4-076

平成 23 年電気学会全国大会

Multilevel Inverter Using H-Bridge and Two-Level Power Modules
Suroso (University of Jenderal Soedirman), and Toshihiko Noguchi (Shizuoka University)
1. Introduction
Multilevel inverters have capability to deliver a multilevel
AC waveform with low-rating devices, lower dv/dt or low di/dt,
and a less-distorted output waveform resulting in reduction ofharmonic losses, reduction of EMI noise and reduction of theoutput filter size [1], [2]. This paper presents a different topologyof the multilevel voltage-source inverter obtained from an
H-bridge inverter and two-level power modules. In the proposed
topology, all of the DC power sources are connected in series,
which has possibility of using non isolated DC voltage sources.
The minimum number of the power devices and its modular
structure are other features of the proposed topology. The
proposed topology is tested and verified through computer
simulations using a PSIM software and experimental tests. The
computer simulation and experimental test results showed thatthe proposed topology works properly to synthesize a multilevel
output waveform.

The number of the capacitors or DC voltage sources C is:(3)C = N +1.
A five-level inverter circuit needs a single power module and an
H-bridge inverter with only six power devices in total, as shownin Fig. 3. If the DC voltage sources of the five-level inverter are
assumed to be the same as V/2, Table 1 lists the switching statesof the proposed five-level inverter for five-level output voltage
waveform generation, i.e. +V, +V/2, 0, -V/2 and –V.

Fig.1. Two-level power module and its output waveform.

2. Circuit Configuration
Reference [3] presented a configuration of the multilevel
inverter achieved by using series-connected sub-multilevel
converter blocks with bidirectional power switches and an
H-bridge inverter. Reference [4] proposed another multilevel
inverter using an H-bridge inverter with auxiliary bidirectional
power switches. However, in practical manner, the use ofbidirectional power switches can be a main drawback.
Bidirectional switches obtained by using two IGBTs or a
combination of a single IGBT and four power diodes increase
power losses of the inverter. Reference [5] presented another new
configuration of the multilevel inverter from several two-level
power cells. The need of isolated DC sources and a large numberof power switches in this topology increase its cost andcomplexity of the inverter in case isolated rectifier circuits areused. Reference [6] presented a new symmetrical hybrid
multilevel inverter using three-level cells and an H-bridge
inverter. Eight power switches are required to construct even a
five-level inverter.
In this paper, a different configuration of the multilevel
inverter using an H-bridge inverter and two-level power modules
are presented. Fig. 1 shows the configuration of a basic two-level
power module and its output waveform. The proposed multilevel
inverter is obtained by connecting some two-level power
modules and an H-bridge inverter as shown in Fig. 2. The DC
voltage sources are connected in series, which makes it possible
to use non isolated DC voltage sources. In addition to thisadvantage, all of the power switches are a single IGBT or power
MOSFET, which is not a bidirectional switch. If N sets oftwo-level power modules are connected to the H-bridge inverter,
the level number the output voltage waveform M can be
expressed as:(1)
M = 3 + 2N .
The number of the power switches P is:(2)P = 4 + 2N .

2011/3/16～18-140大阪( 第 4 分冊 )Fig. 2. General topology of M-level inverter.

Fig. 3. Proposed five-level inverter.
Table 1. Switching states of proposed five-level inverter.
Q1

Q2

Q3

Q4

Q5

Q6

10

10

10

Output
+V

10

1001

+V/2

00

1

10000

10

10

1

-V/2

0

10

1

10-V

©2011 IEE Japan

4-076

平成 23 年電気学会全国大会

Fig. 4. Multi-carrier based sinusoidal PWM.

3. Simulation and Experimental Test Results
The five-level inverter circuit shown in Fig. 3 is connected toan inductive load, i.e. R = 20 Ω, L = 5 mH. The switching andthe output voltage frequencies are 22 kHz and 60 Hz,respectively. The amplitude of the DC voltage sources V1 and V2
are equally 50 V. A triangular level-shifted carrier basedsinusoidal pulse width modulation (PWM) strategy is used togenerate the gating signals of the power switches and to obtain alower distortion of the output waveforms as shown in Fig. 4. Fig.
5 shows a computer simulation result of the five-level inverter
circuit. A proper five-level output waveform was generated byusing the proposed strategy. A sinusoidal current also flows
through the load without remarkable ripples. Furthermore, Fig. 6
shows the experimental waveforms of the five-level inverter
showing a load voltage and a load current when the modulationindex is 0.94. The voltages across the drain-source of the powerswitches Q5 and Q6 are also presented, of which the amplitudes
are half of the five-level output voltage waveform.

Fig. 5. Simulation result waveforms.

4. Conclusions
In this paper a new topology of the multilevel voltage-source
inverter has been introduced. The proposed inverter uses a
combination of two-level power modules and an H-bridge
inverter for multilevel voltage waveform generation with theminimum number of power devices. Computer simulation andexperimental test results of the single-phase five-level inverter
prototype have proven feasibility of the proposed approach.
References
[1]

[2]

[3]

[4]

[5]

[6]

M. Malinowski, K. Gopakumar, J. Rodriguez, and M. A. Pérez, “Asurvey on cascaded multilevel inverters”, IEEE Trans. On
Industrial Electronics, vol. 57, no. 7, p.p. 2197-2206, July 2010.
J. Rodiguez, J. S. Lai, and F. Z. Peng, “Multilevel inverter: a surveyof topologies, controls, and application,” IEEE Trans. on IndustrialElectronics,” vol. 49, no. 4, p.p. 724-738, August 2002.
E. Babaei, “A cascade multilevel converter topology with reduced
number of switches”, IEEE Trans. on Power Electronics, vol. 23.
no. 6, p.p. 2657-2664, November 2008.
G. Ceglia, V. Guzman, C. Sanchez, F. Ibanez, J. Walter and M. I.
Gimenez “A new simplified multilevel inverter topology forDC-AC conversion”, IEEE Trans. On Power Electronics, vol. 21.
no. 5, p.p. 1311-1319, September 2006.
G. Waltrich and I. Barbi, “Three-phase cascaded multilevel inverter
using power cells with two inverter legs in series,” IEEE Trans. On
Industrial Electronics, vol. 57, no. 8, p.p. 2605-2612, August 2010.
D. Ruiz-Caballero, R. Sanhueza, H. Vergara, M. Lopez, M. L.
Heldwein and S. A. Mussa, “Cascaded symmetrical hybrid
multilevel DC-AC converter”, in Proc. of ECCE2010, p.p.
4012-4019.
Fig. 6. Experimental test result waveforms.

2011/3/16～18-141大阪( 第 4 分冊 )©2011 IEE Japan