Passive Overcurrent Shutdown in Semiconductor Power Switches
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Solution Overview
Problem
Existing semiconductor power switches in high-voltage electric drive systems face rapid thermal damage during transient overcurrent conditions due to insufficient response time in actively-controlled protective measures.
Innovation Solution
A passively-activated temperature sensitive element (TSE) is integrated with the semiconductor power switch to quickly turn off the switch during overcurrent events by conducting electric current in response to a threshold temperature, providing rapid protection against thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If actively-controlled protective measures are used to protect the power switch during overcurrent conditions, then the power switch can be protected from thermal damage, but the response time is insufficient due to the rapidity of local heating
Solution Approach 1:
The temperature sensitive element (TSE) automatically detects temperature rise and triggers protection without requiring external control signals or processing. The TSE is positioned in close proximity to the active area and self-activates when local temperature exceeds a threshold, eliminating the time delay associated with active monitoring and control systems.
Solution Approach 2:
The patent replaces electronically-controlled protection systems with a passively-activated thermal response mechanism. The TSE uses inherent temperature-dependent electrical properties to trigger protection, substituting complex active control with a simpler thermal-field-based mechanism that responds more rapidly to overheating conditions.
2Loss of time
If a temperature sensitive element is integrated with the power switch, then rapid protection response is achieved, but the device complexity increases
Solution Approach 1:
The TSE is monolithically integrated with the power switch on the same semiconductor die, merging two functions into a single unitary device. This integration reduces the physical distance between the active area and TSE, enabling faster thermal coupling while avoiding the complexity of separate discrete components and their associated interconnections.
Solution Approach 2:
The semiconductor device is designed to perform multiple functions: the power switch handles normal power conversion operations while the integrated TSE provides overtemperature protection. This multi-functionality is achieved within a single integrated structure, avoiding the need for separate protection circuits and reducing overall system complexity.
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
The TSE enables rapid response to overcurrent conditions, protecting the power switch from thermal damage while minimizing impact on on-state resistance, and can be used in conjunction with active protection methods for enhanced safety.
Implementation Method 1
Conduction of the electric current through the temperature sensitive element is negligible so long as an actual operating temperature of the power switch remains within a predetermined normal operating temperature range of the power switch. Conduction of the electric current increases when the actual operating temperature exceeds an upper limit of the predetermined normal operating temperature range
Data Source
AI summary
A switching device includes a semiconductor power switch and a temperature sensitive element (TSE). The power switch has a normal operating temperature range and an active area. The TSE is connected to the power switch proximate the active area, and configured such that conduction of an electric current through the TSE is negligible when a temperature of the TSE is within the normal operating temperature range. Conduction increases when a temperature of the TSE is above the normal operating temperature range. This continues to a level sufficient for turning off the semiconductor power switch, e.g., by shorting the gate and source of the power switch. The TSE thus protects the power switch from thermal damage during an overcurrent event. An inverter circuit includes a direct current link capacitor and multiple switching pairs of the switching devices.