Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 21)

Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011 21
Detailed Drive Operation Chapter 1
For Field Oriented Control the following motor tests are performed:
For Permanent Magnet Control the following motor tests are performed:
Inertia Test
The final test is the inertia calculation. The motor and load (machine) inertia is
used to set the bandwidth of the speed regulator. During the test the motor will
accelerate to the speed set in parameter 74 [Atune Spd Ref ] at a specified torque
set by parameter 129 [Atune Trq Ref ]. The test then calculates the time in
seconds to accelerate the motor at rated torque from zero to base speed and stores
that value in parameter 9 [Total Inertia].
Autotune Slip Test
The Slip Frequency test allows the drive to establish the slip frequency of the motor. This value is
displayed in parameter 486 [Rated Slip Freq]. The test runs the motor at 85% for frames 1…6
drives and near 50% for frames 9 and up drives. The test repeats three times.
Stator Resistance Test
This test identifies the motor stator resistance and stores the value into parameter
491 [StatorResistance]. The motor should not rotate during this test.
Stator Inductance Test
This test identifies the motor stator inductance and stores the value into parameter
490 [StatorInductance]. The motor should not rotate during this test.
Leakage Inductance Test
This test measures the inductance characteristics of the motor. A measurement of the motor
inductance is required to determine references for the regulators that control torque. The motor
should not rotate during this test. The test runs for approximately 1 minute and then stores the
calculated value into parameter 492 [Leak Inductance]. A typical value is between 15 and 25%.
Flux Current Test
This test is used to identify the value of motor flux current required to produce rated motor torque
at rated current. When the flux test is performed, the motor will rotate. The drive accelerates the
motor to the speed set in parameter 74 [Atune Spd Ref] (default is 85% of base speed) and then
coasts for several seconds. This cycle may repeat several times, then decelerate to a low speed
and shut off. This test stores the value for flux current in parameter 488 [Flux Current].
Stator Resistance Test
This test identifies the motor stator resistance and stores the value into parameter 522 [PM Stator
Resist]. The motor should not rotate during this test.
Stator Inductance Test
This test identifies the motor stator inductance and stores the value into parameter 520 [PM Q
Inductance]. The motor should not rotate during this test.
Encoder Offset
The absolute position sensor counter offset from the rotor flux center position for a Permanent
Magnet (PM) motor. This value is determined by an automated measurement procedure, which
uses parameter 505 [PM TestWait Time], 506 [PM Test Idc Ramp], 507 [PM Test FreqRamp], 508
[PM Test Freq Ref] and 509 [PM Test I Ref]. First, the Flux Producing (d-axis) current is applied to the
stator, starting with 0 A and with 0 Hz. Current increases with the ramp rate defined by parameter
506 [PM Test Idc Ramp] to the peak current value defined by parameter 509 [PM Test I Ref]. The
current is continuously applied at this level for the time interval defined by parameter 505 [PM
TestWait Time]. Then, the DC excitation position will be changed by 90 electrical degrees with the
frequency defined by parameter 508 [PM Test Freq Ref] and the rate change of the frequency
defined by parameter 507 [PM Test FreqRamp]. The 90 degree phase shifted d-axis current with the
current value defined by parameter 509 [PM Test I Ref] is continuously applied for the time interval
defined by parameter 505 [PM TestWait Time]. The value of parameter 504 [PM AbsEncd Offst] is
determined by value in the absolute position sensor counter.
Back EMF
Measures the permanent magnet motor CEMF (motor voltage feedback) coefficient and stores the
value in parameter 523 [PM Mtr CEMF Coef].