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Showing papers on "Flyback converter published in 1993"


Patent
29 Jun 1993
TL;DR: In this article, a power conversion system is described, which includes a power input for accepting a waveform at a given power level and frequency, and a power output for providing an output waveform with a second power level.
Abstract: A power conversion system is described which includes a power input for accepting a waveform at a given power level and frequency, and a power output for providing an output waveform at a second given power level. A DC to AC converter accepts a waveform based on an input wave form from the power input and converts the waveform to an AC waveform having a frequency at least approximately an order of magnatude higher than the frequency of the input waveform for application to a DC to AC converter output. An AC converter accepts the output waveform from the DC to AC converter output and provides a converted waveform from an output of the AC converter to the power output. A coupling device operates at the frequency of the converter output for coupling the output of the DC to AC converter to the AC converter.

245 citations


Journal ArticleDOI
TL;DR: A current-sourcing switch-mode power supply topology is developed by applying a duality principle to a voltage-sourced half-bridge converter that has boost converter characteristics and is suited to low-voltage high-current input applications.
Abstract: A current-sourced switch-mode power supply topology is developed by applying a duality principle to a voltage-sourced half-bridge converter. The converter has boost converter characteristics and is suited to low-voltage high-current input applications. It is shown to compare favorably with the center-tapped transformer converter. Two optional enhancements-nondissipative snubber networks and inductor clamping windings-are also examined. Some results obtained with a low-power prototype are presented. >

241 citations


Journal ArticleDOI
TL;DR: In this paper, the saturable inductor is employed in the full-bridge (FB) zero voltage switched (ZVS) pulse width modulated (PWM) power converter to improve its performance.
Abstract: The saturable inductor is employed in the full-bridge (FB) zero voltage switched (ZVS) pulse width modulated (PWM) power converter to improve its performance. The current and voltage stresses of the switches as well as parasitic oscillations are significantly reduced compared to those of the conventional FB-ZVS-PWM power converter. The qualitative analysis is presented and is verified on a 500 kHz, 5 V/40 A converter. >

159 citations


Journal ArticleDOI
20 Jun 1993
TL;DR: Asymmetrical pulse width modulated (APWM) DC-DC resonant converter topologies which exhibit near zero switching losses while operating at constant and very high frequencies are presented in this paper.
Abstract: Asymmetrical pulse width modulated (APWM) DC-DC resonant converter topologies which exhibit near zero switching losses while operating at constant and very high frequencies are presented. The converters include a bridged chopper to convert the DC input voltage to a high frequency unidirectional AC voltage which in turn is fed to a high frequency transformer through a resonant circuit. The bridged chopper has two switches which alternately conduct. The duty cycles of the conduction of the switches are complementary with one another and are varied to control the output voltage. Three resonant circuit configurations which are suitable for this type of control are presented. Frequency domain analysis of the converter is given and performance characteristics are presented. Experimental results for a 48 V to 5 V, 30 W converter show an efficiency of 88% at a constant operating frequency of 1 MHz. >

127 citations


Journal ArticleDOI
TL;DR: In this article, a high-frequency link series-parallel resonant power converter is analyzed using the state-space approach for both the continuous capacitor voltage and the discontinuous capacitor voltage modes.
Abstract: A high-frequency link series-parallel resonant power converter is analyzed using the state-space approach. Analysis is presented for both the continuous capacitor voltage mode and the discontinuous capacitor voltage mode. Steady-state solutions are derived. Design curves for the converter gain and other component stresses are obtained. A method of optimizing the converter under certain constraints is presented and a simple design procedure is illustrated by a design example. Experimental results are presented to verify the theory. >

