Showing papers on "Flyback converter published in 2005"

High step-up converter with coupled-inductor

Abstract: In this study, a high step-up converter with a coupled-inductor is investigated. In the proposed strategy, a coupled inductor with a lower-voltage-rated switch is used for raising the voltage gain (whether the switch is turned on or turned off). Moreover, a passive regenerative snubber is utilized for absorbing the energy of stray inductance so that the switch duty cycle can be operated under a wide range, and the related voltage gain is higher than other coupled-inductor-based converters. In addition, all devices in this scheme also have voltage-clamped properties and their voltage stresses are relatively smaller than the output voltage. Thus, it can select low-voltage low-conduction-loss devices, and there are no reverse-recovery currents within the diodes in this circuit. Furthermore, the closed-loop control methodology is utilized in the proposed scheme to overcome the voltage drift problem of the power source under the load variations. As a result, the proposed converter topology can promote the voltage gain of a conventional boost converter with a single inductor, and deal with the problem of the leakage inductor and demagnetization of transformer for a coupled-inductor-based converter. Some experimental results via examples of a proton exchange membrane fuel cell (PEMFC) power source and a traditional battery are given to demonstrate the effectiveness of the proposed power conversion strategy.

Three-level LLC series resonant DC/DC converter

Abstract: Paper presents a three-level soft switching LLC series resonant dc/dc converter. Zero-voltage switching (ZVS) is achieved for each main switch without any auxiliary circuit. Voltage stress of each main switch is half of input voltage. Zero-current-switching (ZCS) is achieved for rectifier diodes. Wide input/output range can be achieved under low frequency range because of two-stage resonance. Only one magnetic component is required in this converter. Efficiency is higher in high line input, so this converter is a preferable candidate for power products with the requirement of hold up time. For design convenience, relationship between dc gain and switching frequency, load resistance is deduced. Its open load characteristic and short load characteristic are exposed to provide theory basis for no load operation and over current protection. Design consideration of four dead times is presented to assure that voltage stress for main switches is within half of input voltage and ZVS for each main switch is achieved. Finally the principle of operation and the characteristics of the presented converter are verified on a 500V-700V input 54V/10A output experimental prototype, whose efficiency reaches 94.7% under rating condition.

Analysis of integrated boost-flyback step-up converter

Abstract: The operating principles, theoretical analysis, and design methodology of a high-efficiency step-up converter are presented. The integrated boost-flyback converter (IBFC) uses coupled-inductor techniques to achieve high step-up voltage with low duty ratio, and thus the slope compensation circuit is disregarded. The voltage gain and efficiency at steady state are derived using the principles of inductor volt-second balance, capacitor charge balance and the small-ripple approximation for continuous-conduction mode. Finally, a 35 W, 12 V DC input, 48 V DC output, f/sub sw/= 40 kHz IBFC has been implemented in the laboratory to validate the theoretical analysis. A design procedure is expounded, and design guidelines for selecting critical components are also presented. It is shown that high voltage gain with high efficiency can be achieved by the IBFC system.

High boost converter using voltage multiplier

Abstract: With the increasing demand for renewable energy, distributed power included in fuel cells have been studied and developed as a future energy source. For this system, a power conversion circuit is necessary to interface the generated power to the utility. In many cases, a high step-up DC/DC converter is needed to boost low input voltage to high voltage output. Conventional methods using cascade DC/DC converters cause extra complexity and higher cost. The conventional topologies to get high output voltage use flyback DC/DC converters. They have the leakage components that cause stress and loss of energy that results in low efficiency. This paper presents a high boost converter with a voltage multiplier and a coupled inductor. The secondary voltage of the coupled inductor is rectified using a voltage multiplier. High boost voltage is obtained with low duty cycle. Theoretical analysis and experimental results verify the proposed solutions using a 300 W prototype.

