42 30 nA Comparative Study of Power Semiconductor Devices for Industrial PWM Invertersov16 14nov 1oct 13339 anna g (edit ndit)

International Journal of Power Electronics and Drive System (IJPEDS)
Vol. 7, No. 4, December 2016, pp. 1420~1428
ISSN: 2088-8694, DOI: 10.11591/ijpeds.v7i4.pp1420-1428  1420
Journal homepage: http://iaesjournal.com/online/index.php/IJPEDS
A Comparative Study of Power Semiconductor Devices for
Industrial PWM Inverters
Gianluca Sena1
, Roberto Marani2
, Gennaro Gelao3
, Anna Gina Perri4
1,3,4
Electronic Devices Laboratory, Department of Electrical and Information Engineering,
Polytechnic University of Bari, Italy
2
Consiglio Nazionale delle Ricerche, Istituto di Studi sui Sistemi Intelligenti per l'Automazione (ISSIA), Bari, Italy
Article Info ABSTRACT
Article history:
Received Apr 30, 2016
Revised Dec 1, 2016
Accepted Dec 14, 2016
The growing demand of energy translates into efficiency requirements of
energy conversion systems and electric drives. Both these systems are based
on Pulse Width Modulation (PWM) Inverter. In this paper we firstly present
the state of art of the main types of semiconductors devices for Industrial
PWM Inverter. In particular we examine the last generations of Silicon
Carbide (SiC) MOSFETs and Insulated Gate Bipolar Transistors (IGBTs)
and we present a comparison between these devices, obtained by SPICE
simulations, both for static characteristics at different temperatures and for
dynamic ones at different gate resistance, in order to identify the one which
makes the PWM inverter more efficient.
Keyword:
IGBTs
Power semiconductor devices
PWM Inverter
SiC MOSFETs
SPICE simulation Copyright © 2016 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Anna Gina Perri,
Department of Electrical and Information Engineering,
Polytechnic University of Bari,
Via E. Orabona, 4, 70125 Bari, Italy.
Email: annagina.perri@poliba.it
1. INTRODUCTION
New global energy needs have led to changes in the industrial environments. Pollution restrictions,
costs reductions and the rising demand for energy have been translated into efficiency requirements of the
energy conversion systems and of the electrical drives. Both these systems are based on Pulse Width
Modulation (PWM) Inverter [1]
PWM technique modifies timing of a pulse train in direct proportion to the voltage of control signal,
whose information is transferred to the width of the pulses, in particular the magnitude and frequency of the
fundamental component of the pulse train are controlled by the control signal. Low pass filtering a PWM
waveform extracts the fundamental component and produces an output voltage proportional to the control
signal [2]. Depending on how the pulse train is modified, it determines the specific type of the modulation.
Two of the main kinds of PWM used in power electronics applications are Sinusoidal PWM (SPWM)
and Space Vector PWM (SVPWM).
In SPWM a sine wave is used as control signal and it is compared with a reference triangular wave.
When the voltage of the triangle wave is greater than the voltage of the input signal, the output of the
comparator reaches the low level; otherwise, when the voltage of the input signal is greater than the voltage
of the triangle wave, the output of the comparator is high. This method is the simplest PWM: it produces an
output square wave whose fundamental component has the same frequency and magnitude proportional to
the input voltage but, because of its simplicity, it has some drawbacks (for example poor quality of the
output voltage, weak modulation ability on active and reactive power, higher THD) [3-4].

