Vestil EPT-30 - Manual (Page 62)

62
Curtis PMC 1207/1207A Manual A-7
APPENDIX A: GLOSSARY
when the voltage is brought within the acceptable range. The cutoff voltage and
re-enable voltage are percentages of the battery voltage, and are set at the factory.
Plug braking
Plug braking takes place when a series motor is driven electrically in a direction
opposite from the direction it is turning. The 1207/1207A controls the field
current to obtain smooth and controlled plug braking torque. During plug
braking, the maximum current limit is automatically changed to the plug current
limit, and the PWM frequency is changed to 1.5 kHz.
NOTE
: Plug current limit
on the 1207/1207A controls the field current. The armature current in plug
mode will be higher than the field current.
There are two types of plug braking control — fixed and variable. The fixed
plug current limit is set to a fixed level. The variable plug current limit varies the
current limit to correspond to the throttle position.
If you have a MultiMode™ controller, the plug current limits in Mode 1
and in Mode 2 are independently adjustable via the handheld programmer. If you
have a 1207 controller with the MultiMode™ feature disabled (i.e., a single-
mode controller), you can adjust the plug current limit mechanically via the
appropriate trimpot located on top of the controller.
PWM
Pulse width modulation (PWM), also called “chopping,” is a technique that
switches battery voltage to the motor on and off very quickly, thereby controlling
the speed of the motor. Curtis PMC 1200 series controllers use high frequency
PWM—15 kHz—which permits silent, efficient operation.
Quick-start
Upon receiving a quick throttle demand from neutral, the controller will exceed
normal acceleration momentarily in order to overcome inertia. The “quick-start”
algorithm is applied each time the vehicle passes through neutral and is not in
plug mode. If the vehicle is in plug, the quick-start function is disabled, allowing
normal plug braking to occur.
The quick-start throttle factor is adjustable via the handheld programmer.
Ramp shape (throttle map)
“Ramp shape” is a programmable parameter that determines the static throttle
map of the 1207/1207A controller. Eleven preprogrammed ramp shapes are
available, in 5% steps between 20% and 70% (20, 25, 30, 35, 40, 45, 50, 55, 60,