共查询到20条相似文献,搜索用时 31 毫秒
1.
An analysis and design of single-stage, single-switch bi-flyback ac/dc converter is presented. The main flyback stage controls the output power from the link capacitor voltage with Discontinuous Conduction Mode (DCM) or Continuous Conduction Mode (CCM) operation, while an auxiliary flyback stage supplies the power to the output directly from ac line input with DCM operation. This scheme can effectively reduce the voltage stress on the link capacitor and can achieve the power factor correction (PFC) without a dead band at line zero-crossings, which reduces the harmonic distortion in ac line current. Theoretical analysis of the converter is presented and design guidelines to select circuit components are given. The experimental results on a 60?W (15?V, 4?A), 100?kHz ac/dc converter show that maximum link voltage and maximum efficiency are around 415?V and 82%, respectively. The power factor is above 0.96 under universal line input and load conditions. 相似文献
2.
Gert K. Andersen Christian Klumpner Søren Bækhøj Kjær Frede Blaabjerg 《International Journal of Electronics》2013,100(11-12):737-750
This paper presents a new high-efficiency grid-connected single-phase converter for fuel cells. It consists of a two-stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25?V–45?V) this voltage must be transformed to around 350–400?V in order to be able to invert this dc power into ac power to the grid. The proposed converter consists of an isolated dc–dc converter cascaded with a single-phase H-bridge inverter. The dc–dc converter is a current-fed push-pull converter. The inverter is controlled as a standard single-phase power factor controller with resistor emulation at the output. Experimental results of converter efficiency, grid performance and fuel cell dynamic response are shown for a 1?kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92%) and the inverter operates with a near-unity power factor and a low current THD. 相似文献
3.
《Power Electronics, IEEE Transactions on》1987,2(4):313-319
In view of the growing use of high-voltage (HV) dc in the US as well as other countries, new converter designs that can overcome the shortcomings of the conventional converter and support new applications of HV dc technology are being investigated. An HV dc converter is introduced that can operate without external reactive power compensation under any load conditions, control real and reactive power (or ac bus voltage) independently over a range of operation, and operate into weak ac systems without sophisticated converter control. The hybrid converter is found to be promising, and its full potential remains to be developed. 相似文献
4.
《Industrial Electronics, IEEE Transactions on》2009,56(6):2095-2107
5.
Reddiprasad Reddivari 《International Journal of Electronics》2018,105(10):1785-1803
Nowadays Z-source networks are the most promising power converter networks that cover almost all electric power conversion (dc–dc, dc–ac, ac–dc and ac–ac) applications. However, the controller design is critical for Z-source converter (ZSC) due to the presence right-half-plane zero (RHPZ) in the control-to-capacitor-voltage transfer function. This RHPZ exhibits non-minimum phase undershoot in the capacitor voltage and also in the dc-link voltage waveforms. A perfect small-signal model is required to predict locations of the RHP zero and its dynamics. This paper contributes towards the small-signal analysis of ZSC under continuous conduction mode considering the parasitic resistance of the inductor, equivalent series resistance of the capacitor, internal resistances of active switch and forward voltage drop of the diode. The maximum allowable value of shoot-through duty ratio (STDR) and voltage gain for different values of the internal resistance and load resistance are discussed in this paper. The accuracy of the developed small-signal average model is compared with detailed circuit model in MATLAB/SIMULINK. Finally, the steady-state simulation results of ZSC are validated with hardware results. 相似文献
6.
《Electron Devices, IEEE Transactions on》1971,18(1):3-11
A device for converting microwave power into either dc power or low-frequency ac power has been investigated both theoretically and experimentally. Rotational energy is stored in an electron beam by a Cuccia coupler, then converted to longitudinal energy by interaction with a space-dependent dc magnetic field, and finally recovered as electric energy by a depressed collector. A simple kinematic analysis demonstrates that the Cuccia coupler can convert large amounts of microwave power into electron beam rotation. Limits on the electric field strength and asynchronism between signal frequency and cyclotron frequency are established for both classical and relativistic coupler operation. Efficiency analyses of the process of conversion from orbital energy to dc electric energy, both classical and relativistic, indicate that the efficiency exceeds 95 percent for a particular range of operating conditions. As an ac power supply, the device responds to the modulating frequency of the signal. Theory predicts near-negligible harmonic distortion as well as flatness of frequency response from dc to about 1.0 MHz modulating frequency. Four tubes and a prototype (with "artificial" coupler) were tested experimentally. The first three tubes exhibited efficiencies up to 22 percent, being hindered by reflection of electrons into the coupler. Certain design changes were tested on the prototype, where efficiencies from 36 percent to 75 percent were obtained. Incorporating these design changes into the fourth tube yielded measured efficiencies up to 34 percent, or when corrected to disregard unusually large cavity losses, up to 59 percent. Experimental tests of the tube as an ac converter yielded excellent frequency response and about 20 percent second-harmonic distortion. It is concluded that the theoretical foundation of efficiency predictions has thus far been based on too optimistic assumptions. 相似文献
7.
