Sensorless Junction Temperature Estimation of Onboard SiC MOSFETs Using Dual-Gate-Bias-Triggered Third-Quadrant...

Area of Science:

• Electrical Engineering
• Materials Science
• Power Electronics

Background:

• Silicon carbide (SiC) MOSFETs are critical for electric vehicle (EV) traction inverters, necessitating robust thermal management.
• Current methods for monitoring SiC MOSFET temperature often require extra circuits, increasing cost and complexity.
• A need exists for cost-effective, sensorless thermal monitoring solutions for SiC MOSFETs.

Purpose of the Study:

• To propose a novel, high-efficiency, datasheet-driven method for sensorless estimation of SiC MOSFET junction temperature.
• To enable accurate thermal monitoring without additional hardware, addressing limitations of existing techniques.
• To improve the cost-effectiveness and applicability of thermal management in EV power electronics.

Main Methods:

• Utilizing the third-quadrant characteristics of SiC MOSFETs and a dual-gate bias (DGB) strategy for controlled reverse conduction.
• Introducing a MOSFET operating current, sensitive to temperature-sensitive electrical parameters (TSEPs), into a two-argument function for enhanced accuracy.
• Employing a two-stage current pulse to isolate motor effects and dynamically building a TSEP-combined temperature function.

Main Results:

• The proposed method achieves sensorless junction temperature estimation using bus voltage and current measurements.
• Effectiveness validated via SPICE simulations and a three-phase inverter test bench.
• Demonstrated an average relative estimation error below 7.2% in centigrade.

Conclusions:

• The developed datasheet-driven method offers an accurate and cost-effective solution for sensorless SiC MOSFET thermal monitoring.
• The dual-gate bias strategy and TSEP-current function integration overcome limitations of traditional methods.
• This technique enhances the thermal safety and reliability of traction inverters in electric vehicles.