并联H桥DC/DC变换器软开关技术研究

与传统的Buck电路相比,基于H桥并联的DC/DC变换器可以实现电压的双极性输出和故障时的冗余控制,非常适合用于大功率电动机正反转控制的场合。分析了并联H桥型DC/DC变换器的结构组成和双脉宽调制(PWM)模式。为了降低双脉宽调制下H桥型DC/DC变换器的开通和关断损耗,对无源软开关技术进行了分析,重点探讨了RCD缓冲电路和最小应力缓冲电路之间的性能差异,指出最小应力软开关技术可以获得更好的软开关性能,并就将其用于双脉宽调制下的并联H桥DC/DC变换器进行了仿真研究。仿真结果表明:最小应力软开关技术用于双脉宽调制下并联H桥DC/DC变换器时,可以实现开关管的零电压开通和零电流关断。     

A new zero-voltage switching DC/DC boost converter

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     

ZVT boost converter using a ZCS auxiliary circuit

A soft switching boost converter with zero-voltage transition (ZVT) main switch using zero-current switching (ZCS) auxiliary switch is proposed. Operating intervals of the converter are presented and analyzed. Design considerations are discussed. A design example with experimental results obtained from a 600 W, 100 kHz, 380 V output, power factor corrected, ac-to-dc, boost converter using insulated gate bipolar transistors (IGBTs) is presented, Results show that the main switch maintains ZVT while the auxiliary switch retains ZCS for the complete specified line and load conditions     

A 10 kW DC-DC converter using IGBTs with active snubbers

This full bridge DC-DC converter employs zero voltage switching (ZVS) on one leg and zero current switching (ZCS) on the other. This technique produces exceptionally low insulated-gate bipolar transistor (IGBT) switching losses through the use of an active snubber that recycles energy back to the source. Experimental results are presented for a 10-kW, 20-kHz converter     

Three-phase single-stage ac/dc boost integrated series resonant converter

A new ac/dc 3-/spl phi/ single-stage converter is proposed integrating a 3-/spl phi/ discontinuous current mode (DCM) boost with a dc/dc fixed frequency series resonant converter (SRC). This converter has the following features: natural power factor correction, soft switching, high-frequency (HF) transformer isolation with the series resonant tank operating in above resonance mode, etc. A new complementary gating control scheme is used for simultaneous control of boost converter and the SRC. Modes of operation are presented and analyzed. Based on the analysis, design curves are obtained. An optimum design is given and a design example is presented. Results obtained from SPICE simulation for the designed converter are given to verify the performance of the proposed converter for varying load as well as line voltage. Experimental results obtained from a laboratory prototype converter are presented to verify the theory.     

ZCS-PWM boost rectifier with high power factor and low conduction losses

A new single-phase high power factor rectifier is proposed, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the switches and zero-voltage-switching (ZVS) in the diodes. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 60 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.2% and power factor near 0.99 has been measured. The analysis and design of the control circuitry are also presented.     

State-plane analysis of zero-voltage-switching resonant DC/DCconverters

The state-plane analysis technique is established for the zero-voltage-switching resonant DC/DC power converter family of topologies, namely the buck, boost, buck-boost, Cuk, sepic, and dual-sepic converters. The state plane provides a compression of information, which allows the designer to examine the nonlinear dynamics of resonant converter operation. Utilizing the state plane, modes of resonant converter operation are examined. Expressions are derived for the switching frequencies at the boundaries between these modes and at the boundary of energy conversion     

Zero dynamics-based design of damping networks for switching converters

A new design technique of the input filter damping network for dc-to-dc switching converters of buck type is presented. This technique is derived by means of zero dynamics analysis of the switching converter and yields equivalent results to those obtained using the classical approach based on minimizing the filter output impedance. The new method can be applied in converters of buck type with two inductors, boost with two inductors and dual SEPIC. Simulation and experimental results corresponding to a boost converter with two inductors illustrate the procedure.     

单端正激ZVT功率变换器实现

介绍一种单端正激工作方式的零电压过渡（ＺＶＴ）软开关ＤＣ－ＤＣ变换器;描述该变换器的原理和特征;给出了应用ＺＶＴ软开关技术和集成控制块ＳＧ３５２５Ａ的２４Ｖ／９ＡＤＣ－ＤＣ变换器电路和实验结果。     

Boost变换器软开关技术的研究

提出一种新型有源软开关技术,在辅助开关和谐振电路的作用下,可以实现开关电源中开关管的零电压开通和零电压关断,而且可以减小开关管的电压应力和电流应力。对电路工作原理和参数设置进行了分析,给出了关键参数的选取原则。利用实际电路,验证了有源软开关技术的有效性。     

应用于超级电容储能系统的双向DC/DC变换器混沌控制方法研究

超级电容储能系统(SCESS)主要通过对双向DC/DC变换器进行控制来快速平抑直流母线电压的波动。为了抑制控制过程中所产生的一些分岔和混沌现象,提出了一种应用于SCESS的混沌控制方法。分析了该方法的控制原理,并根据非线性动力学理论建立了双向DC/DC变换器的离散迭代模型;然后设计了一种能够自动调节补偿斜率的混沌控制信号;最后对该信号作用下的异步切换函数和同步切换映射式进行了数值求解,从而绘出系统分叉图。通过仿真和试验证明,该方法能够有效抑制SCESS的分岔和混沌现象,提高了系统的稳定工作范围和动态响应速度。     

