eFuse Residual Current Testing for In-Circuit Fault Diagnosis
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Solution Overview
Problem
Existing methods for testing switchable electronic fuses are inadequate for differentiating between safe and unsafe operating states, particularly in safety-critical systems, and often require redundant structures that increase costs and energy consumption.
Innovation Solution
A method and system for testing switchable fuses that involves switching them to a non-conductive state for a test period, measuring the residual current, and comparing it with target values to determine functional, partially functional, or non-functional states, while accounting for manufacturing tolerances and environmental fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant second efuse is arranged in parallel to enable continuous monitoring, then the operational safety and reliability of testing is improved, but the manufacturing cost and operating cost increase due to increased space requirements and power consumption
Solution Approach 1:
The efuse tests itself by utilizing its own circuit structure and components. The test method employs the efuse's inherent switching capability and resistance characteristics, allowing the single efuse to perform self-diagnosis without requiring redundant components. This eliminates the need for a second efuse while maintaining testing reliability.
Solution Approach 2:
The efuse serves dual functions: it performs its primary protective function of limiting or interrupting current during overcurrent events, and simultaneously serves as the test object for self-diagnosis. The same efuse circuit is used for both protection and testing purposes, eliminating the need for separate redundant components.
2Productivity
If a redundant second efuse is arranged in parallel to enable continuous monitoring, then the ability to perform continuous monitoring is improved, but the power consumption increases because additional efuses must be provided
Solution Approach 1:
The efuse performs self-testing by utilizing its own electrical characteristics and circuit elements. The testing process leverages the efuse's inherent resistance changes and switching behavior, requiring no additional power-consuming test components or redundant efuses.
Solution Approach 2:
The testing method enables continuous or periodic monitoring of the efuse's operational status without interrupting its protective function. The test can be performed at any time by measuring the efuse's resistance or switching characteristics, allowing ongoing monitoring with minimal additional power consumption.
3Ease of operation
If the efuse is tested in an operating mode with a disconnected electrical load, then the testing simplicity is improved, but the applicability for continuous monitoring during operation is reduced
Solution Approach 1:
The efuse can be tested in-circuit without disconnecting the electrical load. The testing method measures the efuse's electrical characteristics (resistance, switching behavior) while it remains connected to the operational circuit, enabling continuous monitoring without requiring system shutdown or load disconnection.
4Ease of operation
If existing test methods measure only complete destruction of the efuse, then the measurement simplicity is improved, but the ability to detect gradual performance degradation is reduced
Solution Approach 1:
The patent replaces simple binary measurement (blown/not blown) with electrical measurement of resistance or current characteristics. By measuring the efuse's electrical properties during operation, the system can detect gradual degradation before complete failure, providing early warning while maintaining relatively simple measurement circuitry.
Solution Approach 2:
The testing method provides feedback on the efuse's operational status by continuously or periodically measuring its electrical characteristics. This feedback mechanism allows the system to detect gradual performance degradation and alert operators before complete failure occurs, enhancing measurement precision without significantly increasing system complexity.
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 cost-effective, energy-efficient, and frequent testing of switchable fuses without affecting ongoing operations, detecting degraded fuses before they fail, and ensuring reliable disconnection of electrical loads during overcurrent events.
Implementation Method 1
the actual residual current value is determined by measuring the discharge time of a capacitor connected in parallel to the electrical load from the supply voltage source via a resistor
Implementation Method 2
The decaying voltage across the control resistor is compared to a reference voltage value using a comparator
Data Source
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AI summary
The invention relates to a test method for verifying the operational state of an eFuse (1) that can be switched between at least a conducting state and a non-conducting state and via which an electrical load (3) is electrically connected to a supply voltage source (2), wherein the electrical load (3) tolerates an interruption in the power supply for a predetermined maximum interruption duration. The switchable eFuse (1) is switched from the conducting to the non-conducting state for a test time, T s , which is at most equal to the maximum interruption duration of the electrical load (3). The residual current flowing through the switchable eFuse (1) during the test time, T s , is detected by means of a test circuit (120) as an actual residual current value and compared with at least one target residual current value. The switchable eFuse (1) is assigned a first operational state if the actual residual current value is below the at least one target residual current value, and otherwise is assigned another operational state. The invention also relates to a test system (100) for carrying out the test method.