Emerson unidrive sp User Manual page 143

Safety Product Mechanical
Information Information Installation
Pr 0.40 {5.12} Autotune
There are three autotune tests available in closed loop vector mode, a stationary test, a rotating test and an inertia measurement test. A stationary
autotune will give moderate performance whereas a rotating autotune will give improved performance as it measures the actual values of the motor
parameters required by the drive. An inertia measurement test should be performed separately to a stationary or rotating autotune.
• 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
autotune measures the stator resistance (Pr 5.17) and transient inductance (Pr 5.24) of the motor. These are used to calculate the current loop
gains, and at the end of the test the values in Pr 4.13 and Pr 4.14 are updated. A stationary autotune does not measure the power factor of the
motor so the value on the motor nameplate must be entered into Pr 0.43. To perform a Stationary autotune, set Pr 0.40 to 1, and provide the
drive with both an enable signal (on terminal 31) and a run signal (on terminal 26 or 27).
• A rotating autotune should only be used if the motor is unloaded. A rotating autotune first performs a stationary autotune before rotating the
motor at 2 of motor rated frequency in the direction selected for approximately 30s. During the rotating autotune the stator inductance (Pr 5.25),
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and the motor saturation breakpoints (Pr 5.29 and Pr 5.30) are modified by the drive. The power factor is also modified for user information only,
but is not used after this point as the stator inductance is used in the vector control algorithm instead. To perform a Rotating autotune, set Pr
0.40 to 2, and provide the drive with both an enable signal (on terminal 31) and a run signal (on terminal 26 or 27).
• The inertia measurement test can measure the total inertia of the load and the motor. This is used to set the speed loop gains (see Speed loop
gains) and to provide torque feed-forwards when required during acceleration.
During the inertia measurement test the drive attempts to accelerate the motor in the direction selected up to
to standstill. The drive uses rated torque/16, but if the motor cannot be accelerated to the required speed the drive then increases the torque
progressively to x 1 , x 1 , x
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is initiated. If the test is successful the acceleration and deceleration times are used to calculate the motor and load inertia which is then written
to Pr 3.18. The motor map parameters must be set up correctly including the power factor before performing an inertia measurement test.
To perform an Inertia measurement autotune, set Pr 0.40 to 3, and provide the drive with both an enable signal (on terminal 31) and a run signal
(on terminal 26 or 27).
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 terminal 31, setting the drive enable parameter Pr 6.15 to OFF (0) or disabling the drive via the control word (Pr 6.42 &
Pr 6.43).
Pr 5.16 Motor rated speed autotune
The motor rated speed parameter (Pr 0.45) in conjunction with the motor rated frequency parameter (Pr 0.47) defines the full load slip of the motor.
The slip is used in the motor model for closed-loop vector control. The full load slip of the motor varies with rotor resistance which can vary
significantly with motor temperature. When Pr 5.16 is set to 1 or 2 the drive can automatically sense if the value of slip defined by Pr 0.47 and
Pr 0.45 has been set incorrectly or if it has varied with motor temperature. If the value is incorrect Pr 0.45 is automatically adjusted. Pr 0.45 is not
saved at power-down, and so when the drive is powered-down and up again it will return to the last saved value. If the new value is required at the
next power-up it must be saved by the user. Automatic optimization is only enabled when the speed is above rated speed/8, and when the load on
the motor load rises above 5
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values of stator resistance (Pr 5.17), transient inductance (Pr 5.24), stator inductance (Pr 5.25) and saturation breakpoints (Pr 5.29, Pr 5.30) should
be stored in the relevant parameters (all these can be measured by the drive by performing a rotating autotune). Motor rated speed autotune is not
available if the drive is not using external position/speed feedback.
The gain of the optimizer, and hence the speed with which it converges, can be set at a normal low level when Pr 5.16 is set to 1. If this parameter
is set to 2, the gain is increased by a factor of 16 to give faster convergence.
Pr 0.38 {4.13} / Pr 0.39 {4.14} Current loop gains
The current loop gains proportional (Kp) and integral (Ki) gains control the response of the current loop to a change in current (torque) demand. The
default values give satisfactory operation with most motors. However, for optimal performance in dynamic applications it may be necessary to
change the gains to improve the performance. The proportional gain (Pr 4.13) is the most critical value in controlling the performance. The values
for the current loop gains can be calculated by one of the following:
• During a stationary or rotating autotune (see Autotune Pr 0.40, earlier in this table) the drive measures the stator resistance (Pr 5.17) and
transient inductance (Pr 5.24) of the motor and calculates the current loop gains.
• By setting Pr 0.40 to 4 the drive will calculate the current loop gains from the values of stator resistance (Pr 5.17) and transient inductance
(Pr 5.24) set in the drive.
This will give a step response with minimum overshoot after a step change of current reference. The proportional gain can be increased by a factor
of 1.5 giving a similar increase in bandwidth; however, this gives a step response with approximately 12.5% overshoot. The equation for the integral
gain gives a conservative value. In some applications where it is necessary for the reference frame used by the drive to dynamically follow the flux
very closely (i.e. high speed closed-loop induction motor applications) the integral gain may need to have a significantly higher value.
Unidrive SP User Guide
Issue Number: 13
Electrical Getting Basic
installation Started parameters
1 and x1 rated torque. If the required speed is not achieved on the final attempt the test is aborted and a tunE1 trip
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rated load. Optimization is disabled again if the load falls below
Running SMARTCARD
Optimization
the motor operation
www.controltechniques.com
Onboard Advanced Technical
PLC parameters Data
3 x rated load rpm and then back
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1 rated load. For best optimization results the correct
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UL Listing
Diagnostics
Information
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