Accurate Online Junction Temperature Estimation of IGBT Using Inflection Point Based Updated I–V Characteristics
Abhinav Arya, Abhishek Chanekar, Pratik Deshmukh, Amit Verma, Sandeep Anand
Abstract
The junction temperature (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> ) estimation of the insulated gate bipolar transistor (IGBT) is important for reliable operation of the power converters in various applications. For T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> estimation, on-state collector-emitter voltage (v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ce</sub> ) at higher collector currents (i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) is widely used temperature sensitive electrical parameter (TSEP). For real-time T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> estimation, this TSEP is calibrated using the I-V characteristics of the new IGBT. Due to bond-wire degradation, the original I-V characteristics of IGBT changes resulting in inaccurate T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> estimation. In this article, a technique is proposed to update the I-V characteristics of the degraded IGBT, without affecting the normal operation of the power converter. It is achieved by estimating the increment in bond-wire resistance (\triangle R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">con</sub> ) by using real-time samples of v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ce</sub> and inductor current. The mathematical analysis is also presented to find an error in estimated \triangle R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">con</sub> . The major contributions of this article are as follows: a) it enables the accurate T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> estimation of the IGBT throughout its lifetime; and b) it also provides the parameter \triangle R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">con</sub> , which could be utilized in condition monitoring of the IGBT. Further no additional circuitry is required. The proposed technique is validated on experimental setup, which is developed in the laboratory. The error in T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> estimation is observed within $1$ °C the degraded IGBT, which shows the effectiveness of the proposed scheme.