Battery Pack Measurement Timing Synchronization
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Solution Overview
Problem
Existing battery pack monitoring systems face challenges in synchronizing pack voltage and pack current readings within a short time frame, leading to less accurate measurements due to daisy-chained communication links that result in varying command arrival times across battery pack sensing modules.
Innovation Solution
A vehicle power system with a controller that generates commands to synchronize voltage and current sampling by aligning the midpoint of the analog to digital conversion operations of battery array sensors, ensuring that pack voltage and pack current measurements are temporally aligned, using a formula that calculates the optimal sampling time based on the time differences between the first and last battery array sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If daisy-chained communication links are used to connect battery pack sensing modules, then the system complexity is reduced and ease of manufacture is improved, but measurement synchronization precision deteriorates due to varying command arrival times
Solution Approach 1:
The controller calculates and applies a time offset to the command sent to the last sensing module based on the known propagation delay through the daisy-chained communication links. This preliminary adjustment ensures that all sensing modules receive and execute their voltage sampling commands simultaneously, achieving synchronized measurements despite the sequential communication architecture
Solution Approach 2:
The system changes the timing parameter of the command sent to the last sensing module by adding a calculated time offset. This parameter adjustment compensates for the propagation delay inherent in the daisy-chained communication structure, aligning the execution time of voltage sampling across all sensing modules with the current sampling timestamp
2Productivity
If voltage sampling commands are sent to multiple battery pack sensing modules simultaneously, then productivity is improved by reducing measurement time, but measurement precision deteriorates due to command arrival time differences
Solution Approach 1:
The controller performs a preliminary calculation of the propagation delay through the daisy-chained sensing modules and pre-adjusts the command timing accordingly. By adding a time offset to the last module's command before transmission, the system ensures simultaneous execution of voltage sampling across all modules, achieving both high productivity and measurement precision
Solution Approach 2:
The system uses knowledge of the communication link propagation characteristics to feedback-adjust the command timing. The controller incorporates the known time delay information into the command generation process, creating a closed-loop timing adjustment that synchronizes voltage sampling across all sensing modules
Data Source
AI summary
A controller generates a first command for battery array sensors to sense voltages of battery cell arrays of a traction battery, and generates a second command to sample a value of current through the traction battery at a time following the first command that is defined by durations of analog to digital conversion operations of some of the battery array sensors and an analog to digital conversion operation associated with sampling the value.