110 citations


Patent
13 Sep 1993
TL;DR: In this article, two essentially symmetrical transformers have their primary windings connected in series and are driven by a full wave switched primary circuit such as a full bridge, and the transformer secondaries are polarized so that their rectifying diodes conduct on opposite phases, so only one transformer secondary conducts for each half cycle.
Abstract: A full wave DC to DC converter that is magnetically integrated so that the function of the output filter inductor is magnetically included in the transformer assembly. Two essentially symmetrical transformers have their primary windings connected in series and are driven by a full wave switched primary circuit such as a full bridge. The transformer secondaries are polarized so that their rectifying diodes conduct on opposite phases, so only one transformer secondary conducts for each half cycle. The conducting secondary winding conducts for each half cycle. The conducting secondary winding conducts both forward current reflected from the primary and flyback current from collapsing core flux. The transformer having the non-conducting secondary stores energy as magnetic flux. On the other half-cycle, the transformers reverse roles. Because stored transformer flux energy is released to the load through the secondary windings, continuous current is maintained and no separate output smoothing inductor is required.

108 citations


Proceedings ArticleDOI
W. Tang, Y. Jiang, G.C. Hua, F.C. Lee, I. Cohen 
07 Mar 1993
TL;DR: In this paper, the authors applied the charge control concept to a flyback power converter for the purpose of power factor correction (PFC), which can operate in continuous conduction mode (CCM) with unity power factor.
Abstract: The charge control concept is applied to a flyback power converter for the purpose of power factor correction (PFC). Using charge control, a flyback converter can operate in continuous conduction-mode (CCM) with unity power factor. The simplicity of the flyback circuit is maintained and the power handling capacity is increased. The properties of charge control related to flyback PFC application are studied. The design guidelines are presented. A 200 W prototype circuit is built. Experimental results show good application prospects. >

100 citations


Proceedings ArticleDOI
20 Jun 1993
TL;DR: In this paper, the development and experimental results of a low-cost 500-W DC-AC power converter for photovoltaic power conversion in residential applications are described, where a step-up chopper is used for MPP tracking and provides a constant 200-V DC link for the following push-pull power converter.
Abstract: The development and experimental results of a low-cost 500-W DC-AC power converter for photovoltaic power conversion in residential applications are described. The converter uses low-cost technology usually applied in consumer products. The DC-AC converter is specially designed for operation at a wide DC input voltage range (30-170 V) in order to allow optimal power conversion with an arbitrary number of series connected solar arrays. A step-up chopper is used for MPP tracking and provides a constant 200-V DC link for the following push-pull power converter. This galvanic isolating power converter operates at 100 kHz and controls the current in the mains sinusoidally. A thyristor bridge alternates the current after each half line period. The required auxiliary power is kept below 7 W and is taken from the choke of the step-up chopper. >

86 citations


Proceedings ArticleDOI
02 Oct 1993
TL;DR: In this paper, an AC line fed switching power supply with a single power converter stage is described, which operates with high input power factor while maintaining good regulation of the desired output DC voltage.
Abstract: An AC line fed switching power supply with a single power converter stage is described which operates with high input power factor while maintaining good regulation of the desired output DC voltage. The single-power converter is a dual active bridge DC-to-DC power converter (DABC), comprising high-frequency transformer-coupled input and output bridge converters. The DABC receives a rectified AC line voltage via a diode-bridge rectifier connected to a small, high-frequency filter capacitor. The two active bridges, generating edge-resonant square waves at their transformer terminals, appropriately phase-shifted from each other to simultaneously perform the high-efficiency DC output regulation while maintaining unity power factor at the AC input. The soft-switching nature of the converter allows increased performance (in terms of efficiency and stresses) and reduction in size/weight at operating frequencies in the range of 50-250 kHz. Simulations, and experimental results are presented to corroborate the analysis. >

82 citations


Patent
Wen-Jian Gu1, Rui Liu1
28 Dec 1993
TL;DR: In this paper, a single-stage high frequency push-pull converter with input power factor correction was proposed. But the converter was not designed for the high frequency switching transistors of the converter.
Abstract: A single stage high frequency push-pull converter with input power factor correction. The boost converter for input power factor correction and the high-frequency push-pull DC/AC inverter are combined into a single stage converter thereby reducing the number of circuit components while at the same time reducing the voltage stress on the high frequency switching transistors of the converter.

