Showing papers on "Converters published in 2003"

A review of single-phase improved power quality AC-DC converters

Abstract: Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

High-efficiency, high step-up DC-DC converters

Abstract: Many applications call for high step-up DC-DC converters that do not require isolation. Some DC-DC converters can provide high step-up voltage gain, but with the penalty of either an extreme duty ratio or a large amount of circulating energy. DC-DC converters with coupled inductors can provide high voltage gain, but their efficiency is degraded by the losses associated with leakage inductors. Converters with active clamps recycle the leakage energy at the price of increasing topology complexity. A family of high-efficiency, high step-up DC-DC converters with simple topologies is proposed in this paper. The proposed converters, which use diodes and coupled windings instead of active switches to realize functions similar to those of active clamps, perform better than their active-clamp counterparts. High efficiency is achieved because the leakage energy is recycled and the output rectifier reverse-recovery problem is alleviated.

High-frequency digital PWM controller IC for DC-DC converters

Abstract: This paper describes a complete digital PWM controller IC for high-frequency switching converters. Novel architecture and configurations of the key building blocks are A/D converter, compensator, and digital pulse-width modulator, are introduced to meet the requirements of tight output voltage regulation, high-speed dynamic response, and programmability without external passive components. The implementation techniques are experimentally verified on a prototype chip that takes less than 1 mm/sup 2/ of silicon area in a standard 0.5 /spl mu/ digital complementary metal oxide semiconductor (CMOS) process and operates at the switching frequency of 1 MHz.

Power converter circuitry and method

Abstract: A control system and method for simultaneously regulating the operation of a plurality of different types of switching power converters. The system utilizes in regulating the power converters sampled data and nonlinear feedback control loops.

Positive output super-lift converters

Abstract: The voltage lift technique has been successfully employed in design of DC/DC converters, e.g., four series Luo converters. However, the output voltage increases in arithmetic progression. This paper introduces a novel approach-super-lift technique that implements the output voltage increasing in geometric progression. It effectively enhances the voltage transfer gain in power law.

Single-inductor multiple-output switching converters with time-multiplexing control in discontinuous conduction mode

Abstract: An integrated single-inductor dual-output boost converter is presented. This converter adopts time-multiplexing control in providing two independent supply voltages (3.0 and 3.6 V) using only one 1-/spl mu/H off-chip inductor and a single control loop. This converter is analyzed and compared with existing counterparts in the aspects of integration, architecture, control scheme, and system stability. Implementation of the power stage, the controller, and the peripheral functional blocks is discussed. The design was fabricated with a standard 0.5-/spl mu/m CMOS n-well process. At an oscillator frequency of 1 MHz, the power conversion efficiency reaches 88.4% at a total output power of 350 mW. This topology can be extended to have multiple outputs and can be applied to buck, flyback, and other kinds of converters.

Background calibration techniques for multistage pipelined ADCs with digital redundancy

Abstract: The proposed digital background calibration scheme, applicable to multistage (pipelined or algorithmic/cyclic) analog-to-digital converters (ADCs), corrects the linearity errors resulting from capacitor mismatches and finite opamp gain. A high-accuracy calibration is achieved by recalculating the digital output based on each stage's equivalent radix. The equivalent radices are extracted in the background by using a digital correlation method. The proposed calibration technique takes advantage of the digital redundancy architecture inherent to most pipelined ADCs. In the proposed method, the SNR is not degraded from the pseudorandom noise sequence injected into the system. A two-channel ADC architecture with negligible overhead is also proposed to significantly improve the efficiency of the digital correlation. Simulation results confirm that 16-bit linearity can be achieved after calibration for an ADC with /spl sigma/=0.1% capacitor mismatches and 60 dB opamp gain.

Comparing DC-DC converters for power management in hybrid electric vehicles

Abstract: The design of DC-DC converters for power electronic interfaces in power management systems for hybrid electric vehicle (HEV) is a very challenging task. To this end, this paper presents an analysis, design, and comparison study of several bi-directional non-isolated DC-DC converter topologies that could be considered potential candidates for the power electronic interface of HEV energy/power sources, in particular an ultracapacitor pack. The considered topologies are the half-bridge, Cuk, SEPIC, and Luo converters. The analysis and design of the converters is performed throughout equations for the stresses of the active and passive components. The comparison study, achieved by means of graphs where the variables of interest are plotted as a function of the voltage ratio Vo/Vi, uses the half-bridge converter as the base case. Particular attention is paid to the stresses of the active and passive components due to the wide input voltage requirements typical of this load-leveling or power-management application.

