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4. BATTERY MANAGEMENT AND OPERATING INSTRUCTIONS
4.1. General principle
Charge and discharge of the Li-ion battery must be monitored and managed with respect to
physical parameters such as cell voltages, battery current and module temperature. This
management is performed by the BMU board inside the BMM, which runs algorithms and
monitors the battery.
The concept is to use the features of the converter to perform the battery management. The
application will receive data from the battery via CAN Open bus and must take the appropriate
actions.
Safety functions will still be ensured by the BMM.
During the use of the battery, if one critical physical parameter goes out of the acceptable
range, the battery contactor is opened and the battery goes in
SAFE
mode (see §4.5 for
mode description), the battery will go back in
STANDBY
mode if critical fault is reset
(software reset or hardware reset). If the customer continue to send the authorization bit to
close the contactor at 1, the battery system will go directly in
NOMINAL
mode (see §5.14.2).
Critical physical parameters are:
- Module temperature
- Cell voltage
- Current versus over current protection
The determination of the acceptable ranges of values for the temperature and the cell
voltages is explained below at §4.2.2, §4.2.3 and §4.2.4.
4.2. Safety functions
4.2.1. Over charge protection
Two kinds of protection are used to prevent over charge: regarding cells voltage, BMM could
open the contactor.
The two kinds of protection are:
- Cell over voltage first level: one cell voltage > 3,86V
- Cell over voltage second level (redundant): one cell voltage > 4,23V