Power Converter Gate Voltage Control for Junction Temperature
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Solution Overview
Problem
Power electronics converters in aerospace and other critical applications face reliability issues due to thermal runaway failures in semiconductor devices, particularly in wide band-gap devices like SiC and GaN MOSFETs, caused by electrical and thermal stresses from inductive loads and varying operating conditions, leading to premature failures.
Innovation Solution
A power electronics converter system with a controller that dynamically adjusts switching gate voltage and frequency based on junction temperature measurements to manage thermal stresses, using thermal models to prevent thermal cycling and shutdown when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If semiconductor switches operate at high power with inductive loads, then power conversion capability is improved, but thermal stresses and reliability deteriorate
Solution Approach 1:
The gate voltage is dynamically adjusted based on real-time junction temperature measurements. When temperature exceeds a reference threshold, the controller reduces gate voltage to decrease conduction losses and reduce thermal stress. This dynamic adaptation allows the system to maintain high power capability during normal operation while automatically reducing stress under thermal conditions, thereby improving reliability without sacrificing overall power conversion capability.
2Loss of energy
If gate voltage is increased to reduce conduction losses, then efficiency is improved, but thermal stress and junction temperature increase
Solution Approach 1:
The system implements a feedback control mechanism where junction temperature is continuously monitored via temperature sensors. Based on this feedback, the controller adjusts the gate voltage to an optimized value that balances conduction losses and thermal stress. When temperature is within acceptable ranges, higher gate voltage is applied to minimize conduction losses. When temperature exceeds thresholds, gate voltage is reduced to prevent thermal runaway, thus dynamically optimizing the trade-off between efficiency and temperature management.
3Reliability
If thermal management is intensified to prevent thermal runaway, then reliability is improved, but system complexity increases
Solution Approach 1:
The thermal management system operates autonomously using self-service principles. Temperature sensors continuously monitor junction temperature and automatically feed this information to the controller, which then adjusts gate voltage without requiring external intervention or complex thermal management hardware. This self-regulating mechanism improves reliability through effective thermal control while minimizing system complexity by utilizing the existing control infrastructure rather than adding separate complex thermal management subsystems.
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
Enhances the reliability and longevity of semiconductor devices by effectively managing thermal stresses, reducing the risk of premature failures and allowing for safe operation within performance limits.
Implementation Method 1
adjust a switching gate voltage applied to the semiconductor switch to reduce a conduction loss if the determined junction temperature exceeds the reference temperature
Implementation Method 2
determine a junction temperature of the semiconductor switch
Implementation Method 3
CTE (coefficient of thermal expansion) mismatches across material interfaces, resulting in failures such as solder fatigue and bond wire lift-off. CTE mismatches will also tend to weaken IGBT interfaces over time due to repetitive thermal cycling
Data Source
AI summary
The disclosure relates to thermal management of a power electronics converter. An example embodiment includes a power electronics converter comprising: a first set of terminals connectable to a first voltage supply; a second set of terminals connectable to a second voltage supply; a plurality of semiconductor switches connected between the first and second sets of terminals; a voltage sensor connected to measure a voltage across the second supply; a current sensor connected to measure a current through the second supply; and a controller connected to provide switching signals to the semiconductor switches and to receive voltage and current signals from the voltage and current sensors, the controller configured, for each of the semiconductor switches, to: determine a junction temperature of the semiconductor switch; compare the determined junction temperature to a reference temperature; and adjust a switching gate voltage applied to the semiconductor switch.