79 citations


Proceedings ArticleDOI
20 Jun 1993
TL;DR: In this article, a multiple-input DC-DC converter is proposed for realizing a clean electric power generation system, and the static and dynamic characteristics are clarified theoretically and are confirmed by experiment.
Abstract: A multiple-input DC-DC converter is proposed for realizing a clean electric power generation system. The two-input buck-boost type converter is analyzed, and the static and dynamic characteristics are clarified theoretically and are confirmed by experiment. >

Patent
20 Apr 1993
TL;DR: An apparatus for a three-level DC/AC converter, in which the width of output pulse having the same polarity as the fundamental wave of the converter output phase voltage is adjusted depending upon the DC component of a differential voltage between two DC voltages in a dipolar modulation system, is described in this paper.
Abstract: An apparatus for a three-level DC/AC converter, in which the width of output pulse having the same polarity as the fundamental wave of the converter output phase voltage is adjusted depending upon the DC component of a differential voltage between two DC voltages in a dipolar modulation system of the converter. Whereby, the imbalance of DC components between the two DC voltages is easily and effectively suppressed.

Proceedings ArticleDOI
27 Sep 1993
TL;DR: An asymmetrical PWM control scheme is used to control the power converter under constant switching frequency operation in this article, where the DC characteristics which can be used in design of the converters are also presented.
Abstract: In this paper, a soft-switched power converter with two variations is discussed. An asymmetrical PWM control scheme is used to control the power converter under constant switching frequency operation. The modes of operation for both variations are discussed. The DC characteristics which can be used in design of the converters are also presented. Two 50 W converters were built to verify the characteristics of the converters. Due to the zero voltage switching (ZVS) operation of the switches and low device voltage and current stresses, the converters have high full load and partial load efficiencies. They are potential candidates for high efficiency, high density power supply applications. >

Patent
14 Sep 1993
TL;DR: A flyback-type power converter with a secondary-side resonant circuit which shapes the current waveform in the secondary winding and secondary circuit to reduce the RMS current values therein is described in this paper.
Abstract: A flyback-type power converter having a secondary-side resonant circuit which shapes the current waveform in the secondary winding and secondary circuit to reduce the RMS current values therein is described. The shaping reduces conduction losses and improves conversion efficiency. With the resonant circuit, the energy stored in the transformer is transferred during the OFF-period in substantially a fixed time duration, enabling a fixed-OFF period operation mode. The converter may further have a primary-side resonant circuit for capturing and recycling the energy stored the leakage inductance of the primary winding, which is normally wasted in snubber circuitry.

Journal ArticleDOI
TL;DR: In this paper, a modified series resonant converter (SRC) which overcomes the problems of the standard SRC is presented, where a state-space approach is used for the analysis.
Abstract: A modified series resonant converter (SRC) (also referred to as the LCL-type SRC) which overcomes the problems of the standard series resonant converter is presented. A state-space approach is used for the analysis. Analysis shows that the converter enters into three different modes. Converter gain and other component stresses are plotted with variation in the load current. Detailed experimental results obtained from a 500 W MOSFET converter are presented to verify the theory. With a proper selection of inductor ratio, only a narrow variation in switching frequency is required to regulate the output voltage for wide variation in the load current. It is shown that, by placing the parallel inductor on the secondary side, the parasitics of the high-frequency transformer can be used profitably. >

Patent
22 Feb 1993
TL;DR: In this article, the primary of a high frequency transformer is connected between the main node and the junction between the first switching device and diode, and the secondary of the transformer was connected to an output circuit which included a rectifier and an inductor and capacitor filter to provide a DC output voltage to a load.
Abstract: A power converter integrates an input boost converter and an output forward converter into a single power stage utilizing only two active switches. AC input power is provided through a rectifier to an input inductor which supplies current to a main node. The diode is connected from a main node to a DC bus supply line and current is returned to the rectifier by DC bus return line. An energy storage capacitor and a series connected switching device and diode are connected across the DC bus lines. A second control switching device is connected from the main node to the DC bus return line. The primary of a high frequency transformer is connected between the main node and the junction between the first switching device and diode, and the secondary of the transformer is connected to an output circuit which includes a rectifier and an inductor and capacitor filter to provide a DC output voltage to a load. When both switching devices are turned off, current from the input inductor is supplied to charge up the energy storage capacitor and to drive the transformer magnetizing current to zero. Turn on of both switching devices causes the capacitor to be discharged via the switching devices through the primary of the transformer to supply power to the load. Intermediate modes in which one or the other of the switching devices is on while the other is off are available. By proper selection of the time of turn on of the devices and the modes of switching of the devices, the AC input current can be controlled to be substantially sinusoidal, or the output voltage can be controlled to a selected level, and in either event the power factor as seen at the AC input lines is substantially unity.

