Battery Current Detection Circuit Open-Circuit Diagnosis
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Solution Overview
Problem
Current battery systems in vehicles, such as hybrid cars, face challenges in reliably detecting open-circuits in current detection lines due to the complexity and cost of existing solutions, which often require two high-precision difference amplifiers.
Innovation Solution
A battery system with a current detection circuit that includes a current detection resistor, an amplifier, and a detection circuit with a voltage source that supplies a test voltage to detect open-circuits by comparing the amplifier output voltage with a reference voltage, allowing for simple and reliable detection of current detection line open-circuits without the need for complex circuit structures or high-cost components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two high precision difference amplifiers are used to detect open-circuit in current detection lines, then the reliability of current detection is improved, but the device complexity and parts cost increase
Solution Approach 1:
The patent applies preliminary action by performing open-circuit detection at a specific timing (when battery current is zero) before normal current measurement. A test voltage is applied to the current detection lines at this preliminary stage to detect open-circuits, avoiding the need for complex continuous monitoring circuits during normal operation.
Solution Approach 2:
The patent implements periodic action by alternately switching between test voltage application and normal current measurement. The switching circuit periodically connects the test voltage source to the current detection lines to perform open-circuit detection, then switches to normal measurement mode, achieving both detection functions with a single amplifier.
2Loss of energy
If the resistance of the current detection resistor is made extremely small to reduce power loss, then the energy efficiency is improved, but the voltage signal for current detection becomes smaller and more difficult to detect
Solution Approach 1:
The patent applies parameter changes by dynamically switching the resistance value of the current detection resistor. When test voltage is applied, a larger resistance is used to generate detectable voltage signals for open-circuit detection. When measuring battery current, the resistance is reduced to minimize power loss, thus optimizing both detection precision and energy efficiency at different operational stages.
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
This solution enables stable and precise detection of battery current while identifying open-circuits, reducing power loss and maintaining high precision in current detection, even when no current is flowing, thus preventing overcharging or over-discharging and extending battery life.
Implementation Method 1
the voltage across the current detection resistor is proportional to the current
Implementation Method 2
an amplifier that amplifies the voltage induced across the terminals of the current detection resistor
Data Source
AI summary
The battery system has a current detection circuit 2, an amplifier 6, and a detection circuit 7 that detects the current flowing through batteries 1 from amplifier 6 output. The current detection circuit 2 is provided with a voltage source circuit 8 that supplies a test voltage to the input-side of the amplifier 6. Current detection lines 10 connect the current detection resistor 5 to the input-side of the amplifier 6, and the detection circuit 7 stores a reference voltage corresponding to the current detection lines 10 in the connected state. When the voltage source circuit 8 supplies the test voltage to the input-side of the amplifier 6, the detection circuit 7 compares the amplifier 6 output voltage with the reference voltage. The detection circuit 7 detects an open-circuit in the current detection lines 10 by the shift in voltage from the reference voltage.