BMS Daisy-Chain Delay Measurement for Synchronized Cell Control
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Solution Overview
Problem
In battery management systems configured in a daisy chain, determining communication delays between the main controller and subsidiary controllers is complex and requires multiple messages, making it challenging to synchronize actions across all controllers simultaneously.
Innovation Solution
A method where the most-remote battery cell controller starts a local-clock counter, and each subsequent controller forwards the message while starting their own clock counter, allowing the main controller to determine communication delays by calculating the difference between its clock counter interval and the local intervals, using a single pair of transmissions, thus simplifying the process regardless of the number of controllers in the chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the main controller sends a message to each subsidiary controller to determine communication delay, then the communication delay can be determined, but multiple messages and responses are required for each subsidiary controller, increasing system complexity
Solution Approach 1:
The patent combines multiple separate delay measurement operations into a single unified process. The main controller sends one message that is forwarded through the entire daisy-chain of subsidiary controllers, and receives one response message back. This merges what would otherwise require N separate measurement transactions (for N controllers) into just one transaction, reducing message exchange complexity while maintaining the ability to measure delay to each controller in the chain.
Solution Approach 2:
The single message transmitted by the main controller serves multiple functions simultaneously: it triggers delay measurement for the main controller, propagates through all subsidiary controllers to enable their individual delay measurements, and elicits a coordinated response. This multi-functional approach eliminates the need for separate dedicated measurement messages for each controller.
2Speed
If each subsidiary controller implements action immediately on receiving the message, then response time is reduced, but synchronicity across all controllers is not achieved
Solution Approach 1:
The main controller performs preliminary action by calculating and storing the communication delay to each subsidiary controller before executing the coordinated control task. This advance preparation enables each controller to pre-calculate its specific delay compensation value, allowing immediate action execution while maintaining synchronicity.
Solution Approach 2:
The system uses feedback from the measured communication delays to adjust the timing of actions at each subsidiary controller. Each controller receives feedback about its specific delay characteristic and uses this to compensate its action timing, ensuring all controllers act simultaneously despite different distances from the main controller.
3Stability of the object's composition
If the main controller waits for the most remote controller to receive the message before initiating action, then synchronicity is achieved, but loss of time occurs due to waiting
Solution Approach 1:
The main controller performs preliminary delay measurements and calculations before the actual coordinated action is needed. By pre-determining the communication delay to each controller and calculating appropriate compensation values, the system eliminates the need to wait during the actual task execution, as all controllers can immediately act with their pre-calculated timing offsets.
Solution Approach 2:
The system dynamically adjusts the action timing for each subsidiary controller based on its specific communication delay characteristics. Rather than using a static wait time for all controllers, each controller applies a dynamic timing offset calculated from its measured delay, enabling immediate action execution while maintaining synchronicity.
Data Source
AI summary
Disclosed is a communication chain comprising a battery management unit (BMU) and a plurality of battery cell controllers (BCC), and method of operating the same, comprising: a most-remote BCCs transmitting a message towards the BMU and starting a local-clock counter; each of the other BCCs receiving and forwarding the message towards the BMU and starting a respective local-clock counter; the BMU receiving the message, starting a BMU-clock counter, transmitting a further message and stopping the BMU-clock counter to determine a BMU-interval-count; each of other BCCs receiving and forwarding the second message, and stopping the respective local-clock counter to determine a respective local-interval-count; the most-remote of the BCCs receiving the further message, and stopping the most-remote-local-clock counter to determine its local-interval-count; the BMU broadcasting the BMU-interval-count and the BCCs determining their respective communication delay