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This paper proposes an Active Gate Current Control (AGCC) strategy for non-insulating gate WBG devices, for example, gallium nitride gate-injection-transistor (GaN-GIT) and silicon carbide super junction transistor (SiC-SJT). It provides a tool for power converter designers to further improve the converter efficiency and to extend the life time of those higher cost power transistors. By continuously...
The use of gallium nitride (GaN) high-electron mobility transistors (HEMTs) is a promising solution for a highly efficient motor drive design due to their high-switching speed and low on-state resistance. However, the higher reverse voltage drop of GaN HEMTs than that of the conventional silicon (Si) devices generates significant reverse conduction loss during the freewheeling period. This phenomenon...
This paper presents an evaluation of a newly released power stage direct drive GaN HEMT. The double pulse test is performed and the dynamic performance is characterized. PCB layout optimization is also investigated for improved switching transients. It is shown that the direct drive system provides simplified circuit design, reduced number of external components, and small gate loop parasitics. Also,...
Gallium Nitride has shown its potential over traditional Silicon devices with low switching and conduction losses. However, fast switching transition poses great challenges in dynamic device characterization due to sensitivity to parasitics and high requirement in testing equipment. An accurate switching behavior characterization method is proposed in this paper with loop inductance minimization and...
Three GaN-based buck switching power stage architectures are implemented using discrete GaN High Electron Mobility (HEMTs) devices and compared with respect to efficiency, switching speed (2 to 10MHz), and power conversion ratio for medium-power applications. The three presented power stage architectures are: a single-stage buck, a multi-phase buck with 2 phases, and a stacked interleaved configuration...
Efficiency evaluation is critical in modern power converter design. For hard-switching converters, the Eon/Eoff is the key to calculating switching losses. Although some datasheets provide the Eon/Eoff curves, the data generated are usually under a typical operating condition. In this paper, the switching loss distribution for GaN HEMTs is summarized. A simple and practical step-by-step Eon/Eoff scaling...
This paper aims to study an active-clamped resonant flyback converter. The proposed resonant technique can increase the zero-voltage switching (ZVS) range. Gallium Nitride high electron mobility transistor (GaN HEMT) devices are also applied in this study to reduce the switching losses at high-frequency operation. Synchronous rectifier is designed on secondary side to minimize the conduction losses...
Due to low loss and fast switching capabilities of gallium nitride (GaN) based power devices; there has been a strong interest in the replacement of silicon (Si) devices in power electronics converters for various applications. However, one of the concerns is that the high switching speed (dv/dt and di/dt) of GaN devices will deteriorate the EMI emission of power converters. Hence, this paper studies...
Wide band gap devices offer significant advantages such as high power density, fast switching and high efficiency. It is important to understand the trade-off involved in switching loss, conduction loss and reverse conduction characteristics for power converter design. Switching characterisation is essential for understanding the behaviour of new enhancement mode Gallium Nitride (GaN) power transistors...
This paper proposes an improved switching loss model for a 650V enhancement-mode gallium nitride (GaN) transistor. The interpolation fitting method is used to fit the strong nonlinear capacitance and transconductance, and it shows a better accuracy than the given function or polynomial fitting method. Meanwhile, because the input capacitance has a strong nonlinear relationship with gate-source voltage...
In this paper, a comparative study on the switching characteristics and power losses in GaN and SiC vertical junction field effect transistors (VJFETs) is presented. Models of VJFETs based on GaN and SiC, were separately built in Sivaco ATLAS and applied to a mixedmode device/circuit simulator for dynamic evaluation under identical test conditions. The device figure of merit (RonQg) of GaN VJFET is...
SiC and GaN power transistors switching energy are compared in this paper. In order to compare switching energy Esw of the same power rating device, a theoretical analysis is given to compare SiC device conduction loss and switching losses change when device maximal blocking voltage reduces by half. After that, Esw of a 650V GaN-HEMT is measured in hard switching condition and is compared with that...
VAR compensators (VARComps) are devices that produce reactive power in AC electrical systems. Electronic inverter circuits can supply currents that are at 90° to the grid voltage to supply reactive power Q. Since no active power P is delivered to the grid, these devices appear as a two terminal device similar to a capacitor or inductor. A VARComp was developed for this purpose. In this research, Si...
SiC and GaN power transistors conduction loss and switching losses are compared in this paper. In order to compare performance of the same power rating device, a theoretical analysis is given to compare SiC device conduction loss and switching losses change when device maximal blocking voltage reduces by half. Then static and dynamic characteristics of commercial SiC and GaN power transistors are...
The loss contribution of a 2.3 kW synchronous GaN-HEMT boost converter for an input voltage of 250 V and an output voltage of 500 V was analyzed. A simulation model which consists of two parts is introduced. First, a physics-based model is used to determine the switching losses. Then, a system simulation is applied to calculate the losses of the specific elements. This approach allows a fast and accurate...
Switching loss is an important and often the dominant source of converter losses. While soft-switching can greatly reduce the impact of switching loss, hard-switching is often preferred due to the simplicity of design, control, and implementation. Wide bandgap (WBG) semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) have greatly reduced switching losses due to faster transition...
GaN Cascode performance optimization for high efficient power applications is presented in this paper. Analytical equations of Cascode capacitance network (Ciss, Coss, Cgd) is demonstrated and the equations accuracy is verified through experimental measurement. Analysis shows that Cascode Cgd is determined by HV D-MISFETs Cds, LV Si FETs Cgd/Coss ratio, and extra zener diode capacitance. With low...
High conversion efficiency is always desired in energy storage device (ESD). In this work a high efficiency GaN and Si device mixed isolated bidirectional dc-dc converter is proposed in the distributed ESD application. To optimize the efficiency of the bidirectional half-bridge push-pull active clamp converter over a wide input/output voltage and load range, it is necessary to accurately predict the...
This paper proposes an improved analytical switching process model to calculate the switching loss of low-voltage enhancement-mode Gallium Nitride high-electron mobility transistors (eGaN HEMTs). The presented eGaN HEMTs models are more or less derived from silicon MOSFETs models, whereas eGaN HEMTs are different from three aspects: higher switching speed, much more reduced parasitic inductance in...
AlGaN/GaN high electron mobility transistors (HEMTs) have attracted considerable attention on high power - high frequency switch applications. With the aim to optimize the switching performances, in this paper the comparison between traditional Schottky and alternative MIS solution for Single-Pole Double-Throw (SPDT) switching circuit working in the Ka band will be presented, enhancing the benefits...
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