Wesley BC-6200-8SA - Manual (Page 41)

Curtis 1268 Manual, Rev. D
35
2
Calibrating the Controller Speed Measurement
to the Vehicle
The
RPM TO SPEED parameter is a conversion factor used to generate a vehicle
speed estimate from the speed sensor input (motor RPM signal). This conver-
sion factor allows the vehicle to be configured for various gear ratios and tire
sizes. It can also be used to convert the displayed vehicle speed values (in the
Program and Monitor menus) between English and metric units. Use the equa-
tions below to calculate the correct value for this parameter.
For English units (mph):
tire diameter (inches)
× 63
gear ratio
For metric units (km/h):
tire diameter (cm)
× 40
gear ratio
step 1. Using the Program menu, set RPM TO SPEED to the correct value
for the vehicle tire size and gear ratio.
step 2. Set TACHO POLES To the number of poles in the motor’s speed
sensor (typically 8).
step 3. Set the M1 FWD SPEED , M2 FWD SPEED and REVERSE SPEED to the desired
top vehicle speeds (in either mph or km/h).
3
Tuning the Controller to the Motor
The 1268 controller has the flexibility to be tuned to nearly any separately
excited motor from any manufacturer. The programmable parameters allow
full control of the motor’s maximum armature current during driving and
braking; they also allow full control of the motor’s maximum and minimum
field current as well as the field current relationship to the armature current.
This flexibility allows motor performance to be maximized while protecting it
from operating outside its safe commutation region.
In order to properly tune the controller, the following information should
be obtained from the motor manufacturer:
Maximum Armature Current Rating
Maximum Field Current Rating
Minimum Field Current Rating
Field Resistance (hot and cold)
Positive and Negative Field Maps.
The performance of a separately excited motor changes depending on tem-
perature. This is due to the change in field winding resistance as the motor
heats up through use. When the field winding temperature increases, so does
its resistance and therefore the maximum current that can be forced through
5 — TUNING GUIDE