Power Switch Saturation Detection Across Wide Supply Voltages
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Solution Overview
Problem
Existing short-circuit detection methods in power semiconductor switches are limited by their inability to function across varying supply voltage ranges, particularly with wide-band gap power semiconductors, as the triggering threshold is fixed and cannot distinguish between normal operating currents and short circuits, leading to potential false shutdowns.
Innovation Solution
The method adjusts the triggering threshold by generating a differential voltage based on a reference voltage that tracks changes in the supply voltage, allowing for dynamic adjustment and ensuring short-circuit detection across a wide supply voltage range, including with high minimum triggering thresholds for wide-band gap power semiconductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed triggering threshold is used for short-circuit detection, then the detection method is simple to implement, but it cannot function reliably across varying supply voltage ranges leading to false shutdowns
Solution Approach 1:
The patent applies dynamics by making the triggering threshold dynamic rather than fixed. The threshold adapts to varying supply voltages through a reference voltage source that provides different threshold levels based on the actual supply voltage conditions, enabling reliable short-circuit detection across the entire supply voltage range while maintaining circuit simplicity
Solution Approach 2:
The patent changes the parameter of the triggering threshold from a fixed value to a variable value that depends on supply voltage. By using a reference voltage source that outputs different voltages based on supply voltage ranges, the detection system can distinguish between normal operating currents and actual short circuits under different voltage conditions
2Reliability
If a high minimum triggering threshold is used to avoid false shutdowns, then false triggering is reduced, but short-circuit detection capability is lost at lower supply voltages
Solution Approach 1:
The patent makes the triggering threshold dynamic by linking it to the supply voltage through a reference voltage source. This allows the threshold to be high enough to prevent false shutdowns at high supply voltages while automatically lowering to maintain detection capability at lower supply voltages, thus achieving both false triggering prevention and wide adaptability
Solution Approach 2:
The patent changes the triggering threshold parameter based on supply voltage conditions. The reference voltage source provides different threshold values corresponding to different supply voltage ranges, enabling the system to maintain optimal detection performance across the entire operating voltage range without false triggering
Data Source
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AI summary
The present invention relates to a method for short-circuit detection by saturation detection in power semiconductor switches and to a corresponding device. A reference voltage (Uref) is provided as a function of a supply voltage (UVDD) of a power semiconductor switch. A differential voltage (Udiff) is generated from the difference of a voltage drop (UΔ) of a load path of the power semiconductor switch and the provided reference voltage (Uref). The generated differential voltage (Udiff) is compared with a predetermined threshold voltage (Ulim). A short-circuit current in the load path of the power semiconductor switch is detected when the differential voltage (Udiff) exceeds the threshold voltage (Ulim). In this case, the power semiconductor switch is opened.