A comparative evaluation of isolated bi-directional DC/DC converters with wide input and output voltage range

Abstract: The working principles and design equations of four different isolated, bi-directional DC to DC converter topologies (a dual active bridge converter, a series resonant converter and two multiple stage topologies) for a 2 kW bi-directional battery charger that can be operated in a wide input and output voltage range are presented in this paper. The results of a detailed mathematical analysis of the converter topologies as well as digital simulation results are used to select the most efficient topology for this specific converter application, where the two-stage series resonant converter is identified to be the most promising, with up to 90% efficiency at rated power.

A novel three-phase high-power soft-switched DC/DC converter for low-voltage fuel cell applications

Abstract: An efficient dc/dc converter is needed as the interface between a low-voltage fuel cell source and a high-voltage bus for inverter operation. In this paper, a three-phase transformer-isolated dc/dc converter utilizing phase-shift (PS) modulation is proposed. The converter must be able to boost the voltage significantly and operate at current levels above 240 A on the source side. Key features of the proposed converter include reduced transformer turns ratio by a factor of two while maintaining the same output voltage, reduced size of passive components including output filter and input dc bus capacitor using three-phase interleaving, eliminated inductor current ripple at PS angles above 120/spl deg/, and achieved soft switching over a wide load range without auxiliary circuitry. The proposed converter has been analyzed, simulated, and implemented in hardware. An efficiency of above 96% was achieved using the prototype unit. Experimental results were used to verify all designs and analyses.

High-efficiency DC/DC converter with high voltage gain

Abstract: A high-efficiency converter with high voltage gain applied to a step-up power conversion is presented In the proposed strategy, a high magnetising current charges the primary winding of the coupled inductor, and the clamped capacitor is discharged to the auxiliary capacitor when the switch is turned on In contrast, the magnetising current flows continuously to boost the voltage in the secondary winding of the coupled inductor, and the voltages across the secondary winding of the coupled inductor, the clamped capacitor and the auxiliary capacitor are connected in series to charge the output circuit Thus, the related voltage gain is higher than in conventional converter circuits Moreover, this scheme has soft-switching and voltage-clamped properties, ie the switch is turned on under zero-current switching and its sustainable voltage is comparatively lower than the output voltage, so that it can select low-voltage low-conduction-loss devices and there are no reverse-recovery currents within the diodes in this circuit In addition, closed-loop control methodology is utilised in the proposed scheme to overcome the voltage drift problem of the power source under the load variations As a result, the proposed converter topology can promote the voltage gain for a conventional boost converter with a single inductor, and deal with the problem of the leakage inductor and demagnetisation of the transformer for a coupled-inductor-based converter Some experimental results via examples of a proton exchange membrane fuel cell power source and a traditional battery are given to demonstrate the effectiveness of the proposed power conversion strategy

Power system method and apparatus

Abstract: Power converter system topologies comprise a first DC/DC converter to pull a positive rail of a high voltage bus up, while a second DC/DC converter pushes a negative rail of the high voltage bus down. One or both the DC/DC converters may be bi-directional. Such topologies are suitable for use with separate primary power sources, and/or auxiliary power sources. Such topologies may include a DC/AC converter, which may be bi-directional. Such topologies may include one or more auxiliary DC/DC converters, which may be bi-directional. Multiple substrates, including at least one stacked above another may enhance packaging.

