Switching Circuit Failure Detection Using Voltage Drop Comparison
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Solution Overview
Problem
Existing semiconductor failure detection methods are inadequate for identifying failures in circuits with multiple semiconductor switch elements connected in series and parallel, leading to unreliable operation and potential complete system shutdown due to excessive stress on remaining elements.
Innovation Solution
A power supply control apparatus and semiconductor failure detection method that utilizes a microcomputer to monitor current, temperature, and potential differences across the switching circuit, employing a combined resistance value table to identify failures by comparing actual voltage drops with calculated assumptions, and performing failure control to prevent further stress on healthy elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple semiconductor switch elements are connected in series and parallel to improve reliability and current switching capability, then the system can handle larger currents and provide redundancy, but it becomes difficult to detect failures in individual elements
Solution Approach 1:
The patent divides the monitoring task into segments by assigning individual monitoring circuits to each semiconductor switch element or series circuit. Each monitoring circuit independently measures current, voltage, and temperature for its specific element, enabling localized failure detection without being overwhelmed by the complexity of the entire parallel-series configuration.
Solution Approach 2:
The patent introduces monitoring circuits as intermediary devices that act as mediators between the semiconductor switch elements and the control system. These intermediaries continuously measure electrical parameters and temperature, converting physical quantities into detectable signals that indicate the health status of each element, thereby solving the detection difficulty in complex configurations.
2Reliability
If a diode is connected in series with the semiconductor switch element to prevent abnormal current from flowing due to reversed polarity voltage, then the circuit is protected from damage, but the diode causes relatively large electric power loss and requires relatively large disposal space
Solution Approach 1:
The patent changes the electrical parameters of the protection mechanism by using a semiconductor element with low forward voltage drop characteristics instead of a conventional diode. By selecting a semiconductor switch element with optimized parameters (lower voltage drop), the protection function is maintained while reducing power loss and improving efficiency.
3Device complexity
If only one semiconductor switch element is used for switching, then the circuit is simple, but sufficient current switching capability and reliability cannot be obtained for very large current applications
Solution Approach 1:
The patent merges multiple semiconductor switch elements into a parallel-series configuration where elements are connected in series within each branch and multiple branches are connected in parallel. This merging approach distributes the total current across multiple elements, enabling the system to handle very large currents while maintaining reliability through redundancy - if one element fails, others can continue operating.
Data Source
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AI summary
A power supply control apparatus detects a failure of a semiconductor switch element in a switching circuit having semiconductor series circuits each having semiconductor switch elements connected in series with reverse polarities. The power supply control apparatus includes a reference resistance value storing unit storing information on a combined resistance value between an input and an output of the switching circuit, a conduction current detection unit configured to detect a current flowing through the switching circuit, a potential difference detection unit configured to detect an input-output potential difference between the input and the output of the switching circuit, a voltage drop calculation unit configured to calculate an assumed voltage drop, a voltage comparison unit configured to compare the input-output potential difference with the assumed voltage drop, and a failure identification unit configured to identify a failure of the semiconductor switch element.