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4.5. Operational states
Figure 13: Battery modes
Off
: in this mode, BMU is not supplied. Thus, the battery is not supervised by the BMM.
Init:
in this mode, the battery is unavailable, meaning it is disconnected from the overall system.
The BMU proceeds to its internal tests:
PBIT self-test (BMU memory Read/W
rite, …)
Software initialization
Contactor test
If the self-test is ok, the BMM will go in
STANDBY
state.
If the self-test is not ok, the BMM will go in
SAFE
state.
The self-test duration is roughly 6 seconds.
Stand-by:
in this mode, the battery pack is not yet operating. BMU is waiting from EMS for the
permission to close the contactor (via the CAN Open Bus).
Nominal:
system is running. The battery is available for discharge and recharge according to
the IMD, IMR, VMD and VMR values. Under these conditions, the BMU performs several
functions (such as monitoring and protection of the battery modules, communication with the
various modules, managing the contactors and managing battery cell balancing).
1
7
2
INIT
NOMINAL
SAFE
STAND BY
SLEEP
6
8
Off
4
10
11
12
3
5
9