EPE Association: EPE-PEMC 2004 - Topic 02-4: Multilevel converters

EPE-PEMC 2004 - Topic 02-4: Multilevel converters
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2004 - Conference > EPE-PEMC 2004 - Topic 02: POWER ELECTRONICS CONVERTERS > EPE-PEMC 2004 - Topic 02-4: Multilevel converters

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   A Novel Two Stage Converter For Low Voltage And High Current Applications
By Kimihiro Nishijima, Koosuke Harada, T. Nakano [View]
[Download]

Abstract: This paper presents a novel converter for removing the output inductor filter and the snubber circuits so that fast response and high reliability may be realized. In this converter, low ripple output is obtained by overlapping of two phase current waves produced from dual transformers of multi-resonant converter. Output surge is sufficiently removed due to multiresonant switching. This converter is suitable especially for low voltage and high current applications such as digital circuits.

   A Simple Hysteresis Based Algorithm For Neutral Point Balance In Three Level Npc Converters With Sv-Pwm
By Igor Perez De Arenaza, Marcelino Caballero, Unai Viscarret, Javier Laguardia, R. Martinez [View]
[Download]

Abstract: One of the most important drawbacks of the threelevel NPC (Neutral Point Clamped) converters is the Neutral Point balance. There are different ways to cope with this problem. In this paper, a simple algorithm of easy implementation that solves this balance is shown. It is based on a SV −PWM (Space Vector − Pulse Width Modulation) and keeps the Neutral Point balanced by means of an hysteresis control. A dSpace based prototype has been built and the correct operation of the algorithm as well as the advantages of this type of converter have been checked.

   Benefits Of Multilevel Converters To Wind Turbines In Terms Of Output Filter Reduction
By A. Gilabert, S. Alepuz, J. Salaet, S. Busquets-Monge, A. Beristain, J. Bordonau [View]
[Download]

Abstract: Wind turbines are becoming more popular in the present energy scenario: there is a global blueprint to achieve a 12% of the world’s electricity from wind power by 2020. The trend on Wind Energy Conversion Systems (WECS) is marked by Multi-Megawatt variable-speed wind turbines, and the latest prototypes glimpse to overcome the barrier of 5MW. However, such a big amount of power is still obtained through low-voltage drives, resulting in high currents (approximately 1kA per MW). Medium-voltage drives, based on multilevel structures, help on decreasing these high current values, improving efficiency, reliability, and then, the so critical availability factor. Indeed, multilevel converters’ features contribute to the integration of WECS to the distribution grid, making easier the accomplishment of the grid owner’s requirements. In this paper, the advantages and drawbacks of using multilevel converters inside WECS’ power circuit are discussed, and benefits with regard to output filter size are verified through MATLAB simulations and preliminary experimental results with a commercial prototype.

   Calculation Of Overvoltage And Losses In Three Level Inverters With Double Snubber Circuit
By Jamal Al Nasseir, Christian Weindl, Gerhard Herold [View]
[Download]

Abstract: In this paper a new circuit design for the protection of multi level inverter is presented. The so-called ‘Double Snubber Circuit’ optimises the behaviour of conventional RCD snubber circuits especially in the direction of the over voltage protection and allows minimizing the total losses in the entire circuit including the power semiconductors. The proposed circuit overcomes hereby the limitations of many of the existing designs, because the losses and the over voltage can be controlled using only a handful of additional passive elements. Because of the high efficiency of the inverter systems based on the proposed snubber circuit, it can be used for high power inverters as well as for the so-called Flexible AC Transmission Systems (FACTS). The presented snubber circuit has been analysed in several test configurations and converter designs. The simulation results are compared with the output of a standardized three level inverter system to verify the opportunities of the new snubber design.

   Elaboration And Comparison Of Two Algorithms Of Algebraic Pwm Strategies Of A Nine -Level Npc Vsi. Application To The Speed Control Of The PMSM
By F. Bouchafaa, E. M. Berkouk, M. S. Boucherit [View]
[Download]

Abstract: The object of this paper is to study new algebraic strategies of the nine-level voltage sources inverter. We propose two algorithms of algebraic PWM strategies of the nine -level NPC voltage source inverter. Firstly, we elabo rate a working model of this inverter, without presumption on its control, using DESIGN method associated to Petri nets. Then, we develop a control model of this converter using generating connection functions. Two algebraic PWM algorithms are proposed. In the last part, we study the performances of the speed control of PMSM fed by this inverter. The results obtained are full of promise to use the inverter in high voltage and great power applications as electrical traction.

   Generalization Of The Current Mode Control Strategy To Multilevel Converters
By M. Aime, G. Gateau, T. A. Meynard [View]
[Download]

Abstract: This article deals with a new Current-Mode Control strategy dedicated to single-phase multilevel converters. The power electronics part presented here is a multicell converter with 3 cells in series, which generates a 4-level waveform on the output voltage. A new algorithm is introduced to control the output current at a fixed switching frequency (Current-Mode Control). The behaviour of this new multilevel strategy (named Multilevel Dual Current-Mode Control – MDCMC) is examined, and the results obtained by digital simulations are presented.

