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EPE-PEMC 2002 - Topic 01: Power Converters
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	A Modular High Power DC-DC Converter with Democratic Current-Sharing   By H. Güldner; H. Wolf; F. Eckholz; J. Losansky	[View]   [Download]
Abstract: Modern technologies in the area of applied physics have high demands on their power supplies. Novel power electronic topologies in magnetron sputter systems, operating in the medium-frequency range, require very stable and precise dc sources. Considering the present power semiconductors, high output power is only achievable using interleaved voltage regulator modules. The paper deals with the design procedure of a high power dc-dc converter for Pulsed Plasma Coating Systems. Special issues of parallel operating converter modules like the current distribution control will be discussed. Finally simulation and experimental results of the prototype will be presented.
	A new solution to the unbalance problem of the input DC voltages of a five levels NPC-VSI by using sliding mode regulation   By R. Chibani; G. Manesse; E. M. Berkouk	[View]   [Download]
Abstract: The aim of this paper is to give a solution to unbalance problem of the input DC voltages of the five levels NPC-VSI used in high voltage and great power applications. For that, a Four two levels PWM current rectifiers – Five levels NPC VSI – PMSM cascade is presented. In the first part, we remind the model, we develop a knowledge model of the five levels NPC VSI and propose a sine triangle strategy of this converter using four bipolar carriers. The characteristics of this strategy are studied and the performances of the drive of the PMSM fed by this inverter are presented too. In the first case the input DC voltages of the multilevel inverter are supposed constant and equals. After that, we propose to study a new high voltage cascade four two-levels PWM currents rectifiers – Five levels NPC VSI – PMSM. This study shows particularly the problem of the stability of the DC voltages of the inverter and its consequence on the performances of the PMSM speed control. Then, we propose a solution to the problem by employed closed loop regulation using sliding mode This cascade found applications in great power and high voltage fields as electrical traction.
	A Novel Control Technique for Multilevel Converters with Limited Output Voltage Range   By G. Buja; S. Castellan; D. Szabo	[View]   [Download]
Abstract: A control technique for multilevel converters with a limited range of the output voltage is proposed, aimed at reducing the switching frequency of the converters. The principle of the technique is the modulation of only some stripes of the output voltage. For this reason it is named stripe modulation. The technique may be conveniently applied to the converters equipping the power line conditioners. An example of stripe modulation for a 5-level converter is arranged and its features are analyzed. In particular, performance data on the arranged solution are calculated and compared with those of the traditional techniques. Application to a flicker compensator is considered.
	A Novel Near Unity Power Factor Converter System Based on Compensated Controlled Rectifier   By G. Zhemerov; N. Iliyna; D. Krylov; E. Sokol	[View]   [Download]
Abstract: Novel power electronics converter systems with near unity power factor are considered. These converter systems are based on the combination of compensated controlled rectifier with 6-pulse mixed thyristor-GTO groups and active filter. Active filter function are twofold: extraction of the energy stored in commutating inductance to the utility network and line current harmonics compensation.
	A Novel Voltage Clamped Snubber Circuit Topology Applied for Multilevel Inverter and Its Low Power Loss Operations   By M. Yamamoto; S. Sato; M. Nakaoka	[View]   [Download]
Abstract: This paper presents a novel prototype of lowered loss snubber circuit topology suitable for multilevel voltage source type inverter and rectifier for high power applications. The reduced power loss characteristics and voltage capability performances of the proposed voltage clamped snubber circuit are evaluated in comparison with conventional RCD-snubber circuit designed for 4-Level voltage-fed inverter using IGBTs on the basis of exprimental results.
