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BASIC OPERATION AND FEATURES
SX TRANSISTOR CONTROL
Section 2.1.3 Braking
Section 2.1.3.a Plug Braking
Slow down is accomplished when reversing direction by
providing a small amount of retarding torque for
deceleration. If the vehicle is moving, and the directional
lever is moved from one direction to the other, the plug
signal is initiated. Once the plug signal has been initiated,
the field is reversed, and the armature current is regulated
to the plug current limit as set by Function 5. Armature
current is regulated by increasing the field current as the
vehicle slows down. Once the field current reaches a
preset value, set by Function 10, and armature plug current
can no longer be maintained, the braking function is
canceled, and the control reverts back to motoring. All
energy produced by the motor during plugging is dumped
as heat into the motor in this braking mode.
Section 2.1.3.b Regenerative Braking to Zero Speed
Slow down is accomplished when reversing direction by
providing a small amount of retarding torque for
deceleration. If the vehicle is moving, and the directional
lever is moved from one direction to the other, the regen
signal is initiated. Once the regen signal has been initiated,
the field current is increased. Armature current is
regulated to the regen current limit as set by Function 9. As
the vehicle slows down, the field current continues to
increase, and transistor Q2 begins to chop. The field
current will increase until it reaches a preset value set by
Function 10, and transistor Q2 on-time will increase until it
reaches 100% on-time. Once both of the above conditions
have been met, and the regen current limit can no longer be
maintained, the braking function is canceled. The fields
will then reverse, and the control reverts back to motoring.
Part of the energy produced by the motor during regen is
returned to the battery, and the remainder is dumped into
the motor as heat.
Section 2.1.3.c Pedal Position Plug Braking
This feature allows control of the plugging distance based
on pedal position when there has been a "directional
switch" change. Pedal position will reduce the plugging
current as the pedal is returned to the creep speed position.
Maximum plug current is obtained with the accelerator in
the top speed position.
Section 2.1.4 Auxiliary Speed Control
Section 2.1.4.a Field Weakening
This function allows the adjustment of the field weakening
level in order to set the top speed of the motor. The function
is enabled when the armature current is less than the value
set by Function 24 . It is important to note that this function
is used to optimize motor and control performance, and this
setting will be determined by GE and OEM engineers at the
time of vehicle development. This setting must not be
changed by field personnel without the permission of the
OEM.
Section 2.1.5 Ramp Operation
Section 2.1.5.a Ramp Start
This feature provides maximum control torque to restart a
vehicle on an incline. The memory for this function is the
directional switch. When stopping on an incline, the
directional switch must be left in its original or neutral
position to allow the control to initiate full power when
restarted. The accelerator potentiometer input will
modulate ramp start current.
Section 2.1.5.b Anti-Rollback
This feature provides retarding torque to limit rollback
speed in the non-travel direction when the ACC pedal is
released when stopping on a grade, or when the brake
pedal is released when starting on a grade. This feature
forces the vehicle to roll very slowly down the grade when
the accelerator or brake is released. Because the vehicle
can gain significant speed during roll-back, the torque
needed to re-start on the ramp is lower than an
unrestricted roll-back speed.
Section 2.1.6 Steer Pump Contactor Time Delay
This feature provides a 0.5 to 63 second time delayed drop
out of the steer pump contactor when the seat switch is
opened.
Section 2.1.7 On-Board Coil Drivers and Internal Coil
Suppression
Coil drivers for the LINE and SP or BYPASS contactors
are on-board the control card. These contactors must have
coils rated for the vehicle battery volts.
Section 2.2 System Protective Override
Section 2.2.1 Static Return to Off (SRO)
This inherent safety feature of the control is designed to
require the driver to return the directional lever to the
neutral position anytime he leaves the vehicle and returns.
Additionally, if the seat switch or key switch is opened, the
control shuts off and cannot be restarted until the
directional lever is returned to neutral. A time delay of
approximately 2 seconds is built into the seat switch input
to allow momentary opening of the seat switch, if a bump is
encountered.
Page 7
July 1999
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Troubleshooting
