A Reliable Ultra-Fast Three Step Short Circuit Protection Method for E-mode GaN HEMTs

The Enhancement-mode (E-mode) Gallium Nitride High-Electron Mobility Transistor (GaN HEMT) has several hundred nanosecond level short circuit withstand time, much shorter than that of the silicon (Si) devices. Reliable ultra-fast protection solutions for the GaN HEMTs are in great demand. In this paper, a three-step GaN HEMT short circuit protection solution is proposed, including ultra-fast detection, active gate clamping and de-saturation circuit confirmation. First, the GaN HEMT short circuit capability under various gate voltages has been explained. Based on the safe protection boundary, the three- step protection solution is proposed. Experimental results prove that with the proposed protection method, the short circuit fault can be detected within 36 ns, and the short circuit energy is reduced with the ultra-fast detection and gate voltage clamping. Eventually, the GaN HEMT can be successfully protected from fatal failure up-to 400 V dc bus.