Gate Leakage Current Detection in Power Switches
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Solution Overview
Problem
Power semiconductor modules, particularly those with insulating gels, are prone to moisture absorption leading to conductivity issues and premature failure due to condensation and humidity, with existing detection methods being either ineffective or causing prolonged downtime for drying processes.
Innovation Solution
A system comprising a power semiconductor module with a gate driver, a sensor connected to detect leakage current across the gate driver, using a resistor and amplifier to measure and amplify voltage, and a controller to send signals to prevent power application when excessive leakage is detected, effectively monitoring moisture levels in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial condensation detectors are used to monitor conditions near the power semiconductor module, then moisture detection capability is provided, but the detection is ineffective because the detectors cannot detect non-condensing humidity that compromises the insulating gel
Solution Approach 1:
The patent uses the gate leakage current as an intermediary indicator to indirectly detect moisture in the insulating gel. Instead of directly measuring humidity or condensation, the system measures the electrical leakage current that increases when moisture compromises the insulating gel, providing reliable detection of the actual failure mechanism.
Solution Approach 2:
The patent replaces mechanical/physical condensation detection methods with an electrical measurement approach. By substituting the mechanical condensation detection system with an electrical leakage current measurement system, the invention achieves accurate detection of moisture effects on the insulating gel that direct condensation detectors cannot detect.
2Reliability
If the system is pre-heated to ensure complete dry-out prior to applying high-voltage, then system failure is prevented, but operation is delayed for prolonged periods of time (typically twenty-four hours)
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors gate leakage current and provides real-time information about moisture levels in the insulating gel. This feedback allows the system to determine when drying is complete and when it is safe to apply power, eliminating the need for fixed prolonged pre-heating periods and enabling dynamic adjustment of the drying process.
Solution Approach 2:
The patent performs preliminary monitoring of gate leakage current to assess moisture levels before power application. By conducting this preliminary electrical assessment, the system can determine readiness for power application without requiring extended pre-heating, thus reducing operational delay while maintaining reliability.
3Reliability
If insulating gel is used in power semiconductor modules, then insulation and moisture resistance are provided, but the gel absorbs moisture from condensation and humidity over time, becoming conductive and causing module failure
Solution Approach 1:
The patent employs the gate driver circuit itself to monitor the condition of the insulating gel. By using the existing gate driver and measuring its leakage current, the system performs self-diagnosis of moisture contamination, eliminating the need for separate external monitoring systems and enabling the module to detect its own degradation.
Solution Approach 2:
The patent replaces physical barriers against moisture (such as hermetic sealing) with an electrical monitoring approach. Instead of relying solely on physical protection that may fail due to manufacturing imperfections or thermal cycling, the system uses electrical measurement of gate leakage current to detect moisture effects, providing a functional monitoring solution.
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
This solution allows for immediate detection of moisture, preventing module failures and reducing downtime by ensuring power is not applied until the module is dry, thus enhancing operational reliability and process control.
Implementation Method 1
a sensor connected to the gate driver so as to detect a leakage of current across the gate driver
Implementation Method 2
An amplifier is connected to the resister so as to measure and amplify voltage across the resistor
Data Source
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AI summary
A moisture detecting system (40) has a power semiconductor module having a gate driver (62) with the gate in which the gate driver has an on condition and an off condition, a power supply (42) connected to the gate driver so as to supply voltage to the gate driver, a controller (46) cooperative between the power supply and the gate driver so as to set the gate driver between the on condition and the off condition, and a sensor (60) connected to the gate driver so as to detect a leakage of current across the gate driver. The controller is cooperative at the power supply so as to turn off the power supply when the signal is indicative of the leakage of current. The gate driver can an IGBT or a MOSFET.