	A Resonant Circuit of an AC to DC Converter for Contactless Electrical Energy Transmission   By R. Stala	[View]   [Download]
Abstract: The paper presents a system of electrical energy transmission to separated, movable appliances. En-ergy is transmitted without galvanic contact via inductive coupling between windings placed on sepa-rated movable parts of a core of a single-phase transformer. Primary winding is supplied through an inverter while secondary winding placed on different part of core is an integral part of a load. Cou-pling between the windings of the transformer changes in a wide range and it is not known. Hence leakage inductances of the windings may change in a wide range. System output voltage is load and coupling sensitive. There are described various types of resonant circuits intended for compensating the windings leakage inductances. There is pointed out the only configuration for which the system output voltage may be accurate controlled by changing frequency of the inverter that supplies the primary wind-ing. In that configuration control of the output voltage may be realized without necessity of knowing leakage inductances of the transformer. The system supplies the separated appliances, therefore the load voltage or other signals on secondary side may not be used for control circuit. It is presented primary cur-rent analyzing method that makes possible to adjust the inverter frequency the optimal value.
	A Simple Power Loss Estimation Method for Soft Switching and Hard Switching Power Conversion System   By E. Hiraki; M. Nkaoka	[View]   [Download]
Abstract: This paper treats a simple power loss analysis simulator which can actually estimate the total power losses of three phase voltage source soft-switching inverter as well as hard-switching inverter. To estimate switching power losses and conduction power losses of switching semiconductor power devices; IGBTs, incorporated into the inverters and converters, proposed practical simulator is making use of feasible switching power loss data tables and conduction power loss data tables which are accumulated from the measured transient switching operation and periodic steady-state conduction voltage and current operating waveforms of semiconductor switching power devices. The effectiveness of feasible simulation technique and power loss evaluations for power electronic conversion circuits and systems has been confirmed on the basis of simulation and experimental results under the conditions of soft switching and hard switching sinusoidal PWM schemes.
	A Single Stage Dual Block Active Power Factor Correction Scheme   By D. Shmilovitz	[View]   [Download]
Abstract: A novel unity power-factor rectifier scheme is proposed, which combines the benefits of both types of APFC: single stage and two stage schemes. Thus it benefits of high efficiency (like a single stage rectifier) and good output voltage regulation (like a two stage rectifier). The proposed scheme employs two stages, connected in series at the output as opposed to cascaded in common two stage rectifiers. The second stage is responsible for dynamic active cancellation of the output ripple solely. Theoretical explanation is provided through the analysis of the power flow in the scheme. A 200W, 220VAC to 48VDC converter prototype was built and tested, which experimentally validates the proposed approach. In this prototype, output ripple was –40dB suppressed from 4.4V to 30mV and an overall efficiency of over 90% was achieved.
	A Soft Switching Sinewave Pulse Modulated Inverter with Novel Pulse Regenerative Type Active Auxiliary Resonant Bridge Leg Link Snubbers   By M. Nakamura; M. Nakaoka; T. Yamazaki; M. Rukonuzzaman; E. Hiraki; S. Sato	[View]   [Download]
Abstract: In this paper, a novel circuit topology of the active auxiliary edge resonant snubber suitable for high power soft switching three phase inverter applications which has some salient features as compared with conventional auxiliary resonant pole type snubber is proposed in order to minimize the switching power losses in addition to the switching surge related electromagnetic noises. The voltage source type sinewave PWM inverter using new types of resonant pole snubber is discussed for utility interactive power supply. This resonant snubber-assisted inverter topology suitable for high power conversion is proposed and its operating principle discussed on the basis of soft switching transition and commutation operation of the voltage source type pulse modulated inverter using this resonant pole snubber. The operating characteristics of this active auxiliary snubber circuit are respectively described, together with the practical design procedure of this unique edge resonant snubber. Furthermore, the three phase soft switching sinewave PWM inverter with the novel auxiliary active edge resonant bridge leg link snubbers treated here is implemented as experimental setup and discussed as compared with three phase hard switching sinewave PWM inverter, along with simulation results.
