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BASIC OPERATION AND FEATURES
SX TRANSISTOR CONTROL
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 circuit shown in Figure 5). Armature current is regulated to the regen current limit as set by
Q2
Function 9. As the vehicle slows down, the field current continues to increase, and transistor Q2 begins to
ARM
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 regen current limit can no longer be maintained, the braking function is canceled. The fields will then
Q1
reverse, and the control reverts back to motoring.
Part of the energy produced by the motor during regen is returned to the battery, and part is dumped in
Figure 5
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 regenerative current to the "value set by this function" as the accelerator is returned to the creep
speed position. Maximum regen current is obtained with the accelerator in the top speed position.
Section 2.1.3.d Auto Braking
This feature is enabled by initiating a "neutral position" using either the directional switch or the accelerator switch. Once
activated, Auto Braking operates similar to Pedal Position Plug Braking and is adjusted by using Function 21 of the Handset.
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 and the accelerator input voltage is less than 1 volt.
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 2.1.4.b Speed Limits
This feature provides a means to control speed by limiting motor volts utilizing three "adjustable speed limits. This motor volt
limit regulates top speed of the transistor controller, but actual truck speed will vary at any set point depending on the loading of
the vehicle. Each speed limit can be adjustable with the Handset using Functions 12 and 13.
Section 2.1.5 Ramp Operation
Section 2.1.5a 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 2.1.5b 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 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 On-Board Coil Drivers & Internal Coil Suppression
Page 9
November 2002
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Troubleshooting