In-Dong Kim Eui-Cheol Nho 《Industrial Electronics, IEEE Transactions on》2005,52(1):181-189
Cathodic protection is widely used to prevent corrosion of steel materials buried underground and in seawater. As a rectifier for cathodic protection, the conventional phase-controlled rectifiers with 50- or 60-Hz isolation transformers have been used so far in spite of such shortcomings as large volume, heavy weight, and poor power factor. In order to overcome such disadvantages, this paper proposes a new module-type switching rectifier for cathodic protection, which is composed of two parts, namely, ac/dc converter and module-type dc/dc converter. The ac/dc converter is a single-phase insulated gate bipolar transistor pulsewidth-modulation rectifier, thus resulting in almost unity power factor and controlled dc output voltage. The module-type dc/dc converter operates under zero-voltage switching/zero-current switching condition to permit high-frequency switching operation. It enables the use of a high-frequency transformer for electrical isolation, thus reducing volume and weight of the overall system and improving system efficiency. It is anticipated that the proposed rectifier techniques will apply to the similar technical areas such as multiple-module power supply systems and modular converter-fed dc motor drives. 相似文献
8.
《Power Electronics, IEEE Transactions on》2009,24(10):2276-2288
9.
《Power Electronics, IEEE Transactions on》2009,24(1):14-24
10.
Flyboost power factor correction cell and a new family of single-stage AC/DC converters 总被引:2,自引:0,他引:2
Shiguo Luo Weihong Qiu Wenkai Wu Batarseh I. 《Power Electronics, IEEE Transactions on》2005,20(1):25-34
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. 相似文献
11.
Tae-Sung Kim Gwan-Bon Koo Gun-Woo Moon Myung-Joong Youn 《Power Electronics, IEEE Transactions on》2006,21(1):89-97
A single-stage power factor correction ac/dc converter based on zero voltage switching (ZVS) full bridge topology with two series-connected transformers is proposed in this paper. The proposed converter offers a very wide ZVS range due to the configuration of two series-connected transformers. It features a high efficiency over wide load ranges. Furthermore, it shows the low voltage stress on a dc link capacitor. The proposed converter also gives the high power factor and low input current harmonics complied with IEC 61000-3-2 Class D requirements by integrating a boost stage operated in a discontinuous current mode. The ZVS conditions, large signal modeling, and design procedure are discussed in detail. Experimental results are presented to show the validity of the proposed converter. 相似文献
12.
A New Method of Integration Control With Instantaneous Current Monitoring for Class D Series-Resonant Converter 总被引:1,自引:0,他引:1
In this paper, the application of the integration control method for class D transistor voltage source series-resonant converters used as dc/dc and dc/ac converters is presented. First, the integration control of the signal as a combination of the resonant frequency and its subharmonics (subharmonic integration control) is discussed. Second, the modulation density of the pulses shorting the bridge diagonal for one current half wave (semi wave integral pulse density modulation) is explained. A detailed control circuit operation, referred to as the four basic algorithms of the resonant current control, is given. The method for the calculation of the value and sequence of the current increments for a dc/dc converter is presented. The results of computer simulations and laboratory experiments demonstrate that the proposed methods allow controlling the converter output quantities fulfilling soft switching conditions (zero-current switching) and provide higher efficiency in comparison to other known methods 相似文献
13.
Wan-Rone Liou Mei-Ling Yeh Yueh Lung Kuo 《Power Electronics, IEEE Transactions on》2008,23(2):667-677
This paper presents the design of a novel wide output current range dual-mode dc to dc step-down (Buck) switching regulator/converter. The converter can adaptively switch between pulsewidth modulation (PWM) and pulse-frequency modulation (PFM) both with very high conversion efficiency. Under light load condition the converter enters PFM mode. The function of closing internal idle circuits is implemented to save unnecessary switching losses. The converter can be switched to PWM mode when the load current is greater than 100 mA. Soft start operation is designed to eliminate the excess large current at the start up of the regulator. The chip has been fabricated with a TSMC 2P4M 0.35 mum polycide CMOS process. The range of the operation voltage is from 2.7 to 5 V, which is suitable for single-cell lithium-ion battery supply applications. The maximum conversion efficiency is 95% at 50 mA load current. Above 85 % conversion efficiency can be reached for load current from 3 to 460 mA. 相似文献
14.
