直流电－直流电开关变流器的统一建模方法

提出一种能通用于脉宽调制（ＰＷＭ）型，准谐振型，桥式串（并）联谐振型等各类开关变流器的统一建模方法，脉冲波形积分法。本法能充分反映各类变流器的自身特点，为变流器动态性能指标的分析与设计提供统一衡量标准，文中以两种类型变流器为例阐明建模原理，并将建模结果与有关文献进行比较，计算机仿真结果证明所建模型是正确的。     

Modeling PWM DC/DC converters out of basic converter units

An alternative approach to modeling pulsewidth-modulated (PWM) DC/DC converters out of basic converter units (BCUs) is presented in this paper. Typical PWM DC/DC converters include the well-known buck, boost, buck-boost, Cuk, Zeta, and Sepic. With proper reconfiguration, these converters can be represented in terms of either buck or boost converter and linear devices, thus, the buck and boost converters are named BCUs. The PWM converters are, consequently, categorized into buck and boost families. With this categorization, the small-signal models of these converters are readily derived in terms of h parameter (for buck family) and g parameter (for boost family). Using the proposed approach, not only can one find a general configuration for converters in a family, but one can yield the same small-signal models as those derived from the direct state-space averaging method. Additionally, modeling of quasi-resonant converters and multiresonant converters can be simplified when adopting the proposed approach     

软开关PWM变换器发展综述

软开关技术已从基本谐振变换器,准谐振变换器和谐振直流环节变换器发展到软开关ＰＷＭ变换器。软开关ＰＷＭ变换器综合了软开关技术和ＰＷＭ技术各自的优点,构成新一类目前发展和应用前景的变换器。本文系统地综述了谐振直流环变换器,零电压和零电流开关ＰＷＭ变换器,零电压转换ＰＷＭ变换器和零电流转换ＰＷＭ变换器的工作原理和特点。     

Equivalent circuit models for resonant and PWM switches

The nonlinear switching mechanism in pulsewidth-modulated (PWM) and quasi-resonant converters is that of a three-terminal switching device which consists only of an active and a passive switch. An equivalent circuit model of this switching device describing the perturbations in the average terminal voltages and current is obtained. Through the use of this circuit model the analysis of pulsewidth modulated and quasiresonant converters becomes analogous to transistor circuit analysis where the transistor is replaced by its equivalent circuit model. The conversion ratio characteristics of various resonant converters and their relationship to a single function, called the quasi-resonant function, is easily obtained using the circuit model for the three-terminal switching device. The small-signal response of quasi-resonant converters to perturbations in the switching frequency and input voltage is determined by replacing the three-terminal switching device by its small-signal equivalent circuit model     

Analysis and design of a new constant frequency control for QRC andMRC based on magnetic elements modification

Multiresonant power converters (MRCs) and quasi-resonant power converters (QRCs) have been modified to provide constant-frequency operation. Transformer leakage inductance has been used to adapt the traditional pulse-width-modulation (PWM) control to these converters. Conventional PWM integrated circuits can be used for the power converter regulation. Several experimental results are developed to test the control method proposed     

A unified approach to modeling, synthesizing, and analyzingquasi-resonant converters

This paper presents a general method of modeling, synthesizing, and analyzing quasi-resonant converters (QRCs), including actively clamped QRCs. First, the concept of the pulse-width modulation (PWM) switch model is generalized to encompass all PWM (nonisolated) converters. Then, by adding inductor-capacitor (LC) elements and auxiliary switches into the PWM switch, QRC families are synthesized. DC and small signal analyses can be carried out based on these switch models. Furthermore, the duality relationship between zero-voltage-switching (ZVS) and zero-current-switching (ZCS) QRCs is established systematically and rigorously     

A unified approach to characterization of PWM and quasi-PWMswitching converters: topological constraints, classification, andsynthesis

Topological constraints are obtained for pulse width-modulation (PWM) (under both continuous and discontinuous current modes) and quasi-PWM (including families of quasi-resonant and quasi-square wave) converters by identifying their three structures. Switching sequences of these converters and a classification of quasi-PWM power converters are presented. A dual circuit of an ideal diode and an ideal switch are proposed and used to obtain duals of the switching converters in one step. A procedure for the synthesis of quasi-PWM converters is presented     

