Curtis 1239E - Page 63

Return to TOC Curtis 1239E-1269E Manual, os 37.0 RevA – May 2021
4 — PROGRAMMABLE PARAMETERS
pg. 59
MOTOR: 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 or PL_Drive_Nominal parameters are
lowered, reset this FW Base Speed parameter.
To determine the correct value, perform this “base speed” tuning test. Run
this test with batteries that have a reasonable charge.
In either Speed Mode or Torque Mode, set the 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, and enter the 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 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.
Quick Links:
Drive Current Limit p.46
PL Drive Nominal p.47
Base Speed Captured p.83