Battery Protection Circuit Overdischarge Detection Logic
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Solution Overview
Problem
Existing battery pack protection and monitoring circuits lack communication mechanisms, making it difficult for the secondary battery monitoring circuit to accurately determine the performance of the protection circuit, especially during overdischarge and overcurrent events, due to power supply voltage inhibition and measurement delays.
Innovation Solution
A protection monitoring circuit that includes a protection circuit capable of detecting overcharge, overdischarge, and overcurrent, and a secondary battery monitoring circuit that receives notifications from the protection circuit, with the protection circuit inhibiting power supply to the monitoring circuit after a predetermined time or upon receiving a control signal, allowing accurate storage of overdischarge detection information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the protection circuit inhibits power supply to the secondary battery monitoring circuit upon detecting overdischarge, then current consumption is reduced and battery protection is improved, but the monitoring circuit cannot accurately detect or store overdischarge information
Solution Approach 1:
The protection circuit performs preliminary action by storing overdischarge detection information in a notification flag before inhibiting power supply to the monitoring circuit. This ensures that the detection information is preserved even when the monitoring circuit is powered down, resolving the contradiction between reducing current consumption and maintaining information accuracy.
2Speed
If the protection circuit operates immediately upon detecting overcurrent, then battery protection response is improved, but the secondary battery monitoring circuit cannot complete current measurement and store accurate data
Solution Approach 1:
The protection circuit performs preliminary action by setting a notification flag to indicate overcurrent detection before the monitoring circuit can complete its measurement. This allows the protection function to operate immediately for safety while still enabling accurate recording of the event through the notification mechanism.
Solution Approach 2:
The notification flag acts as an intermediary between the protection circuit and the monitoring circuit. It transfers the overcurrent detection information from the protection circuit to the monitoring circuit, allowing the monitoring circuit to record accurate data even when the protection circuit operates faster than the measurement cycle.
3Measurement precision
If the secondary battery monitoring circuit continuously monitors voltage and current to determine protection circuit operation, then detection accuracy is improved, but computational load and power consumption increase
Solution Approach 1:
The notification flag serves as an intermediary that directly communicates protection circuit operation status to the monitoring circuit. This eliminates the need for continuous computational monitoring by the secondary battery monitoring circuit, as it can simply read the notification flag state, thereby reducing power consumption while maintaining detection accuracy.
Data Source
AI summary
A protection monitoring circuit 101 includes a protection circuit 130 which detects at least one of overcharge, overdischarge, and overcurrent of a chargeable and dischargeable secondary battery 110 and protects the secondary battery 110 by performing an ON/OFF control of transistors M11 and M12, and a secondary battery monitoring circuit 120 which detects a state of the secondary battery 110. The protection circuit 130 supplies a power supply voltage to the secondary battery monitoring circuit 120. If overdischarge of the secondary battery is detected, the protection circuit 130 inhibits the supply of the power supply voltage to the secondary battery monitoring circuit 120 after a predetermined time has elapsed or after a control signal for inhibiting the supply of power supply voltage is received from the secondary battery monitoring circuit 120.