A Multistage Interleaved Synchronous Buck Converter With Integrated Output Filter in 0.18 μm SiGe Process

The design and analysis of a fully integrated multistage interleaved synchronous buck dc-dc converter with on-chip filter inductor and capacitor is presented. The dc-dc converter is designed and fabricated in 0.18 mum SiGe RF BiCMOS process technology and generates 1.5 V-2.0 V programmable output voltage supporting a maximum output current of 200 mA. High switching frequency of 45 MHz, multiphase interleaved operation, and fast hysteretic controller reduce the filter inductor and capacitor sizes by two orders of magnitude compared to state-of-the-art converters and enable a fully integrated converter. The fully integrated interleaved converter does not require off-chip decoupling and filtering and enables direct battery connection for integrated applications. This design is the first reported fully integrated multistage interleaved, zero voltage switching synchronous buck converter with monolithic output filters. The fully integrated buck regulator achieves 64% efficiency while providing an output current of 200 mA.     

Small Signal Analysis of Energy Factor and Mathematical Modeling for Power DC–DC Converters

Mathematical modeling for power dc-dc converters is a historical problem accompanying dc-dc conversion technology since the 1940s. The traditional mathematical modeling is not available for complex structure converters since the differential equation order increases very high. We have to search for other ways to establish mathematical modeling for power dc-dc converters. We have defined energy factor (EF) and new mathematical modeling for power dc-dc converters that have attracted much attention in recent years. This paper describes the small signal analysis of EF and mathematical modeling for power dc-dc converters in continuous conduction mode and discontinuous conduction mode. EF and the subsequential parameters can illustrate the unit-step response and interference recovery. This investigation may be helpful for system design and dc-dc converters characteristics. Two dc-dc converters: Buck converter and super-lift Luo-converter as the samples, are analyzed in this paper to demonstrate the applications of EF, pumping energy, stored energy (SE), capacitor/inductor SE ratio, energy losses, time constant tau, and damping time constant tau_d     

A Systematic Method for the Stability Analysis of Multiple-Output Converters

The dynamics of multiple-output dc-dc converters are discussed. A multi-input-multi-output (MIMO) feedback system model incorporating effects of the output fluctuation is derived for the converter. Based on system theoretic tools, a set of stability conditions is obtained for the MIMO model; the result is used to formulate a stable margin. A practical five-output converter was selected for illustration of the proposed analytic tool. The effects of the input filter and coupled inductor on system stability margin are investigated.     

Nonisolation Soft-Switching Buck Converter With Tapped-Inductor for Wide-Input Extreme Step-Down Applications

In this paper, a new zero-voltage switching (ZVS) buck converter with a tapped inductor (TI) is proposed. This converter improves the conventional tapped inductor critical conduction mode buck converters that have the ZVS operation range determined by the TI turn ratios. It includes another soft switching range extension method, the current injection method, which gives an additional design freedom for the selection of the turn-ratios and enables the optimal design of the winding ratio of the TI so that the efficiency may be maximized. This soft-switching buck converter is suitable for wide input range step-down applications. The principle of the proposed scheme, analysis of the operation, and design guidelines are included. Experimental results of the 100-W prototype dc-dc converter are given for hardware verification also. Finally, based on the proposed soft-switching technique, a new soft-switching topology family is derived.     

A new ZVS bidirectional DC-DC converter for fuel cell and battery application

This paper presents a new zero-voltage-switching (ZVS) bidirectional dc-dc converter. Compared to the traditional full and half bridge bidirectional dc-dc converters for the similar applications, the new topology has the advantages of simple circuit topology with no total device rating (TDR) penalty, soft-switching implementation without additional devices, high efficiency and simple control. These advantages make the new converter promising for medium and high power applications especially for auxiliary power supply in fuel cell vehicles and power generation where the high power density, low cost, lightweight and high reliability power converters are required. The operating principle, theoretical analysis, and design guidelines are provided in this paper. The simulation and the experimental verifications are also presented.     