   High-Frequency Single-Phase Multilevel Ac/ac Converter For Photovoltaic Power Systems
By J. Beristain, J. Bordonau, A. Gilabert, S. Alepuz, S. Busquets [View]
[Download]

Abstract: This paper introduces a new ac/ac multilevel converter for a single-phase inverter with HF isolation and bidirectional power flow capability. The advantage is to provide compact HF isolation, without an additional DC stage and with lower harmonic distortion in the load. Higher efficiency and better dynamic response are possible as well . The topology is based on a HF inverter, a HF transformer and the new ac/ac multilevel converter. A modulation strategy for the commutation of the ac/ac converter switches is presented. Synthesis, simulation and experimental results of the multilevel converter are presented.

   Multi-Modulaiton Signal Pwm Control For Multi-Level Converter
By Noriyuki Kimura, Toshimitu Morizane, Katsunori Taniguchi, Takanori Oono [View]
[Download]

Abstract: In this paper, new PWM methods for the multi-level converter are described. This method can control dc current flow of each dc capacitor by using multi-modulation signal. It is applied to the dual multilevel converter configuration to stabilize the dc capacitor voltage balance.

   Utility-Connected Multi-Cellular Converter With Optimised Harmonic Performance And Equalisation Of Cell Powers
By J. C. Clare, J. Vassallo, P. W. Wheeler [View]
[Download]

Abstract: Although fundamental frequency switching has been the preferred method for high-power medium-voltage multilevel converters, the technology of current generation power semiconductors has made it possible to use higher rates. In utility-connected applications, where a restricted modulation index range is usually sufficient, a main requirement is for very tight control over individual harmonics. For these reasons, this paper considers the application of Selective Harmonic Elimination PWM (SHEPWM) with 5- or 7-level converters switching at low multiples of the fundamental frequency. An alternative approach for the calculation of multiple solutions of the firing angles is outlined, and is then applied in a modulation scheme that inherently equalizes the power flow from and to the individual DC energy sources. Computer simulation results for a 7-level medium-voltage converter are presented in this paper. A 3 kVA, 380VAC laboratory prototype was designed using the same operating principles as the high-power converter, constructed and tested. Experimental results confirming the expected performance are included.

EPE-PEMC 2004 - Topic 02-4: Multilevel converters
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2004 - Conference > EPE-PEMC 2004 - Topic 02: POWER ELECTRONICS CONVERTERS > EPE-PEMC 2004 - Topic 02-4: Multilevel converters
	[return to parent folder]

	A Novel Two Stage Converter For Low Voltage And High Current Applications By Kimihiro Nishijima, Koosuke Harada, T. Nakano	[View] [Download]
Abstract: This paper presents a novel converter for removing the output inductor filter and the snubber circuits so that fast response and high reliability may be realized. In this converter, low ripple output is obtained by overlapping of two phase current waves produced from dual transformers of multi-resonant converter. Output surge is sufficiently removed due to multiresonant switching. This converter is suitable especially for low voltage and high current applications such as digital circuits.

	A Simple Hysteresis Based Algorithm For Neutral Point Balance In Three Level Npc Converters With Sv-Pwm By Igor Perez De Arenaza, Marcelino Caballero, Unai Viscarret, Javier Laguardia, R. Martinez	[View] [Download]
Abstract: One of the most important drawbacks of the threelevel NPC (Neutral Point Clamped) converters is the Neutral Point balance. There are different ways to cope with this problem. In this paper, a simple algorithm of easy implementation that solves this balance is shown. It is based on a SV −PWM (Space Vector − Pulse Width Modulation) and keeps the Neutral Point balanced by means of an hysteresis control. A dSpace based prototype has been built and the correct operation of the algorithm as well as the advantages of this type of converter have been checked.

	Benefits Of Multilevel Converters To Wind Turbines In Terms Of Output Filter Reduction By A. Gilabert, S. Alepuz, J. Salaet, S. Busquets-Monge, A. Beristain, J. Bordonau	[View] [Download]
Abstract: Wind turbines are becoming more popular in the present energy scenario: there is a global blueprint to achieve a 12% of the world’s electricity from wind power by 2020. The trend on Wind Energy Conversion Systems (WECS) is marked by Multi-Megawatt variable-speed wind turbines, and the latest prototypes glimpse to overcome the barrier of 5MW. However, such a big amount of power is still obtained through low-voltage drives, resulting in high currents (approximately 1kA per MW). Medium-voltage drives, based on multilevel structures, help on decreasing these high current values, improving efficiency, reliability, and then, the so critical availability factor. Indeed, multilevel converters’ features contribute to the integration of WECS to the distribution grid, making easier the accomplishment of the grid owner’s requirements. In this paper, the advantages and drawbacks of using multilevel converters inside WECS’ power circuit are discussed, and benefits with regard to output filter size are verified through MATLAB simulations and preliminary experimental results with a commercial prototype.