IJPEDS ISSN: 2088-8694 
A Comparative Study of Power Semiconductor Devices for Industrial PWM Inverters (Anna Gina Perri)
1421
SVPWM are similar to the SPWM but the voltage reference is provided using a phasor. In this case
magnitude and frequency of the fundamental component are controlled by the magnitude and frequency of
the control vector. This modulation utilizes DC bus voltage more efficiently and generates less harmonic
distortion in a three phase voltage source inverter (VSI) [2].
PWM Inverter is a power electronic DC/AC converter. In industrial applications this AC power is a
three-phases AC power. The input DC voltage is obtained from the electrical grid through (active or passive)
rectification, or from a DC supply e.g. storage battery or photovoltaic panel. The conversion of DC power to
three-phase AC power is performed in the switched mode with Pulse-Width Modulation [5]. In particular
three-phase two-levels PWM inverter can be realized using six switches, which are six power semiconductor
devices driven by low voltage PWM signals that make temporary connections at high repetition rates
between the two DC terminals and the three phases of the AC device, usually a motor, connected to the
output of the inverter. The desired value of the AC currents is achieved by the six PWM signals.
To improve the energy requirements, we need to make the PWM inverter more efficient. There are
many types of techniques to achieve that. Soft switching techniques, different topologies of inverters and
many kinds of control algorithms are constantly subject matter of research. Last but not least, also the power
semiconductors switches are constantly evolving because they represent the primary causes of energy
dissipation: improving these devices means reducing thermal heating or the reactive losses [6].
In this paper, at first the state of art of the main types of semiconductors devices for Industrial PWM
Inverters is presented. In particular we examine the last generations of Silicon Carbide (SiC) MOSFETs and
Insulated Gate Bipolar Transistors (IGBTs) and we present a comparison between these devices, obtained by
SPICE simulations, both for static characteristics at different temperatures and for dynamic characteristics at
different gate resistance, in order to identify the device which makes the PWM inverter more efficient.
2. 4H–SiC STEP TRENCH GATE POWER MOSFET
2.1. An introduction about Power MOSFET and Trench Gate Structure
In a traditional n-channel MOSFET, lateral MOSFET, the saturation drain current, IDsat, is given by
the following equation [7-8]:
 2
TGSoxnsatD VV
L2
W
CI 
where n is the electron mobility, Cox is the oxide capacitance, W and L are the width and the channel length
respectively, VGS is the gate-source voltage and VT is the threshold voltage. Therefore, to increase the
MOSFET currents, we need to made W large and L small. On the other hand, reducing L, we have a
reduction of the breakdown voltage. When the body-to-drain junction is reverse polarized, the depletion
region spreads into short channel, resulting in breakdown at relatively low voltage. This effect limits the
lateral MOSFET in high voltage applications [9]. Planar MOSFET (Figure 1a), also known as DMOSFET
(double diffused), has been developed to obtain short channel.
Figure 1. DMOSFET (a) and Trench Gate MOSFET (b) with RDS components (from [10])
The channel is formed on the surface by the double-diffusion process and the relative diffusion
depth of the P body and N+ source regions control the channel length [11]. The current flows vertically, from
drain to source, crossing N drift region. Due to the two adjacent P body wells, the current was affected by the
JFET-effect when flows in N- drift region [10]. In the trench-gate structure (Figure 1b) the gate is etched

 ISSN: 2088-8694
IJPEDS Vol. 7, No. 4, December 2016 : 1420 – 1428
1422
vertically along the device and the channel is formed on the vertical sidewalls of the trench and the JFET
resistance is reduced drastically [10-11].
2.2. The Silicon Carbide and the newest SiC Power MOSFET
The Silicon Carbide (SiC), as Silicon (Si), is a semiconductor material but, compared with the latter,
offers: a lower intrinsic carrier concentration (9–18 orders of magnitude), a higher electric breakdown field
(4–8 times) that allows a ten times reduction in drift layer thickness, a higher thermal conductivity that allows
high temperature operation up to 350°C, a larger saturated electron drift velocity that allows the increasing of
the switching frequency. Due to difficulty with material processing and presence of crystal defects, silicon
carbide has been adopted for power devices only in the last years after the improvement of the fabrication
processes. Only the 6H– and 4H–SiC poly-types are available commercially but 4H–SiC is preferred in
power devices fabrication because of its high carrier mobility and its low dopant ionization energy [12].
The new generation of SiC Power MOSFET presented in [13] is developed with 4H-SiC because
this material has 10X higher breakdown strength when compared to silicon, leading to realize a 10kV
devices. With SiC technology RDS, total current per die and switching losses per chip are improved.
Furthermore, trench gate technology allows better performance in matter of conduction losses.
3. 7th
GENERATION TRENCH GATE PUNCH THROUGH IGBT
3.1. An introduction about IGBT and Punch-Trough Technology
An IGBT combines the advantages of MOSFETs and BJTs. MOSFETs have high switching
frequency and are voltage controlled but their internal resistance grows with the maximum applicable
voltage. BJTs instead, have a low voltage drop but requires a current as input control signal. IGBT is a
voltage-controlled device, it has a low voltage drop and it is fast for switching operations. If we analyse a
traditional IGBT we can see that its structures are similar to that of vertical MOSFET (DMOS) where N+
interface is replaced by P+ substrate (Figure 2) [14].
Figure 2. Power MOSFET(left) IGBT (right) (from [15])
This configuration is also called Not Punch Trough (NPT), shown in Figure 3.
Figure 3. NPT (left) and PT (right) IGBT (from [13])

