Large-Signal Stability Analysis of Self-Turn-On in Switching Transients

Unstable switching transient oscillation can be detrimental or destructive to power electronics converters. As switching speed increases, the impact of parasitic components became more severe and may lead to unexpected switching behavior. The large-signal and nonlinear nature of the switching transients limits the use of small-signal analysis where operating points must be carefully selected. The Lyapunov function based on Brayton-Moser's mixed potential method is applied here to analyze the self-turn-on phenomena in MOSFETs' turn-off transient. It is shown that the switching transient can be expressed as a gradient descent of a mixed potential function. The large-signal stability theorem provides a metric to quantitatively evaluate the switching transient stability. Comparison with the experimental results shows it can effectively predict the significance of the unstable oscillation and explain the root cause of the self-turn-on phenomena.