Battery Cell Measurement Clock Synchronization Over Daisy-Chain Networks
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Solution Overview
Problem
Existing battery management systems face challenges in achieving synchronization across scattered BMS ICs due to the lack of a common clock distribution via daisy chain or wireless protocols, which is essential for accurate electrochemical impedance measurements.
Innovation Solution
A synchronization element generates a reference clock signal that synchronizes individual clock signals of measurement devices through a communication network, adjusting local oscillators based on time reference signals to ensure synchronization, and includes mechanisms to wait for a free communication network before sending signals to maintain synchronization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If BMS ICs are scattered over the battery pack and connected via daisy chain communication bus or wireless protocol, then device complexity is reduced and ease of manufacture is improved, but synchronization precision deteriorates due to inability to distribute common clock
Solution Approach 1:
The patent introduces a synchronization message as an intermediary carrier that transports timing information through the existing daisy-chain communication bus. This mediator enables synchronization without requiring physical clock distribution, resolving the contradiction by allowing scattered BMS ICs to maintain precise timing through logical rather than physical clock distribution.
Solution Approach 2:
The patent transforms the synchronization approach by changing the parameter being transmitted from physical clock signals to time reference values embedded in communication messages. This parameter transformation allows the system to achieve synchronization precision equivalent to common clock distribution while maintaining the manufacturing advantages of scattered BMS ICs connected via daisy-chain bus.
2Measurement precision
If a common clock is distributed to all BMS ICs, then synchronization precision is improved, but device complexity increases and ease of manufacture deteriorates
Solution Approach 1:
The synchronization message acts as an intermediary that carries timing information through the existing communication infrastructure, eliminating the need for separate physical clock distribution networks. This reduces device complexity while maintaining synchronization precision by reusing existing communication channels for dual purposes: data transmission and timing synchronization.
Solution Approach 2:
The patent makes the communication bus multi-functional by using it for both data transmission and clock synchronization. This universal usage eliminates the need for dedicated clock distribution hardware, reducing device complexity while achieving the same synchronization precision that would otherwise require separate clock routing infrastructure.
3Productivity
If time reference signals are sent immediately without checking network status, then productivity is improved, but measurement precision deteriorates due to signal loss on busy network
Solution Approach 1:
The patent implements preliminary action by checking the communication network status before transmitting time reference signals. This advance verification prevents signal loss by ensuring the network is ready to receive synchronization data, thereby maintaining both productivity (through efficient transmission timing) and measurement precision (through successful signal delivery).
Solution Approach 2:
The system uses feedback from network status monitoring to dynamically adjust transmission timing. By continuously monitoring whether the communication network is busy or free and responding accordingly, the system ensures time reference signals are transmitted only when conditions are favorable, preventing signal loss while minimizing delays to maintain synchronization precision.
Data Source
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AI summary
A battery management system comprising: a synchronisation element comprising an oscillator wherein the synchronisation element is configured to generate a reference clock signal based on an output of the oscillator; and a plurality of measurement devices wherein each measurement device is configured to measure an electrical property of one or more battery cells and comprises a local oscillator configured to generate an individual clock signal; and wherein the plurality of measurement devices are connected in a communication network with the synchronisation element, and wherein: the synchronisation element is configured to send, by the communication network, time reference signals to the plurality of measurement devices based on the reference clock signal; each measurement device is configured to compare each time reference signal to its individual clock signal and, based on any detected difference, adjust its local oscillator to synchronize the individual clock signal with the reference clock signal.