Semiconductor Junction Temperature Sensing During Switching Events
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Solution Overview
Problem
Current methods for measuring the junction temperature of semiconductor devices in power switching applications are inadequate, as they rely on indirect measurements and are not accurate, especially at high switching frequencies, leading to unreliable predictive maintenance and potential equipment failure.
Innovation Solution
A method involving the synchronous measurement of multiple temperature-sensitive parameters during switching events, allowing for direct and accurate calculation of junction temperature, with calibration processes to account for varying operating conditions and potential wear or degradation effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensors are used to measure temperature during operation, then temperature measurement is possible, but the measurement location is not in the main heat conduction path leading to distorted and inadequate temperature data
Solution Approach 1:
The patent uses temperature-sensitive electrical parameters (VGS, ID, VDS) as intermediaries to indirectly measure junction temperature without placing physical sensors in the heat conduction path. These electrical parameters naturally correlate with temperature and can be measured through existing device terminals, serving as mediators between the inaccessible junction temperature and measurable electrical quantities.
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensing system with an electrical measurement system. Instead of using thermal sensors that require physical contact with the heat path, the invention uses electrical parameter measurements (voltage, current) that can be obtained through standard electrical connections, substituting thermal measurement methodology with electrical characterization.
2Measurement precision
If temperature sensors are integrated into the switching element, then direct junction temperature measurement is achieved, but device cost increases prohibitively due to special packaging and dedicated readout electronics
Solution Approach 1:
The patent makes existing electrical measurement infrastructure serve multiple functions. The same electrical terminals and measurement equipment used for characterizing switching performance (VGS, ID, VDS measurements) are also used to derive junction temperature, eliminating the need for separate dedicated temperature sensor packaging and readout electronics.
Solution Approach 2:
The switching element itself provides the means for its own temperature measurement through its inherent electrical characteristics. The device's own electrical parameters (channel resistance, switching behavior) serve as temperature indicators, allowing the component to self-diagnose its thermal state without requiring external sensing infrastructure.
3Ease of operation
If indirect measurement methods are used to calculate junction temperature from external sensor data, then temperature estimation is possible, but the calculated temperatures differ significantly from actual junction temperatures in real modules
Solution Approach 1:
The patent performs preliminary calibration measurements to establish the relationship between electrical parameters and junction temperature for each specific device before actual operation. By pre-determining the correlation between VGS, ID, VDS and Tj for individual devices, the system accounts for manufacturing variations and ensures accurate temperature derivation during subsequent operational measurements.
Solution Approach 2:
The methodology uses feedback from multiple electrical parameter measurements (VGS, ID, VDS) to continuously refine and verify the derived junction temperature. By monitoring how these parameters change together during switching events, the system can validate temperature calculations and adjust for deviations from expected behavior, ensuring accuracy in real-time operation.
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 approach provides a more accurate and reliable measurement of semiconductor junction temperature, enhancing predictive maintenance and reducing the risk of equipment failure by accounting for real-time operating conditions and transient effects.
Implementation Method 1
Each semiconductor switching element has electrical parameters that are sensitive to its junction temperature, Tj, such as its channel resistance, switching times, gate charge and drain current
Data Source
AI summary
A method of measuring the junction temperature, Tj, of a semiconductor switching element in real-time, and a device for carrying out such a measurement are described. A plurality of measurements of a first and a second, different, temperature-sensitive parameter (TSP) of the semiconductor switching element while recording other quantities determining the semiconductor switching element operating point is taken. The junction temperature value based on the measured values of the first temperature-sensitive parameter and the at least one second temperature-sensitive parameter are calculated and compared to determine the actual junction temperature Tj. Each of the plurality of measurements of the first temperature-sensitive parameter and the at least one second temperature-sensitive parameter is synchronized with a switching event of the semiconductor switching element.