IGBT Short-Circuit Detection via Current Derivative Sign
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Solution Overview
Problem
Existing methods for detecting short-circuits in IGBT-type transistors require precise voltage measurements, which is challenging, especially for high-voltage transistors used in applications like the railway field.
Innovation Solution
A method that detects short-circuits by analyzing the sign of the time derivative of the main current, eliminating the need for precise voltage measurements and utilizing a control device that applies setpoint voltages and currents to determine transition moments between switching steps based on the current derivative and voltage measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage measurements are used to detect short-circuits in IGBT transistors, then detection accuracy can be achieved, but measurement precision requirements become excessively high especially for high-voltage applications
Solution Approach 1:
The patent introduces an intermediary approach by measuring the voltage at the gate-emitter junction (Vge) instead of directly measuring the collector-emitter voltage (Vce) for short-circuit detection. This intermediary measurement point provides sufficient detection accuracy without requiring the high measurement precision that would be needed for direct high-voltage measurements, thereby resolving the contradiction between detection reliability and measurement precision requirements
Solution Approach 2:
The patent substitutes the direct voltage measurement approach with an alternative detection method based on analyzing the gate-emitter voltage characteristics during switching transitions. This substitution replaces the need for high-precision high-voltage measurement systems with a more feasible low-voltage measurement approach, maintaining detection accuracy while reducing measurement precision requirements
Data Source
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AI summary
The present invention relates to a method for detecting a short circuit in an electrical circuit comprising an IGBT-type transistor (14), the transistor having a gate (G), a collector (C), and an emitter (E), and defining a conducting state in which a main current flows between the collector and the emitter and a blocking state in which the collector is electrically isolated from the emitter. The detection method comprises observing the sign of the time derivative of the main current (110) within a time window (TOBS) of predetermined length and detecting a short circuit within this time window based on the sign of the time derivative of the main current.