Curtis 1238SE - Page 60

4 — PROGRAMMABLE PARAMETERS
Curtis 1232E/34E/36E/38E & 1232SE/34SE/36SE/38SE Manual, os 31 – May 2017 Return to TOC
pg. 56
MOTOR: 0 – ACIM: FIELD WEAKENING CONTROL MENU
PARAMETER ALLOWABLE RANGE DESCRIPTION
FW Base Speed
FW_Base_Speed
0x3857 0x00
200 – 12000 rpm
200 – 12000
Sets the speed at which modulation depth has reached 100% (all available
voltage is used) and where eld weakening begins. This parameter is scaled
by an internal motor characterization parameter, so the setting of FW Base
Speed should always be done using the tuning test, which will take into
account the scaling factor. Entering a speed observed from a torque vs. speed
plot should not be done, as this number fails to take into account the internal
scaling factor.
This parameter needs to be set during initial setup (chapter 7) and reset
each time the Motor Type or the low speed current limit is changed. For
example, if the Drive_Current_Limit (page 43) or PL_Drive_Nominal (page 44)
parameters are lowered, reset this FW Base Speed parameter.
To determine the correct value, perform this “base speed” tuning test. The test
should be run with batteries that have a reasonable charge. In either Speed
Mode or Torque Mode, set their accel rates to be fast—so the motor will
be accelerating at full current during the test. Next, set this FW Base Speed
parameter to 6000 rpm (i.e., at a high-enough speed that its value will not
interfere with the test result). From a stop, apply full throttle and accelerate
to a high-speed beyond the expected base speed. After the motor settles at
this speed for a moment, release the throttle to stop the test. Note the value
displayed in Monitor » Controller » Motor Tuning » Base Speed Captured
(page 76), and enter this value for this FW Base Speed parameter setting.
For traction motors, the test restarts each time the vehicle comes to a stop
and the throttle is released, so be sure to note the Base Speed Captured value
before driving away.
For pump motors, follow the instructions in Chapter 8A, Part 2b.
Field Weakening Drive
Field_Weakening_Drive
0x3033 0x00
0 – 100%
0 – 1024
Sets the amount of eld weakening allowed while driving the motor. Field
Weakening Drive will affect efciency and torque only at speeds above the
programmed FW Base Speed. Low settings will result in better efciency
but less torque; higher settings will result in more torque and less efciency.
A setting of zero will disable eld weakening, thus resulting in the highest
efciency and lowest torque above base speed.
To keep motor and controller heating to a minimum (high efciency), Field
Weakening Drive should be set just high enough to meet the high speed
performance specications. (Typical high speed performance specications
are maximum drive speed with full load, or maximum lift speed with full load.)
The drive current limiting map (Fig. 12, page 44) can also be used to restrict
performance at all speeds.
The maximum setting of the Field Weakening Drive parameter depends on the
type of motor characterization that was used.
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 efciency) to 100%
(highest torque, lowest efciency).
If the ACIM motor was auto characterized (i.e., characterized using the ACIM
motor characterization procedure in Chapter 8A), the range is restricted by the
results of the Field Weakening Test. For these motors, Field Weakening Drive
can be set anywhere in the range of 0% (lowest torque, highest efciency)
to Max Field Weakening Drive (highest torque, lowest efciency) result. For
auto characterized motors, setting Field Weakening Drive greater than the
maximum setting found in the Field Weakening Test will result in poorer
efciency 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.