Battery Current Detection with Ground Switching and Differential Amplifier
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery charge/discharge current detection systems face accuracy issues due to ground voltage fluctuations and temperature drift of current detecting resistors, making it difficult to detect abnormalities and leading to potential malfunctions, especially when large currents are drawn by electrical loads on vehicles.
Innovation Solution
A battery charge/discharge current detection apparatus with a power supply circuit that includes a ground switching section to bypass the current detecting resistor, allowing for accurate voltage detection, temperature compensation, and abnormality notification, ensuring reliable current measurement and preventing system floatage during resistor failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current detecting resistor is used to detect battery charge/discharge current, then current detection function is achieved, but current detecting accuracy deteriorates due to ground voltage fluctuations and temperature drift
Solution Approach 1:
The patent introduces a differential amplifier as an intermediary device that amplifies the voltage difference across the current detecting resistor while rejecting common-mode voltage fluctuations from ground variations. This mediator isolates the measurement from environmental interference, maintaining both detection function and accuracy
Solution Approach 2:
The patent employs temperature compensation by detecting the temperature of the current detecting resistor and adjusting the measurement parameters accordingly. This parameter change approach compensates for temperature drift effects, preserving measurement precision under varying thermal conditions
2Reliability
If the resistance of the current detecting resistor increases due to deterioration, then voltage across its ends increases, but this causes excessive temperature rise and potential malfunction that cannot be detected
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the voltage across the current detecting resistor and compares it against predetermined thresholds. When abnormal voltage indicating resistor deterioration is detected, the system provides feedback to activate an alarm, enabling timely detection and prevention of excessive temperature rise and malfunction
Solution Approach 2:
The patent establishes predetermined voltage thresholds before deterioration occurs, creating a safety buffer that prevents catastrophic failure. By setting alarm levels in advance, the system cushions against the harmful effects of resistor deterioration before they manifest as excessive temperature rise or complete malfunction
3Device complexity
If vehicle body is used as ground, then grounding is simplified, but power supply voltage fluctuates due to current flowing through vehicle body
Solution Approach 1:
The patent creates equipotential reference points within the detection circuit that are isolated from ground current fluctuations. By establishing local equipotential references, the system maintains stable power supply voltage for the detection circuit while preserving the simple vehicle body grounding arrangement
Solution Approach 2:
The differential amplifier serves as an intermediary that separates the measurement function from the fluctuating ground potential. It transfers the current detection function while blocking the transmission of ground voltage fluctuations to the power supply, resolving the conflict between simple grounding and voltage stability
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
The apparatus provides stable and accurate detection of battery currents, quickly identifies resistor abnormalities, and enables appropriate measures to be taken, such as repairing or replacing the resistor, thereby preventing vehicle engine startup failures.
Implementation Method 1
detect a charge/discharge current of the battery by use of a current detecting resistor connected between a negative terminal of the battery and a ground
Data Source
AI summary
The battery charge/discharge current detection apparatus has a power supply circuit powered by a battery mounted on a vehicle and configured to detect a charge/discharge current of the battery by use of a current detecting resistor connected between a negative terminal of the battery and a ground. The battery charge/discharge current detection apparatus includes a first function of detecting a voltage across the voltage detecting resistor, a second function of detecting a charge/discharge current of the battery on the basis of the voltage detected by the first function, a third function of detecting presence of an abnormality of the current detecting resistor, and a fourth function of informing an abnormality detected by the third function to the outside. The battery-side negative terminal of the power supply circuit is connected to the negative terminal of the battery.