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EPE 2003 - Topic 03c: Multilevel and Matrix Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2003 - Conference > EPE 2003 - Topic 03: POWER ELECTRONICS CONVERTER CIRCUITS > EPE 2003 - Topic 03c: Multilevel and Matrix Converters
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	A new average modeling and control design applied to a nine-switch matrix converter with input power factor correction   By H. Y. Kanaan; K. Al-Haddad; V. Rajagopalan	[View]   [Download]
Abstract: In this paper, a new low-frequency model for the nine-switch converter is proposed. The modeling process is based on the application of the state-space averaging technique. The model is elaborated and presented in DQ reference frames that are tuned to both input and output frequencies. A control law based on the input-output feedback linearization approach is then designed to perform a unity power factor operation at the input of the converter, while its output is feeding a R-L load with a different frequency. The performance of the control system is then verified through computer simulations.
	Direct flux control of slow-switching high-power multilevel active front end   By M. Kail; V. Staudt; A. Steimel
Abstract: An improved control strategy for high-power multilevel active front ends (AFE) with low switching frequency based on the Direct Self Control (DSC) for induction machines in eldweakening operation is presented. The control system and the controller design are described and veried experimentally on a double three-level IGBT converter test bench. The results are presented and evaluated with respect to the suitability of this control method. The advantages as well as aspects for improvement and drawbacks of the proposed direct flux self control for high-power AFE converters with low switching frequency are pointed out.
	Experimental investigation of a three-phase-four-level flying capacitor PWM-VSI   By H. Jacobs; S. Rabich; J. Petzoldt; S. Delfo; T. Reimann	[View]   [Download]
Abstract: This paper presents a practical realization of a three-phase-four-level flying capacitor PWM-VSI. The control and protection system is introduced based on a 32-bit microcontroller board. Measurements were carried out validating simulation results.
	A new single-phase multilevel-converter for traction vehicles operating on AC line voltage   By M. Glinka; R. Marquardt	[View]   [Download]
Abstract: A new converter concept for direct connection to the power line of AC-fed traction vehicles will be introduced. This concept contains a new single phase AC/AC-modular-multilevel-converter (M2LC) and a concentrated medium-frequency transformer. A design for multi-system operation will be investigated that can operate on an AC15kV / 162/3Hz as well as an AC25kV / 50Hz power line. The new single phase M2LC, enabling four quadrant operation, forms the core of this converter concept. The basic characteristics of this new converter will be introduced. Simulations and analytical investigations underline the attractiveness of this new M2LC converter. This versatile traction converter concept stands out due to its modularity, its superior control characteristics as well as its good adaptability to various traction drives. Therefore, the single phase M2LC has the potential to replace the conventional transformer of future AC-fed traction vehicles.
	Comparison of two vector modulated matrix converter topologies   By M. Jussila; M. Salo; H. Tuusa	[View]   [Download]
Abstract: This paper presents the simulation results of two vector modulated 5 kVA matrix converter topologies: a conventional direct matrix converter (DMC) and an indirect matrix converter (IMC). The vector modulation method used with both topologies was indirect vector modulation (IVM), which is presented using space vector theory instead of conventional matrix form. Functionally the IMC is very similar to the DMC but it has separate line and load bridges instead: i.e. it has dc-link without passive components. Both topologies produce sinusoidal input currents and nearly identical output voltages when they are modulated using the IVM. Most research on IMC modulation has been done using triangular wave voltage command modulation. Thus no comparison of these topologies was possible regardless of the modulation method used. When both topologies are modulated with the IVM the effects of the modulation method do not produce differences. Thus the differences observed are caused by the topologies. The benefits of both the IMC and the DMC are sinusoidal input and output current waveforms, low input current distortion and controllable input power factor. Simulations confirmed these benefits.
	A 10kW vector controlled matrix converter induction motor drive using MCTs   By P. W. Wheeler; J. C. Clare; L. Empringham; M. Bland; T. Podlesak; D. Katsis; K. G. Kerris	[View]   [Download]
Abstract: This paper describes the design, construction and testing of a 10kW Matrix Converter induction motor drive. The converter has been built using 65Amp MOS Controlled Thyristors (MCTs). The commutation time has been minimized to avoid any unnecessary waveform distortion. Closed loop vector control has been implemented and tested using a 12HP induction motor.
	A new modular voltage source inverter topology   By A. Lesnicar; R. Marquardt	[View]   [Download]
Abstract: This paper introduces a new modular multilevel converter (M2LC) topology suitable for very high voltage applications, especially network interties in power transmission. The fundamental concept, the applied control scheme and simulation results of a 36MW–network intertie are presented. With reference to the expenditure of components, a comparison between the new modular multilevel converter and a conventional converter topology is given. A suitable structure of the converter control is proposed.
