Battery Cell Voltage Measurement in Daisy-Chain BMS Circuits
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Solution Overview
Problem
The daisy chain architecture used in Battery Management Systems (BMS) for electrified vehicles faces limitations in throughput and latency, affecting the accuracy and frequency of battery cell voltage measurements.
Innovation Solution
The implementation of a first battery management circuit that measures the voltage of a first battery cell, generates a voltage measurement, receives a bit from a second battery management circuit, and sums it with its own measurement to provide a summed bit to a third circuit, optimizing communication in a daisy chain system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a daisy chain architecture is used for communication between battery management circuits, then the system can be implemented with simple wiring and moderate complexity, but the throughput is limited and latency increases
Solution Approach 1:
The patent divides the battery management system into multiple independent battery management circuits, each capable of autonomous measurement and processing. Each circuit measures voltage of its associated battery cell independently and processes data locally before transmission, enabling parallel operation that increases overall throughput while maintaining simple daisy-chain wiring topology.
Solution Approach 2:
The patent combines multiple measurement results from different battery management circuits into a single aggregated response transmitted through the daisy chain. By merging individual cell voltage measurements at the circuit level rather than transmitting all raw data sequentially, the system achieves high throughput using the limited bandwidth of the daisy chain architecture.
2Device complexity
If a daisy chain architecture is used for communication between battery management circuits, then the system can be implemented with simple wiring and moderate complexity, but the latency between command sending and response receiving increases
Solution Approach 1:
Battery management circuits perform voltage measurements and data processing in advance, before receiving transmission commands through the daisy chain. Each circuit maintains a ready queue of measurement results, allowing immediate response transmission upon receiving a read command, thereby minimizing latency without requiring complex communication protocols.
Solution Approach 2:
Each battery management circuit autonomously manages its own measurement data, processing and transmission timing. The circuits independently determine when their measurement results are ready and proactively prepare data for transmission, reducing the need for complex centralized scheduling and minimizing communication latency across the daisy chain.
3Measurement precision
If individual battery management circuits measure and transmit each battery cell voltage separately through the daisy chain, then measurement accuracy can be maintained, but the measurement frequency and usefulness of the data decrease
Solution Approach 1:
The patent merges multiple individual battery cell voltage measurements into aggregated results that are transmitted through the daisy chain. Each battery management circuit combines its measurement data with summaries from other circuits, enabling high-frequency monitoring of all cells while transmitting condensed information that maintains measurement precision and reduces communication overhead.
Data Source
AI summary
In an embodiment, an apparatus is disclosed that includes a first battery management circuit. The first battery management circuit is configured to measure a voltage of a first battery cell of a battery pack and to generate a first voltage measurement based at least in part on the measured voltage of the first battery cell. The first battery management circuit is configured to receive a bit of a first response from a second battery management circuit. The bit of the first response is generated by the second battery management circuit based at least in part on a measured voltage of a second battery cell of the battery pack. The first battery management circuit is configured to sum the bit of the first response with a corresponding bit of the first voltage measurement and to provide the summed bit to a third battery management circuit as part of a second response.