A unified analysis of PWM converters in discontinuous modes

Three discontinuous operating modes of PWM (pulsewidth modulated) converters are considered: the discontinuous inductor current mode (DICM), the discontinuous capacitor voltage mode (DCVM), and a previously unidentified mode called the discontinuous quasi-resonant mode (DQRM). DC and small-signal AC analyses are applicable to all basic PWM converter topologies. Any particular topology is taken into account via its DC conversion ratio in the continuous conduction mode. The small-signal model is of the same order as the state-space averaged model for the continuous mode, and it offers improved predictions of the low-frequency dynamics of PWM converters in the discontinuous modes. It is shown that converters in discontinuous modes exhibit lossless damping similar to the effect of the current-mode programming     

Symbolic analysis methods for averaged modeling of switching powerconverters

Symbolic analysis methods for the averaged modeling of switching power converters are presented in this paper. A general averaging method suitable for computer-aided modeling is discussed first. Then, a symbolic analysis package that uses this averaging method to automatically generate an analytical averaged model for a switching power converter is described. The package is implemented using the computer algebra system Mathematica and can be used for modeling DC/DC power converters employing different switching techniques, including hard-switching pulse-width modulation (PWM), quasi-resonant soft switching, and soft transition. Several examples are provided to demonstrate the applications of the package. Further applications of symbolic analysis methods in power electronics are also discussed     

High-frequency quasi-resonant converter technologies

Resonant switch topologies operating under the principle of zero-current switching (ZCS) and zero-voltage switching (ZVS) are introduced to minimize switching losses, stresses, and noises. Using the resonant switch concept, a host of new quasi-resonant converters (QRCs) are derived from conventional PWM converters. They are capable of operating in the megahertz range, with a significant improvement in performance and power density. Performances of ZCS and ZVS QRCs are compared. Power stages, gate drives, and feedback controls are discussed     

Application of the current-injected modeling approach toquasi-resonant converters

This paper describes how the current-injected (CI) method, which has been applied only to pulse-width modulation (PWM) DC-DC power converters, can be extended to quasi-resonant (QR) power converters. The methodology for extending this small-signal modeling approach is described in detail. It is also shown that QR dynamic models are easy to obtain since they are derived directly from PWM power converter models. These new models result in a unified block diagram from which zero-voltage-switching (ZVS) or zero-current-switching (ZCS) transfer functions of the basic topologies, such as buck, boost, and buck-boost operated in half-wave (HW) or full-wave (FW) modes, are found. As an application of this method, a ZVS boost power converter and ZCS boost power converter were fabricated and tested. In addition, small-signal models of these power converters were derived with the help of the state-space averaging (SSA) method. The agreement of the CI method simulations with the experimental results for the two QR power converters is comparable or better than that of the SSA method     

A general approach to synthesis and analysis of quasi-resonantconverters

A method for systematic synthesis of quasi-resonant (QR) topologies by addition of resonant elements to a parent pulse-width modulation (PWM) converter network is proposed. It is found that there are six QR classes with two resonant elements, including two novel classes. More complex QR converters can be generated by a recursive application of the synthesis method. Topological definitions of all known and novel QR classes follow directly from the synthesis method and topological properties of PWM parents. The synthesis of QR converters is augmented by a study of possible switch realizations and operating modes. In particular, it is demonstrated that a controllable rectifier can be used to accomplish the constant-frequency control in all QR classes. Links between the QR converters and the underlying PWM networks are extended to general DC and small-signal AC models in which the model of the PWM parent is explicitly exposed. Results of steady-state analyses of selected QR classes and operating modes include boundaries of operating regions, DC characteristics, a comparison of switching transitions and switch stresses, and a discussion of relevant design trade-offs     

Zero-voltage switching technique in DC/DC converters

A novel resonant switch operating under the principle of zero-voltage switching is presented. The basic configurations of the voltage-mode resonant switches are presented. The circuit's operating principles are described using a voltage-mode quasi-resonant boost converter. DC analysis of the converter is carried out. A new family of voltage-mode quasi-resonant converters are derived, and several members of this family are presented. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. These two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. The similarities and differences of the voltage-mode quasi-resonant converters and the Class-E converters are discussed. A 5 MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. Design considerations and experimental results of this circuit are presented     

