IEEE Transactions on Industrial Electronics

Volume 49, Number 5, Oct 2002 Access to the journal on IEEE XPLORE IE Transactions Home Page

Special section on Multilevel Inverters

49.5.1	J. Rodriguez, "Guest Editorial," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 946- 947, Oct 2002. Abstract Link Full Text Abstract: Not Available
49.5.2	P.W. Hammond, "Enhancing the reliability of modular medium-voltage drives," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 948- 954, Oct 2002. Abstract Link Full Text Abstract: A method to increase the reliability of modular medium-voltage induction motor drives is discussed, by providing means to bypass a failed module. The impact on reliability is shown. A control, which maximizes the output voltage available after bypass, is described, and experimental results are given.
49.5.3	T.A. Meynard, H. Foch, P. Thomas, J. Courault, R. Jakob, M. Nahrstaedt, "Multicell converters: basic concepts and industry applications," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 955- 964, Oct 2002. Abstract Link Full Text Abstract: Multicell power converters were introduced ten years ago. This paper summarizes the main results obtained through the research done on these converters over this period: topology and derivation of multicell choppers and voltage-source inverters; harmonics cancellation; open-loop modulation techniques; self-balancing understanding; and optimization. During this same period, industrial products using this technique have been developed and the corresponding know-how has contributed to the field in various ways, such as modular design, low inductance busbars, specific drivers, etc.
49.5.4	A. BenAbdelghani, C.A. Martins, X. Roboam, T.A. Meynard, "Use of extra degrees of freedom in multilevel drives," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 965- 977, Oct 2002. Abstract Link Full Text Abstract: Multilevel converters with series connection of semiconductors allow power electronics to reach medium voltages (1-10 kV) with relatively standard components. The increase of the number of semiconductors provides extra degrees of freedom, which can be used to improve different characteristics. This paper is focused on variable-speed drives and it is shown that with the proposed multilevel direct torque control strategy (DiCoIF) the tradeoff between the performances of the drive (harmonic distortions, torque dynamics, voltage step gradients, etc.) and the switching frequency of the semiconductors is improved. Then, a slightly modified strategy reducing common-mode voltage and bearing currents is presented.
49.5.5	T.A. Meynard, H. Foch, F. Forest, C. Turpin, F. Richardeau, L. Delmas, G. Gateau, E. Lefeuvre, "Multicell converters: derived topologies," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 978- 987, Oct 2002. Abstract Link Full Text Abstract: Multicell converters were introduced ten years ago and, over this period, their properties have been thoroughly analyzed. Since then, this concept has lead to some other innovative topologies which are briefly presented in this paper. Different ways to introduce soft switching in multicell converters are investigated. The concept of distributing power over several switches, giving more degrees of freedom and using less passive components, is extended further with the stacked multicell topology. Finally, direct AC-AC converters using the multicell approach are described.
49.5.6	C. Turpin, P. Baudesson, F. Richardeau, F. Forest, T.A. Meynard, "Fault management of multicell converters," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 988- 997, Oct 2002. Abstract Link Full Text Abstract: Component counts and oversimplified reliability rules may lead to the conclusion that multilevel converters are less safe than two-level converters, just because they use more components. A better approach might be to consider that they use a different arrangement of components and also that the consequence of faults may be very different. This paper is focused on the study of the consequences of faults in hard-switching and soft-switching multicell converters. Solutions to minimize the consequences of major faults are described.
49.5.7	G. Gateau, M. Fadel, P. Maussion, R. Bensaid, T.A. Meynard, "Multicell converters: active control and observation of flying-capacitor voltages," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 998- 1008, Oct 2002. Abstract Link Full Text Abstract: The multicell converters introduced more than ten years ago make it possible to distribute the voltage constraints among series-connected switches and to improve the output waveforms (increased number of levels and apparent frequency). The balance of the constraints requires an appropriate distribution of the flying voltages. This paper presents some solutions for the active control of the voltages across the flying capacitors in the presence of rapid variation of the input voltage. The latter part of this paper is dedicated to the observation of these voltages using an original modeling of the converter.
49.5.8	K.A. Corzine, J.R. Baker, "Multilevel voltage-source duty-cycle modulation: analysis and implementation," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1009- 1016, Oct 2002. Abstract Link Full Text Abstract: Multilevel converters have become increasingly popular due to high power quality, high-voltage capability, low switching losses, and low electromagnetic compatibility concerns. Considering these advantages, the multilevel converter is a suitable candidate for implementation of future naval ship propulsion systems. This paper focuses on modulation techniques for the multilevel converter. In particular, a novel voltage-source method of multilevel modulation is introduced and compared to existing methods. The proposed method is discrete in nature and can therefore be readily implemented on a digital signal processor. The method is also readily extendable to any number of voltage levels. Results of experimental implementation are demonstrated using a four-level rectifier/inverter system, which incorporates diode-clamped multilevel converters and an 11-level cascaded multilevel H-bridge inverter.
