Double-Voltage Short-Circuit Protection Circuit for SiC MOSFETs with Temperature Compensation

This paper presents a double-voltage short-circuit protection circuit for SiC MOSFETs with temperature compensation, where the gate voltage reference threshold value <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(V_{ref1}(T))$</tex> is relative to the switching-on Miller platform voltage and is temperature-dependent, and the blanking time for HSF is determined by the time of the gate voltage rise to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{ref1}(T)$</tex> and is dynamically self-adaptive with the junction temperature to assure the short-circuit protection circuit trigger fast. This method can effectively reduce the peak value of overcurrent and protect the device quickly from short-circuit destruction. In double pulse tests, With the temperature-dependent <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{ref1}(T)$</tex>, HSF detection time is 80 ns at room temperature and 62 ns at 120 °C. HSF detecting time is reduced by 25 % compared to the fixed Vref1. The drain current at HSF detecting trigger point is 38.6 A, 25.6 A, and 48.4 A, respectively and the overcurrent peak value after the HSF detection trigger point is 88.9 A, 93.1 A, and 106.6 A, respectively, for the case of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{ref1}(25\ {}^{\circ} C), V_{ref1}(120\ {}^{\circ} C)$</tex> and the fixed <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{ref1}$</tex> for 120 °C. The drain current at HSF detecting trigger point and the overcurrent peak value are reduced by 47 % and 12.71 % respectively for the case of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{ref1}$</tex> (120°C) and the fixed <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{ref1}$</tex> for 120°C. For FUL detecting delay time, it is 69 ns for all junction temperatures. The proposed short-circuit protection method can quickly detect the HSF error, suppress the overcurrent at high junction temperatures, and improve the reliability of SiC MOSFETs.