4 — PROGRAMMABLE PARAMETERS
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Return to TOC Curtis AC F2-A, F4-A, F6-A Motor Controllers – FOS 4.5 – April 2022
MOTOR SETUP/INDUCTION MOTOR (ACIM) — FIELD WEAKENING MENU, cont’d
PARAMETER ALLOWABLE RANGE DEFAULT DESCRIPTION
Field Weakening Drive
Field_Weakening_Drive
0x36C1 0x00
0 – 100 %
0 – 1024
100 % Sets the amount of eld weakening allowed while driving the
motor. Field Weakening Drive will affect efciency and torque only
at speeds above the programmed FW Base Speed. Low settings
will result in better efciency but less torque; higher settings will
result in more torque and less efciency. A setting of zero will
disable eld weakening thus resulting in the highest efciency
and lowest torque above base speed.
To keep motor and controller heating to a minimum (high
efciency), Field Weakening Drive should be set just high enough
to meet the high-speed performance specications. (Typical,
high-speed performance specications are maximum drive speed
with full load or maximum lift speed with full load.) Use the drive
current limiting map to restrict performance at all speeds.
The maximum setting of the Field Weakening Drive parameter
depends on the type (model) of motor in the characterization test.
If the ACIM motor was dyno characterized (i.e. sent to the Curtis
factory for characterization on the motor dyno) Field Weakening
Drive can be set anywhere in the range of 0% (lowest torque
highest efciency) to 100% (highest torque lowest efciency).
If the ACIM motor was auto characterized, the results of the
Field Weakening Test restricts the range. For these motors Field
Weakening Drive can be set anywhere in the range of 0% (lowest
torque highest efciency) to Max Field Weakening Drive (highest
torque lowest efciency) result. For auto characterized motors,
setting Field Weakening Drive greater than the maximum setting
found in the Field Weakening Test will result in poorer efciency
and less torque as the motor will be operating “over the slip curve”.
Note: The Field Weakening Drive setting will have no effect at
motor speeds below FW Base Speed.
Weakening Rate Drive
Field_Weakening_Rate_Drive
0x36C2 0x00
0 – 100 %
0 – 500
5 % Sets the control loop gains for eld weakening. Setting the
rate too low may create surging in the vehicle as it accelerates
at mid to high speeds. Setting the rate too high may create
high frequency oscillations (usually audible) when the vehicle
accelerates at mid to high speeds.
Min Field Current
Min_Field_Current
0x30A3 0x00
0 – 800A
0 – 8000
0 Amps This current pre-fluxes the motor and can improve initial
take-off at the expense of some battery consumption. Set this
parameter only when there is a need to increase the initial
take-off (vehicle launch) without motor torque (e.g., creep
torque at idle).