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EPE-PEMC 2006 - Topic 02: POWER CONVERTERS
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	A Dual-Use Snubber Design for Multi-Level Inverter Systems   By Jamal Al-Nasseir, Christian Weindl, Gerhard Herold, Joerg Flotthmesch	[View]   [Download]
Abstract: In this paper a new snubber circuit design for three-level inverter will be presented. The so-called “Dual snubber Circuit” still comprises most of the positive features as a low number of components, improved efficiency due to the low snubber element and power semiconductor losses, reduced over-voltage across the semiconductor devices and no balancing problems. With these advantages, the new dual-use snubber circuit can be used for high power inverters as well as the so-called Flexible AC Transmission Systems (FACTS). The presented snubber circuit has been analyzed and confronted with different existing converter designs using a simulation environment. The simulation results are compared with the output of a standardized three level converter system to verify the advantages of the new snubber design.
	A General Method for Two-Level Bridge Type DC/DC Converter to Three-Level DC/DC Converter   By Junming Zhang, Zhaoming Qian, Lei Miao, Xinke Wu, Chen Zhao	[View]   [Download]
Abstract: This paper studies the approach of derivation of three-level (TL) half-bridge (HB) topology from conventional full bridge DC/DC topology. The derived TL HB topology has same device count and performance as the corresponding full bridge topology, and it is more suitable for high voltage applications. The derivation approach for different control method, i.e. PWM control, frequency control and phase shift control, are presented. Some novel TL HB topologies are proposed based on the approach. The experimental results from these novel topologies verify the validity of the proposed derivation approach.
	A Hybrid Approach to Improve the Robustness against Unbalanced Voltage Supply and Cancel the Common Mode Voltage for a 3-ph Buck-Type Rectifier   By Junaidi Abdul Aziz, Christian Klumpner, Jon C. Clare	[View]   [Download]
Abstract: This paper investigates the utilization of a buck-type current source rectifier as an active front-end stage for an AC/AC converter for applications that require adjustable step-down DC-link voltage with improved upper voltage limit robust to unbalanced voltage supply and additionally eliminating the low-frequency common mode voltage from its dc-link voltage. The proposed solution is to add two asymmetric H-bridge inverters in series with each of the DC-side terminals of the buck rectifier to allow injection of differential and common mode voltage in order to achieve the above goals.
	A Novel Multiphase Multi-Interleaving Buck Converters for Future Microprocessors   By Dodi Garinto	[View]   [Download]
Abstract: This paper presents a new converter architecture as a candidate for future microprocessors. Because the segmentation, phase shifting and merging principles are implemented, the converter architecture allows a multi-interleaving operation and provides automatic current sharing. The multiphase buck converters with multi-interleaving technique perform better than interleaving technique because the multi-interleaving technique can improve current ripple cancellation effect, can extend duty cycle, can improve transient response without increasing current ripple in each cell, and can raise the switching frequency with low switching, gate drive and body diode losses. Moreover, the concept of bypass LC filter between input and output is given to achieve nonpulsating input current and ‘zero’-ripple output current. As a result, based on losses analysis and simulation results, high efficiency, high power density, fast transient response and low-cost 12 V input VRM with output voltage 0.5 to 1 V and output current 100 to 300 A to power future generation of microprocessors can be realized.
	A Novel ZVS PWM FB DC-DC Converter using Auxiliary Resonant Net   By Sun Tiecheng, Zhu Xueqin, Liu Hongpeng, Liang Lian, Gao Peng	[View]   [Download]
Abstract: In conventional converter phase-shifted zerovoltage- switching DC/DC converter, lagging leg losses ZVS capability at light load conditions, and output rectifier diodes operate with hard switching. A novel soft-switching bi-directional converter employing auxiliary resonant net is proposed to solve these problems. The proposed converter can not only achieve soft switching but also eliminate the circulating current by adding an active clamp circuit in the secondary side and using saturable inductor in the primary side. In result, soft-switching operation range is extended. And all switches satisfy ZVS conditions. Synchronous rectifier technique is adopted in the converter, so the conduction loss is eliminated. In this paper TMS320F240 DSP is used as control chip, and the digital control system of the converter is designed. The experimental results show the feasibility of the proposed converter.
	A Selective Harmonic Elimination Approach to DC Link Balancing for a Multilevel Rectifier   By Alan Watson, Jon C. Clare, Patrick W. Wheeler	[View]   [Download]
Abstract: This paper presents a method of using Selective Harmonic Elimination PWM (SHEPWM) as part of a control strategy for a multilevel rectifier. Such a power converter can be applied as part of a solid-state replacement for a distribution transformer. The paper discusses problems with DC link voltage balancing on the converter and how SHEPWM can be manipulated to solve these problems. The full DC link voltage control algorithm is explained and supported by simulations in the SABERTM platform.