AC to DC power supply with PFC for lamp

Abstract: An AC-to-DC converter with PFC or without PFC generates an output constant voltage at any predetermined value (no matter less or more than input line peak voltage, or even equal to input line peak voltage) with an input line AC voltage with wide range (Typical sinusoidal 110 VAC, 60 Hz or 220 VAC, 50 Hz). It is mainly used as power supply for lamp. Previous power supply for lamp has low frequency component or high frequency component. (1) Low frequency light cause eyes pupil and crystalline lens will adjust 60 times, 120 or many times per second to cause eyes tired. Pupil open wide and crystalline lens adjust to collect more light to focus on retina for seeing clearly at weak light while pupil open narrow and crystalline lens adjust to collect less light to focus on retina at strong light to prevent retina from strong light harm and hurt. In the long run, muscles to control pupil and crystalline lens become very tired and become flabby. Then the muscle can't adjust pupil and crystalline according to distance and brightness so that myopia is caused. (2) High frequency voltage causes lamp brightness changes too fast. Eyes can not adjust fast enough to follow the brightness change of lamp for high frequency voltage. But high frequency large current on the secondary cause high EMI that has risk to harm people's health. High frequency light causes EMI issue. Peoples' eyes can't keep up with high frequency light. Peak strong light shine on the retina for pupil can't shrink at high frequency light. In the long run, retina will be harmed and affect eyesight is affected, cornea dryness or crystalline lens opacity is caused. My invention of power supply lamp has only DC constant voltage on lamp. Lamp's brightness is constant and has no low frequency or high frequency component Thus peoples' eyes and health are protected to maximum extent. The output voltage is regulated at predetermined DC constant value by feedback. You can adjust feedback potentiometer value to set output voltage. Potentiometer and resistor voltage divider with auxiliary winding, (opto-coupler, digital isolator or direct feedback) compose the dimming feedback circuit. It is convenient to adjust the brightness of lamp for eyes' comfort by adjusting the potentiometer resistance value. My invention can be used directly on second category lamp that doesn't need high voltage with ballast to start the lamp. Most of them use heat generated by filament or diode etc to create light. Such as Halogen, Incandescent, LED, PAR lamp, miniature sealed beam lamp, Projection lamp, automotive lamp, some stage and studio lamp, DC fluorescent lamp etc. The converter realized pulse-by-pulse or other current limit protection by sense the current sense resistor or signal transformer. One stage DC sinusoidal to DC constant converter 206 can be implemented by all kinds of topologies other than the following topologies as long as they can convert DC sinusoidal voltage to DC constant voltage. Buck, Boost, Buck-boost, Noninverting buck-boost ,H-Bridge, Watkins-Johnson, Current-fed bridge, Inverse of Watkins-Johnson, Cuk, SEPIC, Inverse of SEPIC, Buck square, full bridge, half bridge, Forward, Two-transistor Forward, Push-pull, Flyback, Push-pull converter basedon Watkins-Johnson, Isolated SEPIC, Isolated Inverse SEPIC, Isolated Cuk, Two-transistor Flyback etc One stage AC to DC converter 206 can be realized by discrete components without controller 209 , active startup circuit, feedback circuit or sample circuit. Main switch and active startup circuit can be integrated in IC controller. The AC to DC converter is not used only for lamp. It is can also be used for any device requires DC power supply in all the industrial areas. (Telecommunication, Storage, Personal computer, cell phone power supply and charger, video game etc) For example, Bus AC to DC converter, PFC converter, PFC converter for lighting Computer power supply, Monitor power supply, notebook adapter, LCD TV, AC/DC adapter, adjusted voltage charger, Power tool charger, Electronic ballast, Video game power supply etc.

New zero-voltage-switching phase-shift full-bridge converter with low conduction losses

Abstract: A new zero-voltage-switching (ZVS) phase-shift full-bridge (PSFB) converter with low conduction losses is proposed. It is based on the PSFB converter with series-connected two transformers, which features wide ZVS ranges. By adding a capacitor, the proposed converter overcomes the disadvantage of the based converter, such as the high circulating energy. Furthermore, the turns ratio of the transformers can be increased as well. Therefore, high efficiency of the proposed converter can be achieved. Operational principles and experimental results for a 100-W (5 V, 20 A) prototype are presented to validate the proposed converter.

Flyboost power factor correction cell and a new family of single-stage AC/DC converters

Abstract: A novel power factor correction (PFC) cell, called flyboost, is presented. The proposed PFC cell combines power conversion characteristics of conventional flyback and boost converters. Based on the flyboost PFC cell, a new family of single-stage (S/sup 2/) ac/dc converters can be derived. Prominent features of newly derived S/sup 2/ converters include: three power conversions, i.e., boost, flyback, and another isolated dc/dc power conversions are simultaneously realized that typically uses only one power switch and one simple controller; part of the power delivered to the load is processed only once; bulk capacitor voltage can be clamped to the desired level; and capable of operating under continuous current mode. Experimental results on example converters verify that while still achieving high power factor and tight output regulation, the flyboost PFC cell substantially improve the efficiency of the converter.

