Voltage Detecting Apparatus for Battery Pack Half-Cut Fuse Diagnosis
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Solution Overview
Problem
Current voltage detecting systems for battery packs cannot accurately determine if a fuse is in a half-cut state, leading to significant differences between detected and intended battery cell voltages.
Innovation Solution
A voltage detecting apparatus that includes a voltage detecting unit, a discharge circuit, and a determination unit to estimate the internal resistance of the protection circuit based on first and second voltages detected in operating and non-operating states, allowing for the detection of a half-cut state and correction of voltage errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection circuit with fuses is used between the battery pack and monitoring circuit, then the monitoring circuit is protected from overcurrent damage, but the fuse may enter a half-cut state that causes significant voltage detection errors without providing complete protection
Solution Approach 1:
The system performs preliminary detection of the fuse state by measuring voltage before complete failure occurs. The voltage detecting apparatus continuously monitors the protection circuit's internal resistance and detects abnormal voltage drops that indicate a half-cut state, allowing early warning before total fuse failure disrupts operation.
Solution Approach 2:
A discharge circuit is introduced as an intermediary component to isolate and measure the internal resistance of the protection circuit separately from the main battery monitoring path. This allows accurate detection of fuse degradation without interfering with normal battery operation or requiring disassembly of the protection circuit.
2Device complexity
If the monitoring circuit directly monitors battery cell voltages without a protection circuit, then voltage detection is simple and direct, but the monitoring circuit is vulnerable to damage from battery overcurrent events
Solution Approach 1:
The discharge circuit serves as an intermediary measurement path that allows the monitoring circuit to indirectly assess the protection circuit's health status without being directly exposed to high currents. By measuring voltage through this isolated path, the system gains diagnostic capability while maintaining circuit simplicity.
Solution Approach 2:
The protection circuit's own voltage characteristics are used to indicate its operational status. The system leverages the natural voltage drop across the fuse's internal resistance as a diagnostic signal, allowing the circuit to self-report its health condition without requiring separate sensors or complex monitoring mechanisms.
3Device complexity
If no discharge circuit is used for isolation, then the voltage detection system is simpler, but accurate measurement of the protection circuit's internal resistance cannot be achieved during normal operation
Solution Approach 1:
The measurement function is segmented from the main power path by introducing a separate discharge circuit. This allows the internal resistance of the protection circuit to be measured independently through a dedicated low-current path, isolating the measurement process from the high-power battery operations and enabling accurate diagnostics without disrupting normal function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate detection of a half-cut state in the protection circuit, reducing voltage detection errors and ensuring reliable battery cell voltage measurements.
Implementation Method 1
a voltage detecting unit configured to detect a voltage of a battery supplying power to a load
Implementation Method 2
a discharge circuit configured to discharge the battery... including a pair of discharge resistors having one ends connected to input terminals of the low pass filters and an opening/closing switch connected between the other ends of the pair of discharge resistors
Implementation Method 3
a determination unit configured to estimate an internal resistance of the protection circuit on the basis of a first voltage detected by the voltage detecting unit when the discharge circuit is in a non-operating state and a second voltage detected by the voltage detecting unit when the discharge circuit is in an operating state
Data Source
AI summary
A voltage detecting apparatus includes: a voltage detecting unit configured to detect a voltage of a battery supplying power to a load; a discharge circuit configured to discharge the battery; a protection circuit disposed between the voltage detecting unit and the battery and between the discharge circuit and the battery; and a determination unit configured to estimate an internal resistance of the protection circuit on the basis of a first voltage detected by the voltage detecting unit when the discharge circuit is in a non-operating state and a second voltage detected by the voltage detecting unit when the discharge circuit is in an operating state and determine a half-cut state of the protection circuit on the basis of a result of the estimation.