49.5.9	H. du Toit Mouton, "Natural balancing of three-level neutral-point-clamped PWM inverters," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1017- 1025, Oct 2002. Abstract Link Full Text Abstract: This paper explores the natural balancing mechanisms of the three-level neutral-point-clamped (NPC) multilevel inverter. An equivalent circuit of the three-level NPC inverter is derived that facilitates an understanding of the balancing mechanisms. This is followed by a detailed analysis of the balancing mechanisms. The theory is applied to a three-level NPC inverter under vector control. It is shown that this inverter possesses natural balancing mechanisms in which the load impedance and spectra of the switching functions play an important role. Finally, it is illustrated how the natural balancing can be enhanced by using a passive balancing circuit which provides a low impedance at the sampling frequency.
49.5.10	J. Pou, D. Boroyevich, R. Pindado, "New feedforward space-vector PWM method to obtain balanced AC output voltages in a three-level neutral-point-clamped converter," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1026- 1034, Oct 2002. Abstract Link Full Text Abstract: In three-level neutral-point-clamped voltage-source inverters, proper modulation allows the average voltages of the DC-link capacitors to be kept at one-half the level of the DC-link voltage. However, in some operating conditions, a low-frequency ripple appears in the neutral-point potential and its frequency is three times that of the output voltages. As a result, the output voltages also have low-frequency distortion, which includes even and odd multiples of the fundamental. In this paper, a new space-vector pulsewidth-modulation strategy is presented to avoid that low-frequency output voltage distortion. This modulation method tries to balance the voltages of the capacitors by using only three vectors per modulation cycle. The duty ratios are directly calculated from the space-vector diagram, even when balance is not achieved. For all cases, the result is a balanced set of three AC output voltages. Some simulated and experimental results are given to validate the method.
49.5.11	G. Venkataramanan, A. Bendre, "Reciprocity-transposition-based sinusoidal pulsewidth modulation for diode-clamped multilevel converters," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1035- 1047, Oct 2002. Abstract Link Full Text Abstract: Modulation strategies for multilevel inverters have typically focused on synthesizing a desired set of three phase sinusoidal voltage waveforms using a fixed number of DC voltage levels. This results in the average current injection and hence the net power drawn from the multiple DC bus terminals to be unmatched and time varying. Subsequently, the DC-bus voltages are unregulated, requiring corrective control action to incorporated. In this paper, the principle of reciprocity transposition in introduced as a means for modeling the DC-bus current injection simultaneously as the modulation strategy is formulated. Furthermore, a new sinusoidal pulsewidth-modulation strategy that features constant and controllable current injection at the DC-bus terminals while maintaining output voltage waveform quality is introduced. The proposed strategy is general enough to be applied to converters with an even number of levels and an odd number of levels. Analytical results comparing the performance of the proposed modulator with a conventional multiple carrier modulator are presented for example multilevel converters with four and five levels. Computer simulation results verifying the analytical results are presented for a four-level converter.
49.5.12	H. Ertl, J.W. Kolar, F.C. Zach, "A novel multicell DC-AC converter for applications in renewable energy systems," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1048- 1057, Oct 2002. Abstract Link Full Text Abstract: This paper presents a novel DC-AC converter for applications in the area of distributed energy generation systems, e.g., solar power systems, fuel-cell power systems in combination with supercapacitor or battery energy storage. The proposed converter is realized using an isolated multicell topology where the total AC output of the system is formed by series connection of several full-bridge converter stages. The DC links of the full bridges are supplied by individual DC-DC isolation stages which are arranged in parallel concerning the dc input of the. total system. Therefore, all switching cells of the proposed converter can be equipped with modern low-voltage high-current power MOSFETs, which results in an improved efficiency as compared to conventional isolated DC-AC converters. Furthermore, the cells are operated in an interleaved pulsewidth-modulation mode which, in connection with the low voltage level of each cell, significantly reduces the filtering effort on the AC output of the overall system. The paper describes the operating principle, analyzes the fundamental relationships which are relevant for component selection, and presents a specific circuit design. Finally, measurements taken from a 2-kW laboratory model are presented.