Proceedings ArticleDOI
20 Jun 1993
TL;DR: In this article, a high power factor three-phase AC-DC-AC power converter for AC machines has been designed and tested, which is controlled by one single 16-b microcontroller.
Abstract: A high power factor three-phase AC-DC-AC power converter for AC machines has been designed and tested. The AC-DC-AC converter is controlled by one single 16-b microcontroller. The converter has two PWM-VSI bridges with common snubber- and drive-circuit topologies. The high power factor rectifier is space vector controlled and the inverter controls an AC-induction machine by an energy optimized strategy. Common software tasks are utilized in order to minimize memory demands in the microcontroller. Measurements show a high power factor of the converter, and, in addition, the converter can very rapidly change from motor to generator operation during reversing of the AC machine. It is concluded that the AC-DC-AC converter works well, can be designed to be very compact, and represents some of the state-of-the-art integration and performance in three-phase AC-DC-AC converters. >

Patent
24 Jun 1993
TL;DR: In this article, a smoothing filter is arranged in series between a converter and the inverter for filtering the DC power intermediate signal, which is determined by a torque current command value and a load angular speed signal.
Abstract: A power converter/inverter system for a load comprises a converter circuit for converting an alternating current power input into a direct current power intermediate signal in response to a first PWM voltage. An inverter inverts the DC power intermediate signal into an AC power output in response to a second PWM voltage. A smoothing filter is arranged in series between a converter and the inverter for filtering the DC power intermediate signal. An instantaneous real power calculating circuit calculates an instantaneous real power (IRP) relative to the inverter and is determined by a torque current command value and a load angular speed signal. A converter controller controls the first PWM voltage of the converter in accordance of a combination a predetermined converter amplitude setpoint, a DC voltage present at the DC power intermediate signal, and the instantaneous real power product. An inverter controller controls the second PWM voltage of the inverter in accordance with the inverter amplitude setpoint and amplitude of the AC power output.

Patent
19 Feb 1993
TL;DR: In this paper, a voltage regulator for a flyback-type high voltage supply has been proposed, consisting of a pulse transformer with its secondary interconnected in series with the primary of the flyback transformer.
Abstract: A voltage regulator for a flyback-type high voltage supply having: a pulse transformer with its secondary interconnected in series with the primary of a flyback transformer; a control circuit for sensing the generation of a flyback pulse, a reference voltage, and a feedback voltage signal appearing at the output of the flyback transformer; and a switch for selectively applying energy to the primary of the pulse transformer while uniformly maintaining the flow of current through the primary of the flyback transformer.

Patent
16 Nov 1993
TL;DR: In this paper, an isolated, multiple output, switching converter is created with a number of unique performance characteristics, including a simple open-loop control circuit connected to the primary side and thus eliminating the need for isolation in the control circuit.
Abstract: The isolated, multiple output, switching converter is created with a number of unique performance characteristics. The converter operates in continuous inductor current mode (CICM) of operation for all load currents from no load to full load on all outputs despite the presence of simple rectifier diodes only on the converter secondary sides. The regulation of output voltages on all outputs against the changes of the input voltage is provided by use of a simple open-loop control circuit connected to the primary side and thus eliminating the need for isolation in the control circuit. The regulation against the load current changes in the single output case is also provided on the primary side by a load current sensing circuit. An additional benefit of the switching converter is in the elimination of the losses and voltage overshoots associated with the leakage inductance of the isolation transformer when operated as pulse width modulated (PWM) converter.

