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EPE 1991 - 38 - Session 4.5: RESONANT CONVERTERS
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	ANALYSIS OF A SERIES-PARALLEL-LOADED RESONANT-CONVERTER WITH "TERTIARY SIDE RESONANCE" FOR HIGH OUTPUT POWER AND LOW OUTPUT VOLTAGE   By H.-P. Lüdeke; N. Fröhleke; H. Grotstollen	[View]   [Download]
Abstract: A series-parallel-loaded resonant-converter operating above resonance is proposed where the parallel tank capacitor is connected to the resonant circuit through a tertiary transformer winding. Thereby a part or the leakage inductance of the transformer is utilized as resonant element and by proper choice of the transformer ratio the ac-current in the parallel tank capacitor and the capacitor volume is reduced. General solutions for the state variables, converter gain, and component stress are obtained by an analysis in the time domain for steady-state operation including effects of the high-frequency transformer.
	SOURCE CURRENT CONTROL OF THE SIX SWITCH AC-AC SERIES-RESONANT POWER CONVERTER   By Freddie de Beer; Henk Polinder; J. Ben Klaassens	[View]   [Download]
Abstract: Three-phase AC-AC series-resonant converters with power-pulse modulation and internal frequencies of 10 kHz, suited for multi-kilowatt power levels, have excellent characteristics like the generating of multiphase bipolar waveforms with reversible power flow, low distortion and fast system response. An alternative circuit configuration for the series-resonant AC-AC converter with only 12 thyristors has been presented recently. This paper presents a method to control the source currents to decrease the harmonic distortion and control the power factor of the converter. Simulation results indicate that the harmonic distortion of the first nine harmonics of the source current is reduced from 24.5 % to 2.2 %. The power factor of the converter 's source current is controllable between 1.0 and 0.1, leading and lagging as well.
	AC-AC CONVERTER WITH SOFT-SWITCHING   By J. Ben Klaassens; Marinus P. N. van Wesenbeeck; Hian K. Lauw; Marc P. Tan	[View]   [Download]
Abstract: A class of polyphase power converters is presented which operate with a high frequency resonant link between the input and output switching matrices. The incoming low frequency power is transformed to a substantially higher frequency directly . The high frequency link includes series-resonant circuits which facilitate the natural current commutation of electronic switching elements like thyristors. The energy is transformed from the high-frequency link to a lower frequency output circuit via another switching matrix. A new method of switching (soft-switching) is introduced to eliminate the dynamic losses. The innovative aspects are in the techniques used to control the flow of energy into and out of the resonant LC circuit. The new multi -purpose power converter can transform electric energy from a polyphase AC source to an AC load of another voltage, frequency or waveform, including DC. The direction of the flow of power is reversible.
	3.0 KW AT 2.2 MHz WITH A RESONANT MOSFET INVERTER   By G. Corticelli	[View]   [Download]
Abstract: We developed a resonant very high-frequency inverter for industrial heating and micro-soldering applications, by using a FULL-BRIDGE final configuration. Converter structure and control circuits were selected in order to maximize efficiency and reduce dimensions. The control scheme allowed proper final-stage operation under every load conditions and efficient power regulation. Design criteria have been selected with emphasis for component choice and layout precautions to optimize high power/high frequency performances. Experimental measurements of the main electrical parameters and waveforms have been compared with a theorical model, and an overall estimate of the system performances have been performed.
	OPTIMIZATION OF SWITCHING FREQUENCY FOR QUASI-RESONANT CONVERTER   By M. Bensoam; E. Laveuve; J. P. Ferrieux; H. Morel	[View]   [Download]
Abstract: This paper presents the high frequency behaviour of Quasi-Resonant Switch Mode Power Supplies. First, the two modules of commutation (zero-current-switching and Zero-Voltage-Switching) are studied and compared on an elementary commutation cell using MOSFET technology. These results are compared with simulation taking into account switching transitions. The next stage refers to passive components (transformers inductors and capacitors). Three different transformers have been built and the losses have been measured with a calorimeter for several switching frequencies. These results will help the choice of frequency for quasi resonant converter.
