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A High-Speed H-Bridge Circuit Based on GaN HFETs and custom resonant gate
drivers
Bo Wang
Student Member, IEEE
University of South Carolina
301 Main Street
Columbia, SC 29208, USA
wangb@engr.sc.edu
Antonello Monti
Senior Member, IEEE
RWTH Aachen University
Wuellnerstrasse 5b
Aachen 52062, Germany
amonti@eonerc.rwth-aachen.de
Marco Riva
Member, IEEE
Universita' degli Studi di Milano
Via Celoria 16 - 20133
Milano,Italy
riva@unimi.it
Abstract -- The paper describes a high-speed high efficiency H-Bridge circuit based upon Gallium nitride (GaN) Heterostructure
Field-effect Transistor (HFET) devices as power switches. The use of a new designed driver integrated circuit (IC) makes it possible
to exploit the capabilities and advantages of GaN technology in power electronic applications by means of a smart and convenient
implementation. Low power losses small size and high reliability are the main advantages of which the design of power systems can
benefit. A full discussion of the design and of the experimental results of a DC to AC H-bridge inverter concludes the paper.
Index Terms -- H-Bridge, High-speed, GaN HFET
I.INTRODUCTION
In power electronics and power systems, the
characteristics of the power semiconductor devices have a
fundamental role on the efficiency, size and weight of the
system. As a result, the power electronics industry, with its
constant urge to provide more efficient and smaller size
systems, has driven the improvements in power
semiconductor device characteristics towards the behavior of
ideal switch. Power devices based upon silicon technology
have been developed and, according to experts, their
characteristics are close to reach the material limit. The
consideration that in the future not too much further
improvements could be easily achieved has pushed the
researchers to investigate alternative materials with which
better power devices can be made.
The rapidly developing research on wide-band III-Nitride
semiconductor materials (such as GaN) has been driven by
the unique properties of these materials, such as high
electron mobility, high saturation velocity, high sheet-carrier
concentration at hetero-junction interfaces, high breakdown
voltages, etc. These properties make the use of III-Nitride
technology a promising approach for high-power, high-
temperature and high-speed applications in power
electronics. These devices can be extremely useful in
industrial power electronic applications and can improve the
efficiency and the regulation in AC-DC and DC-DC
converters. Unfortunately, the use of wide-band III-Nitride
(GaN) devices is currently limited mainly to telecom and
low-power applications. The lack of high-frequency drivers
is one of the factors preventing their application to power
converters [1, 2, 3]. In order to make GaN devices applicable
in power electronics and best exploit the capabilities and
advantages of these devices, the authors have been involved
in the design and fabrication of a novel high-speed, low
power-loss driver IC for 1A, 100V GaN HFET devices. The
gate driver IC, developed at the University of South
Carolina, provides a convenient and smart way to use GaN
devices in power electronics, as well as making it possible to
achieve miniaturization, high efficiency, reliability, and low
cost for power systems [4].
The design of the driver IC has been introduced in [4, 5,
6]. This paper, will discuss the effectiveness of the new
driver IC and the GaN HFET devices in power electronics
applications. The design and the experimental measurements
of a high-speed, low power-loss power system, based upon
the H-Bridge topology will be discussed thereafter.
II.D
ESIGN OF THE H-BRIDGE CIRCUIT
Some high-speed H-Bridge circuits and H-Bridge driver
ICs have been reported in literature and industry [7, 8, 9,
10]. However, most of them can only work at 1MHz and
lower frequencies. In this paper, a GaN-based H-Bridge
which can work around 10MHz is introduced.
The schematic of the power cell considered for the test is
reported in Fig. 1. The H-Bridge is composed of four GaN
HFETs as power switches. The high-speed, low-loss driver
ICs, which the authors designed and fabricated recently, are
used to drive the two low-side HFET transistors directly. For
the high-side transistors, two high-speed opto-couplers are
added to generate the isolated control signals before the IC
driver chips. Two pairs of isolated DC/DC converters are
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