The design and experimentation of the new cascaded DC-DC boost converter for renewable energy

After renewable energy generated, a direct current value is converted to a direct current value at another level for a power electronics and power system application that is often considered. In this article, the design and application of a new generation multi-time cascaded DC-DC converter are discussed. The dc-to-dc converter is three-levels, and the switches for each step have a working time and a non-working time. Mathematical models are established depending on the relationship between current and voltage according to the operating and non-operating states of the switches at each stage. After these mathematical models are creating, the new generation multi-timed DC-DC converter is run in Matlab Simulink and simulation results are validated in experimentation. The output voltage and inductor current are observed with a scope. Then, the results from the proposed converter are compared with the results of the traditional converters. The results show the effectiveness of the proposed dc-dc converter.     

Design issues for monolithic DC-DC converters

This paper presents various ideas for integrating different components of dc-dc converter on to a silicon chip. These converters are intended to process power levels up to 0.5W. Techniques for integrating capacitors and design issues for MOS transistors are discussed. The most complicated design issue involves inductors. Expressions for trace resistance and inductance estimation of on-chip planar spiral inductor on top metal layer of CMOS process are compared. These inductors have high series resistance due to low metal trace thickness, capacitive coupling with substrate and other metal traces, and eddy current loss. As an alternative, a CMOS compatible three-dimensional (3-D) surface micromachining technology known as plastic deformation magnetic assembly (PDMA) is used to fabricate high quality inductors with small footprints. Experimental results from a monolithic buck converter using this PDMA inductor are presented. A major conclusion of this work is that the 3-D "post-process" technology is more viable than traditional integrated circuit assembly methods for realizing of micro-power converters.     

A 233-MHz 80%-87% efficient four-phase DC-DC converter utilizing air-core inductors on package

We demonstrate an integrated buck dc-dc converter for multi-V/sub CC/ microprocessors. At nominal conditions, the converter produces a 0.9-V output from a 1.2-V input. The circuit was implemented in a 90-nm CMOS technology. By operating at high switching frequency of 100 to 317 MHz with four-phase topology and fast hysteretic control, we reduced inductor and capacitor sizes by three orders of magnitude compared to previously published dc-dc converters. This eliminated the need for the inductor magnetic core and enabled integration of the output decoupling capacitor on-chip. The converter achieves 80%-87% efficiency and 10% peak-to-peak output noise for a 0.3-A output current and 2.5-nF decoupling capacitance. A forward body bias of 500 mV applied to PMOS transistors in the bridge improves efficiency by 0.5%-1%.     

Energy-efficient C-dump converters for switched reluctance motors

Two energy-efficient converter topologies, derived from the conventional C-dump converter, are proposed for switched reluctance motor (SRM) drives. The proposed topologies overcome the limitations of the conventional C-dump converter, and could reduce the overall cost of the SRM drive. The voltage ratings of the dump capacitor and some of the switching devices in the proposed converters are reduced to the supply voltage (V_dc) level compared to twice the supply voltage (2V _dc) in the conventional C-dump converter. Also, the size of the dump inductor is considerably reduced. The converters have simple control requirements, and allow the motor phase current to freewheel during chopping mode. Simulation and experimental results of the converters are presented and discussed     

Current-Fed Dual-Bridge DC–DC Converter

A new isolated current-fed pulsewidth modulation dc-dc converter-current-fed dual-bridge dc-dc converter-with small inductance and no deadtime operation is presented and analyzed. The new topology has more than 3times smaller inductance than that of current-fed full-bridge converter, thus having faster transient response speed. Other characteristics include simple self-driven synchronous rectification, simple housekeeping power supply, and smaller output filter capacitance. Detailed analysis shows the proposed converter can have either lower voltage stress on all primary side power switches or soft switching properties when different driving schemes are applied. A 48-V/125-W prototype dc-dc converter with dual output has been tested for the verification of the principles. Both simulations and experiments verify the feasibility and advantages of the new topology     

Comprehensive review of high power factor ac-dc boost converters for PFC applications