	Adaptive Averaged Model Applied to PWM DC-DC Converters   By Carles Jaen, Rafael Pindado, Josep Pou, Antoni Arias, Vicenc Sala	[View]   [Download]
Abstract: An adaptive model applied to PWM DC-DC converters is presented in this paper. Parasitic resistors have been considered in the converter. The coefficients of the state-space matrices, which depend on the parameters of the circuit, are calculated on-line. In the proposed method, the state vector variables should be sampled in real time, and the coefficients of state-space matrices are estimated by means of a simple matrix calculation. The values of the components of the averaged circuit can also be calculated from the matrix coefficients. Therefore, the changes in the values of the parameters of the circuit are quickly updated in the averaged model. As a result, robust control strategies can be implemented by using these models. In this paper, the method is applied to a boost converter. Some simulation results are included in this work to validate the procedure. The estimated matrix coefficients match very well the expected values.
	An Isolated Bidirectional DC-DC Converter based Super-Capacitor Interface for Automobile Electric Power Systems   By Eiji Hiraki, Koji Yamamoto, Toshihiko Tanaka, Tomokazu Mishima, Mutsuo Nakaoka	[View]   [Download]
Abstract: In recent years, power electronic energy storage systems using super capacitor bank have been widely studied and developed for the electronic vehicles. In this paper, a full-bridge/centertapped push-pull circuit-based bidirectional DC-DC converter and its control method are proposed and discussed. From the results of detailed experimental demonstration, the proposed system is able to perform adequate charging and discharging operation between low-voltage high-current super capacitor side and high-voltage low-current side with drive train and main battery. Furthermore, conduction losses and voltage/current surge are drastically reduced by ZVS operation with lossless snubber capacitor in high-voltage side as well as the synchronous rectification in low-voltage high-current super capacitor side.
	An Isolated Single-Phase Rectifier with Power Factor Correction   By Ludvik Kolman, Miro Milanovic, Alenka Hren	[View]   [Download]
Abstract: The paper presents an application example from the large family of the converters with the single-ended switch, or with forward converter. The forward converters with one switch are used for power applications up to 250W. The proposed rectifier construction with one switch and with power-factor correction is derivation from the buck (step down) converter. It also employs the principle of a boost (step up) power-factor-cell. The switching controller is based on that principle as well. The transformer and the output filter are used for galvanic isolation and for the storage of the electric charge. Obtained experimental results for the suggested scheme of 3500W isolated power supply are in good accordance with the simulation results. The comparison of results we have achieved and results reported in the literature confirms the advantage of the proposed rectifier scheme.
	An Optimized Control Technique of Cascaded H-Bridge Multilevel Active Front-Ends   By Gianluca Brando, Adolfo Dannied, Andrea Del Pizzo	[View]   [Download]
Abstract: The paper is devoted to the investigation of a three-phase multilevel H-bridge PWM-Rectifier operating as a first stage of a back-to-back converter in high-power ac drives. First, a predictive control technique is described with reference to a 5-level converter. Starting from properly defined reference values, the algorithm pointed out allows the direct evaluation of the duty-cycles of all the voltage vectors involved in the VSR modulation. By means of the evaluated switching functions, at the end of every sampling interval the line-currents assume values practically equal to the imposed ones. Some unrestrictive hypotheses are introduced in order to efficaciously simplify the analytical expressions. As a second step, in the paper a specially designed modulation technique is shown. In addition to low values of dc-link voltage oscillations and of line-current distortion in steady-state operations together with high values of the power-factor, this modulation technique allows to keep balanced the different capacitor voltages, by properly using the intrinsic redundancy of the converter topology. Numerical results are presented with reference to some significant operative conditions in order to validate the theoretical considerations.
	Analyses of the DC-Link Current in Discontinuous Modulated Three-Phase Inverters   By Folker Renken	[View]   [Download]
Abstract: For reduction of the switching power losses developer of three-phase inverters thinks increasingly about discontinuous modulation strategies. This applies in particular for high power inverters such as for starter generator - or hybrid drive systems. The dc-link current of these discontinuous modulated voltage source inverter are analyzed in this paper. First the dc- and the rms-current of the dc-link circuit are calculated depending on the phase shift angle and the modulation factor. Afterwards the current harmonics of the dc-link circuit for a defined phase shift angle and modulation factor are determined. The calculations are verified by several circuit simulations.
	Calculation of Core Losses in Toroids with Rectangular Cross Section   By Alexander Stadler, Manfred Albach, Alexander Bucher	[View]   [Download]
Abstract: In this paper the electric and magnetic field distribution is investigated in solid toroidal cores with rectangular cross section. An analytical method is used in which the field distribution is calculated by means of orthogonal expansion. Based on the results, the influence of various parameters, such as frequency and conductivity of the core material, on the core losses is discussed. The calculated results are compared with measured data, a good agreement between the two values is achieved.
	Calculation of the DC-bus Capacitors of the Back-to-Back NPC Converters   By Emilio J. Bueno, Santiago Cobreces, Francisco J. Rodriguez, Felipe Espinosa, Marta Alonso, Raul Alcaraz	[View]   [Download]
Abstract: Nowadays the most used multilevel topology for variable-speed wind turbines (WTs) is the a back-to back three-level NPC (Neutral Point Clamped) VSCs (voltage source converter). One of the most critical elements in the design of this type of converters is the DC-bus capacitors. The calculus of these depends on the same factors that the same two-levels topology, and, moreover it is function of a low frequency ripple due to the current by NP point. In this work, the value of these capacitors is obtained from the analytical equations of the DC-bus voltage ripple due to the iDC (DC-bus current) and the iNP (NP current). These expressions are verified through simulation and practical results.
