Battery System Resistor Operability Check Using Modulated Test Current
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Solution Overview
Problem
Current battery system resistance monitoring methods can only be performed after startup, failing to meet the ASIL-C requirement for continuous reliability, which necessitates current monitoring both before and during operation.
Innovation Solution
A device and method utilizing a modulated test current and two independent measuring devices to check the functionality of a system resistor, allowing for continuous monitoring by comparing current values across resistors, even when the battery system is not active, using a modulated test current that differs from other alternating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two system resistors are used to ensure current monitoring with ASIL-C, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent divides the monitoring function into two independent measurement channels (first measuring device and second measuring device) that separately measure the test current through the first resistor and second resistor, respectively. This segmentation allows each channel to operate independently, ensuring ASIL-C reliability without requiring a complex dual-resistor configuration for the system resistance itself.
2Device complexity
If current monitoring is performed only after battery system startup, then device complexity is reduced, but reliability deteriorates
Solution Approach 1:
The patent enables preliminary testing of the first resistor (system resistance) before the battery system is connected to the vehicle's electrical system. The test current circuit can be activated independently to perform resistance measurements in advance, allowing fault detection before actual operation begins, thereby improving reliability without requiring continuous complex monitoring during operation.
Solution Approach 2:
The patent introduces a separate test current circuit with a modulated test current as an intermediary mechanism. This test current circuit acts as a mediator that allows resistance measurement without requiring the main battery system to be active, enabling pre-connection testing while keeping the main system simple.
3Reliability
If a modulated test current is used to enable testing during operation, then reliability is improved, but measurement precision requirements increase
Solution Approach 1:
The patent uses a modulated test current that alternates between different states (e.g., different frequencies or amplitudes) to distinguish the test signal from other currents in the system. This periodic modulation allows the measuring devices to identify and measure only the test current component, improving measurement precision through signal differentiation rather than requiring absolute precision in a continuous measurement.
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 continuous monitoring of the system resistor's functionality according to ASIL-C standards, independent of direct currents and other alternating currents, ensuring reliability both before and during battery system operation.
Implementation Method 1
The first measuring device is configured to detect a first voltage value of an alternating voltage drop across the first resistor, to determine a first current value
Implementation Method 2
The second measuring device is configured to detect a second voltage value of an alternating voltage drop across the second resistor and to determine a second current value
Data Source
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AI summary
The invention relates to a device (100) for checking the functionality of a first resistor (102) of a battery system, which serves as a system resistor. The device (100) comprises a means (105) for providing a modulated test current, a switch (104), a second resistor (103), a first measuring means (106), and a second measuring means (107), wherein the first measuring means (106) is configured to detect a first voltage value of an alternating voltage drop across the first resistor (102), to determine a first current value, and to transmit the first current value to the second measuring means (107) by means of a connection (108), wherein the second measuring means (107) is configured to detect a second voltage value of an alternating voltage drop across the second resistor (103) and to determine a second current value, wherein the means (105) for providing a modulated test current,The first resistor (102) and the second resistor (103) are connected in series and form a test circuit, and the second measuring device (107) is configured to compare the first current value and the second current value and to generate a first signal when the first current value and the second current value are substantially equal, the first signal representing the functionality of the first resistor (102). Further aspects of the invention relate to a corresponding method for verifying the functionality of a system resistor of a battery system and to a vehicle comprising a battery system and such a device (100).