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     

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.     

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.     

New ZVT-PWM DC/DC converters using active snubber

A novel active snubber soft switching method is proposed. The unique location of the resonant inductor and capacitor ensures low current and voltage stresses in the converter. An analytical study of a boost dc-dc converter with the proposed active snubber method is presented in detail to illustrate its operation principles and design considerations. By simple modification, this soft switching method is also suitable for ac-dc boost topology, especially for high power-factor-correction (PFC) universal interface applications. A 500 W prototype system has been made to simulatively and experimentally verify the performance of the soft switching.     

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.     

串联输出DC／DC谐振变换器的稳态分析

分析了高于谐振频率工作的串联输出谐振变换器的工作模式,采用状态变量法计算获得了若干描述稳态工作的特性曲线,为分析和设计这种变换器提供了基础     

Frequency-controlled series-resonant converter with synchronous rectifier

This paper presents an analysis and experimental results for a frequency-controlled series-resonant dc-dc converter that consists of a Class-D zero-voltage-switching (ZVS) series-resonant inverter and a center-tapped synchronous rectifier. If the dc output voltage is low, the efficiency of the converter is dominated by the efficiency of the rectifier. Low on-resistance metal-oxide-semiconductor field-effect transistors (MOSFETs) are used in the rectifier instead of diodes because the forward voltage drop across the rectifying device is low, resulting in a high efficiency. The dc output voltage is regulated against variations in the load resistance and the dc input voltage by varying the operating frequency. Experimental results are presented for a converter with a dc input voltage of 150 V, an output voltage of 5 V, and a dc load resistance ranging from 0.5 to 5.5 R. The measured efficiency was 86% for a 50 W output and 89% for a 25 W output. The theoretical results were in good agreement with the measured results.     

Suitability of pulse train control technique for BIFRED converter

Pulse Train/spl trade/ control scheme is presented and applied to a boost integrated flyback rectifier/energy storage dc-dc (BIFRED) converter operating in discontinuous conduction mode (DCM), which avoids the light-load high-voltage stress problem. In contrast to the conventional control techniques, the principal idea of Pulse Train technique is to regulate the output voltage using a series of high and low energy pulses generated by the current of the inductor. The applicability of the proposed technique to both the input and magnetizing inductances of BIFRED converter is investigated. Analysis of BIFRED converter operating in DCM as well as the output voltage ripple estimation is given. Experimental results on a prototype converter are also presented.     

PWM converter with low stresses and zero capacitive turn-on losses

A buck converter operating at constant switching frequency, whose active switches and recovery diode commutate at zero-voltage-switching (ZVS), with zero capacitive turn-on losses, is proposed. By using the parasitic capacitances of the switches as resonant capacitors, multiresonance is created. The resonant stage takes place only after the resonant inductor has been discharged, thus avoiding a resonant current peak; the devices are subjected to the same stresses as their counterparts in conventional hard-switching converters. A high efficiency is obtained.     

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     

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     

Optimal topologies of resonant DC/DC converters

Generalized and optimal topologies of zero-voltage-switching and zero-current-switching resonant DC/DC power converters are presented. It is shown that many equivalent topologies of the converters can be derived from each of the generalized topologies. The generalized topologies of the converters show clearly which of the parasitic capacitances and inductances can be absorbed into the LC resonant circuit. Utilizing this fact, optimal topologies that are the most suitable for high-frequency operation are derived. In the optimal topologies, the greatest possible number of parasitic reactances is included harmlessly in the resonant circuit. Optimum layout and component selection guidelines for the converters are given. High-order resonant converters are also developed     

CIECA: Application to Current Programmed Switching Dc-Dc Converters

Sundstrand Advanced Technology Corporation The current injection equivalent circuit approach (CIECA) to modeling switching converter power stages is extended to model the current programmed converter power stages operating in fixed frequency, continuous inductor conduction mode. To demonstrate the method, modeling is carried out for the buck, boost, and buckboost converters to obtain small-signal linear equivalent circuit models which represent both input and output properties. The results of these analyses are presented in the form of linear equivalent circuit models as well as transfer functions. Though current programmed converters exhibit single-pole response, the addition of artificial ramp changes converters to exhibit well damped two-pole response. This has been investigated for the first time using CIECA. The results of these analyses are presented in the form of linear equivalent circuit models as well as transfer functions.     

