Nidec Unidrive M200 User Manual page 52

Safety Product Mechanical
information information installation
Pr 38 {05.012} Autotune
There are three autotune tests available in RFC-A mode, a stationary test, a rotating test and a mechanical load 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.
NOTE
It is highly recommended that a rotating autotune is performed (Pr 38 set to 2).
• 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 (05.017) and Transient Inductance (05.024) of the motor. These are used to calculate the current loop
gains, and at the end of the test the values in Pr 04.013 and Pr 04.014 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 09. To perform a Stationary autotune, set Pr 38 to 1, and provide the
drive with both an enable signal (on terminal 11) and a run signal (on terminal 12 or 13).
• A rotating autotune should only be used if the motor is unloaded. A rotating autotune first performs a stationary autotune, a rotating test is then
performed which the motor is accelerated with currently selected ramps up to a frequency of Motor Rated Frequency (Pr 39) x 2/3, and the
frequency is maintained at the level for up to 40 s. During the rotating autotune the Stator Inductance (05.025), and the motor saturation
breakpoints (Pr 05.029, Pr 05.030, Pr 05.062 and Pr 05.063) 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 38 to 2, and provide the drive with both an enable signal (on terminal 11) and a run signal (on terminal 12 or 13).
• The mechanical load test can measure the total inertia of the load and the motor. A series of progressively larger torque levels are applied to the
motor (20 %, 40 % ... 100 % of rated torque) to accelerate the motor up to ¾ x Motor Rated Speed (Pr 07) to determine the inertia from the
acceleration/deceleration time. The test attempts to reach the required speed within 5s, but if this fails, the next torque level is used. When
100 % torque is used, the test allows 60 s for the required speed to be reached, but if this is unsuccessful, a tun.1 trip is initiated. To reduce the
time taken for the test, it is possible to define the level of torque to be used for the test by setting Mechanical Load Test Level (05.021) to a non-
zero value. When the test level is defined, the test is only carried out at the defined test level and 60 s is allowed for the motor to reach the
required speed. It should be noted that if the maximum speed allows for flux weakening then it may not be possible to achieve the required
torque level to accelerate the motor fast enough. If this is the case, the maximum speed reference should be reduced.
1. The motor must be stationary at the start of the test.
2. The motor is accelerated in the required direction up to ¾ of the maximum speed reference and then decelerated to zero speed.
3. The test is repeated with progressively higher torque until the required speed is reached.
To perform a mechanical load measurement autotune, set Pr 38 to 3, and provide the drive with both an enable signal (on terminal 11) and a run
signal (on terminal 12 or 13). 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 drive enable signal from terminal 11, setting the Drive Enable (06.015) to OFF (0) or disabling the drive via the control
word (Pr 06.042 & Pr 06.043).
{04.013} / {04.014} 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 Current Controller Kp Gain (04.013) is the most critical value in controlling the performance. The
values for the current loop gains can be calculated by performing a stationary or rotating autotune (see Autotune Pr 38 earlier in this table) the drive
measures the Stator Resistance (05.017) and Transient Inductance (05.024) of the motor and calculates the current loop gains.
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 Sensorless RFC-A induction motor applications) the integral gain may need to have a significantly higher value.
52
Electrical Getting Basic
installation started parameters
Running the NV Media
Optimization
motor Card
Onboard Advanced
Diagnostics
PLC parameters
Unidrive M200 / M201 Control User Guide
Issue Number: 2
UL Listing