Stray inductance influence on switching waveform design with gate charge control for power MOSFETs

Active gate drive (AGD) is a technique to improve the switching behavior of power devices. Digital AGD, which is AGD assisted by digital hardware, enables precise control of the switching waveform of the power device and makes it easy to reach the optimal waveform. However, considerable computational resources and time are required to find a suitable gate drive condition from the exponentially increased number of candidates. A switching waveform design method has been proposed, which solves the gate drive waveform from a designed switching waveform with a deterministic approach. This paper experimentally investigates the influence of stray inductance on the method since the stray inductance cannot be completely eliminated in practical power converters. A simple and wide-band voltage control current source circuit was built to generate a 100 ns-wide gate charge pulse for measuring the voltage and current responses. The measured switching voltage waveform of a Si MOSFET driven by the gate drive waveform computed using this method demonstrated good agreement with the designed waveform. The impact of stray inductance on the accuracy of the switching waveform design based on the proposed method was examined through simulation. Additionally, the requirements for the performance of digital hardware when the method is implemented into a practical system are estimated. © 2024