Battery Cell Balancing During Sleep With Periodic Wake-Up Control
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Solution Overview
Problem
Existing battery management systems fail to perform cell balancing effectively in sleep or shut down modes, leading to increased voltage differences between battery cells when charged using an external power source or when the upper system is not operating.
Innovation Solution
A battery system with a monitoring unit that wakes up periodically to perform cell balancing in low power modes, adjusting its wake-up cycles based on predetermined conditions, and a control unit that enters sleep or shut down modes when certain conditions are met, ensuring cell balancing is maintained even when the system is inactive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the BMS enters sleep mode or shut down mode to save power, then power consumption is reduced, but cell balancing cannot be performed and voltage difference between cells increases
Solution Approach 1:
The monitoring unit performs cell balancing operations periodically by waking up at predetermined cycles (short cycles or long cycles) rather than continuously. This periodic activation allows the system to maintain cell balancing functionality while consuming minimal power during sleep or shut down modes, directly resolving the contradiction between power savings and balancing reliability.
Solution Approach 2:
The monitoring unit is designed to autonomously perform cell balancing operations without requiring the control unit to be fully active. The monitoring unit can independently wake up, evaluate cell voltage differences, and execute balancing operations based on predetermined conditions, enabling the system to maintain balancing reliability while in low-power states.
2Reliability
If the monitoring unit wakes up frequently to perform cell balancing, then cell balancing reliability is improved, but power consumption increases
Solution Approach 1:
The system implements a dual-cycle mechanism where the monitoring unit wakes up at short cycles for basic cell balancing and at long cycles for more comprehensive balancing operations. This periodic structure with varying intervals allows the system to maintain adequate balancing reliability while minimizing power consumption by not waking up continuously.
Solution Approach 2:
The system dynamically adjusts the wake-up cycle length (short cycle vs. long cycle) based on battery state and balancing needs. By changing the temporal parameter of wake-up intervals, the system optimizes the balance between balancing reliability and power consumption, waking up more frequently only when necessary.
3Manufacturing precision
If the system performs cell balancing for all battery cells every time, then balancing thoroughness is improved, but processing time and power consumption increase
Solution Approach 1:
The monitoring unit evaluates cell voltage differences and selectively performs cell balancing only on cells that require it, rather than uniformly processing all cells. This localized approach focuses resources on cells with voltage deviations, improving balancing precision for problematic cells while reducing overall processing time and power consumption.
Solution Approach 2:
The system performs partial cell balancing by targeting only the necessary subset of cells based on voltage difference thresholds. Instead of applying full balancing operations to all cells, the system applies balancing actions only where needed, achieving sufficient balancing precision with reduced time and energy expenditure.
Data Source
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AI summary
The present invention relates to a cell balancing method and a battery system employing same. The battery system of the present invention comprises: a battery including a plurality of battery cells; a monitoring unit for performing a first low-power mode and a second low-power mode, wherein, in the first low-power mode, wakeup is executed every short term period and cell balancing is performed on each of the plurality of battery cells on the basis of a predetermined first cell balancing execution condition, and in the second low-power mode, if a period extension condition is satisfied, wakeup is executed every long term period that is longer than the short term period by a predetermined period, and cell balancing is performed on each of the plurality of battery cells on the basis of a second cell balancing execution condition; and a control unit for, if a low-power mode entry condition is satisfied, indicating the monitoring unit to enter the first low-power mode, and then entering a sleep mode in which a preconfigured operation is not performed.