《Electron Devices, IEEE Transactions on》1972,19(2):234-238
A thin solid-state X-ray panel of sandwich-type structure using photoconductive (PC) and semiconducting electroluminescent (EL) powder layers has been developed. The PC layer and the semiconducting EL layer are connected electrically in series. Both ac and dc voltages are applied across the combination. The X-ray sensitivity of the converter depends on the dc voltage drop across the PC powder layer and on input X-ray intensity. Gamma and input latitude of the converter performance are widely controllable by adjusting the dc voltage applied across the panel. The ac supplies excitation for the EL phosphor. The light output intensity at a low X-ray intensity level is substantially improved without deteriorating the picture resolution. For X-ray intensity of 30 mR/min, 80 kV peak, the converter produces light output about 800 times as bright as a conventional fluoroscope screen does, and Mo wire of 200-µm diameter is observed. However, seconds are required for image buildup and cutoff. Converted X-ray images using an experimental converter are also shown. 相似文献
15.
A compact size and high efficiency single-inductor dual-output (SIDO) DC–DC converter is proposed. The proposed SIDO DC–DC converter not only provides dual output sources (one buck and one boost outputs) but also has minimized cross regulation without using any external compensation components. Generally speaking, it is important to minimize the number of components and footprint area in the design of SIDO converters. However, usually large external compensation resistors and capacitors are required to stabilize DC–DC converters. Importantly, our proposed hysteresis mode operation can effectively avoid the oscillation problems that may exist in many SIMO designs. Furthermore, the dynamic dc current level like that in the continuous conduction mode (CCM) operation can make the proposed SIDO DC–DC converter achieve high conversion efficiency at light loads owing to small conduction loss. Experimental results show a high efficiency from 85% at light loads to 94% at heavy loads. 相似文献
16.
Jun-Young Lee 《Industrial Electronics, IEEE Transactions on》2007,54(2):724-732
A single-phase single-stage ac/dc converter with input-current dead-zone control is proposed. It is based on flyback topology operating in discontinuous conduction mode (DCM). The current charging into the link capacitor is controlled according to line changes by adjusting the input-current blocking angle to alleviate an excessive increase of the link voltage. The reduced voltage stress can maintain an almost-constant voltage irrespective of load conditions by operating in dc/dc stage in DCM. Experimental results of a 60-W (5-V 12-A output) prototype converter show that the link voltage is limited within 384 V and that the measured power factor is more than 0.91 under universal voltage inputs and entire load conditions. In addition, the maximum efficiency is measured to be about 81% at the rated condition 相似文献
17.
This paper describes a line-interactive single-phase to three-phase converter. A typical application is in rural areas supplied by a single-wire with earth return system. The traditional objective of feeding a three-phase induction motor is not anymore the main concern for such conversion. Due to the evolution of the farm technology, some of the local loads (as electronic power converters, computers, communication equipments, etc) require high power quality that is intended as sinusoidal, symmetrical, and balanced three-phase voltage. Additionally, to maximize the power from the feeder, the system provides a unity power factor to the grid. A three-phase voltage source inverter-pulsewidth modulation converter is used for this purpose. The power converter processes a fraction of the load power and the energy necessary to regulate the dc link voltage. As it does not need to supply active power, it is not necessary to have a source at the dc side. However, if island mode operation is needed, a dc source must be available at the dc link to supply the load. The control strategy, design criteria, and experimental results are presented 相似文献
18.
《Electron Devices, IEEE Transactions on》1962,9(4):358-365
Three tunnel-diode converter circuits-the Storm and Shattuck circuit, a push-pull version, and the Marzolf circuit-are analyzed graphically to obtain waveforms for both inverter and dc converter operation. Simple expressions are found for diode efficiency in ideal dc converter operation. The efficiencies are the same except that the efficiency of the Marzolf circuit is reduced by the magnetizing current required for the square-loop core. However, the Marzolf circuit has a more nearly square waveform and would require less filtering for dc conversion. The results point up the importance of developing tunnel diodes with high peak-to-valley ratios for converter application. 相似文献
19.
Transistor dc-dc converters which employ a resonant circuit are described. A resonant circuit is driven with square waves of current or voltage, and by adjusting the frequency around the resonant point, the voltage on the resonant components can be adjusted to any practical voltage level. By rectifying the voltage across the resonant elements, a dc voltage is obtained which can be either higher or lower than the input dc voltage to the converter. Thus, the converter can operate in either the step-up or step-down mode. In addition, the switching losses in the inverter devices and rectifiers are extremely low due to the sine waves that occur from the use of a resonant circuit (as opposed to square waves in a conventional converter); also, easier EMI filtering should result. In the voltage input version, the converter is able to use the parasitic diode associated with an FET or monolithic Darlington, while in the current input version, the converter needs the inverse blocking capability which can be obtained with an IGT or GTO device. A low-power breadboard operating at 200-300 kHz has been built. Two typical application areas are switching power supplies and battery chargers. The converter circuits offer improvements over conventional circuits due to their high efficiency (low switching losses), small reactive components (high-frequency operation), and their step-up/stepdown ability. 相似文献
20.
《Power Electronics, IEEE Transactions on》2009,24(1):108-115