Komatsu 830E, Shop Manual

Page: 163 / 783

E02016 2/02 Electrical Propulsion Components E2-7
Propulsion
As part of the total software package, a particular
group of regulatory software commands is included
called a “state machine”. The state machine controls
the various operating functions of truck operation.
The software implements the state machine by keeping
track of which state the truck is in, and which state the
truck is allowed to move into if the operator requests a
different mode of operation.
For example, assume the operator has turned the key
switch On to start the control system software, and
then starts the engine. When the accelerator pedal is
pressed to request contactor sequence and excitation,
the state machine enforces a sequence of actions.
First, the software initializes the system. This includes
ensuring that the contactors are all positioned cor-
rectly. (Initialization takes about 8 seconds after control
power has been applied to the FL275 panel.)
Then, when the initialization is completed, the state
becomes the “nomo” , or no motion, state. No propul-
sion or braking contactors are picked up.
Next, the state machine enters the “into accelerate”
state. This state can only be entered if there are no
restriction flags set in the software such as brake (ser-
vice or park), ACCINH, DUMPBS, NAFLT, or GND-
FLT. In this state, contactor sequence is initiated. If all
contactors necessary for acceleration are in their cor-
rect positions, then the state machine enters the
”accelerate” state. If the contactor sequence does not
complete successfully, then a fault, NAFLT , prohibiting
acceleration is tripped.
When the state machine enters the “accelerate” state,
firing commands can be issued. Firing commands are
based on operator request and truck volt and amp
feedbacks. They are used to generate a pulse burst fir-
ing signal from the CPU. The Alternator is thus excited,
generating electrical power (horsepower) to the wheel-
motors which will drive the truck forward or backward,
depending on the position of the selector switch.
Retarding
When the operator presses the retard pedal, accelera-
tion is canceled and the propulsion contactors are
dropped out. The state machine enters the “coast”
state and then the “into retarding” state. It remains in
this state until all of the contactors necessary for
retarding are in the correct position.
The state machine then enters the “retard” state. Fir-
ing pulses are issued to the static exciters based on
operator request and on various system feedbacks.