Multilevel converters have been under research and development for more than three decades and have found successful industrial application. However, this is still a technology under development, and many new contributions and new commercial topologies have been reported in the last few years. The aim of this paper is to group and review these recent contributions, in order to establish the current state of the art and trends of the technology, to provide readers with a comprehensive and insightful review of where multilevel converter technology stands and is heading. This paper first presents a brief overview of well-established multilevel converters strongly oriented to their current state in industrial applications to then center the discussion on the new converters that have made their way into the industry. In addition, new promising topologies are discussed. Recent advances made in modulation and control of multilevel converters are also addressed. A great part of this paper is devoted to show nontraditional applications powered by multilevel converters and how multilevel converters are becoming an enabling technology in many industrial sectors. Finally, some future trends and challenges in the further development of this technology are discussed to motivate future contributions that address open problems and explore new possibilities.

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Recent Advances and Industrial Applications of Multilevel Converters

http://ieeexplore.ieee.org/iel5/5610941/5624686/05624745.pdf

Power electronics

The author evaluates the state of the art in pulsewidth modulation for AC drives fed from three-phase voltage source inverters. Feedforward and feedback pulsewidth modulation schemes with relevance for industrial application are described and their respective merits and shortcomings are explained. Secondary effects such as the influence of load-current dependent switching time delay and transients in synchronized pulsewidth modulation schemes are discussed, and adequate compensation methods are presented. Recorded oscillograms illustrate the performance of the respective pulsewidth modulation principles. The author provides a guideline and quick reference for the practicing engineer to decide which methods should be considered for an application of a given power level, switching frequency, and dynamic response. >

Pulsewidth modulation-a survey

This paper presents a review of recently used direct torque and flux control (DTC) techniques for voltage inverter-fed induction and permanent-magnet synchronous motors. A variety of techniques, different in concept, are described as follows: switching-table-based hysteresis DTC, direct self control, constant-switching-frequency DTC with space-vector modulation (DTC-SVM). Also, trends in the DTC-SVM techniques based on neuro-fuzzy logic controllers are presented. Some oscillograms that illustrate properties of the presented techniques are shown.

Direct torque control of PWM inverter-fed AC motors - a survey

This paper gives an overview of medium-voltage (MV) multilevel converters with a focus on achieving minimum harmonic distortion and high efficiency at low switching frequency operation. Increasing the power rating by minimizing switching frequency while still maintaining reasonable power quality is an important requirement and a persistent challenge for the industry. Existing solutions are discussed and analyzed based on their topologies, limitations, and control techniques. As a preferred option for future research and application, an inverter configuration based on three-level building blocks to generate five-level voltage waveforms is suggested. This paper shows that such an inverter may be operated at a very low switching frequency to achieve minimum on-state and dynamic device losses for highly efficient MV drive applications while maintaining low harmonic distortion.

Medium-Voltage Multilevel Converters—State of the Art, Challenges, and Requirements in Industrial Applications

Steer-by-wire (SbW) systems are candidate to substitute the conventional (mechanical or hydraulic) steering systems in the new generation of vehicles. The task of a SbW system is twofold: turning the road wheels tracking the handwheel rotation and providing the driver with a feeling of the steering effort. In this paper, the issue of designing a SbW system is faced. An approach is proposed, based on three steps. Firstly, the model of a conventional steering system is formulated. Then the SbW system is developed with the same structure as the conventional ones. Finally, performance indexes for the steering maneuver are defined and utilized to set up the parameters of the SbW system. As a case of study, the SbW system of a lift truck is designed according to the proposed approach. Diagrams are given to demonstrate the effectiveness of the resultant SbW system

Approach to steer-by-wire system design

Drive-by-wire (DbW) is an emerging technology in the automotive environment that provides for the transmission and actuation of the driving commands by means of electric devices. The commands are entered by appropriate transducers, forwarded to electrical drives via a communication network and applied to local mechanical actuators. This paper deals with a DbW system for an industrial vehicle, at first presenting the safety requirements for the vehicle and the system architecture arranged to meet the requirements. Then, the design of the communication network is presented. The variables to be conveyed are defined and the specifications for the data exchange are established. Two communication protocols are evaluated for possible implementation. An experimental rig implementing the selected protocol is described and the tasks devised to validate the design of the communication network are illustrated

Design of drive-by-wire communication network for an industrial vehicle

Stringent demands must be fulfilled when designing power supplies (PSs) for particle accelerators, such as stability, efficiency, accuracy, and electromagnetic compatibility. In this context, the paper analyzes the basic requirements to be considered when designing a PS for such applications. After reviewing the main circuitry topologies used in PSs, the electrical specifications and functional modes necessary to set up high-performance PSs are addressed. Problems concerning the fulfillment of the electrical specifications are discussed, followed by an overview of the common PS control methods. Finally, the impact of some of the discussed design considerations is evaluated for the PS of the magnets of particle accelerators.

/pdf/considerations-in-designing-power-supplies-for-particle-3zgdqhrh71.pdf

Considerations in designing power supplies for particle accelerators

The paper deals with the wireless battery chargers (WBCs) of electric vehicles (EVs) and refers to a resonant WBC that utilizes a rectifier-chopper stage in the receiver side to control the charging current/voltage of the EV battery. Two topologies, namely series-series and series-parallel, are considered, and their performance in terms of efficiency and power sizing is investigated. Power sizing is formulated for both the power source and the coil coupling set. Instrumental in the investigation is the proper modeling of the rectifier-chopper stage. Data used for calculating the performance are obtained from a WBC setup for electric city-car. Comparison of the results reveal the overall convenience of the series-series topology.

Efficiency and power sizing of SS vs. SP topology for wireless battery chargers

In present years, the deployment of electric vehicles is arisen globally due to the stressing of the environmental concerns and the demand of energy-efficient road transportation. This paper deals with the battery charging technologies for electric vehicles, giving an overview on their evolutionary process. At first, the wired technology is reviewed and the main existing standards on it (charging modes, connection cases and plug types) are presented. Then the wireless power transfer technology is illustrated, showing the convenience of the resonant coupling topologies in increasing the power transfer efficiency. At last, the in-moving technology is introduced and the preliminary studies on it are addressed.

Giuseppe Buja

Papers

Approach to steer-by-wire system design

Design of drive-by-wire communication network for an industrial vehicle

Considerations in designing power supplies for particle accelerators

Efficiency and power sizing of SS vs. SP topology for wireless battery chargers

From Wired to In-Moving Charging of the Electric Vehicles