Journal ArticleDOI
20 Jun 1993
TL;DR: In this article, the small-signal model for a multiple-output forward power converter with weighted voltage control is derived and the effects of the weighting factors on the small signal behavior are investigated.
Abstract: The small-signal model for a multiple-output forward power converter with weighted voltage control is derived. The effects of the weighting factors on the small-signal behavior are investigated. In addition, the small-signal characteristics of weighted voltage control are compared with the characteristics of a multiple-output power converter with coupled output-filter inductors. Finally, the effects of weighted voltage control on the small-signal characteristics of the converter with coupled inductors are examined. Based on the analysis, the design procedure for loop compensation is presented. The small-signal model and the design procedure are verified on an experimental two-output forward power converter. >

Patent
16 Dec 1993
TL;DR: In this article, a secondary flyback core reset (SFCR) scheme for single-ended forward DC-to-DC converters is proposed, where the magnetic flux built up through the primary winding when the main switch was turned on is reset through this secondary fly-back reset circuit when the primary switch is turned off.
Abstract: A secondary flyback core reset (SFCR) scheme for single-ended forward DC-to-DC converters is disclosed. The transformer secondary magnetizing inductor and a parasitic reset capacitance of the output forward rectifier diode form a secondary flyback reset circuit. The magnetic flux built up through the primary winding when the main switch is turned on is reset through this secondary flyback reset circuit when the main switch is turned off. The secondary flyback reset circuit initiates a half resonant cycle and resets the transformer. With proper design of the reset time, the maximum duty cycle of the main switch can go beyond 50%, while still using the first and third quadrants of the core B-H loop characteristics for optimum use of the core power density, and reduced RMS switching current and rectifier blocking voltages and power switch blocking voltage.

Patent
04 Jan 1993
TL;DR: In this paper, the flyback voltage is felt through the vertical pnp transistor at the drain, which onducts to the substrate, which represents a power loss and a source of heat.
Abstract: When a field effect transistor is used to control the current through an inductive load, the flyback voltage is felt through the vertical pnp transistor at the drain, which onducts to the substrate. This current represents a power loss and a source of heat. This invention supplies a second lateral transistor which conducts this current back to the power supply.

Journal ArticleDOI
TL;DR: An oversampled A/D (analog-to-digital) converter that can be configured as either a sigma-delta converter or an incremental converter is presented, which cancels offset and 1/f noise and leads to a very simple and modular architecture.
Abstract: An oversampled A/D (analog-to-digital) converter that can be configured as either a sigma-delta converter or an incremental converter is presented. This is an oversampled instrumentation converter that cancels offset and 1/f noise. The converter architecture is based on a mixed analog-digital integrator (MADI) concept. This concept is shown to lead to a very simple and modular architecture. The implemented converter also allows selection of the converter order and the decimation factor in order to find the best tradeoff between resolution, conversion time or bandwidth, and power consumption. As the converter architecture is completely modular, it can rapidly be tailored for a specific application with minimized silicon area. The circuit achieves a resolution of 16 b on a range of +or-650 mV and compensates the offset and the even-order harmonics to a nonobservable level. >

Proceedings ArticleDOI
07 Mar 1993
TL;DR: In this paper, the authors considered the case of a three-phase to threephase quasi-direct power converters, and a simple and effective control technique suitable for this purpose, which also provided high power factor and small distortion of the supply currents, was described.
Abstract: The family of quasi-direct power converters, i.e. forced-commutated AC/DC/AC power converters including small energy storage devices in the DC link, is introduced. In particular, the case of a three-phase to three-phase quasi-direct converter is considered. Since energy storage minimization calls for instantaneous input/output power balance, a proper control strategy is needed. A simple and effective control technique suitable for this purpose, which also provides high power factor and small distortion of the supply currents, is described. The general properties of quasi-direct power converters are discussed, design criteria of both power and control sections are given, and experimental results of a 2 kVA prototype are reported. >