	Comparison of Different Design Methods for the Parallel Resonant Converter   By Alexander Bucher, Thomas Duerbaum, Daniel Kuebrich, Alexander Stadler	[View]   [Download]
Abstract: For the voltage-fed parallel resonant converter several different approaches to investigate its steady-state characteristics exist. The exact solution yielded by stateplane analysis is compared to the approximate solution using fundamental components of the waveforms and to its extension regarding the first harmonic of discontinuous capacitor voltage waveforms. In addition, the accuracy in predicting important design criteria as well as the mathematical complexity of both methods is compared.
	Contact-Less Energy Transfer Carried Out by Resonant-Link based AC-DC Converter   By Miro Milanovic, Mitja Truntic, Joze Korelic, Primoz Slibar, Valentin Koblar	[View]   [Download]
Abstract: The contact less energy transfer requires a transformer with air-gap. So organized transformer suffer with the no-negligible leakage inductance. When hard switching principle has been used the undesirable high surge voltage appears on the semiconductor elements. This paper treats the 500W AC-DC converter based on HF-AC resonant link circuit in order to avoid the high surge voltage problems.
	DC-to-DC Solar Conerterwith Controlled Active Clamping System   By Karl H. Edelmoser, Felix A. Himmelstoss	[View]   [Download]
Abstract: In the field of electrical solar power conversion efficiency is the most important topic. In most applications a special DC-to-DC converter is necessary to couple the solar cells, operating at low DC-voltages, to the inverter’s DClink. These converters with rather low input respectively high output voltage ratings have, due to the high current ratings, a relatively low efficiency. Therefore, a special design is required to adapt the different voltage levels and fulfill the requirements of loss reduction. In this paper, a possible solution for such a specific solar converter is presented: a DC-to-DC converter with a controlled active snubber circuit. The input voltage of a (e.g. battery buffered) solar array (12 V or 24 V) is adapted to a 400 V DC-link, for a local grid power inverter supply. The total power to be managed on the output of the DC-to-DC converter is 500 W (12 V) respectively 1 kW (24 V) in our case. So it makes sense to develop a topology which is also well suited for paralleling several power switches. The structure presented here fulfills all of these topics.
	Dependence of Current Pulsations of Multi-Phase Electrical Machine on Reduction of Winding Pitch and Scheme of Semiconductor Converter   By Mikhail Pronin, Alexey Vorontsov	[View]   [Download]
Abstract: There are sizeable pulsations in system with multi-phase electrical machines and PWM converters. They are increased under reduction winding pitch and decreased under using of multi-stage and multi-level converters and multi-phase paralleling reactors. Use of multi-stage converters allows appreciably to decrease current load of capacitors in DC link.
	Design and Implementation of Two-Channel Interleaved Boost Converters with Integrated Coupling Inductors   By Yanshen Hu, Yunxiang Xie, Huamin Xu, Hao Tian	[View]   [Download]
Abstract: A novel integrated magnetic structure, which enables further reduction in an overall volume and weight of main inductors, the losses of the inductor windings and the channels by integrating the inductors in a single core, is proposed, for the telecom power application, and the operations and practical design considerations of the DC/DC boost converters using interleaved two-channel with CCM operation are investigated with common pi-model.
	Design and Simulation of Fast-Response Filter based on Locomotive Battery Testing System   By Lixia Zhang, Xiangwu Yan, Heming Li, Wei Kang	[View]   [Download]
Abstract: The locomotive battery requests its testing system special requirements of excellent DC charge/discharge current which is sensitive to the fluctuation of the voltage. It also needs a fast transfer speed between charge and discharge state. Simple converters without appropriate filter can’t meet the requirement mentioned above. The decay of the Chebyshev filter increases fast with frequency in the stop-band. As a low-pass filter, it avoids the influence to DC component when filtering low order harmonics. It is very benefit in filter design for bidirectional converters. But the traditional theory for filter-order design is based on the decay of not only stop-band but also pass-band, and the latter is not important in DC filter design. This paper extracts an equation of filter-order design for bidirectional converters which care more on the decay in stop band and introduced a method for enhance the response speed between bidirectional transitions. The theoretical deduction and simulation proved the practicability of the methods.
	Design of a High Voltage Direct Resonant Converter   By David J. Cook, Jon C. Clare, Patrick W. Wheeler, Jan S. Przybyla, Robert Richardson	[View]   [Download]
Abstract: This paper is concerned with the development of a new type of power supply for high power RF applications for CW operation. Losses are reduced by the use of zero current switching. This allows for a high operating frequency and minimised transformer and filter size. Preliminary practical results have been found to be promising, with design of the resonant circuit and isolating transformer being fundamental to operation of the circuit.
