Switching performance of a SiC MOSFET body diode and SiC schottky diodes at different temperatures
Switching performance of a SiC MOSFET body diode and SiC schottky diodes at different temperatures
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DOI：
10.1109/ecce.2017.8096916
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发表时间：
2017-10
期刊：
影响因子：
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通讯作者：
M. Ahmed;R. Todd;A. Forsyth
中科院分区：
文献类型：
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作者：
M. Ahmed;R. Todd;A. Forsyth
本文研究了SiC MOSFET本征/体二极管的反向恢复特性，并在不同温度下将二极管的性能与类似额定值的SiC肖特基二极管进行了比较。提出了一种电路级分析建模方法，用于快速准确地预测开关瞬态和损耗。利用MATLAB对分析模型进行了数值求解，结果与实验和LTSpice模拟结果非常吻合。所提出的模型比LTSpice模型更准确地预测开关损耗，需要三分之一的计算时间。发现使用SiC MOSFET的体二极管可以使MOSFET的导通损耗随着其结温从25°C增加到125°C而增加35%到79%（600 V 20 A开关操作）。这是由于体二极管的反向恢复电荷和较高的结电容。这与肖特基二极管形成对比，肖特基二极管表现出几乎不随温度变化的开关特性。还提供了MOSFET开关损耗的详细细分，以量化由于反向恢复以及器件和电路寄生电容引起的损耗，这表明体二极管的反向恢复分别占25°C和125°C下总开关损耗的3%和23%。一个SiC肖特基二极管连接在体二极管，以抑制反向恢复效应和实验结果表明，这种配置的性能优势，在很宽的温度和负载电流范围。
This paper investigates the reverse recovery behaviour of a SiC MOSFET intrinsic/body diode and compares the diode's performance with similarly rated SiC Schottky diodes at different temperatures. A circuit level analytical modelling approach is proposed for rapid and accurate predictions of switching transients and losses. The analytical models were solved numerically using MATLAB and the results showed a very good match with the experiments and LTSpice simulations. The proposed models were more accurate than LTSpice models in predicting the switching losses and required one third of the computation time. It was found that using the SiC MOSFET's body diode could increase the MOSFET turn on losses by 35% to 79% as its junction temperature increases from 25°C to 125°C (600V 20A switching operation). This is due to the reverse recovery charge and higher junction capacitance of the body diode. This is in contrast with a Schottky diode which exhibits switching characteristics which have little variation with temperature. A detailed breakdown of MOSFET switching losses is also presented to quantify the losses due to reverse recovery and device and circuit parasitic capacitances, which shows that the reverse recovery of the body diode is responsible for 3% and 23% of the total switching losses at 25°C and 125°C, respectively. A SiC Schottky diode is connected across the body diode to suppress the reverse recovery effect and the experimental results showed the performance benefit of this configuration over a wide range of temperatures and load currents.