Komatsu 830E-AC, Shop Manual

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E2-32 Electrical Propulsion System Components 10/06 E02020
Wheel Slide Control
The inverters prevent wheel slide by limiting torque to
maintain wheel speeds above preset limits. These
preset limits are a function of truck speed and the
allowable creep; additional compensation will be
applied to provide for differences between wheel
speeds during turns.
Resistor Grid Control
The first resistor grid (RG1) will always be engaged
when retard is active since the grid blower motors are
wired across it.
The second fixed resistor grids (controlled by RP2)
will be engaged as needed to dissipate the energy
produced in retard state.
Chopper Voltage Control
Chopper turn-on voltage will be set to give the motors
as much of the retard envelope as possible (i.e.,
keep the voltage as close to the maximum value as
possible) and to keep the DC link voltage at or below
the maximum link voltage value.
EVENT DETECTION AND PROCESSING
The PSC contains very powerful troubleshooting
software. The PSC software constantly monitors the
AC drive system for any abnormalities (events).
Automatic self-tests are performed periodically on
various parts of the system to ensure its integrity.
Additionally, there are some elaborate tests which
may be run by an electrician with the use of DID
screens. Predictive analysis is used in some areas to
report potential problems before they occur.
The troubleshooting system is composed of two
parts:
• The PSC for detection, event logging, data
storage and fault light indications.
• The TCI (or a PTU) for retrieval of stored event
information, real time vehicle status,
troubleshooting, etc.
The event detection function of the software is
responsible for verifying the integrity of the PSC
hardware and the systems to which the PSC
interfaces by detecting an “event” (abnormal
condition). The events fall into three detection
categories:
Power-On Tests
Three power-on tests are executed once every time
power is applied to the PSC. They are as follows:
• CPU Card Checks - Upon power-up, the PSC will
confirm the integrity of its CPU card hardware
before transferring execution control to the
application program residing in its FLASH
memory.
• Battery-Backed RAM (BBRAM) Test/Adjustable
Parameter Initialization - A battery-backed RAM
(BBRAM) check will be performed to check for
BBRAM data integrity. If the check fails, all TCI/
PTU-adjustable parameters will be initialized to
their default values.
• Inverter Powerup Tests - The purpose of these
tests is to verify that each inverter sub-system is
functional:
1. Enabling Inverter Powerup Tests - The power-
up tests for a given inverter will be enabled if all
of the following conditions are true:
a. The system is in Test state for the purpose of
power-up.
b. The associated gate drive power converter
has been enabled.
c. The engine is running.
d. Battery voltage is at least 25 VDC.
e. The inverter is requesting that the low
voltage and/or high voltage powerup tests be
performed.
f. The inverter has not been physically cut out
of the system.
g. Active event restrictions do not preclude
powering the DC link or running the inverter.
2. Low Voltage Test - A given inverter will
automatically perform its low voltage test if
needed once inverter powerup testing is
enabled per the above requirements. The PSC
will declare the test failed and log an event if the
test does not successfully complete within an
expected time period.
3. High Voltage Test - If the low voltage testing
defined above is successful for a given inverter,
the inverter will automatically perform its high
voltage test if needed once there is sufficient
power on the DC link. The PSC will declare the
test failed and log an event if the test does not
successfully complete within an expected time
after the DC link is sufficiently powered.