Drain–Source Voltage Clamp Circuit for Online Accurate ON-State Resistance Measurement of SiC MOSFETs in DC Solid-State Power Controller

摘要

To obtain the online ON-state resistance (Rdson) of the SiC power MOSFET, during its operation in the dc solidstate-power controller (dc-SSPC), the drain current (Id) and the ON-state voltage (Vdson) need to be accurately measured in real time. Compared to that of Id, the measurement of Vdson needs to solve more problems, i.e., the high accuracy, the influence of the operating temperature (Tw), and the high OFF-state voltage. The drain-source voltage clamp circuit (DVCC) can be accurately used to measure Rdson at low operating temperatures. However, the SiC power MOSFETs, owning the low Rdson characteristics, in the dc-SSPC often operate at the high Tw. Under this high Tw, the existing DVCCs cannot perform well and give inaccurate measurements of Vdson in real time. Therefore, this article presents an innovative design of the DVCC with improved real-time measurement accuracy (<0.5%), over a wide Tw range (25 C-100 C). The DVCC is analyzed and tested by integrating into a dc-SSPC for measuring the online Rdson of the SiC power MOSFET at the high Tw of 100 C. The experimental results validate the accuracy of the proposed DVCC-based measurement method and highlight the potential for its use in the accurate junction temperature measurement.