	A Two Level Power Conversion for High Voltage DC Power Supply for Pulse Load Applications   By N. Vishwanathan; V. Ramanarayanan	[View]   [Download]
Abstract: High voltage power supply with pulse load (125 KHz and 10 % duty cycle) condition is investigated which is of interest for applications like radar power supplies with output voltage of 22 KV. The performance specifications with this type of power supplies are very stringent demanding tight regulation (< 0.01 %) and high efficiency (> 85%). The solution to this problem as a single stage converter is very difficult. In converters operating at high voltage and high frequency the insulation failure of high voltage transformer is very common. Skin and proximity effect result in higher power losses. Because of high turn’s ratio, the winding capacitance results in delays and large current spikes. Hence a two level converter has been contemplated. One stage of it, namely, Base power supply (BPS), operates at low frequency and produces majority of the output voltage and power. The other one, namely, fast power supply (FPS), operating at high frequency and low output voltage supplies the remaining power and takes care of the transient variations of line and load. The final output voltage is obtained as sum of the outputs of BPS & FPS. The combination of the two stages can satisfy the pulse load specifications. Each of the BPS & FPS use phase modulated-series resonant converter as the power-processing unit with zero voltage switching (ZVS). The analysis of the voltage and power division between BPS & FPS has been done for the proposed topology. It is simulated for a power level of 600 watts and an output voltage of 1 KV as a prototype. It has been studied under various operating conditions of line and load. Simulation results are validated by experimental results.
	Active and Reactive Power Limits of Three-Phase PWM Voltage Source Inverter Connected to the Grid   By M. Chinchilla; J. L. Rodríguez; S. Arnalte; J. C. Burgos; J. Sanz	[View]   [Download]
Abstract: The theoretical formulation for the maximum power capability of the inverter determined by its main parameters is given. This formulation can be used for converter sizing or to set power reference limits to the inverter. Two different regions are distinguished depending on the tolerable ac current harmonic distortion. Experimental results in a variable frequency generation system are shown.
	An extended structure of NPC Three Level Converter as a Universal Power Compensator   By J. Rabkowski; R. Barlik; M. Nowak; J. Matulka	[View]   [Download]
Abstract: The paper presents an extended structure of a neutral point clamped three level inverter, which is able to operate in the shunt active power filter application. The extension allows compensation of active power pulses, caused by specific loads, using capacitor energy storage. The bi-directional DC/DC converter, connected to a DC-link of a three level inverter, offers the possibility of energy exchange and, with the appropriate control strategy, has the ability to keep the neutral point potential at the required level. The proposed structure, particularly the additional DC/DC converter, is described. Finally, simulation and experimental results are given as an illustration of the proposed solution.
	Analysis And Simultion Of Multilevel Converter with Self Voltage Balancing Based Of Flying Capacitors Topology   By S. Delfo; J. Petzoldt; H. Jacobs; T. Taleb	[View]   [Download]
Abstract: This paper presents a theoretical analysis about the voltage behavior for three stage flying capacitors voltage source converter. This analysis study a 3-stage Model with self and active voltage balancing and a theoretical analyses for the equivalent average circuit. An additional resonant circuit ensure the passive voltage balancing across each floating capacitor. The simulation results confirm the validity of the proposed model.
	Analysis of a lossless snubber for BIFRED and BIBRED   By V. Tuomainen; J. Kyyrä	[View]   [Download]
Abstract: BIFRED and BIBRED are Single-Stage Power Factor Correction converters. The converters have one active switching stage, which is used to shape the input current and to regulate the isolated output voltage. However, leakage inductance of the transformers in BIFRED or BIBRED causes a high voltage over the switching device at turn-off instant of the switch. In these two converters the problem associated to the leakage inductance is more severe than in more traditional power supply topologies. This is because the current of the transformer, and hence the current of the leakage inductance, have to be changed from a high positive value to a high negative value during a short period of time, rather than to merely suppress the current to zero after the switch has been turned off. A large change in the inductive current requires that a relatively high voltage have to be applied across the inductance. A snubber circuit has to be employed to provide the needed voltage and to provide an alternative path for the currents for the duration of the process of changing the direction of the current. This paper will give a detailed analysis of a lossless snubber in the BIFRED and BIBRED circuits. Especially the turn-off transition is analyzed in detail since this mode of operation differs from the corresponding transition of other power supply topologies. Simulated results presented in the paper will verify the analysis.
