A. Suresh Kumar, G. Mahanandeswara Gowd / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 4, Jul-Aug 2013, pp.2162-2167 2162 | P a g e Simple Boost Control of Five-Level Z-Source Diode-Clamped Inverter by Multi-Carrier PWM Methods A. Suresh Kumar 1 , G. Mahanandeswara Gowd 2 1 Electrical Engineering Department 2 RGM College of Engineering, Nandyal, India Abstract In recent years, multilevel inverters have drawn significant attention in research and high power applications such as AC Transmission systems (FACTS), renewable energy resources, power quality devices, etc. Such power converters have been the prime focus of power electronic researches in order to improve their performance, reliability and energy efficient at minimum cost. Among several reported topologies, diode-clamped multilevel inverter is very used. To control these multilevel inverters several carrier –based PWM strategies have been reported. Traditional inverters are known to produce an output voltage that is lower than the DC source voltage. In order to reach boosted voltage with available switching devices Z- source inverters were invented. Multilevel Z-source inverters have been proposed as a solution for HV applications. This type of inverters decreases the Total Harmonic Distortion (THD) and has a good performance for different applications such as Flexible AC Transmission systems, power quality improvement and connecting renewable energy resources to the network. This paper compares several alternative carrier disposition PWM strategies (Phase Disposition (PD) method, Alternative Phase Opposition Disposition (APOD) method) for a five level Z-source diode–clamped inverter. These strategies are simulated in MATLAB/Simulink.The simulation results will illustrate the performance of Phase Disposition (PD) method, Alternative Phase Opposition Disposition (APOD) method. Keywords- Multicarrier PWM strategies, multilevel inverter, DC-Sources, Z-Source inverter. I. INTRODUCTION There exist two traditional converters: voltage source (VSI) and current source (CSI) [1]. Fig.1 shows the traditional single-phase voltage- source converter (abbreviated as V-Source converter) structure. A dc voltage source supported by a relatively large capacitor feeds the main converter circuit, to a single-phase circuit. The dc voltage source can be a battery, fuel-cell stack, diode rectifier, and/or capacitor. Four switches are used in the main circuit; each is traditionally composed of a power transistor and an antiparallel (or freewheeling) diode to provide bidirectional current flow and unidirectional Voltage blocking capability. The V-source converter is widely used. Fig. 1. Traditional V-source converter It has the following conceptual and theoretical barriers.  The AC output voltage is limited below and cannot exceed the DC input voltage.  External equipment is needed to boost up the voltage, which increases the cost and lowers the overall system efficiency.  There is a possibility for the occurrence of short Through which destroys the device. II. Z-SOURCE INVERTER The main objective of static power converters is to produce an AC output waveform from a dc power supply. Impedance source inverter is an inverter which employs a unique impedance network coupled with the inverter main circuit to the power source. This inverter has unique features in terms of voltage (both buck & boost) compared with the traditional inverters. A two port network that consists of a split-inductor and capacitors that are connected in X shape is employed to provide an impedance source (Z-source) coupling the inverter to the dc source, or another converter. The DC source/load can be either a voltage or a current source/load. Therefore, the DC source can be a battery, diode rectifier, thyristor converter, fuel cell, PV cell, an inductor, a capacitor, or a combination of those [1].