Battery Pack Relay Diagnosis Using Capacitor Current Detection
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Solution Overview
Problem
Conventional methods for diagnosing pack relays in a battery system require significant time due to similarities in voltage readings across connected relays, leading to prolonged diagnosis times even when performed sequentially.
Innovation Solution
A battery system design incorporating a diagnostic circuit with a resistor, switch, and capacitor, allowing simultaneous diagnosis of multiple pack relays by monitoring current flow through closed relays, reducing the time required for diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery control unit requests relay on/off operations to the battery relay unit for each charge/discharge cycle, then the battery system can monitor relay status, but the pack relay undergoes frequent operations reducing its lifespan
Solution Approach 1:
The battery relay unit proactively transmits relay status information to the battery control unit before the control unit requests it. This preliminary action allows the control unit to monitor relay status without频繁ly requesting updates, thereby reducing the number of operational cycles the pack relay undergoes while maintaining effective monitoring capability
2Measurement precision
If the battery relay unit transmits relay status information frequently, then the battery control unit can accurately monitor relay status, but communication load and power consumption increase
Solution Approach 1:
The battery relay unit transmits relay status information at predetermined time intervals rather than continuously or on every operation. This periodic transmission approach maintains adequate monitoring accuracy while significantly reducing communication frequency, thereby lowering power consumption and communication load on the battery control unit
3Reliability
If the battery control unit stores detailed relay operation logs, then diagnostic capability is improved, but storage requirements and data processing complexity increase
Solution Approach 1:
The battery relay unit extracts and transmits only the essential relay status information (on/off states and timing) to the battery control unit, rather than the control unit storing and processing all detailed operation logs. This extraction approach maintains diagnostic capability by providing necessary data while significantly reducing storage requirements and data processing complexity at the control unit
Data Source
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AI summary
A battery system may include a plurality of battery packs, a plurality of first relays connected between a positive electrode of a corresponding battery pack and a first node for each of the plurality of packs, a plurality of second relays connected between an negative electrode and a second node of the corresponding battery pack for each of the plurality of packs, a capacitor having both ends connected between a first wiring connected to the first node and a second wiring connected to the second node, a resistor and a switch connected in series between the first wiring and the second wire, and after waking up and controlling the plurality of first relays and the plurality of second relays to be closed, when a current flowing from the plurality of battery packs to the capacitor is detected, a plurality of pack battery management systems (BMS) for determining the plurality of first relays and the plurality of second relays as normal.