Value Text Description
0 Ur.S Stator resistance and voltage offset measured at each start
1 Ur No measurements
2 FD Fixed boost mode.
3 Ur.Auto
Stator resistance and voltage offset measured at first drive
enable
4 Ur.I Stator resistance and voltage offset measured at each power-up
5 SrE Square law characteristic
6 Fd.tap Fixed boost with zero slip at zero reference
The Open-loopVoltageMode (05.014) defines the voltage output mode, as given below. It should be noted that the maximum output voltage of the drive is
limited to a level just below D.c.LinkVoltage (05.005) / √2. Therefore, if the drive is being supplied via its own rectifier input stage the output voltage is limited
to a level just below that of the supply voltage. If the drive is operating in voltage mode the output voltage is limited to MotorRatedVoltage (05.009) or the
maximum possible output voltage whichever is the lowest (also refer to OverModulationEnable (05.020)).
0: Ur S (Resistance compensation, stator resistance measured at each start)
Resistance compensation is a form of stator flux oriented sensorless motor control. A linear frequency to voltage characteristic is used where the drive output
voltage is increased from 0V to MotorRatedVoltage (05.009). as the |OutputFrequency (05.001)| increases from 0Hz to MotorRatedFrequency (05.006).
When the |OutputFrequency (05.001)| is above MotorRatedFrequency (05.006) the output voltage is limited to MotorRatedVoltage (05.009). Vector based
stator resistance compensation is applied below MotorRatedFrequency (05.006) / 4 and then this is tapered off from MotorRatedFrequency (05.006) / 4 to
MotorRatedFrequency (05.006) / 2. This method controls the flux level correctly in the motor in the steady state provided the correct value of
StatorResistance (05.017) is used.
If slip compensation is not being used (see MotorRatedFrequency (05.006) ) then additional voltage compensation can be applied below
MotorRatedFrequency (05.006) / 10 to have an additional torque boost at very low frequencies, see LowFrequencyEstimatorThreshold,
LowFrequencyTorqueadjustment (05.084).
The StatorResistance (05.017) is measured each time the drive is started. This test can only be done with a stationary motor where the flux has decayed to
zero. Therefore this mode should only be used if the motor is guaranteed to be stationary each time the drive is enabled. To ensure that the measurement is
not carried out before the flux has decayed, there is a period of one second after the inverter has been disabled during which the test is not carried out if the
drive is re-started. The StatorResistance (05.017) is not automatically saved in non-volatile memory after each test.
1: Ur (Resistance compensation with no stator resistance measurement)
Resistance compensation is used as in Ur S mode, but the StatorResistance (05.017) is not measured.
2: Fixed (Fixed boost with linear characteristic)
A fixed frequency to voltage characteristic is used as shown above where the voltage at 0Hz is defined by LowFrequencyVoltageBoost (05.015). The
voltage characteristic moves linearly with output frequency passing through four points determined by [BoostEndVoltage (05.074) and BoostEndFrequency
(05.075)], [SecondPointVoltage (05.076) and SecondPointFrequency (05.077)], Thirdpointvoltage (05.078) and SecondPointFrequency (05.077), and
[MotorRatedVoltage (05.009) and MotorRatedFrequency (05.006)].
By default BoostEndFrequency (05.075) is set to half the MotorRatedFrequency (05.006), SecondPointFrequency (05.077) is set 55%
and Thirdpointfrequency (05.079) is set to 75%. Similarly by default BoostEndVoltage (05.074) is set at half the MotorRatedVoltage (05.009),
SecondPointVoltage (05.076) 55% and Thirdpointvoltage (05.078) is set to 75%. This is to produce the same characteristic as SK by default.
3: Ur Auto (Resistance compensation, stator resistance measured on first start)
Resistance compensation is used as in Ur S mode, but the StatorResistance (05.017) is only measured once when the drive is first enabled. After the test has
been completed successfully the mode is changed to Ur mode and StatorResistance (05.017) is saved to non-volatile memory. If ParameterCloning (11.042)
is set to 3 or 4 the StatorResistance (05.017) is also written to a non-volatile media card fitted in the drive. If the test fails the mode is changed to Ur mode,
but StatorResistance (05.017) is not updated.
4: Ur I (Resistance compensation, stator resistance measured at power-up)
Resistance compensation is used as in Ur S mode, but the StatorResistance (05.017) is only measured when the drive is enabled for the first time after each
power-up.
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