	A space vector modulation technique for NPC inverters   By A. Bellini; S. Bifaretti; S. Costantini	[View]   [Download]
Abstract: The paper takes into account Neutral Point Clamped inverters for high-speed traction drives. In particular, it examines the problems connected to the employment of Space Vector Modulation techniques and proposes a suitable approach that can be easily implemented on a modern microcomputer. The proposed technique preserve the advantages of the SVM used in traditional two-level inverters; to this aim, all the commutations happen only between adjacent states, so that, during each modulation interval, only three commutations occur.
	A newly developed 3-level RCGCT inverter system   By H. Okayama; T. Fujii	[View]   [Download]
Abstract: This paper presents a new 3-level inverter system applying 6-inch 6.0kV/5.0kA RCGCT for large capacity adjustable speed drives. The main circuit topology is well-known as a neutral-point-clamped inverter, so-called NPC inverter. In this field of application, improving power conversion efficiency is important, however, compatibility between large capacity and compactness is also strongly required by customers. For realization of the compatibility, the reverse conducting gate commutated turn-off thyristors (so-called RCGCTs) have been newly applied to the inverter system The rated output capacity is 8MVA, and the overload capacity is 12MVA. The inverter system consists of 3-level RCGCT units with high maintainability. As a result of squeezing the volume, the rated output power density of 1MVA/m3 has been realized.
	Switching performance and demands of bidirectional IGBT-configurations in matrix converters   By J. Adamek; W. Hofmann	[View]   [Download]
Abstract: Various types of bidirectional switches are examined simulatively and experimentally with regard to their commutation properties within a matrix converter arrangement. A newly developed IGBT with reverse blocking capability by means of which it is possible to set up bidirectional switches in an efficient way is dealt with in a more detailed way. Statements are made on the electric stress of the bidirectional switches within the commutation circuit and the losses arising. With the aid of the results obtained, the suitability of the respective bidirectional switches with regard to their application in the matrix converter is discussed. Finally, some ideas concerning the further improvement of the characteristics and properties of the bidirectional switches are touched upon.
	Stability control of the flying capacitor voltage in the imbricated cells multilevel inverter   By M. Ben Smida; F. Ben Ammar; G. Gateau; M. Ghozzi	[View]   [Download]
Abstract: To attain the high power rating for industrial speed drive systems, the multilevel Capacitor – Clamping- Inverters are particularly well suited for high voltage, high power squirrel cage induction motors. In the imprecated cells multilevel inverter, the power semiconductors are protected from overvoltages, by clamping action of DC supply of the flying-capacitors. The analysis of a complete state space description of the system shows that, if the load is pure inductive, the self-balancing phenomena is not accomplished under the conventional sub-harmonic PWM. An appropriate multilevel PWM control has been developed as feedback of each capacitor voltage error, to overcome the dynamic unbalance due to inverter input DC link voltage fluctuation or fast load variation. A simulation results are carried out from Matlab-Simulink circuit simulation. The implementation of this strategy has been done in Field Programmed Gate Array circuit.
	A new Sinusoidal Pulse-Width Modulation (SPWM) scheme for cascaded multilevel voltage source inverter   By J. Aziz; Z. Salam	[View]   [Download]
Abstract: This work proposes a new switching scheme for cascaded multilevel inverter. The scheme is based on symmetric regular sampled unipolar PWM, with multiple modulating waveforms and a single carrier. Mathematical equations that define the PWM switching instants are derived and implemented digitally using a low-cost microcontroller. A five-level cascaded multilevel inverter test-rig is built to prove viability of the proposed algorithm.
	Analytical calculations of AC side harmonic losses in three-level converters   By R. Lund; G. Tomta; R. Nilsen	[View]   [Download]
Abstract: This paper is presenting analytical expressions for the AC side harmonic losses in 3-level converters. Verification is done by comparison to circuit simulations and experimental results from a test setup. A comparison of AC side harmonic losses between 2- and 3-level converters is also given.
	A new approach to the elimination of harmonics in a multilevel converter   By J. N. Chiasson; L. M. Tolbert; K. J. McKenzie; Z. Du	[View]   [Download]
Abstract: A method is presented to compute the switching angles in a multilevel converter so as to produce the required fundamental voltage while at the same time not generate higher order harmonics. Previous work has shown that the transcendental equations characterizing the harmonic content can be converted to polynomial equations which are then solved using the method of resultants from elimination theory. However, when there are several DC sources, the degrees of the polynomials are quite large making the computational burden of their resultant polynomials via elimination theory quite high. Here, it is shown that by reformulating the problem in terms of power sums, the degrees of the polynomial equations that must be solved are reduced significantly which in turn reduces the computational burden. In contrast to numerical techniques, the approach here produces all possible solutions.
