共查询到20条相似文献,搜索用时 0 毫秒
1.
Quasi-square-wave converters: topologies and analysis 总被引:2,自引:0,他引:2
A class of converters with zero-voltage or zero-current switching characteristics is analyzed using a method originally developed for quasiresonant and PWM (pulsewidth-modulated) converters. The method relies on identifying simple three-terminal structures, called converter sections, that contain the switches and the resonant tank elements. The various zero-voltage-switched and zero-current-switched converters are obtained by permutation of these converter sections between source and sink. The method unifies the analysis of this class of converters in a single equivalent circuit model. The voltage and current waveforms in these converters are essentially squarelike except during the turn-on and turn-off switching intervals 相似文献
2.
Synthesis of input-rectifierless AC/DC converters 总被引:1,自引:0,他引:1
Liu C.P. Tse C.K. Poon N.K. Pong B.M.H. Lai Y.M. 《Power Electronics, IEEE Transactions on》2004,19(1):176-182
This paper discusses the basic construction procedure and topological possibilities of creating AC/DC converters out of simple DC/DC converters. It is shown that two separately controlled DC/DC converters are sufficient for producing a regulated DC output and shaping the input current, from an AC voltage source, without the need for input rectifiers. Some design constraints are discussed, emanating from the limitation of the conversion ratios that can be achieved by particular DC/DC converters. Selected topologies are verified experimentally. This kind of rectifierless converter find applications in airborne power supplies where zero-crossing distortions are significant because of the inevitable phase-lead effect of the input rectifier bridge. 相似文献
3.
Unified analysis of switched-capacitor resonant converters 总被引:1,自引:0,他引:1
Yeung Y.P.B. Cheng K.W.E. Ho S.L. Law K.K. Sutanto D. 《Industrial Electronics, IEEE Transactions on》2004,51(4):864-873
A family of switched-capacitor resonant circuits using only two transistors is presented. The circuit operates under zero-current switching and, therefore, the switching loss is zero. It also offers a wide choice of voltage conversions including fractional as well as multiple and inverted voltage conversion ratios. 相似文献
4.
The current trends in development and deployment of advanced switching converters have facilitated the unified activities in topology design, nonlinear analysis, optimization, and control. In this paper, by using nonlinear models of resonant converters, bounded controllers are designed to ensure a spectrum of performance objectives required. To attain high efficiency and power density, new converter topologies were developed. It is recognized that advanced closed-loop configurations must be designed to guarantee a spectrum of specifications and requirements imposed on the converter dynamics. The output voltage of converters is regulated by changing the duty ratio, which is constrained by lower and upper limits. In this paper, to approach design tradeoffs and analyze converter performance (settling time, overshoot, stability margins, and other quantities), the constraints and nonlinearities are thoroughly examined. Innovative controllers are synthesized to ensure performance improvements. To illustrate the control laws designed and to validate these algorithms, analytical and experimental results are presented and discussed. In particular, nonlinear analysis and design with experimental verification are performed and documented for a resonant converter with zero-current-switching 相似文献
5.
A mathematically correct derivation for the operation of implicit RMS detectors is presented and contrasted with the conventional heuristic derivation. The resulting transfer characteristic is used to derive results for converter accuracy in practice. 相似文献
6.
A unified analysis of resonant converters 总被引:4,自引:0,他引:4
Ninomiya T. Nakahara M. Higashi T. Harada K. 《Power Electronics, IEEE Transactions on》1991,6(2):260-270
The general method of analysis for resonant power converters is presented. This analytical method generalizes the idea of state-space-averaging technique to overcome the limitations of the conventional state-space-averaging method. As the result, the characteristics of resonant power converters are clarified so that transfer functions and stability conditions are revealed. In addition, a computer program of analysis based on the proposed method is developed. The program can be applied to various resonant power converters, even when they have parasitic losses and higher-order resonant circuits 相似文献
7.
Law K.K. Cheng K.W.E. Yeung Y.P.B. 《IEEE transactions on circuits and systems. I, Regular papers》2005,52(5):943-948
A switched-capacitor-based step-up resonant converter is proposed. The voltage conversion of the converters is in step-up mode. By adding a different number of switched-capacitor cells, different output voltage conversion ratios can be obtained. The voltage conversion ratio from 2 to any whole number can therefore be generated by these switching-capacitor techniques. A resonant tank is used to assist in zero-current switching hence the current spike, which usually exists for classical switched-capacitor can be eliminated. Both high-frequency operations and high efficiency are possible. Generalized analysis and design method of the converters are also presented. Experimental results verified the theoretical analysis. 相似文献
8.
