WBG Power Switch Self-Diagnostics for Early Fault Isolation
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Solution Overview
Problem
High-power applications using wide bandgap (WBG) semiconductors face reliability and safety concerns due to device degradation over time, leading to complex and costly failure detection and protection systems.
Innovation Solution
A power switch device incorporating a wide-bandgap semiconductor switch and a gate driver with integrated diagnostic and fault detection circuits, which senses electrical characteristics and performs diagnostic tests to detect failures and issue fault signals, thereby disabling the switch to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex failure detection and protection modes are implemented for WBG semiconductor switches, then reliability and safety are improved, but device complexity and cost increase
Solution Approach 1:
The WBG semiconductor switch performs self-diagnostic testing by internally sensing its own electrical characteristics (such as threshold voltage and on-resistance) and comparing them against pre-stored reference values. This self-service approach eliminates the need for external diagnostic equipment or complex protection circuits, thereby improving reliability while maintaining simple device architecture.
Solution Approach 2:
The switch device integrates multiple functions into a single component: it serves as both the power switching element and the diagnostic testing subject. The same switch structure performs both normal power conversion operations and self-diagnostics, eliminating the need for separate dedicated diagnostic hardware and reducing overall system complexity.
2Reliability
If various failure detection modes are accommodated under different operating conditions, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The diagnostic system detects switch degradation by monitoring changes in electrical parameters such as threshold voltage shifts and on-resistance increases. By continuously tracking these parameter variations and comparing them against reference values, the system can identify degradation trends and predict failures before they occur, enabling early intervention and replacement planning.
3Reliability
If diagnostic testing is performed continuously, then early failure detection is improved, but energy consumption increases
Solution Approach 1:
The diagnostic testing is performed periodically at predetermined intervals rather than continuously. The controller executes self-diagnostic tests at scheduled times, comparing electrical characteristics against reference values stored in memory. This periodic approach maintains early detection capability while significantly reducing energy consumption compared to continuous monitoring.
Data Source
AI summary
Power switch device includes a wide-bandgap semiconductor switch, and a gate driver. The gate driver includes a driver circuit and a diagnostic circuit. The driver circuit is configured to provide a driver signal to control the wide-bandgap semiconductor switch. The diagnostic circuit is configured to sense an electrical characteristic of the wide-bandgap semiconductor switch, and perform a diagnostic test for the wide-bandgap semiconductor switch in response to the electrical characteristic of the wide-bandgap semiconductor switch.