Eaton 9000X - Figure 6-3: Motor Equivalent Circuit

9000X AF Drives User Manual
MN04001004E
For more information visit: www.eaton.com 6-9
June 2009
Stator Resistance Measurement Using Dc-brake at Start
1. Define the DC-brake current (=motor nominal current) (P1.4.8).
2. Set the DC-brake time at start to 2 seconds (P1.4.11).
3. Give start command.
The drive will correct the stator impedance to improve the motor torque calculation. This also
improves slip compensation accuracy. (Stator resistance voltage loss compensation, see
picture 3.)
If the DC-brake time at start is set back to zero, the calculated stator impedance value goes
back to default if the drive's power is switched off. (Identification will retain all values in
memory.)
Figure 6-3: Motor Equivalent Circuit
Change the motor control mode to the speed control (P1.6.1 = 1)
Change the V/f-optimization (Auto Torque Boost) to on if more torque is needed on low
frequencies (P1.6.2). Note, this will increase motor voltage while loading motor, check motor
current draw.
Note: In high torque — low speed applications — it is likely that the motor will overheat. If the
motor has to run a prolonged time under these conditions, special attention must be
paid to cooling the motor.
I
s
I
q
I
d
R
R
Air
Gap
Flux
RotorStator
Voltage Loss on
Stator Resistance
V Across L
M
Is
The Magnetizing
Voltage
V at the
Motor Terminals
L
M
= R
S
x I
S
R
S
~
V