	Analytical Power Loss Expressions for Diode Clamped Converters   By R. Lund; R. Nilsen; S. Ovrebo; J. Beverfjord	[View]   [Download]
Abstract: Use of multilevel converters has become popular the recent years for high power applications [1]. Numerous topologies have been introduced and investigated for utility and drive applications. For drive applications, the most popular topology seems to be the diode clamped topology introduced in [2]. When designing a converter it is useful to have analytically formulas to calculate electrical stresses in the switching devices at different loading. This paper is presenting analytical expressions for the power losses in the switching devices in 4- and 5-level diode clamped converters. The equations derived in this paper are based on a method presented in [3] and [4]. It is a method to calculate the discontinuous currents in Pulse Width Modulated (PWM) converters with high switching frequency. The method transforms discontinuous currents or voltages to continuous, which are almost similar with respect to power losses. By using analytical expressions, time consuming time domain simulations are avoided. At last a comparison of the switching and conduction losses between 2-, 3-, 4- and 5-level is done.
	Bidirectional isolated DC/DC converter for energy storage integration in modular photovoltaic systems   By D. Fischer; R. Mecke; C. Rathge	[View]   [Download]
Abstract: This paper proposes a very simple topology for bidirectional DC/DC conversion which can be used for integration of an electricity storage system in modular photovoltaic and wind power plants. The converter is based on the Cuk principle and needs only two IGBT for both energy flow directions. Therefore the power semiconductor losses are low and the efficiency is high. Due to the small number of components the topology is cost-efficient.
	Comparative Evaluation of High Power Factor Diode Rectifiers with Input Resonant Filters   By J. Järvik; T. Sakkos; V. Sarv	[View]   [Download]
Abstract: The paper presents a comparison of three-phase diode rectifier circuits using various input resonant filters for efficient power factor correction. The comparison is based on the normalized volt-ampere rating of the filter elements that ensures the required total harmonic distortion THD of the input currents. The input filters considered are series-resonant, parallel-resonant, and hybrid filters. The diode rectifiers compared are a simple diode-bridge rectifier and diode rectifiers with optimum rerectification of the third-harmonic ripple power. The latter configurations enable to unite the positive properties of the circuits using whether only the input filtering or only the ripple power re-rectification technique. Comparison of the filters considered demonstrates that the parallel-resonant input filter has the lowest normalized volt-ampere rating. In addition, for such rectifiers the high power factor and low total harmonic distortion hold in wide range of the load and supply voltage variation.
	Comparison between Hard and Soft-Switched DC/AC Converters for usage in Uninterruptible Power Supplies   By F. Renken; M. Patt	[View]   [Download]
Abstract: One main aspect in the development of Uninterruptible Power Supply Inverters (UPS) is the reduction of the losses. This paper shows the effects of reducing the losses by hard and soft-switched MOSFET and IGBT Inverters with different dc-link voltage levels. The efficiency-curves of the Inverters will be presented and the losses are in the Transistors divided into switching and forward power losses. All results are measured in practical circuits.
	Consideration of Converter Losses and Generated Harmonics in VSC-HVDC   By H. Konishi; C. Takahashi; H. Sato; H. Kishibe	[View]   [Download]
Abstract: Relationships both converter losses and generated harmonics of VSC-HVDC were studied for the number of PWM pulses and the number of converter stages by EMTDC digital simulation. The following results were cleared. (1) Converter losses increased nearly in proportion to the equivalent pulse number, which was defined by multiplying the number of PWM pulses by the number of converter stages. (2) Harmonic distortion factors could be reduced by increasing both the number of PWM pulses and the number of converter stages. (3) The harmonic distortion factor of the multi-stage converter configuration could be made much smaller than that of the single-stage configuration for the same equivalent pulse number. And (4) The AC harmonic filter capacity was nearly proportional to the 1/(number of PWM pulses (number of converter stages) ). The increase in the number of converter stages was more effective to decrease AC filter size than increasing the number of PWM pulses. Finally, the VSC-HVDC system can be optimized by balancing above calculation results with increased converter stage cost and lowered harmonic filter cost.
