The improvement of the gate driver for GaN transistor is presented in this paper. The proposed topology contains the overcurrent protection with the two-stage turning off and independent control of turn on and off time of the GaN transistor. The operation of driver and its application in the half-bridge converter are described using both simulation and prototype measurements. The overcurrent protection was tested in Double Pulse Test (DPT) conditions.
Słowa kluczowe: Wide Bandgap semiconductors, GaN transistors, power transistors, overcurrent protection, SMPS, gate circuit
Poni˙zszy artykuł prezentuje zaawansowany sterownik bramkowy do tranzystorów mocy GaN. Proponowane rozwia˛zanie zawiera zabezpieczenie nadpra˛dowe/przeciwprzecia˛z˙eniowe z dwustopniowym wyła˛czaniem oraz umoz˙liwia niezalez˙ne ustawienie czasu wła˛czenia i wyła˛czenia tranzystora. Działanie sterownika zostało zbadane symulacyjnie i doswiadczalnie w układzie przekształtnika półmostkowego. Proponowane zabezpieczenie tranzystora zostało przetestowane w warunkach podwójnego pulsu z obcia˛z˙eniem indukcyjnym (DPT).
Keywords: półprzewodniki szerokoprzerwowe, tranzystory GaN, tranzystory mocy, zabezpieczenie przeciwprzecia˛z˙eniowe, układy impulsowe, obwód bramkowy
Nowadays, achieving high efficiency, power density and reduction of overall weight of power electronics devices is the main researcher’s topics . The main merits of Wide Bandgap (WBG) devices are low on-state resistance, small inter-terminal capacitances, ability to operate at the high temperature and extremely low switching times (ns-range). All those factors allow to break the limits appointed by the stateof- art Silicon transistors. The subsequent issue is the protection of short-circuit current (SCC) which can lead to thermal and/or electrical damage of semiconductor. The SCC operation depends on the inductance in power stage, gate voltage and voltage of DC-Bus (VDC). The 600 and the 650 V - class GaN transistors have very stable short-circuit (SC) response and relatively large withstand time for VDC below 300 V. For voltage in the range above 400 V the SC withstand time is on the level of hundreds of nanoseconds[3, 4]. Thus, the properly fast protection of WBG semiconductors has a significant impact and should be considered for power converters. Production process of GaN HEMT transistors is constantly developed. The basis and the simplest technology ensure best performing GaN transistor, however, device structure is "normally-on". In "normally-on" devices negative gate voltage should be apply to switch it off. Moreover, without driving voltage permanent state is "on" and that might cause failure of whole device or system (e.g. short-circuit). Due safety of operation power converters it is recommended to apply normally-off device. Currently there are available three types of "normally-off" GaN Transistor: Enhancement- Mode GaN Transistor (e-HEMT), Gate Injection Transistor (GIT) and Cascode GaN Transistor. Their specific parameters are rather different: gate threshold voltage of e-HEMT is relatively low, GaN GIT transistor is characterized by large current flowing in gate circuit, which is required to switch [...]
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