Journal ArticleDOI
TL;DR: In this paper, a pulsewidth-modulated (PWM) zero-voltage-switching quasi-resonant boost converter operating at constant switching frequency is presented, which possesses better controllability and higher operating performance, and overcomes the instability caused by the parasitic oscillation.
Abstract: A pulsewidth-modulated (PWM) zero-voltage-switching quasi-resonant boost converter operating at constant switching frequency is presented. In contrast to the frequency-modulated (FM) zero-voltage-switching quasi-resonant boost converter, this converter possesses better controllability and higher operating performance, and overcomes the instability caused by the parasitic oscillation. The principle of operation and performance of the converter are presented. Its two-dimensional state trajectories and steady-state characteristic curves are derived which are useful for the converter design. Both the SPICE simulation and experimental result agree with the theoretical prediction. >

Proceedings ArticleDOI
Toshihiro Nishimura1, Katsuya Hirachi1, Y. Maejima1, K. Kuwana1, M. Saito1 
15 Nov 1993
TL;DR: In this paper, a full-bridge resonant converter which transfers several W of power across a large, variable air gap has been designed and built, which can power a rechargeable cardiac pacemaker through intact skin.
Abstract: A full-bridge resonant converter which transfers several W of power across a large, variable air gap has been designed and built. The converter can power a rechargeable cardiac pacemaker through intact skin by utilizing a transformer with an air gap of 0.5-1.5 cm between the primary and the secondary. The secondary winding would be implanted under the skin, and the primary would be placed on top of the secondary outside the body. >

Proceedings ArticleDOI
Jung-Goo Cho1, G.H. Cho1
20 Jun 1993
TL;DR: An offline zero-voltage-switching (ZVS) PWM AC-DC power converter for single-stage preregulation in distributed power systems is proposed and simulation results for a 1-kW prototype are presented.
Abstract: An offline zero-voltage-switching (ZVS) PWM AC-DC power converter for single-stage preregulation in distributed power systems is proposed. The converter provides both input power factor correction and direct conversion from a 110-220-V AC line to a 48-V DC bus with a single power stage. Compared to the conventional two-stage approach (a boost rectifier followed by an offline DC-DC step-down converter), the proposed approach reduces the loss of one power stage. A new simple auxiliary circuit provides the zero-voltage-switching (ZVS) condition to all semiconductor devices without imposing additional voltage and current stresses and loss of PWM capability. The operational principle, analysis, control of the proposed power converter, and simulation results for a 1-kW prototype are presented. >

Patent
03 Aug 1993
TL;DR: In this paper, a mutual inductor (IB) is arranged on the d.c. side of the converter and has two windings (IB1, IB2) which are each connected to a respective one of the supply lines.
Abstract: An HVDC transmission has two converters (SR1, SR2). Each converter is connected between an alternating-voltage network (N1, N2) and a d.c. link (L1, L2) common to the converters. At least one converter is connected to its alternating-voltage network without the use of any full transformer, for example directly, or via an inductor or an autotransformer, or via series capacitors. The transmission has a mutual inductor (IB) which is arranged on the d.c. side of the converter and which has two windings (IB1, IB2) which are each connected to a respective one of the d.c. supply lines of the converter and are magnetically coupled to each other, the inductor being designed and connected so as to exhibit a high impedance to ground mode currents.

Journal ArticleDOI
TL;DR: In this paper, a probabilistic model of the power system harmonics produced by a six-pulse AC/DC power converter undervoltage unbalance was developed and compared with the results obtained from Monte Carlo simulations.
Abstract: Harmonic currents generated by an AC/DC power converter are subject to random variations due partly to fluctuation of the converter's DC load and partly to power source disturbances. The latter are also responsible for the generation of uncharacteristic harmonics. Based on an analytical power converter model and probabilistic models of voltage unbalance and converter load variations, the random behaviour of both characteristic and uncharacteristic power system harmonics produced by a six-pulse AC/DC power converter undervoltage unbalance is analyzed. The probability density functions of the magnitude and the phase angle of harmonic currents are derived and compared with the results obtained from Monte Carlo simulations. It is found that the developed probabilistic harmonic model agrees very well with the results of Monte Carlo simulations and gives significant insight into the effects of voltage unbalance and converter DC load variations upon the random properties of the power converter current spectrum. >