IEEE Power Electronics Magazine - September 2021 - 38

conversion electronics confront HI approaches, where
optimization of various circuits is naturally enabled
using different semiconductor technologies. In this
review article, we first present the traits and principles
of power conversion electronics from both circuit and
mathematical aspects. Then, we highlight the progress of
HI-enabled power conversion electronics. Rather than
presenting an exhaustive literature survey, we instead
describe some prominent research highlights from both
commercial practices and academic frontiers and provide
insight on these case study applications.
I. Introduction
Power conversion electronics play an essential role in various
applications, including power supplies for personal
computers, industrial controls, aerospace central systems,
the internet of things, and telecommunications equipment
[1]. The main function of power conversion is to
Power Conversion
Input Filter
+
Power
In
-
Control Circuit
-
Feedback
FIG 1 Schematic of a typical power conversion system.
Table I. Main characteristics of Si, GaN, and SiC [4].
Material
Bandgap
Breakdown Electric Field
Thermal Conductivity
Electron Mobility
Si
1.12 eV
0.3 × 106 V/cm
1.5 W/cm · K
1400 cm2/Vs
GaN
3.4 eV
3.3 × 106 V/cm
1.3 W/cm · K
1200 cm2/Vs
SiC (4H)
3.3 eV
2.5 × 106 V/cm
4.9 W/cm · K
1000 cm2/Vs
Switching
Matrix
Output Filter
+
modify the presentation/magnitude of an electric quantity
to another, such as the conversion of dc power into ac
and vice versa, or dc voltage into another dc with a different
magnitude.
Figure 1 shows a block diagram of a typical power
conversion system. Besides the control circuit for Gate
control and loop feedback, it consists of an input filter,
switching matrix, and output filter. The input and output
filters mostly comprise passive devices, such as inductors,
transformers, capacitors, and resistors. Traditional
monolithic power converters adopt a switching
matrix of Double-diffused Metal Oxide Semiconductor
Field Effect Transistor (DMOS), Bipolar Junction Transistor
(BJT), and Insulated Gate Bipolar Transistor (IGBT)
for the benefits of high operating voltages and power handling
capability.
It is reported that 5% of the total electricity wastage
in the U.S. is due to battery charging/discharging [2]. To
mitigate power wastage issues, the latest
electrical power products are required
smaller volume, lower cost and higher conversion
efficiency.
Thus, it becomes stringent to develop
Power
Out
1,000
100
10
1
0.1
10
Si
SiC
GaN
[7]
[6]
[5]
100
[13]
[12]
1,000
Breakdown Voltage (V)
FIG 2 Relationship of RON and breakdown voltages of Si, GaN, and SiC devices.
38 IEEE POWER ELECTRONICS MAGAZINE z September 2021
10,000
[14]
Si Limit
[8]
[10]
[9] GaN Limit
SiC Limit
[11]
[15]
an advanced switching matrix with new
devices that exhibit low switching losses,
high operation frequency, and enhanced
temperature/voltage tolerances that are
no longer supported by the traditional Sibased
devices [3]. In the last decade, wide
bandgap (WBG) semiconductors, such as
silicon carbide (SiC) and gallium nitride
(GaN) have attracted lots of attention for
their superior electrical characteristics.
Table I compares the main characteristics
of typical Si, GaN, and SiC devices [4]. The
WBG feature results in lower intrinsic carrier
concentration that reduces junction
leakage current even at temperature as
high as 500 °C and possesses higher breakdown
voltage to enhance the reliability
required for applications in harsh environments.
Meanwhile, as shown in Figure 2,
compared with high-voltage (HV) MOSFETs
[6], [7], GaN HEMTs [12], [13] have
lower on-resistance, smaller input capacitance
and output capacitance under the
same voltage rating. These properties lead
to much lower switching and conduction
losses that increase the system conversion
efficiency.
Recently, researchers have demonstrated
several prototypes using GaN and SiC
devices as switching matrices in power
conversion applications. In [16], Y.-F. Wu
et. al. reported a kW-class GaN-based
dc-dc boost converter with 99% conversion
Specific Ron (mΩ . cm2)
IEEE Power Electronics Magazine - September 2021

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