	RESONANT SWITCHED MODE PRE-CONVERTER FOR HIGH FREQUENCY INDUCTION HEATERS   By J. Pforr; L. Hobson	[View]   [Download]
Abstract: A single-ended parallel-resonant DC-DC Converter has been analysed and its suitability assessed for application as a high voltage pre-converter for RF induction heaters. A design procedure has been fomulated and an example is given of a 3kW dc- dc converter. This design has been simulated using a circuit simulator program called PSPICE. Finally, a prototype has been built and tested to verify the theoretical results. At its maximum operating frequency of 40kHz, the prototype converter delivers a peak output power of 3kW with an output voltage of 3kV. It achieves a wide range of output power control (3kW - 460W) by changing the converter operating frequency in a band between 40kHz and 20kHz. The converter input current waveform, drawn from the 240V mains supply, is nearly sinusoidal and the power factor approaches unity. Experimental results presented show close correspondence with theoretical predictions .
	DESIGN OF A 20 KVA RESONANT DC LINK IGBT INVERTER ON THE BASE OF EXPERIMENTAL DEVICE EVALUATION   By A. Mertens	[View]   [Download]
Abstract: The resonant DC link inverter (RDCLl) is one of the most promising soft switching topologies recently proposed, with a potential to replace PWM voltage source inverters in medium to high power applications. The performance attainable with such a circuit depends largely on the behaviour of the devices employed. Previous designs are based on simplified models of the switching behaviour of lGBTs. However, practice has shown the limitations of such models. This paper presents a detailed experimental evaluation of an IGBT when used in zero voltage switching circuits. Special consideration is due to the losses in a resonant DC link inverter application. Analytic approximations of the measured switching and conduction losses are used in a design study of a 20 kVA RDCLI. Even under restrictive worst case assumptions, the RDCLI is seen to be capable of switching at a link frequency of 50 kHz to 60 kHz, without compromising inverter efficiency.
	Optimum Quantum Sequence Control of Quantum Series Resonant Converter for Minimum Output Voltage Ripple   By Woo H. Kwon; Gyu H. Cho	[View]   [Download]
Abstract: A new control scheme named optimum quantum sequence (OQS) control which minimizes the output voltage ripple of the quantum series resonant converter (QSRC) is proposed. This control scheme is so general that it is irrelevant to the magnitudes of circuit elements as well as to the input/output voltages so far as it is operating in the continuous conduction mode (CCM). This feature is verified by appropriate simulations.
	COMPARATIVE STRESS ANALYSIS OF ZERO-CURRENT-SWITCHED QUASI-RESONANT HALFBRIDGE TOPOLOGIES   By H.-P. Lüdeke; N. Fröhleke; H. Grotstollen	[View]   [Download]
Abstract: Device voltage and current stress analysis is performed for zero-current-switched (ZCS) quasi-resonant (QR) halfbrigde power converters. Results are normalized in terms of converter specifications and dimensionless design constraints to permit stress comparison in terms of peak-, rms- and average-quantities for three halfbrigde converter circuits without any detailed design - hence the stress diagrams obtained represent a powerful selection guide and design tool.
	A NEW METHOD TO CONTROL INVERTERS OPERATING IN QUASI-RESONANT MODE   By K. Elloumi; H. Pouliquen; C. Bergmann	[View]   [Download]
Abstract: This paper examines voltage quasi-resonance when a resonant (lr, er) stage is used in conjunction with a voltage inverter linked to an inductive load (L, R). The study analyses constraints inherent to this type of control and details the equations of the various switching phases. To achieve sinusoidal load current, conventional control methods have a sampling period equal to a period of the resonant interface, which leads to high number of pulses. This paper proposes new PWM control methods based on nonlinear, recurrent modellings of the system. For equivalent performance, these control methods significantly reduce the number of pulses and enables the use of naturally slower digital controls.
