Power MOSFET Switching Loss Analysis: A New Insight

Realistic estimation of power MOSFET switching losses is critical for predicting the maximum junction temperature and efficiency of power electronics circuits. The purpose of this paper is to investigate the internal physics of MOSFET switching processes using a physically based semiconductor device modeling approach, and subsequently examine the commonly used power loss calculation method based on the new physical insights. The widely accepted output capacitance loss term in this calculation method is found to be redundant and erroneous. In addition, the current method of approximating switching times with power MOSFET gate charge parameters grossly overestimates the switching power loss. This paper recommends a new MOSFET gate charge parameter specification and an effective switching time estimation method to compensate for the power loss calculation error introduced by the two slope voltage transition waveform of the power MOSFET