Space Vectors Modulation for Nine Switch Inverter

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IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 25, NO. 6, JUNE 2010

Space Vectors Modulation for
Nine-Switch Converters
Seyed Mohammad Dehghan Dehnavi, Student Member, IEEE, Mustafa Mohamadian, Member, IEEE, Ali Yazdian, Member, IEEE, and Farhad Ashrafzadeh, Senior Member, IEEE

Abstract—Recently, nine-switch inverter and nine-switch-zsource inverter have been proposed as dual output inverters. In this paper, the space vector modulation (SVM) of nine-switch inverter and nine-switch-z-source inverter is proposed. The proposed method increases the sum of modulation indices up to 15% in contrast with the conventional, scheme in which the sum of modulation indices is equal or less than one. The extra voltage available for a given input dc-voltage, translates to a higher torque—a critical factor for defining the capacity of products in marketplace. Also, in order to further reduce the cost of power devices and also thermal heat effect, and to reduce the number of semiconductor switching, specific SVM switching pattern is presented. This feature will be advantageous for high-power inverter applications where cost and efficiency are key decision factors. Furthermore, a novel SVM is proposed for minimizing total harmonic distortion. The performance of the proposed SVM for both nine-switch inverter and nine-switch-z-source inverter is verified by simulation. Experimental results validate the simulation results as well as the superiority of the proposed SVM.

Fig. 1.

Nine-switch inverter.

Fig. 2.

Nine-switch-z-source inverter.

Index Terms—Nine-switch inverter, nine-switch-z-source inverter, space vector modulation (SVM).

I. INTRODUCTION
NVERTERS are used as dc/ac converter and power controller
for ac load such as motor drivers. In many cases, there are
two or more ac loads, which require independent control. The conventional solution is to use separate inverters. This increases cost and volume of system. A dual output inverter has been
presented in [1] using only nine semiconductor switches (see Fig. 1). This inverter is known as nine-switch inverter and is also used as an ac/ac converter in [2] and [3]. The nine-switch inverter is composed of two conventional inverters with three common

switches. In nine-switch inverter, sum of modulation index of two outputs must be less than or equal to one. Therefore, voltage amplitude of outputs is smaller, compared with two separate
inverters [4]. To remedy this problem, this paper proposes using an impedance source (z-source) network in front of nine-switch inverter as a dc/dc boost converter (see Fig. 2). Z-source network was used as front-end boost converter for a conventional inverter in [5], for the first time. This inverter was called z-source inverter and has been proposed for fuel cell, photovoltaic, and wind

I

Manuscript received April 21, 2009; revised July 25, 2009 and August 30, 2009. Current version published June 3, 2010. Recommended for publication by Associate Editor J. R. Rodriguez.
S. M. Dehghan Dehnavi, M. Mohamadian, and A. Yazdian are with the Department of Electrical and Computer Engineering, Tarbiat Modares University, Tehran 14115-143, Iran (e-mail: dehghansm@modares.ac.ir; mohamadian@modares.ac.ir; yazdian@modares.ac.ir).

F. Ashrafzadeh is with the Research and Engineering Center, Whirlpool Corporation, Benton Harbor, MI 49022 USA (e-mail: Farhad.Ashrafzadeh@ ieee.org).
Digital Object Identifier 10.1109/TPEL.2009.2037001

turbine systems [6]–[8]. The z-source network also was used in other converters such as three-level inverters [9], [10].
In [1], carrier-based pulsewidth modulation (PWM) methods
have been proposed for nine-switch inverter. This paper proposes space vector modulation (SVM) methods for the aforementioned nine-switch and nine-switch-z-source inverters. In order to reduce number of semiconductor switching and total

distortion harmonic (THD), some specific switching patterns for SVM are proposed.
This paper is...
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