EV Battery Switching Control for Hazard Isolation and Critical Loads
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Solution Overview
Problem
Electric vehicles equipped with lithium-based batteries face safety concerns due to the risk of fire or poisonous gas emission in case of damage or electrical failure, necessitating a safety system to disconnect the battery. This requires a dual battery setup with both lithium-based and lead acid batteries, increasing volume and mass for energy storage.
Innovation Solution
A battery management system that includes a control unit, switches, and connectors to manage the transfer of electric energy between a lithium-based battery and a lead acid battery. In case of a dangerous situation detected by sensors, the system disconnects the lithium-based battery and switches to the lead acid battery to provide energy to critical loads, ensuring safety without the need for large energy storage volumes or masses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium-based battery is used to increase electric capacity, then the electrical capacity per unit of mass and volume is improved, but safety risks increase due to fire and poisonous gas emission
Solution Approach 1:
The battery system is segmented into two separate batteries: a lithium-based battery for high-capacity energy storage and a lead acid battery for safety-critical functions. This segmentation allows each battery type to fulfill its optimal role while mitigating the safety risks of lithium-based batteries by isolating them from critical systems.
Solution Approach 2:
A control unit acts as an intermediary between the lithium-based battery and the vehicle's electrical systems. It continuously monitors the lithium battery's state and can disconnect it from critical loads when safety risks are detected, while automatically switching to the lead acid battery to maintain power supply to essential systems.
2Reliability
If a dual battery setup is implemented to ensure safety, then safety reliability is improved, but the volume and mass of the energy storage system increase
Solution Approach 1:
The lead acid battery is designed with partial capacity - only sufficient to power critical safety systems during emergency situations, rather than providing full vehicle power. This partial action approach minimizes the mass penalty while maintaining adequate safety backup capability.
Solution Approach 2:
Different parts of the battery system are assigned different functions with different quality requirements: the lithium-based battery provides high energy density for general power needs, while the lead acid battery provides high safety and reliability for critical systems. This local differentiation optimizes the overall system mass by matching battery characteristics to specific functional requirements.
3Object-affected harmful factors
If the lithium-based battery is disconnected in dangerous situations, then safety is improved, but the availability of electric energy to loads is reduced
Solution Approach 1:
The lead acid battery is pre-positioned and pre-charged as a standby power source, ready to immediately take over when the lithium-based battery is disconnected. This preliminary preparation ensures that energy availability to critical systems is maintained without interruption during safety events.
Solution Approach 2:
The system dynamically changes the operational parameters of the battery configuration based on safety conditions. Under normal conditions, the lithium-based battery supplies power to all loads. When safety risks are detected, the control unit changes the system state by disconnecting the lithium battery and reconfiguring the electrical architecture to supply critical loads from the lead acid battery.
Data Source
AI summary
There is provided a battery management system for an electric vehicle. The battery management system comprises a first load connector, a second load connector, a first switch, a first battery connector, a second battery connector and a control unit. The first load connector is connectable to a first group. The second load connector is connectable to a second group. The first battery connector is connectable to a first battery. The second battery connector connectable to a second battery. The battery management system is adapted to transfer electric energy from the first battery via the first switch to the first group and to the second group. The battery management system is adapted to connect the second battery to the second group. The control unit is configured to receive a signal representative of a dangerous situation for the first battery. The control unit is configured, in response to the signal, to switch the first switch to disconnect the first battery from the first group and from the second group, and to start transferring electric energy from the second battery to the second group.