	Control Strategy Of A Solar Power Inverter (Analysis of a Fifth Order System-III)   By K. H. Edelmoser; F. A. Himmelstoss	[View]   [Download]
Abstract: Conventional structures of power inverter filters, required for grid coupling operation and to fulfill EMI requirements, lead to a system which is difficult to control (due to its high system order) and problematic to realize due to unknown mains impedance behavior. In case of the presented structure, a dedicated band-stop filter was used to enhance the output characteristics. The matching filter used here in conjunction with an optimal controller can overcome most of the known limitations. In this paper it is shown that the optimal adaptation of the suggested structure leads to a simple, insensitive, easy to use and very robust solution.
	Converter for Mains Supply – Low-Priced and Intelligent   By S. Soter; S. Buchhold	[View]   [Download]
Abstract: A converter for mains supply with fuelcell energy was built as a prototype. Latest components lead to high efficiency and low price. It can adjust active and reactive power, compensate harmonics and operate in an insular mode. The research project in cooperation with the industry continues to achieve series products.
	Coupled inductors method for current ripple minimising in modular converters   By M. S. Carmeli; F. Castelli-Dezza; G. Superti-Furga	[View]   [Download]
Abstract: This paper focuses on modular converters with series-parallel connection modules. In particular the effect of output inductances on global output ripples and on each parallel branch ripple is analysed. Inductive coupling between parallel branches is proposed to reduce branch and global ripple amplitude. A general method to foresee the possible results during design stage is also discussed in details.
	Current Feeded Full Bridge Multiresonant Converter   By S. Jalbrzykowski; T. Citko	[View]   [Download]
Abstract: A full bridge configuration multiresonant converter feeded by a current source is presented in paper. The converter operation is basing on Class E and parallel loaded series resonant converter. It is characterized by small devices switching losses and absence of parasitic oscillations. Converter operation and control principle and parameter design are analysed and simulation and experimental results are included also.
	Design Methodology for Shunt Active Filters   By F. Ronchi; A. Tilli	[View]   [Download]
Abstract: This article deals with the design of a three-wire shunt active filter based on a AC/DC converter. A methodology to select suitable values of the components is presented for two design objectives. The first one is to select components values strictly dependant on the level of current distortion imposed by the load. The second goal is to find the minimum capacitor value necessary to compensate all the possible loads compatible with a specific current size of the switches. Both the algorithms are based on a model inversion and are control-oriented.
	Efficiency of a Voltage Sourced Inverter with Controllable Intermediate DC Voltage   By P. Pinho; J. Kyyrä	[View]   [Download]
Abstract: The efficiency of a low cost three-phase PWM (Pulse-Width-Modulated) VSI (Voltage Source Inverter) is evaluated in this paper based on the fact that a controllable DC-link is available. The study was conducted considering that a VSI should supply a three-phase low-voltage induction motor, with rated power of 500 kW supplied with a industrial voltage of 690 V. Results presented in this paper are based on computer simulations and analytical expressions for calculation of losses. The goal is to improve the overall efficiency on the inverter part of the ASD (Adjustable-Speed-Drive), especially at low speed region without harming the current and torque quality, which should be kept within acceptable values. The circuit topology is a conventional two level IGBT-based three-phase voltage source inverter. A two-level natural sampling PWM with sine-wave modulation was used in order to generate the control pulses for the IGBT’s and hence allowing the output voltage level to be varied. Scalar control of the inverter output voltage was implemented in order to allow the maximum air gap flux in the motor. Using an ideal (without ripple) and controllable intermediate DC-link voltage stage, several computer simulations are accomplished and waveforms are used to evaluate the inverter performance. The objective of the so-called open-loop simulations is to verify how the circuit behaves and to have a simple indication on trend of the results. The final results clearly show that by lowering the DC-link voltage, the switching losses of the inverter can be reduced, especially at low speeds. Also torque quality and total harmonic distortion of the output current are slightly improved.