49.5.13	L.A. Tolbert, Fang Zheng Peng, T. Cunnyngham, J.N. Chiasson, "Charge balance control schemes for cascade multilevel converter in hybrid electric vehicles," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1058- 1064, Oct 2002. Abstract Link Full Text Abstract: This paper presents transformerless multilevel converters as an application for high-power hybrid electric vehicle (HEV) motor drives. Multilevel converters: (1) can generate near-sinusoidal voltages with only fundamental frequency switching; (2) have almost no electromagnetic interference or common-mode voltage; and (3) make an HEV more accessible/safer and open wiring possible for most of an HEV's power system. The cascade inverter is a natural fit for large automotive hybrid electric drives because it uses several levels of DC voltage sources, which would be available from batteries, ultracapacitors, or fuel cells. Simulation and experimental results show how to operate this converter in order to maintain equal charge/discharge rates from the DC sources (batteries, capacitors, or fuel cells) in an HEV. Drive Control
49.5.14	M. Febssen, A. Steimel, "Direct self control with minimum torque ripple and high dynamics for a double three-level GTO inverter drive," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1065- 1071, Oct 2002. Abstract Link Full Text Abstract: A highly dynamic control scheme with very low torque ripple-direct self control (DSC) with torque hysteresis control-for very high-power medium-voltage induction motor drives fed by a double three-level inverter (D3LI) is presented. In this arrangement, two three-level inverters that are connected in parallel at their DC sides are feeding the open motor windings. The DSC, well known from two- and three-level inverters, is adapted to the D3LI and optimized for a minimum torque ripple. An 18-corner trajectory is chosen for the stator flux of the induction machine since it is approaching the ideal circle much better than the hexagon known from DSC for two-level inverters, without any detriment to the torque ripple. The machine and inverter control are explained and the proposed torque quality and dynamics are verified by measurements on a 180-kW laboratory drive.
49.5.15	D. Soto, T.C. Green, "A comparison of high-power converter topologies for the implementation of FACTS controllers," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1072- 1080, Oct 2002. Abstract Link Full Text Abstract: This paper compares four power converter topologies for the implementation of flexible AC transmission system (FACTS) controllers: three multilevel topologies (multipoint clamped (MPC), chain, and nested cell) and the well-established multipulse topology. In keeping with the need to implement very-high-power inverters, switching frequency is restricted to line frequency. The study addresses device count, DC filter ratings, restrictions on voltage control, active power transfer through the DC link, and balancing of DC-link voltages. Emphasis is placed on capacitor sizing because of its impact on the cost and size of the FACTS controller. A method for the dimensioning the DC capacitor filter is presented. It is found that the chain converter is attractive for the implementation of a static compensator or a static synchronous series compensator. The MPC converter is attractive for the implementation of a unified power flow controller or an interline power flow controller, but a special arrangement is required to overcome the limitations on voltage control.
49.5.16	J. Bocker, J. Febning, H. Jebenstreit, "High dynamic control of a three-level voltage-source-converter drive for a main strip mill," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1081- 1092, Oct 2002. Abstract Link Full Text Abstract: A high dynamic control system for the Alspa VDM 7000 medium-voltage drive was implemented, which provides fast torque response times of a few milliseconds despite the typically low switching frequency of gate-turn-off thyristors which is necessary to achieve high efficiency. The drive system consists of a three-level voltage-source converter with active front end and a synchronous motor. The drive has most recently been applied to a main strip mill. It provides a maximum of 8.3-MW mechanical power with a rated motor voltage of 3 kV. Besides motor torque as the main control objective, the control system has to comply with a number of additional objectives and constraints like DC-link voltage regulation and balancing, current and torque harmonics, motor flux, and excitation.
49.5.17	J. Rodriguez, J. Pontt, G. Alzarnora, N. Becker, O. Einenkel, A. Weinstein, "Novel 20-MW downhill conveyor system using three-level converters," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1093- 1100, Oct 2002. Abstract Link Full Text Abstract: This paper presents a very new drive system used to transport ore from the mine down to the concentrator plant in the copper mine "Los Pelambres". Eight 2500-kW motors are driven by three-level inverters with gate-turn-off thyristors (GTOs). A three-level active front end is used at the input side of each inverter. A GTO chopper is used to provide controlled electrical braking in case of line loss. The paper presents the requirements and alternatives for the drive system and the control strategies for the converters and the belt. A novel application of the selective harmonic elimination method is used to reduce the input current harmonics. Special attention is dedicated to the interaction with the electrical network. The most relevant features of the system are: (1) fuseless operation; (2) adjustable power factor; (3) reduced input current harmonics; (4) smooth transition between motoring and regenerating modes; and (5) 15 MW of regenerated power with more than six months of successful operation.