Advanced DC/DC Converters

Abstract: INTRODUCTION Historical Review Multiple Quadrant Choppers Pump Circuits Development of DC/DC Conversion Technique Categorize Prototypes and DC/DC Converters Family Tree VOLTAGE-LIFT CONVERTERS Introduction Seven Self-Lift Converters Positive Output Luo-Converters Negative Output Luo-Converters Modified Positive Output Luo-Converters Double Output Luo-Converters POSITIVE OUTPUT SUPER-LIFT LUO-CONVERTERS Introduction Main Series Additional Series Enhanced Series Re-Enhanced Series Multiple-Enhanced Series Summary of Positive Output Super-Lift Luo-Converters Simulation Results Experimental Results NEGATIVE OUTPUT SUPER-LIFT LUO-CONVERTERS Introduction Main Series Additional Series Enhanced Series Re-Enhanced Series Multiple-Enhanced Series Summary of Negative Output Super-Lift Luo-Converters Simulation Results Experimental Results POSITIVE OUTPUT CASCADE BOOST CONVERTERS Introduction Main Series Additional Series Double Series Triple Series Multiple Series Summary of Positive Output Cascade Boost Converters Simulation and Experimental Results NEGATIVE OUTPUT CASCADE BOOST CONVERTERS Introduction Main Series Additional Series Double Series Triple Series Multiple Series Summary of Negative Output Cascade Boost Converters Simulation and Experimental results MULTIPLE-QUADRANT OPERATION LUO-CONVERTERS Introduction Circuit Explanation Mode A (Quadrant I Operation) Mode B (Quadrant II Operation) Mode C (Quadrant III Operation) Mode D (Quadrant IV Operation) Simulation Results Experimental Results Discussion SWITCHED-COMPONENT CONVERTERS Introduction A Two-Quadrant SC DC/DC Converter Four-Quadrant Switched Capacitor DC/DC Converter Switched Inductor Four-Quadrant DC/DC Converter POSITIVE OUTPUT MULTIPLE-LIFT PUSH-PULL SWITCHED-CAPACITOR CONVERTERS Introduction Main Series Additional Series Enhanced Series Re-enhanced Series Multiple-Enhanced Series Theoretical Analysis Summary of this Technique Simulation Results Experimental Results NEGATIVE OUTPUT MULTIPLE-LIFT PUSH-PULL SWITCHED-CAPACITOR CONVERTERS Introduction Main Series Additional Series Enhanced Series Re-Enhanced Series Multiple-Enhanced Series Summary of this Technique Simulation and Experimental Results MULTIPLE-QUADRANT SOFT-SWITCHING CONVERTERS Introduction Multiple-Quadrant DC/DC ZCS Quasi-Resonant Converters Multiple-Quadrant DC/DC ZVS Quasi-Resonant Converter Multiple-Quadrant Zero-Transition DC/DC Converters SYNCHRONOUS RECTIFIER DC/DC CONVERTERS Introduction Flat Transformer Synchronous Rectifier Converter Active Clamped Synchronous Rectifier Converter Double Current Synchronous Rectifier Converter Zero-Current-Switching Synchronous Rectifier Converter Zero-Voltage-Switching Synchronous Rectifier Converter MULTIPLE ENERGY-STORAGE ELEMENTS RESONANT POWER CONVERTERS Introduction Bipolar Current and Voltage Source A 2-Element RPC Analysis P-CLL CURRENT SOURCE RESONANT INVERTER Introduction Mathematic Analysis Simulation Results Discussion CASCADE DOUBLE G-CL CURRENT SOURCE RESONANT INVERTER Introduction Mathematic Analysis Simulation Results Experimental Results Discussion CASCADE REVERSE DOUBLE G-LC RESONANT POWER CONVERTER Introduction Steady-State Analysis of Cascade Reverse Double G-LC RPC Resonance Operation and Modeling Small-Signal Modeling of Cascade Reverse Double G-LC RPC Discussion DC ENERGY SOURCES FOR DC/DC CONVERTERS Introduction Single-Phase Half-Wave Diode Rectifier Single-Phase Bridge Diode Rectifier Three-Phase Half-Bridge Diode Rectifier Three-Phase Full-Bridge Diode Rectifier with Resistive Load Thyrister Rectifiers CONTROL CIRCUIT. EMI AND APPLICATIONS EXAMPLES OF DC/DC CONVERTERS Introduction Luo-Resonator EMI, EMS and EMC Some DC/DC Converter Applications

Isolated DC-DC converters with high-output voltage for TWTA telecommunication satellite applications

