NOTE: It is not possible to perform this test if, after autotune, the ratio No load Lq (05.072) / Ld (05.024) < 1.1 and Pr 05.064 has been set to Non-

salient.

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. The test may give inaccurate results, if the motor rated speed is not

set to the correct value for the motor, or if standard ramp mode is active. During the inertia measurement test a series of progressively larger torque

levels are applied to the motor (20 %, 40 % ... 100 % of rated torque) to accelerate the motor up to 3/4 x Rated Speed (05.008) to determine the

inertia from the acceleration/deceleration time. The test attempts to reach the required speed within 5 s, 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 unsucessful an Autotune 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 quickly enough. If this is the case, the maximum speed reference should be reduced. To perform an Inertia

measurement autotune, set Pr 00.040 to 4, and provide the drive with both an enable signal (on terminal 29) and a run signal (on terminal 24).

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 29, setting the drive Enable Parameter (06.015) to OFF (0) or disabling the drive via the control word

(Pr 06.042 & Pr 06.043).

Pr 03.079 Sensorless Mode Filter

When RFC-S sensorless mode is active the measured speed can include some ripple, which increases as the drive passes into field weakening. A

filter is applied to the estimated speed and Sensorless Mode Filter (03.079) defines the time constant. The default time constant is 4 ms, but this can

be extended to improve the filtering. This is particularly useful when using standard ramp or spinning start with a low friction high inertia load, and

can prevent over voltage trips when the drive has no braking resistor.

Pr 05.071 Low Speed Sensorless Mode Current

Injection mode

For low speed sensorless operation with signal injection (RFC Low Speed Mode (05.064) = 0) it is necessary to have a ratio of Lq/Ld = 1.1. Even if

a motor has a larger ratio on no load, this ratio normally reduces as the q axis current is increased from zero. Low Speed Sensorless Mode Current

(05.071) should be set at a level that is lower than the point where the inductance ratio falls to 1.1. The value of this parameter is used to define the

drive current limits when signal injection is active and prevent loss of control of the motor.

Non-salie0nt mode

For low speed sensorless operation for non-salient motors (RFC Low Speed Mode (05.064) = 1) this defines a current applied in the d axis to aid

starting. For most motors and application requiring up to 60 % torque on starting the default value is suitable. However the level of current may need

to be increased to make the motor start.

Pr 00.017 {04.012} Current Reference Filter 1 Time Constant

Current Reference Filter 1 Time Constant (00.017 / 04.012) defines the time constant of a first order filter that can be applied to the Final Current

Reference (04.004). The filter is provided to reduce acoustic noise and vibration produced as a result of position feedback quantisation. The filter

introduces a lag in the speed controller loop, and so the speed controller gains may need to be reduced to maintain stability as the filter time

constant is increased. The time constant used is dependent on Speed Controller Gain Select (03.016) so that different time constants can be used

with different gains. Current Reference Filter 1 Time Constant (00.017 / 04.012) is used if Speed Controller Gain Select (03.016) = 0, and Current

Reference Filter 2 Time Constant (04.023) is used if Speed Controller Gain Select (03.016) = 1.

Pr 00.038 {04.013} / Pr 00.039 {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. The proportional gain (Pr 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 00.040, 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.

Powerdrive F300 User Guide

Issue Number: 2

Electrical

Getting

Basic

installation

started

parameters

the motor

Running

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