Battery Relay State Detection via Synchronized Voltage Measurement
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Solution Overview
Problem
Conventional battery monitors fail to accurately detect the state of contactors, particularly when they are not conducting current, due to timing differences in voltage detection and potential misinterpretation of voltage fluctuations during battery charge or discharge.
Innovation Solution
A battery monitor system that includes a microcomputer and high-voltage measurement interface circuits to synchronize voltage measurements across multiple contact points, allowing for real-time detection of relay states and preventing false positives from voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If voltage detection is performed at different timings on battery side and output side, then the detection circuit can be simple, but the relay state cannot be detected correctly when voltage fluctuation occurs
Solution Approach 1:
The patent implements periodic voltage detection at multiple specific timing points (when relay is off, turning on, and turned on) to capture the voltage relationship at different stages. This periodic sampling approach ensures that voltage fluctuations during battery charge/discharge do not lead to incorrect relay state determination, as the detection covers the complete transition cycle.
Solution Approach 2:
The patent uses feedback by comparing voltage relationships detected at different timings to determine relay state. The control unit analyzes the voltage detection results from multiple timing points and uses this feedback information to accurately determine whether the relay is in a stuck-closed or stuck-open state, even when voltage fluctuations occur.
2Ease of operation
If voltage detection timing is not synchronized, then detection can be performed independently, but false positives occur due to voltage fluctuation during battery charge or discharge
Solution Approach 1:
The patent performs voltage detection periodically at three specific timing points: when the relay is off, when it is turning on, and when it is turned on. This periodic detection strategy ensures that voltage relationships are captured at critical moments, preventing false positives caused by voltage fluctuations during battery charge or discharge operations.
Solution Approach 2:
The patent performs preliminary voltage detection when the relay is in the off state before actual operation begins. This preliminary detection establishes a baseline voltage relationship that is used for comparison during subsequent operations, enabling accurate determination of relay state changes while filtering out normal voltage fluctuations.
3Device complexity
If simple voltage comparison is used, then detection method is simple, but adhesion cannot be detected when contactor cannot conduct current
Solution Approach 1:
The patent implements periodic voltage detection at multiple timing points including when the relay is off, turning on, and turned on. By comparing voltage relationships across these different timing points, the system can detect adhesion conditions even when the contactor cannot conduct current, as the voltage comparison method remains valid across all operational states.
Solution Approach 2:
The patent uses voltage as an intermediary parameter to indirectly detect relay adhesion state. Instead of directly measuring current flow through the relay, the system measures voltage relationships at different points in the circuit, which serves as an intermediary indicator of relay functionality. This allows detection of adhesion conditions without requiring current conduction through the contactor.
Data Source
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AI summary
The present invention enables correct detection of the state of a relay provided on each of the positive and negative terminal sides of a secondary battery. A positive-side main relay 12 makes or breaks continuity between first and second positive contact points, and a negative-side main relay 15 makes or breaks continuity between first and second negative contact points. A microcomputer 2 can measure a first voltage between the first positive and first negative contact points, a second voltage between the second positive and first negative contact points, and a third voltage between the first positive and second negative contact points. The microcomputer 2 detects the state of the positive-side main relay 12 based on a voltage measurement result obtained when the first and second voltages are measured synchronously, and detects the state of the negative-side main relay 15 based on a voltage measurement result obtained when the first and third voltages are measured synchronously.