Emerson Powerdrive F300 Reference Manual page 72

Value Text
0 Ur S
1 Ur
2 Fixed
3 Ur Auto
4 Ur I
5 Square
Open-loop Control Mode (05.014) defines the drive output mode, which can either be a voltage mode or a current 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. Bus Voltage (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 Rated Voltage (05.009) or the maximum possible output voltage whichever is the lowest. (If Quasi-square Enable (05.020) = 1 the maximum possible output voltage can be increased. See Quasi-square Enable (05.020) for
details.)
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 Rated Voltage (05.009). as the
|Output Frequency (05.001)| increases from 0Hz to Rated Frequency (05.006). When the |Output Frequency (05.001)| is above Rated Frequency (05.006) the output voltage is limited to Rated Voltage (05.009). Vector based stator
resistance compensation is applied below Rated Frequency (05.006)/4 and then this is tapered out from Rated Frequency (05.006)/4 to Rated Frequency (05.006)/2. This method controls the flux level correctly in the motor in the steady
state provided the correct value of Stator Resistance (05.017) is used.
The Stator Resistance (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 Stator Resistance (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 Stator Resistance (05.017) is not measured.
2: Fixed (Fixed boost with linear characteristic)
A fixed frequency to voltage characteristic is used as shown below where the voltage at 0Hz is defined by Low Frequency Voltage Boost (05.015).
3: Ur Auto (Resistance compensation, stator resistance measured on first start)
Resistance compensation is used as in Ur S mode, but the Stator Resistance (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
Stator Resistance (05.017) is saved to non-volatile memory. If Parameter Cloning (11.042) is set to 3 or 4 the Stator Resistance (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 Stator Resistance (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 Stator Resistance (05.017) is only measured when the drive is enabled for the first time after each power-up.
5: Square (Fixed boost with square characteristic)
A fixed square frequency to voltage characteristic is used as shown below. When the |Output Frequency (05.001)| is below Rated Frequency (05.006) the Output Voltage (05.002) is given by:
Output Voltage (05.002) = Low Frequency Voltage Boost (05.015) + [Rated Voltage (05.009) - Low Frequency Voltage Boost (05.015)] x (Output Frequency (05.001) / Rated Frequency (05.006))
6: Current 1P (Single phase current output)
If this mode is selected it overrides all the normal control system for Open-loop mode and is used to produce a single phase square wave current output using the system shown below.
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Powerdrive F300 Parameter Reference Guide
Issue: 01.15.00