Curtis 1214-/15-/19-8 Manual
APPENDIX A: FEATURES & FUNCTIONS
A-7
Overvoltage protection
Overvoltage resets the microprocessor, inhibits the PWM, and opens the contac-
tors, thereby shutting down the controller. Overvoltage can result during battery
charging or from an improperly wired controller. Controller operation resumes
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 1214-/15-/19-8 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
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.
The Mode 1 and Mode 2 plug current limits are independently adjustable
via the handheld programmer.
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 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.
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