Singh M. Koren I. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2003,11(5):839-852
Reliability of systems used in space, avionic, and biomedical applications is highly critical. Such systems consist of an analog front-end to collect data, an analog-to-digital converter (ADC) to convert the collected data to digital form, and a digital unit to process it. Though a considerable amount of research has been performed to increase the reliability of digital blocks, the same cannot be claimed for mixed-signal blocks. The reliability enhancement that we employ begins with fault-sensitivity analysis followed by redesign. The data obtained from the sensitivity analysis is used to grade blocks based on their sensitivity to faults. The highly sensitive blocks can then be replaced by more reliable alternatives. The improvement gained by opting for more robust implementations might be limited due to the number of possible implementations. In these cases, alternative reliability enhancement techniques such as adding redundancy may provide further improvements. The steps involved in the reliability enhancement of ADCs are illustrated in this paper by first proposing a sensitivity analysis methodology for /spl alpha/-particle induced transients and then suggesting redesign techniques to improve the reliability of the ADC. A novel concept of node weights specific to /spl alpha/-particle transients is introduced, which improves the accuracy of the sensitivity analysis. The fault simulations show that, using techniques such as alternative robust implementations, adding redundancy, pattern detection, and transistor sizing, considerable improvements in reliability can be attained. 相似文献
9.
Jian Sun 《Power Electronics, IEEE Transactions on》2005,20(2):308-314
The input impedance of single-phase boost power factor corrected (PFC) AC-DC converters is modeled and analyzed in this paper. A large-signal model is presented for the input impedance which overcomes the limitations of traditional piece-wise linearized models. The model is valid at frequencies ranging from the crossover frequency of the output voltage loop to half the switching frequency of the converter. Experimental results from a boost single-phase PFC converter are provided to validate the model. Input characteristics of typical boost PFC converters, such as input impedance dipping, leading phase of the input current, and responses to distorted input voltages are studied by using the model. A simple compensation technique to reduce the dipping in the input impedance, thereby improving converter performance and minimizing the potential for undesirable interactions with the input filter or the ac source, is also presented. 相似文献
10.
General analysis of harmonic transfer through converters 总被引:2,自引:0,他引:2
Harmonic transfer from DC-side to AC-side and vice-versa through a three-phase bridge power converter is treated by using space vectors. The dependency of the relative frequency of a harmonic and its sequence (positive/negative) is illustrated. It is shown that the derived relationships are valid for both voltage-source and current-source power converters. Thereby, the relationships for the frequency transformation through power converters are also valid for both voltage and current harmonics. This analytical method is validated by digital simulations with EMTP software 相似文献
11.
Graphical phasor analysis of three-phase PWM converters 总被引:1,自引:0,他引:1
A graphical steady-state analysis technique based on the complex 0-sequence, forward-rotating, and backward-rotating (0fb) phasors is described for balanced three-phase PWM inverters, rectifiers and cycloconverters. The technique avoids the cumbersome algebra of the 0fb transformation, and the coupling between the subcircuits resulting from the real direct-axis/quadrature-axis (dq) transformation. Using symmetric and de-coupled subcircuits that are time-invariant under steady state, the graphical method makes the analysis of three-phase converters straightforward and insightful. In the paper, time-invariant transient models with respect to an arbitrary reference node are first derived for all three-phase converter components. Application of the component models to steady-state analysis is demonstrated for the buck-boost inverter. The steady-state equivalent circuits for the popular buck and boost inverters, rectifiers, and cycloconverters are given along with the steady-state values for their capacitor voltages and inductor currents 相似文献
12.
In this paper, based on the switching cell approach, a unified steady state analysis for families of soft-switching DC-DC converters with complete unified design equations will be presented. The concept of the unified approach and step by step procedure for a generalized process are discussed and applied to selected soft-switching families such as zero-voltage-switching (ZVS) and zero-current-switching (ZCS)-quasi-resonant converter families, ZVS-clamped voltage quasi-square-wave (QSW) family, ZCS-clamped-current (CC) QSW family, and zero-voltage-transition and zero-current-transition pulse-width modulation families. Also, it has been noted that all the analyzed families have one generalized transformation table. The basic unified equations are summarized and the cell-to-cell comparison will be introduced. It will be shown that the unified analysis leads to several advantages such as improving the computer-aided analysis and design, simplified mathematical modeling, and giving more insight into the converter-cell operation. 相似文献
13.