	Soft Switched Matrix Converter for High Frequency Direct AC-to-AC Power Conversion   By Jung G. Cho; Gyu H. Cho	[View]   [Download]
Abstract: A soft switched matrix converter is proposed by adopting the zero voltage switching technique being used in some resonant pole inverters. High operating frequency with safe and efficient switching improves dynamic and spectral performances and simplifies protection logics and snubber networks. Further, it can be implemented using simple analog circuits, having similar transfer characteristics to those of the modern pulse width modulated matrix converters such as, maximum voltage transfer ratio and unity input displacement factor. Analyses, design and simulation results are presented to verify the operating principle.
	A NEW QUASI-RESONANT DC LINK INVERTER   By Jin-Woo Lee; Jeong-Joon Lee; Seung-Ki Sul; Min-Ho Park	[View]   [Download]
Abstract: This paper deals with a new quasi-resonant dc link inverter with only one additional switch connected between dc voltage source and resonant inductor. First, circuit states for given switching and load current states are analyzed and classified into one of three operating modes, i.e., free-wheeling, inverting, and rectifying mode, The operating principle of the proposed inverter at inverting mode is analyzed by using the analogy to the DC/DC buck ZCS-QRCs. This analysis shows that the stable oscillation of resonant link and the soft swïtching of both the added switch and the inverter are guaranteed by only appropriately controlling the inserted switch according to the circuit state. Compared with the known resonant dc link inverters with well controlled oscillation of resonant link, the proposed inverter is the simplest one from the viewpoint of power circuit. Based on the analysis a proper current control algorithm is suggested. Operating characteristics of the proposed inverter with about 50 (KHz) resonant frequency are verified through simulation and experiment.
	A NEURAL CONTROLLER FOR QUASl-RESONANT CONVERTERS   By J. M. Quero; J. M. Carrasco; L. G. Franquelo	[View]   [Download]
Abstract: A neural controller implementing an energy feedback control law is proposed to improve the stability and dynamic characteristics of the series resonant converter (SRC). The energy feedback control is introduced and analysed in discrete time domain. A novel formulation of the control law is suggested. The adaptive control law is learnt by an analog neural network (ANN). An easy implementation of this controller is proposed and applied to a SRC circuit. Simulation results show a good improvement in the SRC response and confirm the validity of the controller.
	LINK DC RESONANT CONVERTER WITHOUT OVERVOLTAGE: STUDY OF A BUCK CONVERTER   By Henrique José Avelar; Porfirio Cabaleiro Cortizo	[View]   [Download]
Abstract: The drawbacks of the Link DC Resonant Converters proposed by Divan are the voltage stresses across the devices and the discrete pulse modulation. Structures of converters with Link DC Resonant have been proposed, allowing the PWM operation and reducing the voltage stresses about to 1.3 times of the source voltage. This paper presents a new structure that allows the PWM operation with no voltage stresses over the semiconductors . Detailed analysis, simulations and experimental results are presented to verify operating principles of the power converter.
	THE NONLINEAR RESONANT INVERTER: A NEW SOFT SWITCHING TOPOLOGY   By J. A. Ferreira; P. C. Theron; J. D. van Wyk; A. van Ross; J. J. Schoeman; K. Matsemela	[View]   [Download]
Abstract: A new soft switching converter concept, namely nonlinear resonant inverters, is introduced. The objective is to achieve high frequency switching of inverter phase arms (poles) and at the same time reduce the current and voltage stresses on semiconductors and limit the number and size of additional components. The nonlinear resonant pole inverter is discussed in detail, a topology which requires, apart from two series connected smoothing capacitors on the supply, only a parallel resonant tank including a non-linear inductor with a current feedback winding per phase. Major features of the circuit are: little over dimensioning of installed rating of semiconductors in the inverter, low reactive power rating of resonant tank and soft reverse recovery of the inverter diodes.