1423
A NPT IGBT presents two main drawbacks for switching applications: it has equal forward
and reverse breakdown voltages and presents a long tail current (due to the storage charge in N-drift region).
To solve these problems, Punch Trough (PT) technology has been developed. PT structure is obtained adding
a N+ substrate in NPT IGBT between P+ substrate and N– drift region. The new N+ region is a buffer layer
that makes the P+N– diode like a PIN type diode: the carrier lifetime is reduced (consequently the tail current
is reduced) and it provides a reverse breakdown voltage greater than the forward breakdown voltage despite
the increase of voltage drop during the ON-state [14] [15].
3.2. The Newest generation of IGBT
The 7th generation of IGBT, as described in [16], is shown in Figure 4 and represents the newest
generation of Trench Gate Punch Through IGBT.
Figure 4. Cross-sections of the 6th generation IGBT (left) and the 7th generation IGBT (right) (from [16]).
Compared to previous trench generation, the electrical characteristics have been improved, the die
size has been reduced and higher efficiency was achieved. This technology leads to a new generation of
highly compact and efficient power conversion systems.
The drift layer thickness is reduced compared to the 6th generation achieving a lower on-state
voltage drop and a reduction of the miller capacitor. Additionally, the trade-off relationship between on-state
voltage drop and turn-off losses is improved by optimization of the surface structure. The Field Stop layer
have been optimized, realizing the suppression of voltage oscillations and improving the breakdown voltage
capability. The reduction of the drift layer has led to the reducing of the forward voltage of the 7th generation
diode. By optimization of the local lifetime control, the 7th generation diode realized a softer switching
waveform, contributing to reduction of the reverse recovery losses [16].
4. SiC-BASED MOSFET VS Si-BASED IGBT: ANALYSIS OF RESULTS
In this section we present a comparative evaluation, through static and dynamic results, obtained for
SiC-MOSFET (ST STGW15H120DF2 [17]) and Si-IGBT (ST SCT20N120 [18]) with the same 1200 V
voltage rating and similar current rating, 15 A of IGBT and 20 A of MOSFET. Both power devices have an
intrinsic recovery antiparallel diode. To characterize the switching performance of the devices, a real test-bed
is simulated using values estimated in [19-20]. The equivalent test circuit is shown in Figure 5. A 100 uH
inductor is used as test load with 20 pF equivalent parallel capacitance and 3 mΩ equivalent series resistance.
4.1. Static Characterization
Figure 6 shows the transfer characteristics at various VCE/VDS using 10 Ω gate resistance at the
junction temperature of 125 °C. Solid lines with square symbols show IGBT characteristics (IC vs VGE)
and dashed lines with “x” symbols show MOSFET characteristics (ID vs VGS). Figure 7 shows the output
characteristics at various gate bias using 10 Ω gate resistance at the junction temperature of 125 °C. Solid

 ISSN: 2088-8694
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lines with square symbols show IGBT characteristics (IC vs VCE) and dashed lines with “x” symbols show
MOSFET characteristics (ID vs VDS).
Figure 6. Transfer characteristics Figure 7. Output characteristics
Figure 5. Test Circuit
4.2. Dynamic Characterization
The dynamic characteristics of the simulated IGBT are shown in Figures 8 and 9. In particular in
Figure 8 we have highlighted the turn-on behaviour, while in Figure 9 the turn-off behaviour is highlighted.
Top graphs present the driving voltage as dashed line and VGE as solid line. In middle graphs collector
current is shown and bottom graphs present the VCE. The driving pulse had 2 µs pulse and a 4 µs period at the
junction temperature of 125 °C.
Similarly the dynamic characteristics of the simulated MOSFET are shown in Figures 10 and 11. In
particular Figure 10 shows the turn-on behaviour, while in Figure 11 the turn-off behaviour is highlighted.

