GE IC3645SR3R404R2 Installation And Operation Manual page 6

BASIC OPERATION AND FEATURES
SX TRANSISTOR CONTROL
Section 2.1.1.a Standard Operation
With the accelerator at maximum ohms or volts, the creep
speed can be adjusted by Function 2 of the Handset or a
trimpot. The field control section allows the adjustment of
the field weakening level in order to set the top speed of
the motor. This top speed function (Minimum Field Current)
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. Top Speed can be adjusted by Function 7 of
the Handset or a trimpot.
The percent on-time has a range of approximately 0 to 100
percent. The SX controllers operate at a constant
frequency and the percent on-time is controlled by the
pulse width of the voltage / current applied to the motor
circuits.
Section 2.1.1.b Creep Speed
With the accelerator at maximum ohms or volts
(approximately 3.7 to 3.5 VDC), the creep speed can be
adjusted by Function 2 of the Handset. At creep speed, the
ON time can decrease to approximately 5%, with the OFF
time at approximately 95%. At full transistor operation, this
condition will be reversed (short OFF time, long ON time).
This variation of ON and OFF time of the oscillator varies
the voltage applied to the motor, thereby varying the speed
of the motor for a given load.
Section 2.1.1.c Control Acceleration
This feature allows for adjustment of the rate of time it
takes for the control to accelerate to 100% applied battery
voltage to the motor on hard acceleration Armature C/A is
adjusted by Function 3 from 0.1 to 22 seconds.
Section 2.1.2 Current Limit
This circuit monitors motor current by utilizing sensors in
series with the armature and field windings. The
information detected by the sensor is fed back to the card
so that current may be limited to a pre-set value. If heavy
load currents are detected, this circuit overrides the
oscillator and limits the average current to a value set by
Function 4 and Function 8 of the Handset. The C/L setting
is based on the maximum thermal rating of the control.
Because of the flyback current through 3REC, the motor
current is usually greater than battery current, except at
100% ON time.
Section 2.1.3 Braking
Section 2.1.3.a 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
Q2
moving, and the directional lever is
ARM
moved from one direction to the
other, the regen signal is initiated.
Once the regen signal has been
initiated, the field current is
Q1
increased (armature circuit shown in
Figure 5
Figure 5). 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 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 part is dumped in the motor as
heat.
Section 2.1.3.b 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.c 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
Page 6
March 2000