Integrated circuits and power supplies

Abstract: This invention relates to integrated circuits for power conditioning units, that is circuits to supply power to a mains supply, such as domestic grid mains from, for example, a fuel cell or photovoltaic device, and also to circuits for supplying power to a mains supply, such as domestic grid mains, from a dc supply from a low voltage power source such as a photovoltaic device or fuel cell. We describe a semiconductor-on-insulator integrated circuit die comprising a substrate bearing a power conditioning circuit, the power conditioning circuit comprising at least two power devices, one of said power devices being a lateral power device, another of said power devices being a vertical power device. We further describe a power conditioning circuit for providing power from a DC supply to an alternating current mains power supply line, the circuit comprising: a DC input to receive DC power from said DC supply; an AC output for connection to said AC mains power supply line; a DC-to-DC converter having an input coupled to said DC input and having an output; a DC-to-AC converter having a DC input and an AC output to convert DC power to AC power for output onto said power supply line; and a DC voltage regulator coupled between the output of said DC-to-DC converter and the input of said DC-to-AC converter to regulate said DC voltage input to said DC-to-AC converter; and wherein said regulator is configured to control an AC output current of said circuit by controlling said DC voltage input to said DC-to-AC converter.

Analysis and implementation of full-bridge converter with current doubler rectifier

Abstract: A zero voltage switching DC/DC converter is presented, which gives a stable output voltage and high circuit efficiency. In the adopted DC/DC converter, a full-bridge inverter with phase-shift PWM technique is used to achieve zero voltage switching for active power switches and to regulate the output voltage. To increase the converter efficiency at the transformer secondary side, a current doubler rectifier with the property of one diode conduction drop, frequency doubling in the output capacitor and low current rating in the transformer secondary winding are used in the adopted circuit. The detailed circuit operation, mathematical analysis and design example of the converter are presented. The measured full-load efficiency of a 100 kHz experimental prototype was higher than 92%. Experimental results are presented to verify the performance of the adopted circuit.

A low cost, triple-voltage bus DC-DC converter for automotive applications

Abstract: Before the automotive industry completes moving the 14 V vehicle loads to the 42 V net, HEVs and fuel cell vehicles will likely employ a triple voltage-14 V/42 V/high-voltage (200~500 V) bus system. This paper presents a low-cost, soft-switched, bidirectional DC/DC converter for connecting the three voltage nets. The converter consists of two half-brides and a high-frequency transformer, which provides voltage level matching and galvanic isolation between the two half-bridges for safety requirements. The use of dual half-bridges minimizes the number of switching devices and their associated gate drive components. Moreover, snubber capacitors and the transformer leakage inductance are utilized to achieve soft-switching. Therefore, no extra active switches or passive resonant components are required for softswitching, further reducing component count. Control of power flow among the three voltage buses is achieved by adjusting the duty ratio and phase angle between the half-bridge output voltages. Simulation and experimental data on a 2 kW lab unit are included to verify the power flow control scheme

Portable hybrid applications for AC/DC load sharing

Abstract: Portable hybrid applications for AC/DC load sharing includes circuitry for simultaneously using at least one of external AC, internal DC power and/or external DC power. The apparatus also includes an input power receptacle for receiving at least one of AC power and external DC power. A power router inside the apparatus routes at least one of AC power, internal DC power, and external DC power to provide power for an application. An apparatus for providing DC to DC conversion includes a tip and a DC to D C whip connected to the tip. A male plug is connected to the second end of the whip. A buck converter within the male plug converts DC power to a DC power level associated With the whip and transmits the converted DC power along the DC to DC whip to the tip. Alternatively, an internal DC source provides internal DC power.

A three-phase ZVS PWM DC/DC converter with asymmetrical duty cycle for high power applications

Abstract: This paper proposes the application of the asymmetrical duty cycle to the three-phase dc/dc pulse-width modulation isolated converter. Thus, soft commutation is achieved for a wide load range using the leakage inductance of the transformer and the intrinsic capacitance of the switches, as no additional semiconductor devices are needed. The resulting topology is characterized by an increase in the input current and output current frequency, by a factor of three compared to the full-bridge converter, which reduces the filters size. In addition, the rms current through the power components is lower, implying the improved thermal distribution of the losses. Besides, the three-phase transformer allows the reduction of the core size. In this paper, a mathematical analysis, the main waveforms, a design procedure, as well as simulation and experimental results obtained in a prototype of 6 kW are presented.

