Battery Cell Monitoring Circuit for Micro-Short Detection
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Solution Overview
Problem
Existing battery management systems (BMS) struggle to efficiently detect micro-short-circuits (MSCs) in battery cells due to high-speed processing requirements and noise interference, which are typically filtered out by software algorithms.
Innovation Solution
A monitoring circuit comprising a sigma-delta modulator, decimation filters, and a difference module to down-sample cell voltage signals, allowing for hardware-based detection of MSCs by analyzing differences between down-sampled signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software-based detection algorithms are used to detect micro-short-circuits, then detection capability is provided, but high-speed processing requirements and noise filtering issues arise
Solution Approach 1:
The patent replaces software-based detection algorithms with a hardware-based monitoring circuit that uses analog signal processing. The circuit employs a difference module to directly compare cell voltage signals and generate monitoring outputs for micro-short-circuit detection, eliminating the need for complex software processing and high-speed computational requirements while maintaining reliable detection capability
Solution Approach 2:
The patent extracts and amplifies the specific signal characteristic associated with micro-short-circuits by using a difference module that compares adjacent cell voltages. This extraction approach isolates the MSC signal from general noise, enabling detection without requiring high-speed processing or complex software algorithms
2Measurement precision
If noise control filtering is applied to cell voltage signals, then signal quality is improved, but micro-short-circuit current spikes are filtered out
Solution Approach 1:
The patent converts the harmful effect of noise by using a difference module that compares cell voltage signals. The differencing operation amplifies the MSC signal characteristic while canceling out common-mode noise, thereby transforming noise rejection from a filtering problem into a signal processing advantage that preserves current spike information
Solution Approach 2:
Instead of filtering out noise as conventional approaches do, the patent inverts the approach by using differential measurement to reject noise. The difference module subtracts adjacent cell voltages, which causes common-mode noise to cancel out while preserving the differential MSC signal, thus inverting the traditional noise handling methodology
Data Source
AI summary
A monitoring circuit for a battery cell, the monitoring circuit comprising: a sigma-delta modulator, configured to receive an analog cell voltage signal and output a digital cell voltage signal; a first decimation filter configured to receive the digital cell voltage signal and down-sample the digital cell voltage at a first down-sampling rate to output a first down-sampled cell voltage signal; a second decimation filter configured to receive the digital cell voltage signal and down-sample the digital cell voltage at a second down-sampling rate, different to the first down-sampling rate, to output a second down-sampled cell voltage signal; and a difference module configured to receive the first down-sampled cell voltage signal and the second down-sampled cell voltage signal and output a cell monitoring signal based on a difference between the first down-sampled cell voltage signal and the second down-sampled cell voltage signal.