Battery Pack Voltage Detection Device Self-Diagnosis
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Solution Overview
Problem
Conventional voltage detection devices for battery packs cannot accurately detect nonconformity in measurement equipment between battery cells and A/D converters, limiting the ability to quickly identify and address deteriorated cells.
Innovation Solution
A voltage detection device with a voltage selector, A/D converter, reference voltage output unit, switches, and a controller that applies reference voltages to connection lines, allowing for the digitization of voltage signals to diagnose the multiplexer and A/D converter, enabling comprehensive nonconformity detection in the voltage measurement equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage detection devices only detect A/D converter conformity, then the detection scope is limited, but the device complexity remains low
Solution Approach 1:
The patent applies preliminary action by introducing a self-test function that proactively tests the voltage selector and A/D converter before actual voltage measurement. The controller periodically switches to self-test mode, applies test voltages through the reference voltage output unit, and verifies system conformity without requiring external test equipment. This prevents undetected faults from affecting measurement accuracy.
Solution Approach 2:
The patent uses the reference voltage output unit as an intermediary to generate known test voltages that are routed through the voltage selector and A/D converter. This intermediary test signal allows the system to self-diagnose by comparing the digitized test voltage against expected values, thereby detecting faults in the voltage selector or A/D converter without external intervention.
2Reliability
If the voltage detection device includes self-test function with reference voltage output unit and switches, then the reliability of voltage measurement system is improved, but the device complexity increases
Solution Approach 1:
The reference voltage output unit serves multiple functions: it provides reference voltages for normal A/D converter operation and generates test voltages for self-diagnosis. The voltage selector also functions dually by selecting either battery cell voltages during normal operation or test voltages during self-test mode. This multi-functionality reduces the need for separate dedicated test equipment.
Solution Approach 2:
The voltage detection device performs self-diagnosis using its own internal components. The controller manages the switching between measurement mode and self-test mode, the reference voltage output unit generates test signals, and the system evaluates its own conformity by comparing digitized test voltages against expected values. This self-service capability eliminates the need for external test equipment and continuous external monitoring.
3Measurement precision
If the system performs fault diagnosis on voltage selector and A/D converter, then the detection capability is improved, but the measurement speed is reduced due to additional switching operations
Solution Approach 1:
The system implements periodic self-test operations rather than continuous testing. The controller periodically switches to self-test mode at predetermined intervals to verify the conformity of the voltage selector and A/D converter. During normal operation, the system continuously measures battery cell voltages without interruption. This periodic approach balances fault detection capability with measurement speed by minimizing the time spent in test mode.
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 high-accuracy detection of nonconformity in the entire voltage measurement system, allowing for quick identification and prevention of overcharge and over-discharge in battery packs, ensuring reliable operation of vehicle-mounted secondary batteries.
Implementation Method 1
an A/D converter for digitizing a signal of the output voltage selected by the voltage selector
Implementation Method 2
a reference voltage output unit capable of supplying different levels of reference voltages to the respective connection lines
Data Source
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AI summary
A voltage detection device connects the positive electrodes of unit cells (BT1 to BT4) and terminals (T1 to T4) of a multiplexer (12) via connection lines (L1 to L4), respectively, and includes first switches (SW11 to SW14) between the connection lines and the unit cells. The voltage detection device connects first to fourth series-connected circuits (N1 to N4) to the respective connection lines to apply reference voltages to the connection lines. Subsequently, in a state where the first switches (SW11 to SW14) are turned off, reference voltages are applied to the respective connection lines and each of the reference voltages is selected by the multiplexer (12), level-shifted, and then digitized by an A/D converter (13). Based on the digitized voltages, the voltage detection device determines whether or not each of the multiplexer, level shifter, and A/D converter is nonconformity.