	Design of Flyback Converter with Voltage Driven Synchronous Rectifier   By Bong-Suck Kim, Ho-Seon Ryu, Man-Su Shin, Joo-Hyun Lee, Ik-Hun Lim	[View]   [Download]
Abstract: In low output voltage dc-dc converters, power losses is significant, due to the conduction of rectifying device. Using synchronous rectifiers instead of the conventional fast recovery diodes is an effective solution to this problem in most topologies. However, for synchronous rectifier to perform effectively, it requires an external gate drive with proper sensing and timing control circuits. This can increase the complexity and cost in converter hardware implementation. Design of Flyback Converter with Voltage Driven Synchronous Rectifiers is proposed. The proposed SR is the voltage driven synchronous rectifier (VDSR), which operates depending on the voltage drop across the drain and source of the MOSFET. Experimental results for the 85W (12V/7.1A) proposed converter are shown.
	Discrete-Time Model for PWM Converters in Discontinuous Conduction Mode   By Mohammed S. Al-Numay	[View]   [Download]
Abstract: A new discrete-time model for pulse-width modulated (PWM) converters operating in the discontinuous conduction mode (DCM) which leads to the exact discretetime mathematical representation of the averaged values of the output signal is proposed. This model can also provide the averaged values of other internal signals with little increase in simulation time. The use of piecewise linear (PL) iteration method dramatically reduces the simulation time, while introducing a little simulation approximation. It is compared to other existing models with respect to accuracy and simulation speed through a numerical example of boost converter. This method gives the exact one-cycle-average (OCA) values of signals at switching instants if PL iteration is not used and, by far, more accurate than other methods if PL iteration is not used. Numerical simulations demonstrate the superiority of the proposed method in terms of accuracy and speed.
	Dynamic Thermal Simulation of Power Devices Operating with PWM Signals in a Three-Phase Inverter Drive System   By Zhongfu Zhou, Salah Khanniche, Nebojsa Jankovic, Stephen Batcup, Petar Igic	[View]   [Download]
Abstract: Fast power devices thermal simulation method based on averaging power losses over each cycle of PWM switching frequency is presented in this paper. For implementing a long real time dynamic thermal simulation of power devices, device power losses during transient process and static characteristics are defined as a function of device conduction current and junction temperature, and are represented by a lookup table. By carrying out the circuit electrical simulation, the device conduction current can be obtained. By combining the device conduction currents, global device temperature (GDT) and the data from the lookup table, the average power loss over each cycle of PWM switching frequency is then calculated for carrying out the thermal simulation. With the proposed method, a relative large simulation time step can be employed and simulation speed can be increased dramatically. The method is suitable for a long real time thermal simulation for complex power electronics systems.
	Dynamical Characterization of Voltage-Mode Controlled Buck Converter Operating in CCM and DCM   By Mikko Hankaniemi, Matti Karppanen, Teuvo Suntio	[View]   [Download]
Abstract: The paper investigates the dynamical differences imposed by the continuous and discontinuous operation modes under direct-duty-ratio or voltage-mode control. The safe load and source profiles for CCM and DCM converters are derived. It is shown e.g. that the DCM converter is more prone to instability caused by the load, while the CCM converter is sensitive to capacitive loads. The safe source profiles are shown to be almost the same for both converters but the source interactions caused e.g. by EMI-filter are shown to be smaller in the DCM converter at the vicinity of the converter output filter resonant frequency. Even if a larger magnitude variation as function of input voltage is observed in the control-to-output transfer function in DCM, the variation of magnitude in the loop gain can be made equal for both conduction modes by a proper controller design.
	EMI-Filter Interactions in a Buck Converter   By Mikko Hankaniemi, Matti Karppanen, Teuvo Suntio	[View]   [Download]
Abstract: The paper investigates the effects of EMI filter in the dynamics of a buck converter. It is shown theoretically that the EMI filter may increase significantly the load sensitivity of the voltage-mode-controlled converter but the peak-current-mode-controlled converter is quite insensitive to the EMI filter interactions. Experimental validations are carried out using a buck converter under three different control modes - voltage-mode, peak-current-mode and output-current-feedforward peak-current-mode control. The investigations show that the phenomenon causing the instability under peak-current-mode control is the negativeresistor– oscillation (NRO) phenomenon, and confirm also the excess EMI-filter sensitivity of the voltage-mode controlled converter.
	Experimental Results for the Single Capacitor Single Inductor Active Snubber   By Gerardo Ceglia, Victor M. Guzman, Maribe G. de Guzman, Julio Walter	[View]   [Download]
Abstract: In this work the practical results obtained with the Single Capacitor Single Inductor Active Snubber (SCSIAS) circuit using the Diode Bridge Switch Configuration are presented, proving the advantages of this proposed topology, which can be implemented with minimum component count. The SCSIAS configuration ensures that the main power devices undergo a ZVS offcommutation and a ZCS on-commutation, minimizing commutation losses in all operating conditions. Snubber topology also ensures that most auxiliary commutations take place under zero voltage/zero current conditions.
	Fast Magnet Power Supplies for Dynamic Proton Beam Control for Tumor Treatment   By Rene Kuenzi, Felix Jenni	[View]   [Download]
Abstract: A new tumor treatment facility is currently under construction at the Paul Scherrer Institute, Switzerland. The treatments are performed by actively scanning a threedimensional target volume, the tumor, with a thin proton beam, depositing a defined energy dose. To allow multiple rescanning of moving target volumes without increasing the treatment time, the proton beam is deflected rapidly and independently in two directions by means of dipole magnets. For that purpose, two highly dynamic magnet power supplies were developed and commissioned. This paper describes the requirements, some design considerations and the test results of these power supplies.
