Youssef Ounejjar

Bio: Youssef Ounejjar is an academic researcher from École Normale Supérieure. The author has contributed to research in topics: Capacitor & Inverter. The author has an hindex of 13, co-authored 31 publications receiving 884 citations. Previous affiliations of Youssef Ounejjar include École de technologie supérieure & University College of Engineering.

Packed U Cells Multilevel Converter Topology: Theoretical Study and Experimental Validation

Abstract: In this paper, authors propose a new power multilevel converter topology that is very competitive compared to the existing ones. It consists of packed U cells (PUC). Each U cell consists of an arrangement of two power switches and one capacitor. It offers high-energy conversion quality using a small number of capacitors and power devices and consequently, has a very low production cost. An averaged model of the topology is detailed. The operating principle of the transformerless seven-level inverter is analyzed and detailed. The multilevel sinusoidal modulation has been adapted for use with the PUC-based structure. The control strategy has been designed to reduce the harmonic contents of the load voltage. With such converters, filters' rating is considerably reduced. A comparative study is performed to highlight the advantages of the new packed U cells topology. The operation of the proposed converter topology has been verified through simulation. Experimental validation was performed using DS1103 DSP of dSpace.

A Novel Six-Band Hysteresis Control for the Packed U Cells Seven-Level Converter: Experimental Validation

Abstract: In this paper, the authors propose a novel six-band hysteresis technique to efficiently control the seven-level packed U cells (PUC) converter. The proposed PUC combines advantages of the flying capacitor and the cascaded H-bridge topologies. The novel control strategy is proposed in order to insure a good operation of the PUC converter in both inverter and rectifier modes. In case of rectifier operation, the proposed six-band controller is designed to draw a sinusoidal line current (load current in case of inverter operation) with a unity power factor. Harmonics contents of line current (or load current) and rectifier input voltage (or inverter output voltage) are very low which permits the reduction of the active and passive filters ratings resulting on a very high energetic efficiency and a reduced installation cost. The proposed concept was validated through experimental implementation using real-time controller, the DS1103 of dSpace.

Crossover Switches Cell (CSC): A new multilevel inverter topology with maximum voltage levels and minimum DC sources

Abstract: Renewable energy resources are widely used because of providing green and economic energy for the consumers. Multilevel inverters generates low harmonic waveforms at the output, therefore they are most suitable for energy conversion to deliver efficient power to the loads from renewable energy sources like photovoltaic systems. In this paper a new dc source less topology has been introduced for multilevel inverters. It uses crossover switches to generate the maximum output voltage levels. The Crossover Switches Cell (CSC) multilevel inverter can generate all possible voltage level among the DC supply and regulated DC voltage capacitor. A voltage controller has been proposed to keep the DC capacitor voltage regulated in case of load changes. The simulation results prove the capability of CSC in producing maximum voltage levels as well as the controller ability in balancing the capacitor voltage even if the DC supply voltage changes.

Multilevel electric power converter

Abstract: There is described a multilevel electric power converter circuit comprising: N s switching elements connected in series in a closed loop; NAE additional elements, the additional elements being one of a direct current source and at least one passive element, connected within the closed loop such that each additional element is connected to four of the switching elements, the ratio of a number of additional elements N AE to a number of switching elements N s corresponding to N s = 2N AE + 2; and one of a load and an alternating current source connected across the closed loop at nodes between adjacent switching elements that are separate from nodes to which the additional elements are connected.

A novel high energetic efficiency multilevel topology with reduced impact on supply network

Abstract: In this paper, authors propose a novel competitive multilevel topology. It combines advantages of the flying capacitor and the cascaded H-bridge topologies. It presents several advantages which will be thereafter detailed. The proposed topology is characterized by a reduced impact on the utility supply, a good energetic efficiency and a small number of switches and passive components. It presents also the possibility and the simplicity of changing the number of voltage levels only by acting on-line on the ratio of the desired output voltages. An average model of the proposed topology is performed and the control strategy is designed to draw a nearly sinusoidal current in order to avoid the use of filters. The modeling and control strategy of the proposed topology were verified by simulation.

Multi-level conversion : high voltage choppers and voltage-source inverters

Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>

Multilevel Inverter Topologies With Reduced Device Count: A Review

Abstract: Multilevel inverters have created a new wave of interest in industry and research. While the classical topologies have proved to be a viable alternative in a wide range of high-power medium-voltage applications, there has been an active interest in the evolution of newer topologies. Reduction in overall part count as compared to the classical topologies has been an important objective in the recently introduced topologies. In this paper, some of the recently proposed multilevel inverter topologies with reduced power switch count are reviewed and analyzed. The paper will serve as an introduction and an update to these topologies, both in terms of the qualitative and quantitative parameters. Also, it takes into account the challenges which arise when an attempt is made to reduce the device count. Based on a detailed comparison of these topologies as presented in this paper, appropriate multilevel solution can be arrived at for a given application.

Hybrid Multilevel Inverter Using Switched Capacitor Units

Abstract: In this paper, two new topologies are proposed for multilevel inverters. The proposed topologies consist of a combination of the conventional series and the switched capacitor inverter units. The proposed topologies reduce the number of switches and isolated dc voltage sources, the variety of the dc voltage source values, and the size and cost of the system in comparison with the conventional topologies. In addition, the proposed topologies can double the input voltage without a transformer. There is no need for complicated methods to balance the capacitor voltage. The simulation and experimental results of single-phase 25- and 17-level inverters are given to prove the correct operation of the proposed topologies.

A Novel Multilevel Inverter Based on Switched DC Sources

Abstract: This paper presents a multilevel inverter that has been conceptualized to reduce component count, particularly for a large number of output levels. It comprises floating input dc sources alternately connected in opposite polarities with one another through power switches. Each input dc level appears in the stepped load voltage either individually or in additive combinations with other input levels. This approach results in reduced number of power switches as compared to classical topologies. The working principle of the proposed topology is demonstrated with the help of a single-phase five-level inverter. The topology is investigated through simulations and validated experimentally on a laboratory prototype. An exhaustive comparison of the proposed topology is made against the classical cascaded H-bridge topology.

Multilevel Converters: Control and Modulation Techniques for Their Operation and Industrial Applications

Abstract: In the last decades, multilevel converters have been developed usually for medium-voltage high-power applications. They have become a mature solution for the increasing power demand of multiple applications such as renewable energy systems, power quality improvement, and motor drives. In this paper, the operation of multilevel converters is addressed focusing on control and modulation techniques for different well-known applications. The new developments are presented as an extension of conventional methods for two-level voltage-source converters which are still the mainstream solution for most cases.