IGBT Power Module Design for Suppressing Gate Voltage Spike at Digital Gate Control

Abstract

This paper clarifies the effect of gate inductance $L_{g}$ inside IGBT modules on gate voltage spikes when a digital gate driver is employed. Three IGBT modules with different $L_{g}$ 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 $V_{g\_{}spike}$ was positively correlated to the $L_{g}$ . Although the $V_{g\_{}spike}$ 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 $L_{g}$ inside the IGBT modules should be reduced to suppress the $V_{g\_{}spike}$ while improving the tradeoff by the digital gate driver at the same time. Furthermore, by analyzing the oscillation of the $V_{g\_{}spike}$ , it indicates that there should be some other stray elements, which couple $L_{g}$ and the stray capacitance inside IGBT chips, affecting the $V_{g\_{}spike}$ .

Keywords

• IGBT power module
• gate inductance
• digital gate driver
• switching loss
• current overshoot
• voltage overshoot