Switching Device Short-Circuit Detection Using Current Change Thresholds
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Solution Overview
Problem
Existing power conversion apparatuses using Rogowski coils to detect short circuits in switching devices are slow to determine when a short circuit occurs, as they rely on integrated voltage thresholds rather than temporal changes in current.
Innovation Solution
A short circuit determination apparatus that includes a sensor to detect temporal changes in current and a determination unit to identify a short circuit based on threshold values, with a timing detection mechanism to trigger the determination process after a specific timing, allowing for earlier detection and integration of current changes to confirm the short circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage integration method is used to detect short circuit, then measurement reliability is improved, but detection speed deteriorates
Solution Approach 1:
The patent segments the detection process into two distinct methods: a first determination unit that monitors temporal changes (di/dt) for rapid detection, and a second determination unit that integrates voltage for reliable confirmation. This segmentation allows the system to achieve both fast response and high reliability by using appropriate methods for different detection stages.
Solution Approach 2:
The patent applies preliminary action by having the first determination unit perform initial short circuit detection using temporal change monitoring before the second determination unit performs voltage integration. This preliminary detection enables the system to identify potential short circuits immediately, while the integration method provides subsequent confirmation, thus reducing overall detection time while maintaining reliability.
2Speed
If temporal change threshold method is used, then detection speed is improved, but measurement precision deteriorates
Solution Approach 1:
The patent implements feedback by having the second determination unit continuously monitor the integrated voltage value and compare it against a threshold to confirm or refute short circuit conditions initially detected by the first determination unit. This feedback mechanism ensures that rapid temporal change detection is validated by precise voltage integration, thereby maintaining both speed and precision.
Solution Approach 2:
The patent uses the integrated voltage value as an intermediary between the rapid temporal change detection and the final short circuit determination. The first determination unit's temporal change detection serves as an early warning, while the second determination unit's integration result acts as a mediator that confirms the actual short circuit condition, ensuring both speed and precision in the final determination.
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 faster and more accurate detection of short circuits in switching devices, particularly in high-speed wide bandgap semiconductor devices, by utilizing a Rogowski coil sensor and integrated circuit components to interrupt the short circuit current and prevent device breakdown.
Implementation Method 1
a sensor configured to detect, in a switching device that has a control terminal, a first main terminal, and a second main terminal, a temporal change of a main current flowing between the first main terminal and the second main terminal. The sensor may be a Rogowski coil.
Data Source
AI summary
There is provided a short circuit determination apparatus including: a sensor configured to detect, in a switching device that has a control terminal, a first main terminal, and a second main terminal, a temporal change of a main current flowing between the first main terminal and the second main terminal; and a short circuit determination unit configured to determine that the switching device is short-circuited, in a case where the temporal change of the main current is larger than or equal to a first threshold value, after a first timing after a control signal for driving the control terminal is turned on.