Curtis PMC 1297 Manual
A-8
APPENDIX A: GLOSSARY
PWM
Pulse width modulation (PWM), also called “chopping,” is a technique that
switches battery voltage to the motor on and off very quickly, thereby control-
ling the speed of the motor. Curtis PMC 1200 series controllers use high
frequency PWM—in this case, 16 kHz—which permits silent, efficient opera-
tion.
Regenerative braking
The 1297 controller uses regenerative braking to slow the vehicle to a stop and
to reduce speed when traveling downhill. Regenerative braking means that the
energy used to slow the vehicle is channeled back into the batteries, resulting in
longer vehicle range between charges.
Reset
Some faults require a cycling of the KSI or interlock switch input to reset the
controller and enable operation; see Fault recovery for exceptions.
Restraint
When the vehicle speed exceeds the requested throttle, the restraint feature
causes the motor to apply a braking force and “restrain” the vehicle to the
requested speed—see Section 3, page 27.
Reverse polarity protection
The 1297 controller is protected against reverse polarity by an internal diode.
If the battery’s B+ and B- connections to an otherwise properly wired controller
are reversed, the main contactor will not engage—thus protecting the controller
from being damaged.
Safe commutation region
The safe commutation region includes all the combinations of field current and
armature current that allow proper commutation between the traction motor’s
brushes and the armature. If the motor operates outside this region, arcing and
severe heating and brush wear will occur. The motor manufacturer should be
able to provide curves defining the safe combinations of field and armature
current. We highly recommend that you obtain these curves and use them when
tuning the 1297 controller to a particular motor—see Section 5.
Sequencing delay
The sequencing delay feature allows the interlock switch to be cycled within a
set time (the sequencing delay), thus preventing inadvertent activation of
various lockout features—see Section 3C, page 57.
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