1425
Top graphs presents the driving voltage as dashed line and VGS as solid line. In middle graphs drain current is
shown and bottom graphs present the VDS. The driving pulse had 2 µs pulse and a 4 µs period at the junction
temperature of 125°C.
Figure 8. IGBT turn on. Figure 9. IGBT turn off.
Figure 10. MOSFET turn on Figure 11. MOSFET turn off
Figure 12 compares IGBT (a) and MOSFET (b) turn-on dynamics at various gate resistances. On the
top the current is shown, on the bottom the VGE/VGS. Solid lines are referred to RG = 5 Ω, dashed lines are
referred to RG = 10 Ω and dotted lines are referred to RG = 20 Ω. The higher the gate resistance, the
smoother the characteristics but turn-on time increases.
Figure 13 compares IGBT (a) and MOSFET (b) turn-off dynamics at various gate resistance. On the
top the current is shown, on the bottom the VGE/VGS. Solid lines are referred to RG = 5 Ω, dashed lines are
referred to RG = 10 Ω and dotted lines are referred to RG = 20 Ω. As in turn-on dynamics, the higher the
gate resistance, the smoother the characteristics but turn-off time increases.

 ISSN: 2088-8694
1426
(a) (b)
Figure 12. Turn-on comparison
(a) (b)
Figure 13. Turn-off comparison.
Finally, the energy losses as a function of gate resistance are shown in Figure 14.
Figure 14. Switching Losses

1427
5. CONCLUSION
In this paper, after a brief examination of the main types of semiconductors devices for Industrial
PWM Inverters, we have examined the last generations of Silicon Carbide (SiC) MOSFETs and Insulated
Gate Bipolar Transistors (IGBTs). SPICE simulations for static characteristics have been evaluated at
different temperatures while dynamic ones have been performed at different gate resistance, in order to
identify the device which makes the PWM inverter more efficient. Contrary to Si-IGBTs, no tail current was
noticed for SiC-MOSFET leading to high switching capabilities for these devices. The SiC MOSFET showed
superior performance in terms of switching as well as conduction loss but ringing effect may cause some
problems.
REFERENCES
[1] T. Fujihira, et al., “The State-of-The-Art and Future Trend of Power Semiconductor Devices”, Proceedings of
PCIM Europe 2015, pp. 27-34, Nuremberg, Germany, 19 - 21 May 2015.
[2] K.V. Kumar, et al., “Simulation and comparison of SPWM and SVPWM control for three phase inverter”, ARPN
Journal of Engineering and Applied Sciences, vol. 5, no. 7, pp. 62-74, 2010.
[3] J. Caldwell, “Analog Pulse Width Modulation (SLAU508),” Texas Instruments, 2013.
[4] Z. Ibrahim, “Simulation Investigation of SPWM, THIPWM and SVPWM Techniques for Three Phase Voltage
Source Inverter”, International Journal of Power Electronics and Drive System (IJPEDS), vol. 4, pp. 223-232,
2014.
[5] J. Holtz, “Pulse Width Modulation for Electronic Power Conversion”, Proceedings of IEEE, vol. 82, no. 8, pp.
1194-1214, 1994.
[6] B. Cao and L. Chang, “A Variable Switching Frequency Algorithm to Improve the Total Efficiency of Single-Phase
Grid-Connected Inverters”, Applied Power Electronics Conference and Exposition (APEC), 2013 Twenty-Eighth
Annual IEEE, pp. 2310-1315, 2013.
[7] A.G. Perri, “Fondamenti di Dispositivi Elettronici”, Ed. Progedit, Bari, Italy, ISBN 978-88-6194-080-2, 2016.
[8] A.G. Perri, “Dispositivi Elettronici Avanzati”, Ed. Progedit, Bari, Italy, ISBN 978-88-6194-081-9, 2016.
[9] R. Vaid and N. Padha, “Comparative Study of Power MOSFET device structures”, Indian Journal of Pure &
Applied Physics, vol. 43, pp. 980-988, 2005.
[10] “Power MOSFET Basics”, ALPHA & OMEGA Semiconductor, http://www.aosmd.com/products, 2016.
[11] A. Sattar, “IXYS Power MOSFET Products (IXAN0062)”, IXYS Corporation, http://ixdev.ixys.com.
[12] A. Elasser and T.P. Chow, “Silicon Carbide Benefits and Advantages for Power Electronics Circuits and Systems”,
Proceedings of the IEEE, vol. 90, no. 6, pp. 969-986, 2002.
[13] J.B. Casady, et al., “New Generation 10 kV SiC Power MOSFET and Diodes for Industrial Applications”,
Proceedings of PCIM Europe 2015, Nuremberg, Germany, 19 - 21 May 2015.
[14] A. Sattar, “Insulated Gate Bipolar Transistor (IGBT) Basics (IXAN0063)”, IXYS Corporation,
http://ixdev.ixys.com.
[15] “IGBT Fundamentals”, SIEMENS Semiconductor Group.
[16] T. Heinzel, et al., “The New High Power Density 7th Generation IGBT Module for Compact Power Conversion
Systems”, Proceedings of PCIM Europe 2015, pp. 1-9, Nuremberg, Germany, 19 - 21 May 2015.
[17] “STGW15H120DF2 Datasheet (DocID023751 Rev 5)”, ST Microelectronics, 2015.
[18] “SCT20N120 Datasheet (DocID026413 Rev 4)”, ST Microelectronics, 2015.
[19] K. Peng, et al., “Characterization and Modeling of SiC MOSFET Body Diode”, 2016 IEEE Applied Power
Electronics Conference and Exposition (APEC), pp. 2127-2135, 2016.
[20] M. Nawaz and K. Ilves, “On the comparative assessment of 1.7 kV, 300 A full SiC-MOSFET and Si-IGBT power
modules”, 2016 IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 276-282, 2016.
BIOGRAPHIES OF AUTHORS
Gianluca Sena received the B. S. degree in information engineering, curriculum electronics, from
Università del Salento, Lecce (Italy), in 2011. He worked from 2012 to 2015 in Power
Electronics R&D Group of Energy Factory Bari, an integrated multidisciplinary laboratory for
research activities in aerospace and energy fields. Actually he is a student of M. S. course of
electronics engineering of Polytechnic University of Bari (Italy) and he works in the Electronic
Device Laboratory of Bari Polytechnic for the design and realization of energy conversion
systems.

