Curtis MultiMode 1207B Manual page 34

APPENDIX A: GLOSSARY
A-2
The shunt winding of a compound motor can be wired directly to the
shunt driver, provided that the maximum current does not exceed the driver's
current rating.
Creep speed at first throttle
Creep speed is activated when a direction is first selected. The output maintains
creep speed until the throttle is rotated out of the throttle deadband (typically
10% of throttle). Creep speed is adjustable from 0 to 25% of the controller
duty factor; the adjustment can be made via the handheld programmer.
Current limiting
Curtis controllers limit the motor current to a preset maximum. This feature
protects the controller from damage that might result if the current were limited
only by motor demand. PWM output to the power section is reduced smoothly
until the motor current falls below the set limit level.
In addition to protecting the controller, the current limit feature also pro-
tects the rest of the system. By eliminating high current surges during vehicle
acceleration, stress on the motor and batteries is reduced and their efficiency
enhanced. Similarly, there is less wear and tear on the vehicle drivetrain, as well
as on the ground on which the vehicle rides (an important consideration with
golf courses and tennis courts, for example).
The main current limit, plug current limit, and ramp start current limit
in Mode 1 and in Mode 2 are independently adjustable via the handheld pro-
grammer, as is the emergency reverse current limit.
Current multiplication
During acceleration and during reduced speed operation, the Curtis controller
allows more current to flow into the motor than flows out of the battery. The
controller acts like a dc transformer, taking in low current and high voltage
(the full battery voltage) and putting out high current and low voltage. The
battery needs to supply only a fraction of the current that would be required
by a conventional controller (in which the battery current and motor current
are always equal). The current multiplication feature gives vehicles using Curtis
controllers dramatically greater driving range per battery charge.
Deceleration rate
The deceleration rate is the time required for the controller to decrease from
100% duty factor to zero. The deceleration rate is fixed, and cannot be adjusted.
The shape of the deceleration curve is controlled by the dynamic throttle re-
sponse, which is linear.
Curtis 1207B Manual