	Fixed Frequency PWM High Frequency Inverter for Induction Heating using SIT   By H. Ogiwara; M. Nakaoka; M. Itoi	[View]   [Download]
Abstract: This paper describes a quasi-resonant PWM soft switching high frequency inverter using Static Induction Transistors(SITs) under fixed frequency mode. It is designed so as to operate at soft switching PWM condition in order to minimize switching losses, EMI noise and electrical dynamic stresses in its switching power devices over wide output power regulation ranges. The operating principle of this inverter and its PWM controlled power regulation procedure are presented for induction heating. In addition to these, the characteristics of this high frequency inverter in the steady state are illustrated in this paper. The inverter using SIT is trially produced for an induction heating power supply and its performance is evaluated and discussed from a practical point of view.
	High frequency low voltage AC Common bus to feed power converters for vehicle application   By F. Gustin; A. Berthon	[View]   [Download]
Abstract: This paper presents simulation and experimental results of new energy distribution converters using a HF common bus for electrical vehicle applications. In this domain it is necessary to adapt different kinds of voltage sources to loads. One can be found on board of a vehicle, batteries (12V up to 42V), ultracapacitors, electronic devices, electromechanical devices (AC or DC motors). With this new structure we propose to feed different kind of loads from one (or several) DC source. A common AC high frequency bus associated with transformers and converters will control electronic devices or motors. To design this converter a test bench has been realised and Saber software is used as CAD system. For the experimental test bench, a 10 kW AC HF (20kHz) common rail link converter has been designed to feed 400V brushless wheel motor and 100 V DC electronic load from a single low voltage simulated battery source (40 to 67V).
	High Voltage Pulse Generator   By J. Nastran; G. Sersa; D. Miklavcic; D. Voncina; M. Petkovsek; P. Zajec	[View]   [Download]
Abstract: The paper focuses on a new topology of a high voltage source with variable output pulse pattern and featuring an independent adjustment of the magnitude, repetition frequency, pulse duration and polarity. Power stage of the multilevel converter consists of eight individual unipolar sources that can be arbitrary connected in series to obtain the desired output voltage pulse of several amps and with extremely high du/dt.
	IGBT Battery Charger 150 A, 24 V for Tram   By N. Cobanov; I. Bahun; Z. Ivanovic	[View]   [Download]
Abstract: The paper describes an IGBT battery charger for trams. Full bridge topology with IGBTs and ferrite transformer is used. Working frequency is 20kHz. Input voltage supply from catenary voltage with frequent overvoltages and disconnections during operation is especially demanding. Main design guidelines and results of measurements made on a realised charger are given.
	Improved switching condition for a Forward with Active Clamp   By J. Kyyrä; V. Tuomainen	[View]   [Download]
Abstract: Forward with active clamp is an excellent converter topology for a low voltage high current power supply. Efficiency, size and EMI behavior are important design parameters in such a converter. Efficiency and EMI behavior can be improved, for example, by applying soft switching, which reduces switching losses and dv/dt-values in the circuit. Better efficiency allows the designer to design a smaller overall size for the product. It is, therefore, beneficial to turn on switches of the converter so that there is as low voltage over them as possible during the turn-on instant. This paper contains a study of the requirements for low-voltage on switching for the primary switch of a Forward with active clamp. Analytical equations to determine the voltage over the switch prior to turning on and to determine crucial time intervals that are required to lower the voltage to a desired level prior to turning on are provided. It is proposed in the paper that the voltage level prior to turning on can be lowered, for example, by adding an inductor in parallel with the primary winding of the transformer. A number of simulated and some measured results from a 3.4 V 30 A prototype confirm the analysis and verify that the additional component can be used to alter the voltage level over the switch prior to turning on the device.
	Overlapping Current Commutation Inductor Snubber assisted Series Resonant Soft Switching PFM DC-DC Converter with High Frequency Transformer Link and Voltage Mu   By T. Myoi; M. Nakaoka; M. Ishitobi	[View]   [Download]
Abstract: In this paper, the lossless inductor and transformer parasitic parameter-assisted high frequency zero current soft switching (ZCS) inverter type DC-DC converter for the high voltage magnetron drive is developed for industrial and consumer applications. The piecewise linear circuit model represented by the measured v-i characteristics of the high voltage magnetron is considered for the converter analysis. The high frequency transformer is inserted into the output port of the voltage source type full bridge inverter because of the electrical insulation in addition to the output high voltage matching. A highly efficient zero current soft switching DC-DC converter considering the magnetizing current of the high frequency transformer is evaluated and discussed on the basis of simulation and experimental results. Furthermore, the performances of the converter are evaluated by using the measured v-i database of the power semiconductor device (IGBT) with anti-parallel diode and high frequency transformer model are discussed on the basis of simulation and experimental data.