Spectral modeling of switched-mode power converters

A new modeling approach for the spectral analysis of pulsewidth modulated (PWM) converters with independent inputs is developed. The key of this approach is to extend the Volterra functional series to nonlinear systems with multiple independent inputs. After formulating the state-space equations describing the dynamical behavior of PWM converters, the Volterra transfer function characterizing the output frequency response can be obtained, which is then symmetrised to form the spectral model. Since the model is developed in a closed form, it is suitable for computer analysis. The modeling approach has been applied to various PWM converters, and the results are verified. The spectral models of different power converters can readily be obtained by using this general approach     

A systematic approach to developing single-stage soft switching PWMconverters

A systematic approach to developing soft switching PWM converters based on the synchronous switch scheme is presented in this paper. With the approach, several families of passive and active soft switching PWM converters, such as buck-boost, Zeta, Cuk, and Sepic, can be generated from the two basic converters, buck and boost. Also, the approach is used to integrate multiple converters to form a single-stage soft switching PWM converter. It has been shown that analysis of the converters can be conveniently performed from the derived general configurations, reducing the complexity significantly. Therefore, employing the technique can not only explore more physical insights into the converters in a family but reveal more relationships among the soft switching converters over conventional approaches. Measured results from a prototype have verified the feasibility of the derived single-stage converters     

基于ZVS QRC Boost电路仿真研究

以零电压开关准谐振升压变换器（Boost ZVS-QRC）为例,论述了准谐振变换器的工作原理。应用推广的状态平均法原理建立了准谐振变换器的状态空间平均法模型,并通过MATLAB软件进行典型Boost ZVS-QRC的电路模型和数学模型仿真对比,结果表明合理利用状态空间平均法,同样适用于谐振变换器的建模。同时给出了处理复杂系统的MATLAB仿真方法。     

Computer-aided modeling of quasi-resonant converters in thepresence of parasitic losses by using the MISSCO concept

The DC and small-signal models of quasi-resonant converters, operating in both half-wave and full-wave modes, are developed in a suitable form for computer simulation. The starting step is the extraction of a minimum separable switching configuration (MISSCO) containing all power switches but a minimum number of other components (resonant ones). By using the step-response analysis and average technique, and by perturbing and separating the DC and AC components in the resulting equations, the equivalent models of MISSCO are derived. They are introduced in the converter structure to replace the circuit initially extracted. Models of different quasi-resonant converters can be obtained by this general approach. The analysis takes into account the conduction losses of the switching devices and reactive elements, which improves considerably the model accuracy. Model-based computer simulation agrees with the experimental results     

A simple large-signal nonlinear modeling approach for fastsimulation of zero-current-switch quasi-resonant converters

A nonlinear modeling approach for zero-current-switch (ZCS) quasi-resonant converters (QRC) is proposed which can be derived easily using simple analytical techniques. The converter model obtained is readily absorbed by MATLAB for analysis and design of both the open- and closed-loop configurations in fast speed. Simulations have shown its accuracy, even for large-signal transient responses. Applications of this modeling approach to the three basic topologies of buck, boost, and buck-boost converters are given as illustrative examples. The condition for zero-current switching is identified from the model. The feasibility of applying this proposed modeling approach to the extended period QRC topologies is to be discussed. Simulation results for the three basic topologies are given to show the merits of the proposed modeling approach     

DC-to-AC inversion using quasi-resonant techniques

It is demonstrated that two basic approaches can be taken to achieve DC-to-AC inversion. The first, the differential load excitation (DLE) scheme, uses two converters, driven out of phase, to drive a load differentially. Unfortunately, this scheme requires a large number of components when it is implemented using quasi-resonant techniques. A more component-effective approach uses switched source excitation (SSE) schemes. One SSE approach uses two converters, each handling one polarity of the signal. By appropriate switching, an amplified signal is reconstructed at the output. The second SSE approach entails only one converter but with a slightly more involved switching requirement. It allows a significant overall reduction in the number of components needed and reduced performance requirements on most of the switches, since most switch at the lower inversion-frequency rate. A number of quasi-resonant inverter topologies from two broad categories are presented. For applications that require inverters to supply reactive power, three schemes which can be applied to various inverters, thus affording them reactive load handling capability, are discussed     

DC—DC 开关功率变换器分析方法的述评

本文对ＤＣ－ＤＣ开关功率变换器分析方法作了一个较全面的述评，着重介绍了拓扑不变的等效电路模型，寄生效应的处理方法，状态空间平均在准谐变换器的应用以及渐近法在变换器中的应用等四个方面，另外，介绍了不稳定分析一些结果。