 ISSN: 2088-8694
1428
Roberto Marani received the Master of Science degree cum laude in Electronic Engineering
from Polytechnic University of Bari, where he received his Ph.D. degree in Electronic
Engineering. He worked in the Electronic Device Laboratory of Bari Polytechnic for the design,
realization and testing of nanoelectronic systems. Moreover he worked in the field of design,
modelling and experimental characterization of devices and systems for biomedical applications.
Currently Dr. Marani is a Reseacher of the National Research Council of Italy (CNR), at the
Institute of Intelligent Systems for Automation (Bari). He has published over 160 book chapters,
journal articles and conference papers and serves as referee for many international journals.
Gennaro Gelao received the Laurea degree in Physics from University of Bari, Italy, in 1993 and
his Ph.D. degree in Physics in 1996, with a thesis based on a CERN experiment. He worked at
ENEA in a high precision electrical calibration Laboratory. From 2004 Dr. Gelao cooperates
with the Electronic Device Laboratory of Polytechnic University of Bari for the design and
modeling of nanometrical electronic systems, quantum devices and CNTFETs. Actually he also
works in the design and realization of energy conversion systems. Dr. Gelao has published over
80 papers.
Anna Gina Perri is Full Professor of Electronics at Polytechnic University of Bari, Italy.
In 2004 she was awarded the “Attestato di Merito” by ASSIPE (ASSociazione Italiana per la
Progettazione Elettronica), Milano, BIAS’04, for her studies on electronic systems for
domiciliary teleassistance. Her current research activities are in the design of nanoelectronic
systems, FET on carbon nanotube and in the field of experimental characterization of electronic
devices for energy conversion systems. Prof. Perri is the Head of the Electron Devices
Laboratory of the Polytechnic University of Bari, and is author of over 250 journal articles,
conference presentations, twelve books and currently serves as a Referee of a number of
international journals. Prof. Perri is the holder of two italian patents and the Editor of three
international books.

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