Lithium Battery Over-Current Protection Locking Unit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium battery management systems (BMS) lack maturity and reliability in detecting and protecting against over-current conditions, particularly during charging and discharging, with a high risk of circuit failure and safety hazards due to the dependence on software and limited hardware-based protection.
Innovation Solution
An over-current protection method and device that includes a detection unit for bi-directional current detection, a determining unit for over-current determination, a locking unit to maintain the over-current state until unlocked, and a circuit cut-off unit to disconnect the main circuit, allowing for independent hardware-based protection even if software fails, with a central processing unit managing unlocking and identification signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software-based current detection and protection is used in BMS, then the system can perform voltage sampling, temperature sampling, and current sampling to determine over-voltage, under-voltage, charging over-current, discharging over-current, high temperature abnormality, and low temperature abnormality, but the reliability is low and the system may fail when software fails
Solution Approach 1:
The protection system is segmented into independent functional modules: detection unit for current sensing, determining unit for over-current judgment, locking unit for state maintenance, and circuit cut-off unit for physical disconnection. Each module operates independently to ensure that software failure does not compromise hardware protection functionality.
Solution Approach 2:
A dedicated locking unit acts as an intermediary between the determining unit and the circuit cut-off unit. This locking unit maintains the over-current state independently and controls the cut-off operation, ensuring that the protection action is executed reliably even when the central processing software fails.
2Reliability
If hardware-based independent protection is implemented, then protection can be maintained when software fails, but the device complexity increases with additional locking and cut-off units
Solution Approach 1:
The locking unit is pre-configured to maintain the over-current state and control the circuit cut-off unit before any software intervention is needed. When over-current is detected, the locking unit immediately locks the protection state and triggers the cut-off, ensuring protection action precedes any potential software failure response.
Solution Approach 2:
The protection system performs self-service through the locking unit that autonomously maintains the over-current state and controls the circuit cut-off without requiring continuous software input. The identification signal outputting unit also provides self-monitoring capability, allowing the system to track its own protection state independently.
3Reliability
If a locking unit is added to maintain over-current state until unlocked, then protection state can be maintained after main circuit cut-off, but the device complexity and number of components increase
Solution Approach 1:
The locking unit combines multiple functions into a single component: it maintains the over-current state, controls the circuit cut-off unit, and works with the identification signal outputting unit to provide state feedback. This merging reduces the need for separate components for each function while maintaining reliable protection state maintenance.
Solution Approach 2:
The locking unit serves multiple purposes: it locks the over-current state to maintain protection memory, triggers the circuit cut-off unit for physical disconnection, and interfaces with the identification signal outputting unit for state monitoring. This multi-functionality reduces overall system complexity despite adding the locking unit.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Embodiments of the present invention provide an over-current protection method and device for a lithium battery, where the device includes: a locking unit, configured to lock an over-current state of a lithium battery according to a charging/discharging over-current signal of the lithium battery, so as to continuously indicate that the lithium battery is in the over-current state; and a circuit cut-off unit, configured to output, after the locking unit locks the over-current state of the lithium battery, a drive signal to cut off a main circuit where the lithium battery is located. In the embodiments of the present invention, a locking unit locks an over-current state of a lithium battery, and the cutting-off of a switch of a main circuit is driven by using the locking unit and a circuit cut-off unit, so that execution of an over-current protection action for the lithium battery no longer depends on a CPU, and even if a CPU software fails, an over-current protection state may still be entered when an over-current state occurs, or original over-current state protection may still be effectively maintained.