	General Analysis of Multi-Phase Systems based on Space Vector Approach   By Gabriele Grandi, Giovanni Serra, Angelo Tani	[View]   [Download]
Abstract: In this paper the space vector approach is applied to the analysis of multi-phase electric systems. This approach builds on an existing but non systematic knowledge base, partially available in literature. In particular, power and RMS are expressed in terms of space vectors, and a comparison is carried out with respect to the Fortescue’s symmetrical components in the case of n-phase circuits with sinusoidal waveforms. The use of space vectors allows real time analysis and regulation of both multi-phase converters and multi-phase machines with an elegant and effective vectorial approach.
	High-Frequency Transformer Isolated Soft-Switching DC-DC Converter for Fuel Cell Cogeneration System   By Shinichiro Sumiyoshi, Hideki Omori, Yoshimichi Nakamura, Nozomi Tan, Yasuyuki Nishida	[View]   [Download]
Abstract: A high-frequency transformer isolated soft-switching DC-DC converter for fuel-cell cogeneration systems with utility-interactive inverter is investigated. The new type dc-dc converter offers a high efficiency in a wide power range, from rated to low power, by means of a new soft-switching topology. A prototype of the DC-DC converter and utility-interactive inverter cascade system is practically evaluated to confirm the fine performance.
	Investigation on Switching Function Algorithm of Matrix Rectifier under Abnormal Power Supply Conditions   By Xi-jun Yang, Peng-sheng Ye, Xing-hua Yang, Jian-quan Wang, Luan-guo Zhang	[View]   [Download]
Abstract: Based on the switching function algorithm of the traditional matrix converter, that of matrix rectifier (MR) is derived in positive and negative phase sequence with fourquadrant capability. Afterward that of MR under unbalanced input voltage conditions is also derived by detecting and using instantaneous values of input voltages. But the gained algorithm in the case is not fully suitable for the unbalanced conditions without any modification, such as amplitude unbalance, initial phase angle unbalance and waveform distortion. This is mainly because the constraints of switching function algorithm would be destroyed, even worse at high desired DC output voltage. The constraints include two aspects: the sum of relative switching functions for an output phase is always zero and the value of each switching function is within [0, 1]. At this point, a simple process method is proposed to meet the constraints to a large extent by means of regulating each switching function according to the actual unbalance before use. Eventually thorough simulations are performed with Simulink6.0 under balanced and unbalanced conditions, inclusive of input voltage and input current waveforms, output DC voltage waveforms, etc. The simulation results prove the theoretical analysis.
	Iron Losses under Voltage Excitation by Novel and Classical Frequency Converters   By Juan Sagarduy, Anthony J. Moses, Fatih J Anayi, Jon C. Clare, Patrick W. Wheeler	[View]   [Download]
Abstract: Iron losses due to flux harmonics in stator cores of Pulse-Width-Modulation [PWM] back -to-back inverter-fed induction motors have a major effect on system efficiency. A new generation of direct ac-ac matrix converters offer important advantages over classical frequency converters such as absence of bulky and temperature sensitive dc-links and possible adjustment of power factor. The paper presents experimental results of magnetic losses in three nonoriented electrical steels magnetised under different types of voltage excitation. Characteristic waveforms of real 3x3 matrix converter and PWM inverter under various modulation indices were recorded and used by a signal generator feeding a Single Strip Tester [SST] used to measure iron loss. Harmonic distortion, contribution of high frequency components and sideband effect were analysed. Influence of flux density curve as well as form factor of voltage excitation were also investigated.
	Low Power Multiple Output DC Supply – Part I: Flyback Converter with Wide Input Voltage Range   By Danijel Voncina, Marko Petkovsek, Janez Nastran, Peter Zajec	[View]   [Download]
Abstract: The paper deals with a front-end topology of a low power switched-mode power supply intended for a plug and play use. During its design, a special attention has been paid to a simple and cost effective solution confronted with a wide input line-voltage range (57 ÷ 3× 240)⋅(1 ± 0.2) VRMS and with the frequency range from 40 Hz to 65 Hz. Such extreme demands are particularly of interest in industrial applications where devices should be supplied either from the single- two- or three-phase network. In order to reduce human errors and production cost, no mechanical switches are allowed. The paper proposes a novel concept of the Flyback converter that solves the designated task with variable turns ratio of the transformer, while keeping the switching frequency constant. The implemented transformer with its control circuit enables on-line adaptation to the temporary value of input phase-voltage. As a consequence, voltage stress of implemented switching transistors is also reduced.
