Autotune; Open Loop Control Mode - Emerson Unidrive M702 User Manual

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Pr 0.40 {5.12} Autotune
There are two autotune tests available in open loop mode, a stationary and a rotating test. A rotating autotune should be used whenever possible so
the measured value of power factor of the motor is used by the drive.
• A stationary autotune can be used when the motor is loaded and it is not possible to remove the load from the motor shaft. The stationary test
measures the Stator Resistance (05.017), Transient Inductance (05.024), Voltage Offset At Zero Current (05.058), Maximum Voltage Offset
(05.059) and Current At Maximum Voltage Offset (05.060) which are required for good performance in vector control modes (see Open Loop
Control Mode (00.007), later in this table). The stationary autotune does not measure the power factor of the motor so the value on the motor
nameplate must be entered into Pr 00.043. To perform a Stationary autotune, set Pr 00.040 to 1, and provide the drive with both an enable
signal (on
terminals 11 and 13)
• A rotating autotune should only be used if the motor is unloaded. A rotating autotune first performs a stationary autotune, as above, then a
rotating test is performed in which the motor is accelerated with currently selected ramps up to a frequency of Rated Frequency (05.006) x 2/3,
and the frequency is maintained at that level for 4 seconds. Stator Inductance (05.025) is measured and this value is used in conjunction with
other motor parameters to calculate Rated Power Factor (05.010). To perform a Rotating autotune, set Pr 00.040 to 2, and provide the drive with
both an enable signal (on
Following the completion of an autotune test the drive will go into the inhibit state. The drive must be placed into a controlled disable condition
before the drive can be made to run at the required reference. The drive can be put in to a controlled disable condition by removing the SAFE
TORQUE OFF signal from
terminals 11 and 13
Control Word Enable (06.043).
Pr 00.007 {05.014} Open Loop Control Mode
There are several voltage modes available which fall into two categories, vector control and fixed boost.
Vector control
Vector control mode provides the motor with a linear voltage characteristic from 0 Hz to motor Rated Frequency (00.047), and then a constant
voltage above motor rated frequency. When the drive operates between motor rated frequency/50 and motor rated frequency/4, full vector based
stator resistance compensation is applied. When the drive operates between motor rated frequency/4 and motor rated frequency/2 the stator
resistance compensation is gradually reduced to zero as the frequency increases. For the vector modes to operate correctly the Rated Power
Factor (00.043), Stator Resistance (05.017) and Voltage Offset At Zero Current (05.058) are all required to be set up accurately. The drive can be
made to measure these by performing an autotune (see Pr 00.040 Autotune). The drive can also be made to measure the stator resistance and
voltage offset automatically every time the drive is enabled or the first time the drive is enabled after it is powered up, by selecting one of the vector
control voltage modes.
(0) Ur S = The stator resistance and the voltage offset are measured and the parameters for the selected motor map are over-written each time
the drive is made to run. 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 made to run. 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 made to run
again. In this case, previously measured values are used. Ur S mode ensures that the drive compensates for any change in motor parameters
due to changes in temperature. The new values of stator resistance and voltage offset are not automatically saved to the drive's EEPROM.(4)
(4) Ur I = The stator resistance and voltage offset are measured when the drive is first made to run after each power-up. This test can only be
done with a stationary motor. Therefore this mode should only be used if the motor is guaranteed to be stationary the first time the drive is made
to run after each power-up. The new values of stator resistance and voltage offset are not automatically saved to the drive's EEPROM.
(1) Ur = The stator resistance and voltage offset are not measured. The user can enter the motor and cabling resistance into the Stator
Resistance (05.017). However this will not include resistance effects within the drive inverter. Therefore if this mode is to be used, it is best to
use an autotune test initially to measure the stator resistance and voltage offset.
(3) Ur_Auto= The stator resistance and voltage offset are measured once, the first time the drive is made to run. After the test has been
completed successfully the Open Loop Control Mode (00.007) is changed to Ur mode. The Stator Resistance (05.017) and Voltage Offset At
Zero Current (05.058)) parameters are written to, and along with the Open Loop Control Mode (00.007), are saved in the drive's EEPROM. If
the test fails, the voltage mode will stay set to Ur Auto and the test will be repeated next time the drive is made to run.
Fixed boost
Neither the stator resistance nor the voltage offset are used in the control of the motor, instead a fixed characteristic with low frequency voltage
boost as defined by Pr 00.008, is used. Fixed boost mode should be used when the drive is controlling multiple motors. There are two settings of
fixed boost available:
(2) Fixed = This mode provides the motor with a linear voltage characteristic from 0 Hz to Rated Frequency (00.047), and then a constant
voltage above rated frequency.
(5) Square = This mode provides the motor with a square law voltage characteristic from 0 Hz to Rated Frequency (00.0 47), and then a
constant voltage above rated frequency. This mode is suitable for variable torque applications like fans and pumps where the load is
proportional to the square of the speed of the motor shaft. This mode should not be used if a high starting torque is required.
Unidrive M702 User Guide
Issue Number: 3
Electrical Getting Basic
installation started parameters
and a run signal (on terminal 7 or 8).
and a run signal (on terminal 7 or 8).
terminals 11 and 13)
, setting the Drive Enable (06.015) to OFF (0) or disabling the drive via the Control Word (06.042) and
Running NV Media Card
Optimization
the motor Operation
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