Control of high-frequency AC link electronic transformer

Abstract: An isolated high-frequency link AC/AC converter is termed an electronic transformer.The electronic transformer has size and cost advantages over a conventional transformer because of high-frequency operation of the magnetic core. Of the various topologies of electronic transformer, the high-frequency AC link electronic transformer achieves high-frequency AC power transformation without a DC link. The circuit uses the standard H-bridge, one on either side of the high-frequency transformer. A novel PWM scheme is proposed, which symmetrically delays and advances the phase of the left and right legs of the front-side converter with respect to the output side converter. The proposed scheme introduces free wheeling sub-periods, which results in zero voltage switching in the output-side converter. The electronic transformer as an AC automatic voltage regulator (AVR) offers distinct advantages over a conventional servo voltage stabiliser in terms of size and speed of response. The AVR application is discussed and experimental results of a 500VA AVR are presented. A four-quadrant switch presents difficulties in turning off inductive load current because of the absence of a free wheeling path in the switch. A biasing circuit is proposed to convert the potentially lossy switching transition into lossless transition. Simulation and experimental results with the biasing circuit are presented.

Primary side constant output current controller

Abstract: A lower-cost and more precise control methodology of regulating the output current of a Flyback converter from the primary side is provided. The methodology regulates the output current accurately in both continuous current mode (CCM) and discontinuous mode (DCM) and can be applied to most small, medium, and high power applications such as cell phone chargers, power management in desktop computers and networking equipment, and, generally, to a wide spectrum of power management applications. Two highly integrated semiconductor chips based on this control methodology are also described that require very few components to build a constant current Flyback converter.

A three-phase step-up DC-DC converter with a three-phase high frequency transformer

Abstract: This paper presents a new 3-phase step-up DC-DC converter with a 3-phase high frequency isolation transformer. This converter was developed for industrial applications where the DC input voltage is lower than the output voltage, for instance in, installations fed by battery units, photovoltaic arrays or fuel cell systems. The converter's main characteristics are: reduced input ripple current, step-up voltage, high frequency isolating transformer, reduced output voltage ripple due to three pulsed output current and the presence of only three actives switches connected at the same reference, this being a main advantage of this converter. By means of a specific switch modulation, the converter allows two operational regions. Theoretical expressions and experimental results are presented for a 6.8 kW prototype, operating in region R2 and for a 3.4 kW prototype operating in region R3, both in continuous conduction mode.

More compact and higher reliability power source system

Abstract: This invention features a more compact and higher reliability power source system for computing loads, the system including a high voltage DC bus (32) connected to a number of DC sources each connected to the high voltage DC bus by a switch configured to deliver to the high voltage DC bus the DC source with the highest DC voltage, a low voltage DC bus (60) connected to the computing loads (60), and a power supply including a number of DC/DC converters (150,152,154,156,158,160) connected in parallel between the high voltage DC bus and the low voltage DC bus, and a controller (80) configured to modulate each DC/DC converter to convert the high voltage on the high voltage DC bus to a low voltage output on the low voltage DC bus.

A three-level converter and its applicationto power factor correction

Abstract: The first part of this paper introduces a novel three-level dc-dc converter topology. It is shown that a floating capacitor connected across the clamping diodes of a conventional three-level converter enables phase-shift control while retaining zero voltage switching. Design constraints and experimental results are shown for a 6-kW, 100-kHz dc-dc prototype. The second part of the paper discusses the same three-level topology operated as a single-stage front-end converter. In this application, the converter realizes power factor correction and dc output voltage regulation. To ensure low harmonic distortion, the input currents are operated in discontinuous conduction mode, and the performance, including soft switching, is also verified on a 3-kW, 50-kHz ac-dc converter.