Obermann K. Koltchanov I. Petermann K. Diez S. Ludwig R. Weber H.G. 《Quantum Electronics, IEEE Journal of》1997,33(1):81-88
This paper deals with a general problem concerning semiconductor-laser amplifiers used for frequency conversion. The amplified spontaneous emission (ASE) of a saturated amplifier is investigated experimentally and theoretically. An analytical solution accounting for the spatial dependence of the inversion parameter as well as the spectral dependence of the ASE is derived. Hence, the results can be applied to arbitrary saturation conditions and frequency shifts. Our theory is applied to frequency converters based on four-wave mixing and is found to be in good agreement with both the numerical results and the experimental data. In order to quantify the performance of a frequency converter, a noise figure is defined and shown to be strongly dependent on the frequency detuning and the power of the input waves 相似文献
14.
Foster M.P. Sewell H.I. Bingham C.M. Stone D.A. Hente D. Howe D. 《Power Electronics, IEEE Transactions on》2003,18(4):985-993
The paper describes the development and application of a cyclic-averaging technique for the rapid analysis of high-order resonant power converters. To provide a focus to the paper, particular emphasis is given to a 3rd-order LCC voltage output converter topology. The proposed methodology predicts steady-state voltages and currents throughout the circuit, and provides estimates of the stresses on the resonant circuit components. State-space simulations and experimental results from a 350 V-input/150 V-output converter are used to demonstrate a prediction accuracy comparable with time-domain integration-based techniques is achievable, while requiring only 1/10,000th of the computation time. In addition, a comparison with Spice simulation results shows that cyclic averaging provides commensurate predictions of voltage and current stresses on the resonant circuit components. Issues arising from the stray capacitance associated with the resonant inductor, and the corresponding sensitivity of the predicted output voltage, are also considered. 相似文献
15.
《IEEE transactions on circuits and systems. I, Regular papers》2004,51(8):1596-1611
State space averaging methods are used to derive time-invariant models that bound the envelope of trajectories of pulsewidth modulated (PWM) dc-dc converters. The results are compared to conventional averaging methods used in power electronics, and it is shown that, at times, designing a dc-dc converter based on the averaged output of a converter can be ineffective because peak output values sometimes significantly deviate from the averaged output. This paper attempts to quantify this deviation by using both small-signal transfer functions and nonlinear models to model the maximum and minimum values of outputs of PWM converters. Issues in simulation and control loop design are also mentioned. 相似文献
16.
A compact formula is given for the Goos-Haenchen shifts occurring for total internal reflection of light from anisotropic media. This is used in a coupled-wave analysis of polarization conversion in thin-film waveguides deposited on optically birefringent substrates. A numerical example illustrates the considerable influence of the Goos-Haenchen shifts on the conversion length. 相似文献
17.
Qingquan Liu Qing-An Huang 《Electronics letters》2001,37(12):755-756
A microelectromechanical digital-to-analogue converter (DAC) based on the weighted-stiffness (WS) principle analogous to a weighted-resistor DAC for use in electronic circuits is proposed. To convert the digital voltage input to the analogue displacement, the stiffness of the vertical beams is employed as the scale factor. Finite element analysis and design optimisation are performed. Simulation shows that the error for the proposed DAC is less than 0.001 μm 相似文献
18.
Small-signal characteristics of current-mode-controlled PWM converters with a second-stage LC filter are analyzed. It is shown that a secondary filter can be designed to provide good attenuation of the switching ripple while maintaining adequate stability margins with capacitive loading. The resonant frequencies and damping coefficients of the second filter are derived, and design guidelines are given. It is shown that the current-loop gain of the buck converter is not affected by the addition of the second-stage filters when a small filter inductance is used. Three design examples are presented to demonstrate the use of analysis results. Two filter examples are designed for a buck converter. One of the second filters shows the problems that arise with a poor design. A third example is the design of a second-stage filter for a buck-boost converter. In each of the design examples, the small-signal analysis was performed using EASY5 software and the circuits were simulated using the state-space simulation program COSMIR 相似文献
19.
Jong-Lick Lin Hsin-Ying Hsieh 《Power Electronics, IEEE Transactions on》2000,15(2):205-214
A small signal model for zero-voltage-transition pulse width modulation (ZVT-PWM) buck converters is proposed in this paper. It shows that the ZVT-PWM buck converter exhibits better dynamical behavior than the conventional PWM buck converter. Based on the derived model consisting of line voltage disturbances and load variations, μ-synthesis is applied for a robust controller design to achieve performance requirement. In addition, a classical controller and a sliding mode controller with modified integral variable structure are also designed for performance comparisons. Finally, simulation and experimental results are presented to verify the requirement for robust performance of ZVT-PWM converters 相似文献