High-Voltage Battery Control Arrangement for Deep Discharge Protection
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Solution Overview
Problem
High-voltage batteries in motor vehicles with 48-volt supply voltage face issues of irreversible damage and communication disruptions due to deep discharge, making it difficult to diagnose faults and leading to increased costs and regulatory challenges, especially with lithium-ion batteries classified as dangerous goods.
Innovation Solution
A control arrangement for high-voltage batteries that includes a switching mechanism to disconnect the battery from the intermediate circuit when the state of charge falls below a certain limit, allowing the control unit to operate from a separate power source, ensuring energy supply security and enabling reliable status determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the BMS is powered from the high-voltage battery itself, then the quiescent current consumption is very low, but the high-voltage battery can become discharged below a defined electrical voltage limit value causing irreversible damage
Solution Approach 1:
The power supply system is segmented into two independent sources: the high-voltage battery powers the motor vehicle consumers, while a separate auxiliary battery (12V or 48V) powers the BMS. This segmentation prevents the BMS from discharging the high-voltage battery below critical limits while maintaining low quiescent current consumption.
Solution Approach 2:
An intermediary auxiliary battery is introduced as a mediator between the high-voltage battery and the BMS power supply. This auxiliary battery acts as a buffer that ensures the BMS has continuous power without directly drawing from the high-voltage battery, thus preventing deep discharge damage.
2Object-affected harmful factors
If insulation is designed between the battery voltage and the control unit power supply, then safety is improved, but the security of energy supply is lower and costs increase
Solution Approach 1:
The auxiliary battery serves as an intermediary power source that eliminates the need for direct insulation between the high-voltage battery and BMS power supply. By introducing this intermediate energy storage device, the system achieves both safety (through physical isolation) and energy supply security (through the auxiliary battery's ability to continuously power the BMS).
3Reliability
If the high-voltage battery is disconnected from the intermediate circuit, then deep discharge is prevented, but communication with the motor vehicle becomes impossible
Solution Approach 1:
The auxiliary battery acts as an intermediary power source that enables the BMS to remain powered and communicative even when the high-voltage battery is disconnected from the intermediate circuit. This mediator ensures continuous operation of the control unit during battery protection events.
Solution Approach 2:
The auxiliary battery is pre-charged and positioned in advance to provide power to the BMS when needed. This preliminary preparation ensures that communication capability is maintained before the high-voltage battery requires disconnection for protection.
4Measurement precision
If the control unit is always connected to the high-voltage battery, then real-time monitoring is improved, but the risk of deep discharge damage increases
Solution Approach 1:
The system is segmented so that the BMS can monitor the high-voltage battery state through electrical connections while being powered by a separate auxiliary battery. This allows real-time monitoring capability to be maintained without the control unit being continuously powered from the high-voltage battery, thus preventing deep discharge damage.
Data Source
Figure 1~2
AI summary
Control arrangement (1) for a high-voltage battery (2) in a motor vehicle (3), comprising at least a high-voltage battery (2) and a control unit (4) for the high-voltage battery (2); wherein the high-voltage battery (2) is connected to an electrical intermediate circuit (6) of the motor vehicle (2) via a switchable electrical first connection (5) and to the control unit (4) via a switchable electrical second connection (7); wherein the control arrangement (1) has a switching arrangement (8) by which the first connection (5) and the second connection (7) are switchable, such that in a first state (9) of the switching arrangement (1) the high-voltage battery (2) is connected to the intermediate circuit (6) and the control unit (4) is connected to the high-voltage battery (2); wherein in a second state (10) the high-voltage battery (2) is disconnected from the intermediate circuit (6) and in a third state (11) the control unit (4) is disconnected from the high-voltage battery (2) and connected to the intermediate circuit (6).