	A cascaded multilevel converter with a common non-isolated DC-link   By D. Soto; R. Peña; M. Vasquez; L. Reyes	[View]   [Download]
Abstract: This paper proposes the use of inductors to implement a single DC link interface in a cascaded multilevel converter. The positive DC rails of consecutive converter are connected via a single inductor. This may eliminate the need for separate DC links normally required in applications demanding the exchange of active power. The operation principle of this novel multilevel converter topology is presented in detail and its performance verified both by simulation and experimental results from a 5-level, low power prototype. The current converter rating, compared with a standard cascaded converter, and the sizing of inductors is also addressed.
	A voltage-balance strategy for multi-level, multi-cellular converters   By D. Gerry; P. Wheeler; J. Clare
Abstract: This paper presents a method of achieving voltage balance between the multiple DC links within a multicellular converter. This method is termed ’link position switching’. Simulation and experimental results taken from a multi-cellular converter employing the voltage-balance method are presented, along with details of the converter structure and control-loop structure.
	An approach to the analysis of efficiency and device power loss distribution for matrix converters   By M. Apap; J.C. Clare; P.W. Wheeler; M. Bland; K. Bradley	[View]   [Download]
Abstract: This paper investigates the device power loss in a direct AC-AC converter drive and compares the results with the predicted loss in diode rectifier-PWM inverter drives and active front-end inverter drives. A comparison of the matrix converter modulation algorithms is also presented in terms of converter efficiency and input harmonic distortion.
	Characteristics of a PAM controlled five-level inverter for induction motor drives   By T. Oota; T. Ishida; K. Matsuse; K. Sasagawa; L. Huang	[View]   [Download]
Abstract: In this paper, the device loss characteristics of the five-level inverter applying a pulse amplitude modulation (PAM) control method are compared with that of a pulse width modulation (PWM) control method. In the proposed control method, the generated losses at switching devices in the five-level inverter will be reduced by adjusting the dc link voltage.
	Gradient system modelling of matrix converters with input and output filters   By D. Jeltsema; J. M.A. Scherpen; J. B. Klaassens	[View]   [Download]
Abstract: Due to its complexity, the dynamics of matrix converters are usually neglected in controller design. However, increasing demands on reduced harmonic generation and higher bandwidths makes it necessary to study large-signal dynamics. A unified methodology that considers matrix converters, including input and output filters, as gradient systems is presented.
	Investigations of double stator asynchronous machine-three levels PWM inverter set   By N. Madani; M.F. Benkhoris; C. Millet; R. Le Doeuff	[View]   [Download]
Abstract: We investigated the use of three levels inverters instead of two levels inverters to reduce circulating currents in a double star asynchronous machine (DSAM). For this, we developed a basic model of DSAM to explain the origin of circulating currents. Firstly, we investigated a DSAM supplied by two levels inverters, and then by three levels inverters to show improvements introduced by three levels inverters. Secondly, We have studied three possibilities to choose the two carrier frequency signals to control three levels inverters. Our simulation results showed that the currents harmonic content was lower with three levels inverters than two levels inverters. Moreover, we showed that torque ripple, electronic components commutation frequency, and amplitude of circulating currents can be reduced with three levels inverters controlled with two unipolar carriers signals in opposition phase.
	Mitigation of non-eliminated harmonics of three-level multipulse three-phase active front end converters with low switching frequency   By J. Pontt; J. Rodríguez; R. Huerta; J. Pavez	[View]   [Download]
Abstract: A Three-Level 12 pulse Three-Phase Active Front End ensures the influence of reduced low order harmonics influence and therefore minimizes volume and amount of network side filters. This paper presents the experimental study concerning the regenerative unity-power factor operation of a 3LAFE converter, highlighting the possible reduction of non-eliminated harmonics by the introduction of slight variations of modulation index and DC-Link voltage regarding a selective harmonic distortion factor (SHD). This work opens new possibilities for avoiding or reducing harmonic filters, especially by operating within weak networks and stringent conditions to be studied in further projects.
	Optimal waveform generation for utility-connected multilevel converters   By J. Vassallo; P. W. Wheeler; J. C. Clare	[View]   [Download]
Abstract: Several modulation methods may be used in high-power, medium voltage, multilevel converters operating at low switching frequencies. This paper considers the application of Selective Harmonic Elimination PWM (SHEPWM) for utility-connected converters where very tight control over individual harmonic amplitudes is essential, and a restricted modulation index range is usually sufficient. An alternative approach for the calculation of firing angles is outlined, in particular for 5- and 7-level inverters switching at frequencies typically 3 to 5 times fundamental. A modification to the method allows inherent equalisation of the power flow to/from the individual DC energy sources, whilst still allowing elimination of specified harmonics. The modified method is used to generate firing angles to enable closed loop current control of the multilevel converter. Results from computer simulations are presented in this paper.
