user.
Closed-loop vector
At light load the losses in the motor can be reduced by reducing the motor flux. When flux optimization is selected the flux producing current in the
motor is reduced under light load conditions so that it is equal to the torque producing current with a minimum limit of half the rated flux producing
current. This optimizes the copper losses in the motor and reduces the iron losses.Flux optimization is disabled if closed-loop vector mode is used
without position feedback (i.e. Pr
3.24
is set to 1 or 3).
0: Ur_S, Stator resistance and voltage offset measured at each start
The stator resistance (Pr
5.17
) and the voltage offset (Pr
5.23
) are measured and the parameters over-written each time the drive is started. This test
can only be done with a stationary machine where the flux has decayed to zero. Therefore this mode should only be used if the machine is
guaranteed to be stationary each time the drive is enabled. To prevent the test from being done before the flux has decayed there is a period of 1
second after the drive has been in the ready state during which the test is not done if the drive is re-started. In this case, previously measured values
are used. The new values of stator resistance and voltage offset are not automatically saved to EEPROM or the SMARTCARD.
1: Ur, No measurements
The stator resistance and voltage offset are not measured. The user can enter the motor and cabling resistance into the stator resistance parameter.
However this will not include resistance effects within the drive inverter. Therefore if this mode is to be used, it is best to use the auto-tuning stationary
test initially to measure the stator resistance.
2: Fd, Fixed boost mode.
Neither the stator resistance nor the voltage offset are used, instead a fixed characteristic with boost applied as defined by Pr
5.15
is used.
3: Ur_Auto, Stator resistance and voltage offset measured at first drive enable
The stator resistance and voltage offset are measured once, the first time the drive is enabled. After the test has been completed successfully the
mode is changed to Ur mode. The stator resistance and voltage offset are written to the parameters for the currently selected motor map and these
parameters along with this parameter are saved in the EEPROM (and the SMARTCARD if Pr
11.42
= 3 or 4). If the test fails the stator resistance and
voltage offset are not updated, the mode is changed to Ur, but no parameters are saved.
4: Ur_I, Stator resistance and voltage offset measured at each power-up
The stator resistance and voltage offset are measured when the drive is first enabled and at each subsequent power-up. The new values of stator
resistance and voltage offset are not automatically saved to EEPROM or the SMARTCARD.
5: SrE, Square law characteristic
Neither the stator resistance nor the voltage offset are used, instead a fixed square law characteristic with boost applied as defined by Pr
5.15
is used.
5.13
Dynamic V to F / flux optimise select
Drive modes
Open-loop, Closed-loop vector
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU
PS
1
1
1
Default
Open-loop, Closed-loop vector
0
Update rate
Background read
5.14
Voltage mode select
Drive modes
Open-loop
Coding
Bit
SP
FI
DE Txt VM DP
ND
RA NC NV
PT
US RW BU
PS
1
1
1
1
Range
Open-loop
0 to 5
Default
Open-loop
4
Update rate
Background read
Summary of Contents for unidrive sp
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