Modeling and Stability Analysis for a Closed Loop Active IGBT Gate Drive

This paper presents modeling and stability analysis for a closed loop active current source IGBT gate drive (ACSD) with di c/dt and dv c/dt feedback control. A constant current source is applied to drive the IGBT, and feedback circuits based on di c/dt and dv c/dt detection generate extra current to regulate the net gate drive current. Thus, the switching speed is controlled with little sacrifice in switching time and losses. However, the stability issues of the closed-loop control are inevitable and should be carefully considered for reliable and proper operations. The di c/dt and dv c/dt detection circuit models are clarified considering the parasitic inductance between the IGBT die emitter and gate drive ground ($L_{\mathrm{e}}$) which is a key parameter affecting the stability. A simplified IGBT model is proposed to simplify the overall control model and stability analysis. With the proposed models, the influences of the feedback parameters and IGBT gate parasitic parameters on the stability can be discussed by the root locus plots. The experimental results verify the effectiveness of the proposed models.