	Power losses evaluation of the half bridge configuration parallel – loaded resonant DC-DC converter controlled with constant frequency   By W. Wojtkowski	[View]   [Download]
Abstract: In this article power losses in the half bridge configuration, parallel – loaded resonant DC-DC converter controlled with constant frequency are considered. A comparison between power losses in semiconductor elements in a DC/DC converter controlled with constant frequency and power losses in equivalent DC/DC converter controlled with variable frequency is presented. A breadboard system has been built to experimentally verify the models and to complement the theoretical work.
	Practical Configuration of Single-Pulse Soft-Switching PFC Converter   By K. Taniguchi; T. Morizane; H. Baba	[View]   [Download]
Abstract: A new driving circuit for the SPSS (Single-Pulse Soft-Switching) PFC converter is proposed. The switching device of a SPSS converter switches once in every half cycle of an AC commercial power source. Therefore, it can be solved many problems caused by the high frequency operation. The proposed SPSS converter achieves the soft-switching operation and the EMI noise can be reduced. The resonant capacitor voltage supplies to the resonant inductor even if the input AC voltage is the vicinity of zero cross voltage. Then, the power factor and input current waveform can be improved without delay time. A new driving circuit achieves the operation of SPSS converter by one switching drive circuit. The proposed converter can be satisfied the IEC standard sufficiently.
	Practical Evaluation of Three-Phase PWM Buck-Mode PFC Rectifier   By Y. Nishida; S. Nakamura; M. Ishikawa; K. Yasui	[View]   [Download]
Abstract: Practical evaluation of a new 3-phase-bridge PWM Buck-Mode (or Current-Source-Type) PFC rectifier for Telecommunications Energy System is introduced. The necessity, the advantages and disadvantages of this type PWM rectifier in the application are briefly discussed first. Then, the new power circuit topology and the modulation scheme to eliminate or mitigate the disadvantages and obtain further new advantages of the PWM Buck-Mode PFC rectifier are introduced. The features of the new rectifier obtained by the new PWM scheme, i.e., - high efficiency (95% at rated load) due to significant reduction of inductance of the dc-inductor (less than 0.5 [mH]), - simple modulation process (even simpler than PWM-boost-type) and - robustness of the line-current waveshaping performance against large dc current ripples (under a small dc-inductor) have been confirmed through experimental results obtained from a 12 [kW] real product. Furthermore, variation of the efficiency and Total-Harmonic-Distortion of the input line current for several dc-inductor arrangements are evaluated, and some hints to improve the performance are described.
	Preferable Methods of Direct Frequency Conversion   By L. Ribickis; I. Galkins; J. Stabulnieks; L. Rutmanis	[View]   [Download]
Abstract: Apart from the classical cycle conversion there exist also other methods of direct frequency conversion. The paper characterizes different developments in this field. The first of the considered conversion methods is based on the approximation of the converter output voltage to the reference (standard) voltage by selection of such a two-value three-phase voltage combination that possesses the most long-lasting integral voltage deviation from the reference in a respective time interval. Here summation of different on-load input voltages is performed by a 3 - phase input voltage regulator. The second method is characterized through the formation of the direct rectified voltage without pulsations theoretical and practical capabilities overview. The third of these control methods is pulse - width modulation that can be performed in matrix structures. The aim of the work is to contribute to development of yet unknown or untapped potentialities of direct conversion. Based on these solutions, the environment-friendly conversion of the necessary electric energy parameters could be expected.
	Selection criteria for the switching intervals in DC-AC converters for harmonic reduction using the Walsh transform   By V. Rodrigo; I. Martínez Teixidor; R. Pindado Rico	[View]   [Download]
Abstract: The use of the Walsh transform allows the calculation of the switching angles as linear equations dependent on the fundamental amplitude. This paper describes a method to select the switching intervals that permits a greater regulation of the fundamental and establishes the criteria for the amplitude reduction of non-eliminated harmonics. Also, it is presented a performance comparison of the Walsh transform method and the programmed harmonic reduction method. Finally, obtained experimental results are shown.
