System Description

SYSTEM

System Description


SYSTEM DIAGRAM







INPUT/OUTPUT SIGNAL ITEM

Input signal item





Output signal item






DESCRIPTION

The Li-ion battery controller (LBC) constantly monitors the conditions inside the battery, and transmits the battery charge status (SOC), the electrical power that can be input and output in the vehicle, and other information via HEV system CAN communication.
Vehicle information from each unit is received via HEV system CAN communication.
The Li-ion battery controller performs the following control.
- The battery status is monitored constantly, and the available charge/discharge power is transferred to the
HPCM (Hybrid Powertrain Control Module) so that battery malfunctions (overvoltage, over-discharge, or overheating) may not occur.
- The battery malfunctioning status (overvoltage, over-discharge, or overheating) is immediately detected when it occurs. The system main relay cut-off request is transmitted to HPCM, and the charge/discharge line is shut off.
- The battery is maintained in optimal conditions according to the cell capacity adjustment function so that a decrease in the battery charge/discharge capability, which may be caused by cell capacity fluctuation, can be prevented.
- The insulation resistance status is detected according to the detection function for isolation resistance drop between high voltage and low voltage. The status is transmitted to the HPCM so that the vehicle may not be started in a malfunctioning status.
Li-ion Battery Operating Stop Condition





After IGN OFF, LBC does not stop immediately, and instead starts a shutdown operation.
The shutdown time varies according to the battery capacity adjustment time that is performed in order to eliminate voltage differences between the cells.

BATTERY PROTECTION

The Li-ion battery has a voltage range capable of charge/discharge. If charged/discharged exceeding the range, excessive low capacity or malfunction may be caused. To prevent this, the Li-ion battery controller detects voltage of each cell and requests the control of charging/discharging energy to HPCM so that the cell voltage stays within the voltage range.






CELL CAPACITY ADJUSTMENT METHOD

During cell capacity adjustment, the capacity of each cell is estimated based on the no-load voltage when the system starts, and the capacities are adjusted so that they are all at the target level. The voltage of each cell is detected inside the Li-ion battery controller. The bypass switches are then turned ON to discharge the cells that have excess capacity. In this way, capacity adjustment by the Li-ion battery controller allows the capacity of all cells to be fully utilized.