High power factor rectifiers have been consolidated as an effective solution to improve power quality indices in terms of input power factor correction, reduction in the total harmonic distortion of the input current and also regulated dc voltages. Within this context, this subject has motivated the introduction of numerous converter topologies based on classic dc-dc structures associated with novel control techniques, thus leading to the manufacturing of dedicated integrated circuits that allow high input power factor by adding a front-end stage to switch-mode converters. In particular, boost converters in continuous current mode (CCM) are widely employed since they allow obtaining minimised electromagnetic interference levels. This work is concerned with a literature review involving relevant ac-dc single-phase boost-based topologies with high input power factor. The evolution of aspects regarding the conventional boost converter is shown in terms of improved characteristics inherent to other ac-dc boost converters. Additionally, the work intends to be a fast and concise reference to single-phase ac-dc boost converters operating in CCM for engineers, researchers and experts in the field of power electronics by properly analysing and comparing the aforementioned rectifiers.     

Z-Source AC–AC Converters Solving Commutation Problem

A new family of Z-source ac-ac converters with buck-boost ability are proposed, including four switches single-phase structure and six switches three-phase structure. New commutation strategies for these converters are proposed and safe commutation can be achieved without snubber circuit. The commutation strategies are easily to realize by sampling only voltage signals, and two switches are always turned on, so switching loss can be reduced. Analysis based on state-space averaging reveals the relationship between Z-source inductor current and filter inductor current as well as voltage ratio. The design considerations of voltage-fed single-phase topology are given as an example. Simulation results on the voltage-fed topologies and experimental results on voltage-fed single-phase topology verified the unique features of Z-source ac-ac converters and the proposed commutation strategies. These converters have merits such as less conduction and switching loss, less devices, therefore high efficiency and reliability can be achieved.     

Low cost high efficiency DC-DC converter for fuel cell powered auxiliary power unit of a heavy vehicle

In this paper, a new dc-dc converter for solid oxide fuel cell (SOFC) powered auxiliary power unit (APU) is proposed. The proposed converter does not consider the leakage inductance of the transformer as a parasite and uses it for energy transfer, thus avoiding problems of low efficiency and difficulty in control, caused by leakage inductance. The need for a separate filter inductor is also eliminated. Soft switching is done for some of the switches of the proposed converter, thereby further increasing the efficiency of the converter. Thus, the achieved low cost and high efficiency of the proposed converter make it suitable for SOFC powered APU applications. Simulation and experimental results are presented to verify the proposed dc-dc converter. The achieved cost and efficiency of the prototype are 50.8$/kW and 90%, respectively.     

Sustained Slow-Scale Oscillation in Higher Order Current-Mode Controlled Converter

DC-DC converters under current-mode control have been known to exhibit slow-scale oscillation as a result of a Hopf-type bifurcation as one or more of the parameters of the outer voltage loop are varied. In the absence of the outer voltage loop (i.e., open loop), slow-scale oscillation was generally not observed in simple low-order dc-dc converters, i.e., buck, buck-boost, and boost converters. In this paper, slow-scale bifurcation in a higher order current-mode controlled converter is studied. It has been found experimentally that, even in the absence of a closed outer voltage loop, a current-mode controlled Cuk converter can exhibit a slow-scale Hopf-type bifurcation. The phenomenon was observed in a commercial low-ripple dc-dc converter which has been designed using the Cuk converter and the LM2611 controller. Such slow-scale oscillation of the inner current loop can also be observed in full-circuit SPICE simulations. An averaged model has been developed and implemented in SPICE to find the Hopf bifurcation boundaries. With this averaged model, the Hopf bifurcation can be explained conveniently using the traditional loop gain analysis. Specifically, the extra degrees of freedom in higher order dc-dc converters have opened up a new possible mode of instability which has not been found in simple low-order dc-dc converters.     