49.5.18	S.L.T. Marin, J.M.Q. Reboul, L.G. Franquelo, "Digital stochastic realization of complex analog controllers," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1101- 1109, Oct 2002. Abstract Link Full Text Abstract: Stochastic logic is based on digital processing of a random pulse stream, where the information is codified as the probability of a high level in a finite sequence. This binary pulse sequence can be digitally processed exploiting the similarity between Boolean algebra and statistical algebra. Given a random pulse sequence, any Boolean operation among individual pulses will correspond to an algebraic expression among the variables represented by their respective average pulse rates. Subsequently, this pulse stream can be digitally processed to perform analog operations. In this paper, we propose a stochastic approach to the digital implementation of complex controllers using programmable devices as an alternative to traditional digital signal processors. As an example, a practical realization of nonlinear dissipative controllers for a series resonant converter is presented.
49.5.19	Bong-Hwan Kwon, Gang-Youl Jeong, Sung-Hoon Han, Duk-Ho Lee, "Novel line conditioner with voltage up/down capability," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1110- 1119, Oct 2002. Abstract Link Full Text Abstract: In this paper, a novel pulsewidth-modulated line conditioner with fast output voltage control is proposed. The line conditioner is made up of an AC chopper with reversible voltage control and a transformer for series voltage compensation. In the AC chopper, a proper switching operation is achieved without the commutation problem. To absorb energy stored in line stray inductance, a regenerative DC snubber can be utilized which has only one capacitor without discharging resistors or complicated regenerative circuit for snubber energy. Therefore, the proposed AC chopper gives high efficiency and reliability. The output voltage of the line conditioner is controlled using a fast sensing technique of the output voltage. It is also shown via some experimental results that the presented line conditioner gives good dynamic and steady-state performance for high quality of the output voltage. Power Electronics
49.5.20	Eun-Soo Kim, Yoon-Ho Kim, "A ZVZCS PWM FB DC/DC converter using a modified energy-recovery snubber," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1120- 1127, Oct 2002. Abstract Link Full Text Abstract: The conventional high-frequency phase-shifted zero-voltage-switching (ZVS) full-bridge DC/DC converter has a disadvantage, in that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of the transformer and switching devices are increased. To alleviate this problem, this paper proposes an improved zero-voltage zero-current switching (ZVZCS) phase-shifted full-bridge (FB) DC/DC converter with a modified energy-recovery snubber (ERS) attached at the secondary side of transformer. Also, the small signal model of the proposed ZVZCS FB DC/DC converter is derived by incorporating the effects introduced by a transformer leakage inductance and an ERS to achieve ZVZCS. Both analysis and experiment are performed to verify the proposed topology by implementing a 7-kW (120 VDC, 58 A) 30-kHz insulated-gate-bipolar-transistor-based experimental circuit.
49.5.21	Yu-Kang Lo, Sheng-Yuan Ou, Huang-Jen Chiu, "On evaluating the current distortion of the single-phase switch-mode rectifiers with current slope maps," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1128- 1137, Oct 2002. Abstract Link Full Text Abstract: This paper presents a simple way to evaluate the distortion level of the input current for single-phase switch-mode rectifiers (SMRs). Based on the possible conducting paths of various topologies of SMRs, slopes of the input and command currents are defined to form a slope map. By comparing the defined current slopes, the causes of current distortion are examined. Distorted waveforms of the input currents under hysteresis control are reviewed and classified into three types. Design criteria for the circuit parameters are also studied to reduce the current distortion level. Simulations and experiments are performed and the results show strong conformity to the theoretical analysis.
49.5.22	J. Leyva-Ramos, J.A. Morales-Saldana, M. Martinez-Cruz, "Robust stability analysis for current-programmed regulators," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1138- 1145, Oct 2002. Abstract Link Full Text Abstract: Uncertainty models for the three basic switch-mode converters: buck, boost, and buck-boost are given in this paper. The resulting models are represented by linear fractional transformations with structured dynamic uncertainties. Uncertainties are assumed for the load resistance R=R/sub O/(1+/spl delta//sub R/), inductance L=L/sub O/(1+/spl delta//sub L/), and capacitance C=C/sub O/(1+/spl delta//sub C/). The interest in these models is clearly motivated by the need to have models for switch-mode DC-DC converters that are compatible with robust control analysis, which require a model structure consisting of a nominal model and a norm-bounded modeling uncertainty. Therefore, robust stability analysis can be realized using standard /spl mu/-tools. At the end of the paper, an illustrative example is given which shows the simplicity of the procedure.