Analysis and design of (LC)(LC)-type series-parallel resonantconverter

A series-parallel resonant converter employing (LC)(LC)-type tank circuit operating in lagging power factor (PF) mode is presented and analyzed using complex ac circuit analysis. Design curves are obtained and the converter is optimized under certain constraints. Detailed Space Integrated Control Experiment (SPICE) simulation results are presented to evaluate the performance of the designed converter under varying load conditions. Results obtained from an experimental converter are also presented. The results obtained from the theory, SPICE simulation, and the experimental converter are compared. The proposed converter has high efficiency from full load to very light load (<10%). Switching frequency variation required for a wide change in the load (near load open circuit to full load) is narrow compared with the series resonant converter (SRC)     

移相全桥变换器寄生振荡的抑制方法研究

移相全桥变换器是中大功率直流/直流变换场合的一种理想拓扑,但在其输出整流桥上会产生寄生振荡,二极管上存在很高的尖峰电压。这将带来电路损耗并影响整流桥的使用寿命,因此应该想办法抑制。文中分析了寄生振荡产生的原因,介绍了几种可行的抑制方法,并进行了比较研究和实验验证。     

Comparison of half-bridge off-line, ZCS-QRC and ZVS-MRC

The performance of the half-bridge (HB) zero-current-switched (ZCS) quasi-resonant converter (QRC) and zero-voltage-switched (ZVS) multiresonant converter (MRC) is compared with respect to their efficiency, input voltage range, semiconductor stresses, power density, and reliability. The efficiency of the HB ZVS-MRC at a given nominal input is shown to be highly dependent on the range of the input voltage, and it suffers when the converter has to be designed to cover a wide range. However, this is not the case for the HB ZCS-QRC. Experimental versions of the HB ZCS-QRC and HB ZVS-MRC were designed for the input voltage range from 150 to 350 V and a maximum output power of 100 W, under the same constraints, to facilitate their comparison     

Analysis, design, and practical considerations for 500 W power factor correctors

This paper presents analysis, design, and practical considerations for 500 W boost power factor correctors (PFCs). The boost PFCs with three active soft-switching cells, which are boost, forward and flyback, and a passive soft-switching cell are first discussed. The operating principle and performance characteristics of the PFCs are then presented in detail, from which the boost with a flyback soft-switching cell and that with a passive soft-switching cell are designed and implemented. Performance comparison among these PFCs is also presented. Hardware measurements are used to verify the theoretical discussion. The presented information can provide designers a good application reference.     

Generalized approach for μ synthesis of robust switchingregulators

A general method using μ synthesis to design controllers applicable to pulsewidth modulated (PWM) converters is described. System uncertainties from component tolerances are included in the synthesis procedure, adding a quantifiable measure of robustness. Furthermore, these uncertainties have been implemented in a structured format which maximizes available system performance. A boost converter example is presented demonstrating the controller synthesis procedure and advantages of this method     

Fault-tolerance wide voltage conversion gain DC/DC converter for more electric aircraft

In this paper, a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft (MEA) is proposed. The proposed converter consists of a basic Cuk converter module and n expandable units. By adjusting the operation state of the expandable units, the voltage conversion gain of the proposed converter could be regulated, which makes it available for wide voltage conversion applications. Especially, since mutual redundancy can be realized between the basic Cuk converter module and the expandable units, the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter, which reflects the fault tolerance of the converter and significantly improves the reliability of the system. Moreover, the advantages of small input current ripple, automatic current sharing and low voltage stress are also integrated in this converter. The working principle and features of the proposed converter are mainly introduced, and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.     

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.