零电流开关大功率DC/DC双全桥变换器设计

提出了一种基于双全桥结构的单向零电流开关大功率（兆瓦级）DC/DC变换器,该变换器通过采用两个全桥变换器来实现零电流开关,实现了较低的功率损耗和输出滤波电感。为了验证提出的变换器在大功率应用中的有效性,构建了小型样机并在大功率直流电网进行了实际测试。实验证明,相比传统的两种单向大功率全桥变换器,提出变换器所需的滤波电感和半导体器件的功率损耗均较少,分别仅为1.72mH和924.5kW。     

DC-DC converter: four switches V/sub pk/=V/sub in//2, capacitive turn-off snubbing, ZV turn-on

A new four-switch full-bridge dc-dc converter topology is especially well-suited for power converters operating from high input voltage: it imposes only half of the input voltage across each of the four switches. The two legs of a full-bridge converter are connected in series with each other, across the dc input source, instead of the usual topology in which each leg is connected across the dc source. The topology reduces turn-off switching losses by providing capacitive snubbing of the turn-off voltage transient, and eliminates capacitor-discharge turn-on losses by providing zero-voltage turn-on. (Switching losses are especially important in converters operating at high input voltage because turn-on losses are proportional to the square of the input voltage, and turn-off losses are proportional to the input voltage). The topology is suitable for resonant and nonresonant converters. It adds one bypass capacitor and one commutating inductor to the minimum-topology full-bridge converter (that inductor is already present in many present-day converters, to provide zero-voltage turn-on, or is associated with one or two capacitors to provide resonant operation), and contains a dc-blocking capacitor in series with the output transformer, primary winding, and some nonresonant converters (that capacitor is already present in resonant power converters). The paper gives a theoretical analysis, and experimental data on a 1.5-kW example that was built and tested: 600-Vdc input, 60-Vdc output at up to 25A, and 50-kHz switching frequency. The measured performance agreed well with the theoretical predictions. The measured efficiency was 93.6% at full load, and was a maximum of 95.15% at 44.8% load.     

A Single Phase Voltage Regulator Module (VRM) With Stepping Inductance for Fast Transient Response

A single-phase fast transient converter topology with stepping inductance is proposed. The stepping inductance method is implemented by replacing the conventional inductor in a buck converter by two inductors connecting in series. One has large inductance and the other has small inductance. The inductor with small inductance will take over the output inductor during transient load change and speed up dynamic response. In steady state, the large inductance takes over and keeps a substantially small ripple current and minimizes root mean square loss. It is a low cost method applicable to converters with an output inductor. A hardware prototype of a 1.5-V dc-dc buck converter put under a 100-A transient load change has been experimented upon to demonstrate the merit of this approach. It also serves as a voltage regulator module and powers up a modern PC computer system     

Multiphase voltage-mode hysteretic controlled DC-DC converter with novel current sharing

Today's on-board high-density, low-output-voltage, high-output-current, fast transient point-of-load (POL) dc-dc converters design requirements for the new generation of integrated circuits, digital signal processors, and microprocessors are increasingly becoming stricter than ever. This is due to the demand for high dynamic performance dc-dc conversion with tight dynamic tolerances for supply voltages coupled with very high power density. In this paper, a multiphase voltage-mode hysteretic controlled POL dc-dc converter with new current sharing is presented. Theoretical analysis is provided for multiphase and interleaved dc-dc converters with new current sharing method. The simulation and experimental results are compared based on a specific design example.     

A design method for paralleling current mode controlled DC-DC converters

This paper proposes a new current sharing method. It is based on current mode controlled dc-dc converters and achieves the current sharing by forcing all inner current loops to have the same current reference. Meanwhile, this method decouples control loops from the voltage regulation and current-sharing regulation instead of adding control loops as in traditional master-slave methods. Therefore, the large signal performance is good while its stability is guaranteed. Further, unlike multi-module methods, the modularity of single dc-dc converter is retained. Design rules and small signal analysis are presented. The advantages of the proposed method are verified by experimental results.     

A single-phase converter with a high-frequency current-sourced link

Duality relationships that have proved useful in the development of DC-DC converter topologies are applied to existing voltage stiff high-frequency link force-commutated converters. This new area of application of the duality concept results in the development of new current stiff link converters that retain the advantages of current fed DC-DC converters. The requirements on the converters enforced by the need for instantaneous balance of input and output powers are examined. A current control technique has been developed that controls the charge delivered to the load during each switching cycle. This allows a wide bandwidth voltage regulator to be applied. Finally, the results obtained with a low-power prototype and a reactive load are presented. The new converter requires only four power MOSFETs and relatively simple controls and is reversible