Reflected wave phenomenon in motor drive systems using wide bandgap devices

Fast switching transients from power devices can produce large voltage spikes in motor drive systems with long feeder cable lengths. Referred to as the reflected wave phenomenon, it has been previously demonstrated that the maximum cable length for a given per unit overshoot decreases with increasing switching speed. With the emergence of higher switching speed components based on wide bandgap (WBG) semiconductors, this issue will present itself at shorter feeder cable lengths than comparably rated silicon (Si) devices. This work explores the reflected wave phenomenon for a gallium nitride (GaN) device and compares it to a Si MOSFET. A PSPICE model is created to predict the behavior of this issue. It is validated with experimental results. Tests were performed on a 600 V GaN device, a 600 V Si CoolMOS MOSFET, and a 650 V SiC MOSFET.