IGBT Health Monitoring via Gate Driver Voltage
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Solution Overview
Problem
Existing methods for monitoring the health of power electronics switches like MOSFETs and IGBTs in critical applications are inadequate, particularly in harsh conditions, as they often rely on high-voltage measurements and are prone to signal noise, and may not accurately predict premature failures.
Innovation Solution
A method involving the measurement of parameters such as rate of change of voltage, rate of change of current, gate charge, peak overshoot voltage, and reverse recovery current, with a processor-based system to estimate the health and remaining useful life of semiconductor power electronic switches, using embedded or external processors to normalize and compare these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threshold voltage limit measurements are used to estimate device health, then health monitoring capability is provided, but measurement precision deteriorates due to signal noise masking the voltage variation
Solution Approach 1:
The patent introduces an intermediary measurement approach by measuring the gate-emitter voltage variation at the gate driver stage rather than directly measuring the collector-emitter threshold voltage. This intermediary measurement point provides access to the threshold voltage information while avoiding the high-voltage noise environment, thereby resolving the contradiction between obtaining health monitoring data and maintaining measurement precision
Solution Approach 2:
The patent creates a copy of the threshold voltage information by measuring the gate-emitter voltage swing required to turn on the device. This copy of the threshold voltage data is obtained at a low-voltage, low-noise location (the gate driver) rather than at the high-voltage power switch terminals, thus preserving measurement precision while enabling health monitoring
2Reliability
If high-voltage measurements are performed to monitor device health, then health information is obtained, but device complexity increases due to voltage clamping requirements
Solution Approach 1:
The patent uses the gate driver circuit as an intermediary to obtain threshold voltage information without requiring direct high-voltage measurements. The gate driver naturally operates at low voltage and provides the necessary electrical characteristics for health monitoring, eliminating the need for complex voltage clamping circuits at the high-voltage side
Solution Approach 2:
The gate driver circuit, which is already present in the power electronic system, is utilized to provide health monitoring functionality. By measuring the gate-emitter voltage characteristics during normal switching operations, the system performs self-diagnosis without requiring additional complex measurement circuits or voltage clamping arrangements
3Reliability
If bandpass filters are used to extract ringing components for health monitoring, then switching behavior information is obtained, but device complexity increases due to high-frequency measurement requirements
Solution Approach 1:
The patent measures the gate-emitter voltage waveform at the gate driver stage as an intermediary to infer the switching behavior and threshold voltage characteristics. This low-frequency, low-noise measurement approach provides the necessary health information without requiring complex high-frequency bandpass filters or ringing component extraction circuits
Data Source
AI summary
A method of monitoring the health of a semiconductor power electronic switch such as an insulated gate bipolar transistor (IGBT) is provided. The method having the steps of: measuring one or more parameters selected from the group consisting of: a rate of change of voltage(dVdt)across the switch; a rate of change of current(didt)through the switch, a charge present on a gate of the switch (QG), a peak overshoot voltage (VPO) across the switch, and a peak overshoot or reverse recovery current (IRR) through the switch; and estimating the health of the switch based on the measured parameter(s).