Analyses and Simulation of Three-Phase MLI with High Value of Resolution per Switch Employing SVM Control Scheme Md.Mubashwar Hasan Mahrous Ahmed Saad Mekhilef Department of Electrical Engineering Aswan Faculty of Engineering Department of Electrical Engineering University of Malaya Aswan university University of Malaya 50603 Kuala Lumpur, Malaysia Egypt 50603 Kuala Lumpur, Malaysia mubashwar_hasan@yahoo.com eahmed7@ieee.org saad@um.edu.my Abstract— This paper proposes a three-phase voltage source inverter employing space vector modulation control scheme. The proposed inverter is a modular type that can increase its level by adding more cells to each arm. The phase ‘a’ arm consists of ‘m’ cells and each cell consists of single isolated dc source with two switches. Switches are connected in such a way that one switch is in series with the isolated capacitor and the second switch is connected in parallel with the series dc source and the series switch. In order to increase the resolution of the proposed inverter, isolated dc source voltages with different values are used in such a way that the dc source voltage of a cell equals half of the next cell dc source voltage (V dc , 2V dc , 4V dc , …). A space vector modulation control technique is employed to generate the different output voltages. The proposed inverter is suitable for renewable energy applications, where many batteries with different values can be available. Analyses and simulation have been executed to validate the the proposed inverter. The proposed inverter has been compared with the existence latest counterpart inverter under the conditions of identical supply dc voltage and switching frequency. Some selected simulation results have been provided for validation. Index Terms —Multi-Level Inverter, space vector modulation, inverter resolution, THD. I. INTRODUCTION Multi-Level Inverters (MLI) began with the neutral point clamped inverter topology proposed by Nabae et al. [1]. Recently, multilevel inverters have become more attractive for researchers due to their advantages over conventional three- level pulse width-modulated (PWM) inverters. MLI has two main advantages compared with the conventional H-bridge inverters [2-4], the higher voltage capability and reduced the harmonic content of the output waveform due to the multiple dc levels. MLI is now preferred in high power medium voltage applications due to the reduced voltage stresses (dv/dt) on the devices. MLI incorporates a topological structure that allows a desired output voltage to be synthesized among a set of isolated or interconnected distinct voltage sources. Numerous topologies realize this connectivity, and can be generally divided into three major categories, namely, diode clamped MLI, flying capacitor MLI and separated dc sources (cascaded voltages) MLI Increasing level numbers of MLI with decreasing its power electronic devices is a vital issue for researchers. As a result of that, not only its output waveform performance can be improved, but also the complexity of its layout, which is a big challenge, can be decreased. Therefore the definition of the ratio of the level number per switch (RLS) has been emerged recently to figure out the trade-off between increasing MLI levels and decreasing its power electronic devices used. Many research papers were trying to use different techniques to increase the RLS which can be found in the literature. Each system has some advantages and disadvantages based on the control method techniques. These systems and their performances can be summarized in the following sections. The first systems are using the conventional three-phase-three- level inverter [5] – [7]. In these systems, the conventional selective harmonic elimination controls (SHE) and space vector PWM (SVPWM) techniques are used to drive the induction motor load. These systems suffer from the harmonic components injected in the machines and it is suitable only for certain value of power level rating based on the electronic devices ratings. Another systems use dual three-phase three-level inverters [8]- [12]. Some of these system [10] – [11] are used for one opening end of the load (IM) to validate a second emergency path for the power to be used and thus these system are more robust especially in case of any of the inverter faced malfunction problem, while the second inverter can be used alone. From the point of view of performances, both of these systems are used to increase the power level and to decrease the harmonic contents injected to the load. As a result of that five-level inverter waveform can be generated which is still do not meet the requirements for the new era of the high performance IM. In another word, five-level waveforms are not so improved compared with the three-level waveforms. In addition, a low value for RLS got (5/12) [8] – [11] or (9/24) as in [12]. The other MLI [13] – [15] are using cascaded or customizing cells to build the system. They are attaining high performance 2012 IEEE International Conference on Power and Energy (PECon), 2-5 December 2012, Kota Kinabalu Sabah, Malaysia 978-1-4673-5019-8/12/$31.00 ©2012 IEEE 7