Battery Management Power Cutoff for Over-Discharge Protection
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Solution Overview
Problem
Conventional storage battery systems fail to effectively prevent over-discharge during software hang-ups or malfunctions, posing safety risks during maintenance and potentially leading to battery damage.
Innovation Solution
A storage battery system with a power supply control circuit that includes an SOC estimator and a shutdown controller, which monitors the state of charge (SOC) of battery cells and interrupts power supply to the BMU and load when over-discharge is detected, even in cases of software failure, using a heartbeat-based SOC signal to ensure continuous protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If software-based over-discharge detection is implemented in the BMU, then cost and operational simplicity are improved, but reliability deteriorates due to potential software hang-ups or malfunctions
Solution Approach 1:
An independent hardware monitoring circuit is introduced as an intermediary between the battery and the BMU. This circuit directly monitors battery voltage and independently controls the discharge relay, acting as a mediator that bypasses the unreliable software in the BMU while still enabling cost-effective software-based monitoring in the main control unit.
Solution Approach 2:
The monitoring function is segmented into two independent parts: a hardware-based protection circuit that handles critical over-discharge protection independently, and a software-based BMU that provides additional monitoring and control functions. This segmentation ensures that software failures do not compromise safety.
2Reliability
If power supply to the BMU is interrupted to prevent over-discharge, then battery protection is improved, but maintenance capability deteriorates
Solution Approach 1:
The power supply interruption is applied locally and selectively - only to the BMU when over-discharge is detected, while the independent hardware protection circuit remains operational. This allows maintenance personnel to access the system for troubleshooting while the protection function continues to operate independently.
Solution Approach 2:
The hardware protection circuit is pre-configured to automatically interrupt power supply before over-discharge damage occurs, creating a preliminary protective action that operates independently of BMU software status or maintenance activities.
3Ease of operation
If the discharge relay remains closed to maintain power supply during maintenance, then maintenance work is facilitated, but over-discharge protection is compromised
Solution Approach 1:
The independent hardware monitoring circuit acts as an intermediary that directly controls the discharge relay based on real-time battery voltage monitoring, bypassing the BMU software. This ensures that maintenance activities cannot prevent the relay from opening when over-discharge conditions are detected, while still allowing BMU power to be maintained for maintenance purposes.
Data Source
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Figure 2(A)~2(D)
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AI summary
According to an embodiment, a storage battery system includes a battery management unit that is detectable of an over discharge state of a cell module including storage battery cells, receives power supply from the cell module to operate, is able to output a status signal for determining whether the cell module is likely to enter the over discharge state, and is able to place a contactor in a closed state while receiving the power supply, the contactor having a normally open contact inserted in a current supply path through which stored power is supplied from the cell module to an outside; a determiner that determines output or no output of the status signal; and an interrupter that interrupts the power supply to the battery management unit from the cell module after determination of no output of the status signal. The storage battery system interrupts power supply to a load or a BMU when the cell module is likely to enter over discharge.