Study of a Fast Over-Current Protection Based on Bus Voltage Drop for Gallium Nitride Power Device

Abstract

Due to the low threshold voltage, gallium nitride (GaN) high electron mobility transistor (HEMT) is prone to mis-conduction. Meanwhile, compared with silicon (Si) insulated gate bipolar transistors (IGBT) and silicon carbide (SiC) metal- oxide- semiconductor field effect transistor(MOSFET) devices, GaN HEMT have a shorter short-circuit withstand time at highvoltages, only a few hundred nanoseconds, which leads to a serious challenge to overcurrent protection. Traditional inductor detection and desaturation overcurrent detection have a long execution time, which are no longer suitable for over-current protection of GaN. Therefore, this paper proposes a new fast over-current protection method, which is based on the bus voltage drop. Through simulation and experimental verification, the result proves that the proposed protection method can detect the over-current signal within 100ns and turn off the GaN device within 400 ns, achieving fast and reliable over-current protection.

Highly Reliable Short-Circuit Protection Circuits for Gallium Nitride High-Electron-Mobility Transistors

“…Recently, research has been conducted on short circuit detection methods based on the DC bus voltage drop. In [6,22,23], short-circuit protection is performed based on the DC bus voltage, which is the voltage across the high-side device drain and low-side device source. The DC bus voltage exhibits an instantaneous voltage drop when a short circuit occurs because a high di/dt current flows through parasitic inductances present in the power loop.…”

“…This voltage drop is used to detect whether a short circuit has occurred, and the response time of the detection circuit can be within hundreds of nanoseconds. In [22,23], the circuit is protected from a short circuit within 280 ns and 370 ns, respectively. However, when using DC bus voltage sensing, the voltage dip caused by the normal switching of the device can result in false short-circuit protection behavior.…”