	Low Power Multiple Output DC Supply – Part II: Crossover Voltage Control in Multiple Output DC Supply   By Peter Zajec, Danijel Voncina, Janez Nastran, Marko Petkovsek	[View]   [Download]
Abstract: The paper proposes a new topology for multiple outputs DC supplies allowing for implementation of commercial low power AC/DC converters. A special attention is paid to supplying mixed analogue/digital circuits that give rise to permissive voltage deviations when discontinuous load currents are applied. To avoid this problem, the paper is particularly concerned with the backend requirements of the power supply stage generally generating two system voltages, i.e. the bipolar voltage (± 12 V) and the unipolar voltage (+5 V), the latter supplying digital circuits. Here, the main concern is to ensure efficient output voltages ranging within set tolerances of ± 5 % and ± 2 %. This requirement is to be satisfied even in the case of short cutouts of net voltage at no system functionality minimization. The described back-end power stage topology consisting of two buck converters generating three voltages controlled with only one secondary side PWM controller has proven to be appropriate for the achievement of this target. With an adequate crossover control of output voltages the component and manufacture costs are kept on the low level. Experimental results confirm the minimization of output voltages dependence on output currents discontinuity. Moreover, voltage ratings as well as the size of electrolytic capacitor providing back-up energy are reduced, too.
	Matrix Converter Induction Motor Drive   By Jiri Lettl	[View]   [Download]
Abstract: The presented paper deals with the matrix converter induction motor drive with emphasis on the PWM modulation strategies design. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. They possess many advantages compared to the conventional voltage or current source inverters. A matrix converter does not require energy storage components as a bulky capacitor or an inductance in the DC-link, and enables the bidirectional power flow between the power supply and load. The most of the contemporary modulation strategies are able to provide practically sinusoidal waveforms of the input and output currents with negligible low order harmonics, and to control the input displacement factor. Sophisticated pulse width modulation strategies in terms of various optimization criteria are known in case of indirect frequency converters, whereas both the inverter and the rectifier can be operated with pulse width modulation. The instantaneous state of both the output and the input converter waveforms depend at any time on the switch state of the converter power switches. Suitable switch states sequence of the nine matrix converter switches can be indirectly derived from the given switch states sequence of the twelve switchers of the indirect frequency converter.
	Matrix-Reactance Frequency Converter based on Buck-Boost Topology   By Zbigniew Fedyczak, Pawel Szczesniak, Marius Klytta	[View]   [Download]
Abstract: This paper deals with a three-phase direct matrix-reactance frequency converter (MRFC) with buckboost topology and includes a description of its topology and operation plus presentation of the results of an investigation of its properties. Presented too is a conceptual development of the frequency converter based on a buck-boost matrixreactance chopper (MRC) with source switches arranged as in a matrix converter (MC). The averaged state space method is used in the analysis. In the control circuit, a classical control strategy, attributable to Venturini, is used for the study of the presented conception. The simulation test results are also presented in order to verify the results of the theoretical analysis. Furthermore, simplified description of the experimental setup, which will be used in next investigations is also presented.
	Modified Interleave Winding of Transformer to Improve SMPS’s Performance   By Babak Abdi, Jafar Milimonfared, Seyed Hamid Fatthi	[View]   [Download]
Abstract: This paper presents a new method of modifying interleave winding so the transformer leakage inductance and winding resistance, which are the main parameters in switch mode power supplies (SMPSs) design. The results are applied to the design of a single switch forward SMPS with an output of 1500 watts and good result as 92.5% efficiency and high reliability achieved.
	Multi-phase Converter for Wide Range of Input Voltages with Integrated Filter Inductor   By Michael Stadler, Johannes Pforr	[View]   [Download]
Abstract: This paper presents results of the analysis and design of a multi-phase buck converter with integrated filter inductor when operated with a wide range of voltage conversion ratios. Included are the analysis of the converter input and output currents to optimize the required filter capacitors, the analysis and design of the integrated filter inductor and results of a state-space controller that provides robust control of the output voltage for the required wide range of input voltages and loads ranging from full to no-load conditions. The influence of the wide range of input voltages to the operation of the converter is demonstrated. A prototype converter with four phases and an integrated filter inductor has been built and tested to verify predictions from the analysis.
	Multicell DC/DC Converter with DSP/CPLD Control. Practical Results   By Stanislaw Pirog, Marcin Baszynski, Jaroslaw Czekonski, Stanislaw Gasiorek, Andrzej Mondzik, Adam Penczek, Robert Stala	[View]   [Download]
Abstract: The paper presents practical investigations of dc/dc multilevel, multicell converter with DSP/CPLD control. A flying capacitors topology, natural balancing process and method of control of three-cell dc/dc converter are presented. Practical realization of the controller with use of programmable logic, discrete regulators in signal processor, procedures of initial flying capacitors charging, protection and turn-off the converter are described.
	MV Grid Reactive Power Compensator based on a Four Level NPC Converter   By Gaizka Almandoz, Gonzalo Abad, Izaskun Zamakona, Mikel Telleria, Mikel Zulaika, Francisco Jose Pazos	[View]   [Download]
Abstract: The present research study is focused on the design, development and validation of a device based on multilevel converter for medium voltage distribution networks. It regulates the reactive power exchanged with the grid (up to 3 MVAR), allowing to achieve the following objectives: Network voltage regulation, reactive power compensation and power factor control. The device is composed by an IGBT based 4 level NPC (Neutral Point Clamped) converter. The adopted modulation strategy is the space vector modulation and it takes into account the bus capacitor voltage balancing. The reactive power regulation will be carried out by a vector control technique. The correct behavior of the electronic system connected to a radial distribution network is validated in simulation. Firstly the behavior of the system is analyzed under normal operation conditions. After that, its robustness is analyzed when sudden network voltage changes occur.
