| Summary: | This paper clarifies the effect of gate inductance <inline-formula> <tex-math notation="LaTeX">$L_{g}$ </tex-math></inline-formula> inside IGBT modules on gate voltage spikes when a digital gate driver is employed. Three IGBT modules with different <inline-formula> <tex-math notation="LaTeX">$L_{g}$ </tex-math></inline-formula> were fabricated to implement double pulse tests by conventional gate driving and digital control gate driving with three-step vectors. It was found that the tradeoff between switching loss and voltage/current overshoots can be improved by digital control, but a large gate voltage spike was generated when gate-driving vectors were changed. And the spike voltage <inline-formula> <tex-math notation="LaTeX">$V_{g\_{}spike}$ </tex-math></inline-formula> was positively correlated to the <inline-formula> <tex-math notation="LaTeX">$L_{g}$ </tex-math></inline-formula>. Although the <inline-formula> <tex-math notation="LaTeX">$V_{g\_{}spike}$ </tex-math></inline-formula> can also be suppressed by decreasing the difference of gate driving vectors between the first and the second steps, the improvement of the tradeoff is weakened. Therefore, it is required that the <inline-formula> <tex-math notation="LaTeX">$L_{g}$ </tex-math></inline-formula> inside the IGBT modules should be reduced to suppress the <inline-formula> <tex-math notation="LaTeX">$V_{g\_{}spike}$ </tex-math></inline-formula> while improving the tradeoff by the digital gate driver at the same time. Furthermore, by analyzing the oscillation of the <inline-formula> <tex-math notation="LaTeX">$V_{g\_{}spike}$ </tex-math></inline-formula>, it indicates that there should be some other stray elements, which couple <inline-formula> <tex-math notation="LaTeX">$L_{g}$ </tex-math></inline-formula> and the stray capacitance inside IGBT chips, affecting the <inline-formula> <tex-math notation="LaTeX">$V_{g\_{}spike}$ </tex-math></inline-formula>.
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