Battery Pack Relay Diagnosis in Parallel Battery Systems
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Solution Overview
Problem
Existing methods struggle to accurately diagnose stuck-closed relays in battery systems when multiple battery packs are connected in parallel, making it difficult to identify which relays are stuck-closed and how many battery packs are affected.
Innovation Solution
A battery system with a one-to-one correspondence between battery packs and Battery Management Systems (BMS) that measures voltage and current differences to determine if relays are stuck-closed by sequentially controlling relays and comparing threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple battery packs are connected in parallel to increase system capacity, then the overall power and energy storage are improved, but the ability to accurately diagnose stuck-closed relays deteriorates
Solution Approach 1:
The patent divides the battery system into multiple independent battery packs, each with its own BMS that can independently diagnose its relays. By segmenting the diagnosis process at the pack level and using sequential relay control within each pack, the system maintains accurate diagnosis capability while scaling to multiple parallel packs.
Solution Approach 2:
The patent performs preliminary actions by sequentially controlling relays to specific states (open or closed) before conducting voltage measurements. This preliminary relay state control isolates each relay's contribution to the overall system behavior, enabling accurate identification of stuck-closed relays even in parallel configurations.
2Device complexity
If traditional voltage comparison methods are used for relay diagnosis, then the diagnosis process is simple, but the ability to identify specific stuck-closed relays in parallel systems deteriorates
Solution Approach 1:
The patent implements feedback by measuring voltage differences after sequentially controlling relays to specific states. Each voltage measurement provides feedback about the state of specific relays, allowing the BMS to identify which relays are stuck-closed based on the pattern of voltage differences observed during the sequential control process.
Solution Approach 2:
The patent introduces dynamic relay control where relays are sequentially switched between open and closed states during the diagnosis process. This dynamic manipulation of relay states creates distinct electrical pathways that allow the system to identify which specific relays are stuck-closed, transforming a static diagnosis approach into a dynamic one that preserves identification information.
3Productivity
If voltage difference threshold comparison is performed without sequential relay control, then the diagnosis is faster, but the precision of identifying affected battery packs deteriorates
Solution Approach 1:
The patent performs preliminary relay state control actions before conducting voltage measurements and threshold comparisons. By pre-setting specific relays to open or closed states, the system ensures that when voltage differences are measured and compared to thresholds, the results precisely indicate which relays are stuck-closed and which battery packs are affected, maintaining both speed and precision.
Data Source
AI summary
A battery system includes: a plurality of battery packs; a plurality of positive relays, each respective battery pack including a respective positive relay, connected between a positive electrode and a positive link of the respective battery pack; a plurality of negative relays, each respective battery pack including a respective negative relay, connected between a negative electrode and a negative link of the respective battery pack; and a plurality of pack BMSs (Battery Management Systems) connected to the plurality of battery packs in a one-to-one correspondence. Each pack BMS of the plurality of pack BMSs, in an opening control condition of the plurality of positive relays and the plurality of negative relays, may be configured to determine whether the positive relay of the pack BMS's corresponding battery pack is stuck-closed based on a first battery pack current flowing to the pack BMS's corresponding battery pack.