	Parallel Connected Voltage Source Inverters without Intermodule Reactors   By Toni Itkonen, Kimmo Rauma, Hanni Saren, Ossi Laakkonen, Olli Pyrhonen, Pertti Silventoinen	[View]   [Download]
Abstract: Connecting power converters in parallel is useful method for solving high power requirements. Parallel structure without intermodule reactors would be desirable because of its low cost and compact size. Due to the finite tolerances in power stages and delays in control circuits, switchings of the parallel connected units will not be absolutely simultaneous. Asynchronous switchings leads to a current imbalance at the parallel inverter legs. In the ideal situation switchings would be exactly simultaneous and each leg would take the same amount of the load current. In this paper simulation and measurement results of the parallel connected voltage source inverters (VSI) without intermodule reactors are presented. These results show that a method is needed to synchronize the parallel power converters to get a full use of the parallel system.
	SEPP-ZVS High Frequency Inverter for Induction Heating using B-SIT with Extremely Low On-resistance   By Takuya Sugai, Hiroyuki Ogiwara, Misao Itoi, Masataka Tatsuta, Mutsuo Nakaoka	[View]   [Download]
Abstract: B-SIT has an advantage that its on-resistance is extremely low compared to those of other power semiconductor switching devices. Accordingly, we can suppress its conduction losses during large current operation. Then, high conversion efficiency is expected when B-SITs are utilized as the switching devices of high frequency inverters. Here, we adopt newly developed BSITs which have the maximum ratings 150V/50A and prepare a breadboard of a conventional single-ended pushpull (SEPP) high frequency inverter, which has a simplified circuit constitution and relatively wide range applications. This paper describes the characteristics of B-SIT on the basis of the experimental results of the breadboard. Its operational frequency is fixed at 50 kHz with PWM control technique for output power regulation. Its load is induction fluid heating systems for super-heated-steam production.
	Simulation Methods for 3x3 Matrix Converter   By Alvis Sokolovs, Ilja Galkin, Oskars Krievs, Juhan Laugis	[View]   [Download]
Abstract: Simulation strategies for a classical three phase matrix converter are presented in this paper. A simple control method, which can be realized on the basis of the table functions and elementary calculation algorithms, is described. Both - MATLAB and more detailed schematic simulation in PSpice environment are covered. The simulation results have confirmed the validity of the proposed control method
	Soft-Switching PWM DC-DC Converter for High Power Applications   By Jaroslav Dudrik, Juraj Oetter	[View]   [Download]
Abstract: Soft switching full-bridge phase-shifted PWM converter using IGBTs with auxiliary transformer is presented in this paper. Zero-voltage and zero-current switching for all power switches is achieved for full load range from no-load to short circuit by adding active energy recovery snubber and auxiliary circuits. The principle of operation is explained and analysed and experimental results are presented. The properties of the converter are verified on a laboratory model.
	Steady-State Analysis of a Novel Forward-Flyback-Mixed Converter   By Yoshito Kusuhara, Tamotsu Ninomiya, Shin Nakagawa	[View]   [Download]
Abstract: Based on the conventional forward converter, the transformer’s magnetizing inductance is made small, and a reset winding of the transformer is moved to the secondary side, and furthermore, the anode terminal of the freewheeling diode is connected at a different point. Then a novel topology of DC-DC converter is proposed, and its power efficiency is predicted to be improved. This converter has both operations of forward and flyback manners, and both of two diodes in the output side are maintained to be ON for a portion of the switching period. This operation results in the zero ripple of the output inductor current. This novel converter is confirmed to have some prominent features of withstandvoltage reduction for the main switch and ripper reduction of the output inductor current. As a result, this converter obtains a higher efficiency over the conventional forward converter. This paper describes its basic operation, and analyzes the steady-state characteristics by means of the extended state-space averaging method. The analytical results are confirmed experimentally, and an experimental result of a high efficiency of 94% was obtained for the input voltage of 140V and the output load of 18V and 4A.
	Study of Stabilization Design for On-Board Distributed Power Architecture   By Seiya Abe, Masahiko Hirokawa, Toshiyuki Zaitsu, Tamotsu Ninomiya	[View]   [Download]
Abstract: The bus architecture consisting of bus converter and Point of Load (POL) is generally used as distributed power supply system for IT infrastructure equipments. The most important factor is the system stability in bus architecture design. The overlap between the output impedance of bus converter and input impedance of POL causes system instability, and it has been an actual problem. Increasing the bus capacitor, system stability can be reduced easily. However, due to the limited space on the system board, increasing of bus capacitors is impractical. The urgent solution of the issue is desired strongly. This paper presents the stability design for on-board distributed power system consisting of full-regulated bus converter and POLs. The output impedance of the bus converter and the input impedance of the POL are analyzed, and it is conformed by experimentally for stability criterion. As a result, the standard of the discrimination of stability on a frequency response of input and output impedance is clarified. Furthermore, the design process for system stability is proposed.