	An adaptive energy-based control of a multilevel rectifier   By A. Dell Aquila; C. Cecati; M. Liserre; V. G. Monopoli; P. Rotondo	[View]   [Download]
Abstract: In this paper an adaptive control algorithm of a multilevel H-bridge rectifier is proposed. The balance of the DC voltages under different operating conditions is guaranteed due to the energy-based approach. The knowledge of the load is not needed and new sensors are not introduced due to the adaptive control law used.
	Over-voltage problems of diode-clamped converters during switchings   By P. Bartholomeüs; P. Le Moigne; J.B. Akoe Mba	[View]   [Download]
Abstract: This paper presents a switching cell for high voltage applications based on a generalized diode-clamped converter. The concept and the working principle are presented. Thanks to the association of a low power diode network and a particular switching sequence, it allows for a dynamic equalization of the transistor voltages. A prototype (1000V/20A) has been developed in order to study the dynamic behaviour during the transistor switching. Experimental results highlight several over-voltage problems during the ON-Switching of the transistors. These problems have been analyzed. Simulations and experimentations have allowed us to determine the origin of these overvoltages.
	A new PWM control technique for a three-phase inverter suitable in solar energy conversion applications   By C. Galea; M. Lucanu; A. Alistar	[View]   [Download]
Abstract: A multilevel pulse-width modulated (PWM) three-phase voltage-source inverter, modulating under performance 7-level low frequency voltage waveform [1], for the harmonic spectrum load system is presented in the paper. A 7-level to 3-level voltage waveform across the load is generated for high and low modulation indexes respectively. Inverter switching control signals are provided, along with the performance characteristics including total harmonic distortion within the operating range for the inverter. Using the 6-anti-diodes bridge is possible to be used without danger to close supply’s low resistance current circuit [2]. Theoretical considerations discussed in the paper are supported with simulation results taken from simulation program.
	Analysis of digital implementation effects on matrix converters stability   By D. Casadei; G. Serra; A. Tani; L. Zarri	[View]   [Download]
Abstract: Switching converters coupled with input filters, usually adopted to reduce input current distortion, can become unstable according to the operating conditions and the converter topology. In this paper the stability of a system composed by a matrix converter with controlled output voltage, an input filter and a linear passive load is analyzed by means of a linearized model that takes into account the effects related to the digital implementation. The analytical approach leads to general relationships showing that the system becomes unstable as the voltage transfer ratio exceeds a limit value related to the supply, filter and load parameters, and delay effects introduced by the digital controller.
	Modeling and design of a neutral point voltage regulator for a three level diode clamped inverter using multiple carrier modulation   By A. Bendre; G. Venkataramanan; V. Srinivasan; D. Rosene	[View]   [Download]
Abstract: This paper presents the design and implementation of a novel neutral point voltage regulator for a three level diode clamped multi level inverter, which uses a multiple carrier sine triangle modulator in conjunction with a closed loop controller for neutral point regulation. Redundant state choices are controlled via a continuous voltage offset that controls the dc current injection into the midpoint of the dc bus. Small signal dynamic models are developed for closed loop regulators with this voltage offset as the control variable. Besides maintaining dc bus voltage balance, a significant reduction is seen in the voltage distortion at the neutral point when the regulator is used and this leads to a definitive reduction in the required dc bus capacitance. Analytical, computer simulation and experimental results verifying the approach are presented in the paper.
	Asymmetric space vector PWM for the three-level flying-capacitor inverter   By M. A. Severo Mendes; P. F. Seixas; B. G. de Andrade	[View]   [Download]
Abstract: This paper presents an improved space vector PWM method for a 3-level ying-capacitor inverter. Simple algebraic equations are used to calculate the pulse widths of the gate signals from the sampled reference voltages. This feature makes easy the implementation in real time. At low voltage levels, asymmetric modulation is introduced to reduce harmonic distortion. The voltages on the ying capacitors are regulated by simple ON-OFF controllers independently of the output voltage control. The main features of the proposed technique are analyzed by computer simulations. The algorithm was implemented using a commercial DSP without ony external logic. The experimental tests obtained conrm the expected results.
	Matrix converter commutation strategy using both output current and input voltage sign measurement   By D. Casadei; A. Trentin; M. Matteini; M. Calvini	[View]   [Download]
Abstract: This paper deals with commutation problems in direct AC-AC matrix converters. It gives an overview of existing commutation strategies and presents a new 3-STEP commutation control strategy that using both output current and input line-to-line voltage sign allows the modulation errors, inherent in other commutation strategies, to be eliminated. As a consequence, it is possible to extend the linear modulation region of the converter with respect to four-step commutation strategies. Simulation results showing the effectiveness of the new commutation strategy are given.