49.5.23	R.L. Newsom, W.C. Dillard, R.M. Nelms, "Digital power-factor correction for a capacitor-charging power supply," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1146- 1153, Oct 2002. Abstract Link Full Text Abstract: The design and construction of a low-power low-cost power supply capable of charging an energy storage capacitor from a 120-V AC source and capable of power-factor correction (PFC) is presented. The load that is generally connected to a capacitor-charging power supply (CCPS) is a pulsed power load (i.e., laser, cardiac defibrillator, or flash lamp). A flyback converter was incorporated into the CCPS because it is capable of charging a capacitor while maintaining a high power factor. The control system of the CCPS uses peak current control to achieve PFC and is implemented using standard "off-the-shelf" digital logic components. A 300-V prototype has been constructed and tested. The experimental results show that a high power factor is obtained by the CCPS utilizing a flyback converter and the digital logic control system. Emerging Technology
49.5.24	M.G. Simoes, P. Vieira, "A high-torque low-speed multiphase brushless machine-a perspective application for electric vehicles," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1154- 1164, Oct 2002. Abstract Link Full Text Abstract: This paper presents the design, analysis, simulation, and modeling of a high-torque low-speed multiphase permanent-magnet brushless; machine. The machine fits an in-wheel motor arrangement to be used for electric vehicle applications. This paper presents issues regarding the high-level modeling comprised of a transient model in conjunction with their corresponding experimental evaluation. Analysis was made to combine the modeling efforts with the expected behavior concerned with mutual inductance and armature reaction effects, so as to have realistic simulation results verified by the experimental setup. Comprehensive experimental results corroborate the work.
49.5.25	L. Almeida, E. Tovar, J.A.G. Fonseca, F. Vasques, "Schedulability analysis of real-time traffic in WorldFIP networks: an integrated approach," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1165- 1174, Oct 2002. Abstract Link Full Text Abstract: The WorldFIP protocol is one of the profiles that constitute the European fieldbus standard EN-50170. It is particularly well suited to be used in distributed computer-controlled systems where a set of process variables must be shared among network devices. To cope with the real-time requirements of such systems, the protocol provides communication services based on the exchange of periodic and aperiodic identified variables. The periodic exchanges have the highest priority and are executed at run time according to a cyclic schedule. Therefore, the respective schedulability can be determined at pre-run-time when building the schedule table. Concerning the aperiodic exchanges, the situation is different since their priority is lower and they are bandied according to a first-come-first-served policy. In this paper, a response-time-based schedulability analysis for the real-time traffic is presented. Such analysis considers both types of traffic in an integrated way, according to their priorities. Furthermore, a fixed-priorities-based policy is also used to schedule the periodic traffic. The proposed analysis represents an improvement relative to previous work and it can be evaluated online as part of a traffic online admission control. This feature is of particular importance when a planning scheduler is used, instead of the typical offline static scheduler, to allow online changes to the set of periodic process variables. Letters to the Editor
49.5.26	Yu-Kang Lo, Tzu-Herng Song, Huang-Jen Chiu, "Analysis and elimination of voltage imbalance between the split capacitors in half-bridge boost rectifiers," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1175- 1177, Oct 2002. Abstract Link Full Text Abstract: The voltage imbalance between the split capacitors in a halfbridge boost rectifier is reviewed in this letter. It can be proven that the optimal compensation strategy is to add only a DC component in the source current. The adverse effects of the imbalance elimination control loop to the input power factor are studied. The analytical results are verified through experiments.
49.5.27	A. Derdiyok, M.K. Guven, H. Rehman, N. Inanc, Longya Xu, "Design and implementation of a new sliding-mode observer for speed-sensorless control of induction machine," IEEE Trans. on Industrial Electronics, vol. 49, no. 5, pp. 1177- 1182, Oct 2002. Abstract Link Full Text Abstract: In this letter, a new sliding-mode-sensorless control algorithm is proposed for the field-oriented induction machine drive. In the proposed algorithm, the terms containing flux, speed, and rotor time constant, which are common in both current and flux equations, in the current model of the induction machine are estimated by a sliding function. The flux and speed estimation accuracy is guaranteed when the error between the actual current and observed current converges to zero. Hence, the fourth-order system is reduced to two second-order systems, and the speed estimation becomes very simple and robust to the parameter uncertainties. The new approach is verified by simulation and experimental results.