	The Effect of the Transformer Winding on the Reliability of Switching Power Supplies   By Babak Abdi, Mohammad Bagher Menhay, Leila Yazdanparast, Jafar Milimonfared	[View]   [Download]
Abstract: Today reliability is one of the serious requirements of electronic systems, and, using that, the number of system failures, repair cost, guarantee, etc are estimated by this factor. In this paper, the reliability of a switching power supply (SMPS) is evaluated and the effect of the type of transformer winding on the reliability is fully discoursed. It is proven that the interleaved winding will increase the reliability of SMPS’s.
	The Inductance Set Design in Wide Bandwidth Multiswitching Converters   By Maria Stefania Carmeli, Francesco Castelli-Dezza, Marco Mauri, Gabrio Superti-Furga	[View]   [Download]
Abstract: The present paper focuses on multiswitching converters, widely used in high power applications. Power system performances in terms of switching frequency and current ripple strongly depends on output inductance. This paper analyses the effect of output inductances on global and parallel branch current with the aim of exploiting multiswitching system potentialities.
	Theoretical and Experimental Analysis of the Line Current in Matrix Converters   By Domenico Casadei, Mirko Ghirelli, Giovanni Serra, Angelo Tani, Luca Zarri	[View]   [Download]
Abstract: In this paper a general approach for the determination of the line current harmonic content in matrix converters is presented. The input disturbances, such as voltage unbalance and voltage harmonics, are considered as perturbations of the fundamental component, and a small-signal analysis is used to determine the spectrum of the line current. The proposed analytical approach has a general validity, because it takes into account the effects of the line and filter impedance, the supply harmonics and the input current modulation strategy as well. Hence, it could be usefully employed to evaluate the line current quality in the point of common coupling for different filter topologies and supply distortions. Experimental results are given to confirm the analytical solution.
	Three-Level Rectifier Fed Four-Level Inverter for Electric Drives   By Nikolay Lopatkin, Gennady Zinoviev, Alex Usachev, Helmut Weiss	[View]   [Download]
Abstract: A special four-level three-phase diode clamped inverter fed by a correspondingly adapted untypical threephase rectifier with two typical transformers is presented. The three-level rectifier is formed by consecutive connection of three rectifiers under the circuit of Scott for the bi-phase orthogonal voltage received from corresponding windings of two three-phase transformers. The inverter is realized by 4,5kV IGBT modules and provides a voltage of 6 kV (RMS) for a high power induction machine without transformer. The dependences of THD and integral values of THD of output voltage are simulated and shown for simple variants of three-carriers PWM and SVM.
	Three-Phase Z-Source AC-AC Converter   By Xupeng Fang	[View]   [Download]
Abstract: The paper proposes a novel three-phase Zsource ac-ac converter topology, presents its circuit configuration, operating principle and control method. The proposed ac-ac converter employs a unique LC network to suppress the over-current and surge voltage due to the shoot-through or the opencircuit of the two switches. By controlling the duty cycle, the Z-source can provide buck-boost function, produce greater or less voltage than the line voltage. As a result, the new Z-source ac-ac converter reduces line harmonics, improves power factor and reliability. Analysis, simulation and experimental results are presented to demonstrate these new features.
	Up-to-date, Integrated, Multifunctional Energy Converters of Welding Technologies   By Miklos Horvath, Jozsef Borka	[View]   [Download]
Abstract: The paper summarises the most wide-spread welding technologies and up-to-date energy converters for welding. Besides, it discusses the sensing, measuring, commanding and controlling problems of energy converters for welding, taking the multifunctional features into consideration. Some measurement results for both steadystate and transient conditions are presented, as well.
	Voltage Ripple Cancellation in Buck Converter based on Hybrid Structured Connection   By Aljaz Kapun, Miro Milanovic, Joze Korelic	[View]   [Download]
Abstract: In applications where size and efficiency are critical switched mode power supply converters are used. A switched mode DC-DC buck converter or step-down converter use output filter capacitor to reduce output voltage ripple. To reduce size of buck converter, the elimination of the capacitor must be done. Instead of the capacitor the structure with additional linear amplifier is introduced for output voltage ripple reduction. The amplifier reduces ripple in output current and consequently ripple in output voltage. The structure operation is theoretically investigated and verified by simulations and experimental results.
	Wide Input Voltage Isolated DC-DC Converter with Interleaving Control   By Wei Lu, Xinke Wu, Zhengyu Lu, Zhaoming Qian	[View]   [Download]
Abstract: In this paper, a novel interleaving control strategy for dc/dc converters is proposed and applied to a new isolated dc-dc converter configuration with two paralleled half-bridge structure at the primary side and a new rectification method at the secondary side of the transformers, aiming at to optimize the design of transformers and reduce the rectifier diodes voltage stresses. The concept of this new control scheme is to interleave the gate signals with an angle in two identical PWM controlled half-bridges. The two half-bridges work alternatively when the input voltage is high, but in series when the input voltage is low. The rectifier diode voltage stresses are reduced distinctly. The operation principle and key features of the proposed interleaving control scheme are illustrated and experimentally verified by a 50V/10A prototype.