	Soft Commutated DC-DC Power Converter with High Frequency Transformer Secondary Side Control Scheme   By M. Rukonuzzaman; M. Nakaoka; M. Abdullah Al; S. Moisseev; S. Sato	[View]   [Download]
Abstract: This paper presents a novel soft-switching DC-DC power converter with a high frequency transformer link which has two active power controlled switches in full bridge rectifier with capacitor input type smoothing filter. In this DC-DC power converter, ZVS on the power switches of the inverter in transformer primary side and ZCS of active rectifier area in transformer secondary side can be completely achieved by taking advantage of parasitic inductor component of high-frequency transformer and lossless snubber capacitors. Its operation principle and salient features are revealed in this paper. The steady-state operating characteristics of the proposed DC-DC power converter using IGBTs are illustrated and discussed on the basis of simulation and experimental results. Experimental result is evaluated by 2 kw-40 kHz power converter breadboard set up.
	Static Sources for Railway Passenger Wagons   By L. Moroianu; V. Radulescu; V. Serbu; F. Bozas; S. Gheorghe; E. Tudor; D. Vizireanu; C. Goia; I. Strainescu; F. Huzlau	[View]   [Download]
Abstract: The article describes a series of power supplies for railway passenger wagons, power supplies that have different characteristics depending on the car's auxiliary services. The converters fed from the main line of the train (1500Vac, 50Hz) have several outputs: 28Vdc-6Kw, 230Vac-50/60Hz at 6..8Kw and 3x400Vac, 50/60Hz at 10..35Kw. The battery charger and the single-phase and three-phase inverters are controlled by DSP’s based main boards, which increase performances and reduce maintenance.
	Structure and Design of High Power Chopper for DC arc furnace   By Ph. Ladoux; C. Bas; H. Foch; J. Nuns	[View]   [Download]
Abstract: In this paper, the authors present the structure of a new converter for DC arc furnace. This converter uses diode rectifiers associated with choppers to control the arc current. A constant power control is used on the chopper. With this special control, the flicker effect on the power network is very low and the productivity of the furnace can be increased. The sizing of the chopper is discussed and IGCT’s and IGBT’s solutions are compared with SABER software.
	The Conception of the Two-Section Direct Frequency Converter   By R. T. Shreiner; A. I. Kalygin; K. N. Korukov; A. A. Efimov; I. A. Mukhamatshin	[View]   [Download]
Abstract: The paper presents the design conception of a novel frequency converter type − Two-Section Direct Frequency Converter (TSDFC) that results, as direct frequency converter, direct AC/AC electric energy converting and is free from the matrix direct frequency converter switching contradictions. The proposed conception provides sinusoidal network and load currents, input power factor regulating and energy recuperation. A mathematical model of the TSDFC and an adopted space vector modulation control algorithm are worked out. Simulation and experimental results are presented.
	Three-Phase Power Factor Correction Using Extended-Period Quasi-Resonant Boost Converters   By K. K. Law; Y. Lu; Y. P. B. Yeung; K. W. E. Cheng	[View]   [Download]
Abstract: A modular configuration of extended-period quasi-resonant power converters is developed. In this paper, the described converters offer advantageous features such as high power factor, effective in reducing EMI emission, improving overall efficiency, direct output coupling and automatic power factor correction. Also, the zero switching technique is applied to achieve the zero turn on and turn off losses. The operating principles are confined with the computer simulation and the experiment. The results of the converter were analysis and tested to verify the theory.
	Train-Heating Converter   By N. Rister; J. Ungarov; N. Cobanov; B. Furcic	[View]   [Download]
Abstract: In this paper converter for supplying of train-heating line directly from diesel generator of locomotive traction circuit is presented. Converter units are described, and main converter characteristics are outlined. First experience with locomotive upgraded with train-heating converter is presented.