提出一种耐高温200℃的碳化硅 MOSFET 驱动电路.该驱动电路采用双极性结型晶体管(BJT)作为开关器件,避免了高温下硅基MOSFET关断能力弱化而引起的驱动电路失效.该驱动电路利用充电与放电两条支路将0V/5V源驱动信号调整为-5V/18V的栅极驱动电平.每条支路都采用自举电容加速BJT的开通过程,从而加快驱动电流的建立.建立该驱动电路的等效模型,通过该模型得到计算驱动电路中四个主要无源器件的等式以及主要无源器件与 BJT 电流放大系数之间的关系,并以此确定温度补偿策略.在85V/14.5A 的负载条件,不同温度对驱动电路进行双脉冲测试,可知MOSFET的开通暂态时间随温度升高由133.6ns缩短为112.4ns,而关断暂态时间由99.2ns增加到109.8ns.温度对其影响主要体现在随温度升高,碳化硅MOSFET的跨导增大,米勒平台降低,进而影响开关过程的时间.%This paper proposed an isolated gate driving circuit for Silicon Carbide MOSFET, which could survive high environment temperature up to 200℃. In this circuit, bipolar junction transistors (BJTs) were used as switch devices instead of Si MOSFETs because high temperature would weaken their turn-off capability. This circuit included two branches, gate charging branch and gate discharging branch, by which the source driving signal of 0V/5V could be adjusted to driving level of-5V/18V. Each branch used a bootstrap capacitor to accelerate the BJT turn-on process, thereby speeding up the gate driving current. The equivalent model of the driving circuit was built. The equation for calculating four main passive components was obtained, and the relationship between the main passive components and BJT current amplification coefficients was available. Accordingly, the temperature compensation principle was introduced. With the load condition of 85V/14.5A, the results from double-pulse test under a series of step-up temperature points were obtained. The turn-on time of SiC MOSFET decreased from 133.6ns at room temperature to 112.4ns at 200℃, while the turn-off time increased from 99.2ns at room temperature to 109.8 ns at 200℃. The influence of temperature is that, with the increase of temperature, the transconductance of SiC MOSFET increases, and the Miller platform voltage declines, which in turn affects the turn-on and turn-off time.
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