	PWM INVERTER FOR WHITE RESONANT CIRCUIT   By L. van Lieshout	[View]   [Download]
Abstract: In the field of particle accelerators a resonant circuit, a so called "White circuit", is used to provide a highly stabilized (10to-4) low distored (10to-4) accurately timed waveform for the bending and focussing magnets. This current is composed of a DC- and AC-part with equal amplitude. PWM technics have been applied to develop a new GTO-inverter concept for the AC-part. A study of the existing solutions for one of the European institutes (ESRF) led to the application of PWM technics for this AC-part. A strong reduction of mains flicker is achieved. A new generation of GTO-inverters has been developed to meet the severe specifications. A range of inverters from 5 to 350 kW is built. The current source inverter contains diode-bridge, filter, GTO-chopper with DC-choke and GTO-inverter. This paper describes the White circuit, AC-inverter diagram, applied PWM technics and typical current and voltage waveforms. Also mains interaction, control philosophy and precise timing is discussed.
	A family of extended period circuits for power supply applications, using high conversion frequencies   By K. W. E. Cheng; P. D. Evans	[View]   [Download]
Abstract: Extended period circuits derive from the quasi-resonant circuits. The favourable device switching conditions provided by the quasi-resonant circuits are retained, but one or other of the resonant components is disabled for an extended period during the cycle thereby converting it to a switched-mode type of circuit. The duration of the extended period is the regulation mechanism for the circuit, which therefore operates with a constant switching frequency. A family of extended period circuits is identified and discussed and experimental and theoretical results for them are presented and compared.
	PROGRAM FOR THE COMPUTER AIDED DESIGN OF THE NON REVERSIBLE SERIES-RESONANT CONVERTER OPERATING ABOVE NATURAL FREQUENCY   By P. Kuo-Peng; Y. Cheron; Ph. Cussac	[View]   [Download]
Abstract: In this paper, a computer aided design software for series resonant converter operating beyond the natural frequency is presented. The converter can be equipped with snubbers. This software allows dimensioning the converter from the specifications, plotting its static output characteristics, determining the various constraints corresponding to particular points of operation (peak current in the inductor, peak voltage across the capacitor of the resonant circuit) thus giving the values allowing straightforward steady state simulation with a simulation software such as S.U.C.C.E.S.S. [7].
	QUASl-RESONANT ZERO-VOLTAGE-SWITCHING CONVERTER WITH CONSTANT FREQUENCY OPERATION   By G. A. Alesso; E. R. Cabral da Silva; E. H. Watanabe	[View]   [Download]
Abstract: This work presents a buck quasi-resonant zero-voltage-switching converter controlled by pulse-width modulation. This topology incorporates to conventional quasi-resonant converters the well-known advantages of constant-frequency operation. The pulse-width modulation is achieved by the introduction of an active switch in the resonant tank. The added switch operates with zero-current switching, thereby not adding significative dissipative losses to the converter. Principle of operation, steady-state analysis, simulation and experimental results are presented. Advantages and shortcomings of the topology are discussed and a family of PWM ZVS QR converters is proposed.
	High-Current High-Frequency Inductors for Resonant Converters   By M. A. Preston; R. W. De Doncker; R. C. Oney; C. M. Stephens	[View]   [Download]
Abstract: Resonant or soft-switched converters offer signincant technical advantages over more traditional hard-switched converters. These advantages are lower device switching losses and the capability of attaining higher switching frequencies. However, they are often offset by added active and passive components and associated losses. The resonant inductor can be one of the most significant loss contributors. The paper will consider the design of high-current high-frequency resonant inductors with appropriate characteristics. lt will discuss design philosophy and give predicted and measured data for several inductor geometries including potcore and rectangular. lt will also consider issues related to ac performance including: series parallel combinations of conductors, the tradeoff between concentrated and distributed airgap designs, the use of Litz wire vs. sheet conductors.