Tapped-inductor filter assisted soft-switching PWM DC-DC power converter

A novel high-frequency transformer linked full-bridge type soft-switching phase-shift pulsewidth modulated (PWM) controlled dc-dc power converter is presented, which can be used as a power conditioner for small-scale photovoltaic and fuel cell power generation systems as well as isolated boost dc-dc power converter for automotive ac power supply. In these applications with low-voltage large-current sources, the full-bridge circuit is the most attractive topology due to the possibility of using low-voltage high-performance metal-oxide-semiconductor field-effect transistor (MOSFET) and achieving high efficiency of the dc-dc power converter. A tapped-inductor filter including the freewheeling diode is newly implemented in the output stage of the full-bridge phase-shift PWM dc-dc converter to achieve soft-switching operation for the wide load variation range. Moreover, in the proposed converter circuit, the circulating current is effectively minimized without using additional resonant circuit and auxiliary power switching devices. The practical effectiveness of the proposed soft-switching dc-dc power converter was verified in laboratory level experiment with 1 kW 100 kHz breadboard setup using power MOSFETs. Actual efficiency of 94-97% was obtained for the wide duty cycle and load variation ranges.     

具有功率因数校正的零电压开关谐振变换器设计

传统型PWM控制的开关电源是硬件开关，开关损耗大，不利于向小型化，轻量化发展。本提出利用零电压开关谐振技术实现功率开关管的软开关技术，从而降低开关损耗，并采用SG3525为核心的主开关控制电路，提高系统的动态响应性能，同时采用UC3854对AC／DC变换过程作了功率因数校正，以改善输入电流的波形，提高电力资源的利用率。     

Phase modulated DGPS transmitter implemented with a clamped-mode resonant converter

A clamped-mode resonant converter (CMRC) is proposed to be used as a transmitter which broadcasts correction signals in a differential Global Positioning System (DGPS). The digital information of the DGPS modulates the carrier with different modulation methods minimum shift keying (MSK) (recommended for the marine radiobeacon band), stepped binary phase shift keying (S-BPSK) and BPSK. The first two methods allow keeping the converter's operation in soft switching mode. Extensive trials under impedance mismatch and modulation conditions confirm that the soft switching mode is preserved.     

General rules for signal flow graph modeling and analysis of dc-dc converters

Signal flow graph (SFG) nonlinear modeling approach is well known for modeling dc-dc converters. However, all possible SFGs of a given dc-dc converter system will not yield the generalized graph. A systematic procedure and guidelines for developing unified flow graph models of the dc-dc boost converters, from which complete behavior can be determined is presented. Usefulness of the proposed method is demonstrated through examples. As an illustration a 2-cell cascade boost and interleaved boost converter systems are taken as examples. Derivation of large, small-signal and steady-state models from generalized flow graph is also demonstrated. Large-signal model is developed and programmed in TUTSIM simulator. Large-signal, responses against supply and load disturbances are obtained. Experimental observations are provided to validate the proposed algorithm.     

Design optimization for asymmetrical ZVS-PWM zeta converter

In this paper, a new soft-switching Zeta converter with an asymmetrical pulsewidth modulation (PWM) control is proposed. The proposed Zeta converter has the features of constant frequency operation, zero voltage switching (ZVS), and low voltage stress on the active switches. Moreover, it can achieve high power density, high efficiency, low switching loss, and low component count, which make converter operation at low to medium power level feasible. Operational principle of the Zeta converter is presented in detail, and a specific example is designed and implemented to verify its feasibility.     

Voltage-based maximum power point tracking control of PV system

Photovoltaic (PV) generators exhibit nonlinear v-i characteristics and maximum power (MP) points that vary with solar insulation. An intermediate converter can therefore increase efficiency by matching the PV system to the load and by operating the solar cell arrays (SCAs) at their maximum power point. An MP point tracking algorithm is developed using only SCA voltage information thus leading to current sensorless tracking control. The inadequacy of a boost converter for array voltage based MP point control is experimentally verified and an improved converter system is proposed. The proposed converter system results in low ripple content, which improves the array performance and hence a lower value of capacitance is sufficient on the solar array side. Simplified mathematical expressions for a PV source are derived. A signal flow graph is employed for modeling the converter system. Current sensorless peak power tracking effectiveness is demonstrated through simulation results. Experimental results are presented to validate the proposed method     

Improved ZCS-PWM commutation cell for IGBTs application

An improved zero-current-switching pulsewidth-modulated (ZCS-PWM) commutation cell is presented, which is suitable for high-power applications using insulated gate bipolar transistors (IGBTs) as the power switches. It provides ZCS operation for active switches and zero-voltage-switching (ZVS) operation for passive switches. Besides operating at constant frequency and reducing commutation losses, the proposed ZCS-PWM switch cell has no additional current stress and conduction loss in the main switch. To demonstrate the feasibility of the proposed ZCS-PWM commutation cell, it was applied to a boost converter. Operating principle, theoretical analysis, design guidelines, and a design example are described and verified by experiment results obtained from a prototype rated 1 kW and operating at 40 kHz. The PWM switch model and state-space averaging approach is also used to estimate and examine the steady-state and dynamic character of ZCS-PWM boost converter system. Finally, the application of the proposed soft-switching technique in the dc-dc nonisolated converters is presented.     

Computer Simulations of Optimum Boost and Buck-Boost Converters

The development of mathematical models suitable for minimum weight boost and buck-boost converter designs are presented. The facility of an augumented Lagrangian (ALAG) multiplier-based nonlinear programming technique is demonstrated for minimum weight design optimizations of boost and buck-boost power converters. ALAG-based computer simulation results for those two minimum weight designs are discussed. Certain important features of ALAG are presented in the framework of a comprehensive design example for boost and buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight and loss profiles of various semiconductor components and magnetics as a function of the switching frequency.