94 Powerdrive F300 Getting Started Guide
Issue Number: 5
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 Getting Started Guide English Iss2.book Page 94 Tuesday, July 28, 2015 3:23 PM
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