Parallel powering of portable electrical devices

Abstract: A portable electrical device may include a DC to DC converter coupled to a common node, a load coupled to the common node, and a controller configured to control the DC to DC converter. The DC to DC converter may be configured to provide a charging current to a rechargeable battery from an adapter when the controller operates said DC to DC converter in a first adapter supply mode. The DC to DC converter may be configured to provide a battery supply current to the load via the common node when the controller operates the DC to DC converter in a second adapter supply mode. The adapter supply current and the battery supply current may add together at the common node to simultaneously provide a load supply current to the load in the second adapter supply mode.

Power losses and efficiency analysis of multilevel dc-dc converters

Abstract: This paper presents a detailed analysis about the power losses and efficiency of multilevel dc-dc converters. The analysis considers different loss mechanisms and gives out quantitative descriptions of the power losses and useful design criteria. The analysis is based on a three-level multilevel dc-dc converter and can be extended to other switched-capacitor converters. The comparison between the theoretical analysis and the experimental results are shown to substantiate the theory

A multiple-input DC/DC converter for renewable energy systems

Abstract: This paper presents a multiple-input DC/DC converter for renewable energy systems. The proposed DC/DC converter can be used to obtain well-regulated output voltage from several power sources, such as wind turbines, photovoltaic arrays, fuel cells, etc. The energy provided by these power sources can be simultaneously transferred into the load. The proposed multiple-input DC/DC converter has the advantages of simple configuration, fewer components, lower cost and high efficiency. The operating principle, theoretical analysis, and design criteria are provided in this paper. A laboratory prototype with two different power sources was successfully implemented and tested. The simulation and experimental results are given to verify the feasibility of the proposed scheme

Interleaved power converter

Abstract: A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DC converters with three rather than four high voltage inverter legs.

Zero-Voltage Transition Flyback Inverter for Small Scale Photovoltaic Power System

Abstract: A zero-voltage transition (ZVT) flyback inverter is proposed. The current in the flyback transformer is controlled in the fixed frequency, and the pulse width is varied to make the inductor current sinusoid. In order to reduce switching losses and noises, a soft-switching technique is adopted. The soft-switching technique is called the switched snubber circuit or the primary current steering technique. It is suitable for the pulse-width modulation (PWM), because the time of the resonant transition is very short and the time is independent of the switching frequency. A laboratory prototype using a digital controller for the ZVT flyback inverter was built. From the simulation using the PSPICE and experimental results, the zero-voltage transition operation of the main switch is confirmed. The proposed inverter is suitable as a power conditioner for PV power systems

A control method for the matrix converter based on virtual AC/DC/AC conversion using carrier comparison method

Abstract: This paper proposes a novel control method based on the virtual AC/DC/AC conversion for the matrix converter. The virtual AC/DC/AC conversion method is a very simple strategy to control the input current and the output voltage for the matrix converter. There are two new topics proposed in this paper. First, this paper proposes the minimum switching loss modulation on the virtual rectifier. In our proposed modulation, only two arms switching in the virtual rectifier using DC link current control by the virtual inverter can obtain clean sinusoidal input current. Second, a novel lean controlled carrier modulation on the virtual inverter is proposed. The leans of the triangle carrier are controlled by the duty ratio of the rectifier side pulse. The lean controlled carrier reduces harmonic distortion of the input current by avoiding interference between the rectifier control and the inverter control. These new proposals are confirmed by simulation and experimental results. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 65–73, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20144

Highly efficient isolated AC/DC power conversion technique

Abstract: An AC-to-DC power converter that is capable of generating a regulated, isolated DC voltage output from a power factor corrected AC voltage input with improved efficiency. The AC-to-DC power converter is a two-stage power converter including a PFC stage connected in series to a power conversion stage. The PFC stage performs power factor correction using a zero current switching technique, and the power conversion stage includes a zero voltage switched half-bridge converter. The power conversion stage includes a transformer for providing the isolated DC voltage output. The AC-to-DC power converter includes a single feedback control loop for transferring error information from the DC voltage output to the PFC stage, thereby obtaining regulation of the DC voltage output.