Curtis PMC 1297 Manual
25
CURRENT RATIO
The
current ratio
parameter defines how much of the programmed drive
current will be available to the traction motor at reduced throttle requests. The
current ratio parameter can be set to 1, 2, 3, or 4. These settings correspond to
the following ratios:
SETTING
RATIO
1
1 : 1
2
2 : 1
3
4 : 1
4
8 : 1
For example, with the current ratio set at 1 and 20% throttle requested, 20%
of the battery voltage and 20% of the drive current will be allowed to flow in the
motor (assuming a 50% throttle map setting). If the current ratio is set at 2
under these same conditions, 40% of the current will be available; if it is set at
3, 80%. The controller will not allow more than the programmed drive current to
flow in the motor. If the current ratio is set at 4 with 20% throttle requested, the
controller will allow only 100% of the drive current and not 160%.
High current ratio values will allow quicker startup response and improved
ramp climbing with partial throttle, but may cause too much jumpiness.
The current ratio is tuned as part of the vehicle performance adjustment
process (Section 5).
NOTE
: Current ratio is only effective in drive; it does not affect regenera-
tive braking.
BOOST ENABLE
In situations where the controller detects that the motor is about to stall, the
boost enable
feature provides a burst of extra torque by briefly applying a higher
current (120% of the programmed drive current limit). This can be useful for
occasionally getting the vehicle out of a pothole or over an obstacle. If the
operator rocks the vehicle by reversing and rethrottling while in boost, the field
will remain at max field to provide the maximum stall torque and minimum
delay time. Boost enable can be programmed On or Off.
Each boost is limited to 6 seconds, followed by a 30 second cool-down
period, with a total of 15 seconds of boost allowed within each 3 minute period.
Performance is more consistent if boost enable is programmed Off.
M1–M2, BRAKE C/L
The
braking current limit
parameter allows adjustment of the maximum
current the controller will supply to the motor during braking. The braking
current limit is adjustable from 50 amps up to the controller’s full rated braking
3
A
— PROGRAMMABLE TRACTION PARAMETERS: Braking
Braking Parameters