	DESIGN OF A 12 kW, 100 kHz POWER CONVERTER IN PARALLELED MODULES OF 3 kW FOR RADAR APPLICATION   By J. Martinez; V. Garcia; M. Perez; J. Diaz; J. Lopera; M. Rico	[View]   [Download]
Abstract: This paper presents the analysis, design and performance of a high density prototype converter that could be used in parallel, which be called MIB. The input voltage to the MIB is delivered by the input block, which includes a three-phase rectifier, an inrush current limiter and a LC filter, whose input voltage is a Three-Phase voltage network (220 ± 10% V Phase-Phase). The MIB accepts, as its input, the whole range of the rectified voltage (242
	Power Rectifiers for High Frequency Applications Offer Low Loss, Low Noise Performance   By William C. Roman; Sam Anderson; Kim Gauen	[View]   [Download]
Abstract: Reverse recovery of the rectifier diode becomes the dominant source of diode power dissipation in high frequency power supply topologies. Optimization of the lifetime control techniques and high efficiency rectifier diode processes result in device performance compatable with power supply topologies operating with switching frequencies from 100 kHz to 1 mega hertz. This paper investigates the optimization tradeoffs for rectifier diodes in the high frequency power supply application.
	Voltage Source Series Inverter with Transformer Coupled Load   By J. Fabianowski; R. Ibach; G. Gierse	[View]   [Download]
Abstract: The load of series resonant inverters for inductive heating at high working frequencies is preferably connected via a matching transformer. Asymmetries in inverter design and control cause voltage asymmetries in the inverter output voltage which can result in transformer core saturation. A possibility is shown by monitoring the inverter output current to generate a correcting signal for influencing the inverter control to avoid transformer core saturation. Furthermore, it is demonstrated how the inverter can be started without the aid of additional equipment by selectively bringing the transformer to a certain remanence point. Oscillograms recorded from industrial 400 kW/10 kHz inverters show that these methods achieved faultless operation.
	A METHOD TO DEFINE A RESONANT INVERTER STATE FOLLOWING THE SHAPE OF THE CURRENT PULSE   By St. Tabakov; P. Goranov; K. Radonova	[View]   [Download]
Abstract: The paper considers the possibility to use the parameters of the current pulse through the semiconductor element to obtain complete information about the power unit of the resonant inverter. The study has been made on the basis of a generalized bridge resonant inverter circuit with different leads - an active one and a complex one. The most frequently used in practice variations of the bridge resonant inverter have been considered - bridge resonant inverter with and without antiparallel diodes, and these with double output frequency. Based on the analysis of the resonant current pulse parameters a method has been devised to determine the values of the passive elements and semiconductor devices' state in the circuit. The mathematical description of this relation is done so as to allow an algorithm to be written to monitor the circuit's behaviour at any stage of its operation, facilitating thus regulation of its initial start and operation mode and development of adaptive control, diagnosis and prediction procedures.
	PRINCIPLES OF IMPROVING THE QUALITY OF ELECTRIC POWER ON THE BASIS OF INVERTERS WITH INTERMEDIATE HIGH FREQUENCY   By O. G. Bulatov; V. A. Shitov	[View]   [Download]
Abstract: The comparison of means of reactive power compensation is carried out on the basis of current and voltage converters. To ensure accuracy and stability of the network current forming it is necessary to realize a compensator having a characteristic of a power source. If the compensator is constructed on the basis of silicon-gate-controlled ac switches, the power supply mode is ensured through increasing the internal resistance of the compensator, for example, through putting a reactor at the compensator output with the simultaneous use of current feedback. It is shown that it is reasonable to construct compensators with intermediate high frequency. A reactor is used for an intermediate accumulator of energy and a device containing GTO-thyristors and a capacitor is used for a commutator.
	SERIES RESONANT CONVERTER WITH PIEZOELECTRIC CERAMIC TRANSDUCER FOR ULTRASONIC CLEANING SYSTEM   By P. Fabijanski; L. Palczynski	[View]   [Download]
Abstract: The article presents orginal results of digital analysis and experimental research of the transistor, series, resonant inverter which feeds the group of SANDWICH type piezoelectric ceramic transducer in ultrasonic cleaners. The purpose of the analysis was to determine optimal parameters of resonant inverter circuit, which, in the case of the elements of tuning the generator vibration frequency to the mechanical resonanse frequency of transducers, make it possible to obtain maximum output power, as well as to determine the extreme values of currents and voltages when the untuning of the groups of transducers from resonant, frequency occurs. In the summary we compared the results of digital analysis with experimental results of half-bridge inverter system with MOSFET transistors whose output power is 5kW and operating frequency 26 kHz.