	Calculation Of Overvoltage And Losses In Three Level Inverters With Double Snubber Circuit By Jamal Al Nasseir, Christian Weindl, Gerhard Herold	[View] [Download]
Abstract: In this paper a new circuit design for the protection of multi level inverter is presented. The so-called ‘Double Snubber Circuit’ optimises the behaviour of conventional RCD snubber circuits especially in the direction of the over voltage protection and allows minimizing the total losses in the entire circuit including the power semiconductors. The proposed circuit overcomes hereby the limitations of many of the existing designs, because the losses and the over voltage can be controlled using only a handful of additional passive elements. Because of the high efficiency of the inverter systems based on the proposed snubber circuit, it can be used for high power inverters as well as for the so-called Flexible AC Transmission Systems (FACTS). The presented snubber circuit has been analysed in several test configurations and converter designs. The simulation results are compared with the output of a standardized three level inverter system to verify the opportunities of the new snubber design.

	Elaboration And Comparison Of Two Algorithms Of Algebraic Pwm Strategies Of A Nine -Level Npc Vsi. Application To The Speed Control Of The PMSM By F. Bouchafaa, E. M. Berkouk, M. S. Boucherit	[View] [Download]
Abstract: The object of this paper is to study new algebraic strategies of the nine-level voltage sources inverter. We propose two algorithms of algebraic PWM strategies of the nine -level NPC voltage source inverter. Firstly, we elabo rate a working model of this inverter, without presumption on its control, using DESIGN method associated to Petri nets. Then, we develop a control model of this converter using generating connection functions. Two algebraic PWM algorithms are proposed. In the last part, we study the performances of the speed control of PMSM fed by this inverter. The results obtained are full of promise to use the inverter in high voltage and great power applications as electrical traction.

	Generalization Of The Current Mode Control Strategy To Multilevel Converters By M. Aime, G. Gateau, T. A. Meynard	[View] [Download]
Abstract: This article deals with a new Current-Mode Control strategy dedicated to single-phase multilevel converters. The power electronics part presented here is a multicell converter with 3 cells in series, which generates a 4-level waveform on the output voltage. A new algorithm is introduced to control the output current at a fixed switching frequency (Current-Mode Control). The behaviour of this new multilevel strategy (named Multilevel Dual Current-Mode Control – MDCMC) is examined, and the results obtained by digital simulations are presented.

	High-Frequency Single-Phase Multilevel Ac/ac Converter For Photovoltaic Power Systems By J. Beristain, J. Bordonau, A. Gilabert, S. Alepuz, S. Busquets	[View] [Download]
Abstract: This paper introduces a new ac/ac multilevel converter for a single-phase inverter with HF isolation and bidirectional power flow capability. The advantage is to provide compact HF isolation, without an additional DC stage and with lower harmonic distortion in the load. Higher efficiency and better dynamic response are possible as well . The topology is based on a HF inverter, a HF transformer and the new ac/ac multilevel converter. A modulation strategy for the commutation of the ac/ac converter switches is presented. Synthesis, simulation and experimental results of the multilevel converter are presented.

	Multi-Modulaiton Signal Pwm Control For Multi-Level Converter By Noriyuki Kimura, Toshimitu Morizane, Katsunori Taniguchi, Takanori Oono	[View] [Download]
Abstract: In this paper, new PWM methods for the multi-level converter are described. This method can control dc current flow of each dc capacitor by using multi-modulation signal. It is applied to the dual multilevel converter configuration to stabilize the dc capacitor voltage balance.

	Utility-Connected Multi-Cellular Converter With Optimised Harmonic Performance And Equalisation Of Cell Powers By J. C. Clare, J. Vassallo, P. W. Wheeler	[View] [Download]
Abstract: Although fundamental frequency switching has been the preferred method for high-power medium-voltage multilevel converters, the technology of current generation power semiconductors has made it possible to use higher rates. In utility-connected applications, where a restricted modulation index range is usually sufficient, a main requirement is for very tight control over individual harmonics. For these reasons, this paper considers the application of Selective Harmonic Elimination PWM (SHEPWM) with 5- or 7-level converters switching at low multiples of the fundamental frequency. An alternative approach for the calculation of multiple solutions of the firing angles is outlined, and is then applied in a modulation scheme that inherently equalizes the power flow from and to the individual DC energy sources. Computer simulation results for a 7-level medium-voltage converter are presented in this paper. A 3 kVA, 380VAC laboratory prototype was designed using the same operating principles as the high-power converter, constructed and tested. Experimental results confirming the expected performance are included.