Abstract: Two alternatives for the implementation of an isolated DC-DC converter operating with a high output voltage and supplied by an unregulated low input voltage are presented in this paper. The proposed topologies are especially qualified for the implementation of travelling wave tube amplifiers (TWTA) utilized in telecommunication satellite applications due to their low mass and volume and their high-efficiency. The converters studied follow different principles and the main operational aspects of each topology are analyzed. A two-stage structure composed by a regulator connected in series with a ZVS/ZCS isolated DC-DC converter is the first topology proposed. The second topology studied is an isolated single-stage converter that continues being highly efficient even with a large input voltage variation. The experimental results obtained from two prototypes, implemented following the design procedures developed, are presented, verifying experimentally the characteristics and the analysis of the proposed structures. The prototypes are developed for an application requiring an output power of 150 W, a total output voltage of 3.2 kV and an input voltage varying from 26 V to 44 V. The minimum efficiency obtained for both converters operating at the nominal output power, is equal to 93.4% for the two-stage structure and equal to 94.1% for the single-stage converter.

Simple topologies of PWM AC-AC converters

Abstract: This letter proposes a new family of simple topologies of PWM AC-AC converters with minimal switches. With extension from the basic DC-DC converters, a series of AC-AC converters such as buck, boost, buck-boost, Cuk, and isolated converters are obtained. By PWM duty ratio control, they become a "solid-state transformer" with a continuously variable turns ratio. All the proposed AC-AC converters in this paper employ only two switches. Compared to the existing circuits that use six switches or more, they can reduce cost and improve reliability. The operating principle and control method of the proposed topologies are presented. Analysis and simulation results are given using the Cuk AC-AC converter as an example. The analysis can be easily extended to other converters of the proposed family.

Optimal control of wide conversion ratio switching converters

Abstract: A switch state controller generating a pulse train is used in a power converter utilizing a plurality of converter stages all simultaneously controlled by a single switch controlled by said pulse train. On time of the pulse train is controlled according to an input or interim node characteristic of the supply and period is controlled by a characteristic of the output of the converter. This allows development of AC-to-DC converters, including power-factor-correction converters, and DC to DC converters with high conversion ratio with minimal parts count & high reliability.

Modeling, control and implementation of three-phase PWM converters

Abstract: Three-phase voltage- and current-source converters are the building blocks of a great number of power electronic systems. The origin of difficulties in the control of the above converters is in their nonlinear nature. In this paper, a novel modeling technique is introduced to derive the linear models of the converters from the nonlinear transformations of the conventional nonlinear models. Then, based on the derived linear models, a high-performance linear controller with satisfactory performances is designed. The bold feature of the new model is the independence of the controller design from the operating point. A DSP-based control system has been built in the lab to verify the performance of the new models and the control algorithm. The simulation and experimental results are in close agreement. The results show that the DC term and the AC-side reactive power can be controlled independently in less than one cycle.

Magnetic integration for interleaved converters

Abstract: In this paper several techniques for integration of magnetic components in interleaved converters are analyzed Magnetic components define the way the energy is transformed Several opposite approaches can be considered: from decoupled integrated inductors to tightly coupled inductors The integration of inductors in the same core for multiphase converters is especially analyzed from the point of view of size, losses and coupling

Balanced switching converter to reduce common-mode conducted noise

Abstract: Because conventional switching converters have usually used unbalanced circuit topologies, parasitic capacitance between the drain/collector of an active switch and the frame ground through its heat sink may generate the common-mode conducted noise. This paper proposes a balanced switching converter circuit, which is an effective way to reduce the common-mode conducted noise. As an example, a boost converter version of the balanced switching converter is presented, and the mechanism of the common-mode noise reduction is explained using an equivalent circuit. This good feature is confirmed by experimental results. The concept of the balanced switching converter is applied to some other types of switching converters.

A comparison study on the number of wavelength converters needed in synchronous and asynchronous all-optical switching architectures

Abstract: The objective of this study is to investigate the performances of packet-switching architectures working in a synchronous and asynchronous way; in such architectures, the packet contention is resolved in the wavelength domain and the used wavelength converters are shared. We investigate on the saving of the number of converters that the sharing technique allows to obtain in the synchronous and asynchronous architectures and compare the obtained results. These ones show that when a packet loss probability is fixed, in the synchronous case a greater number of converters is saved. In some cases, the gain is 40% more than the asynchronous case. Furthermore, in the asynchronous case, a more expensive switching matrix is needed. The analysis is performed by introducing analytical and simulation models, and when both unicast and multicast traffic scenarios are considered.

New start-up schemes for isolated full-bridge boost converters

Abstract: Two new start-up schemes for isolated full-bridge boost converters are proposed in this paper. The control timing for each scheme, which is compatible with pulse-width modulated (PWM) control timing for normal boost mode operation, are investigated. Design considerations on the relationship between the turns ratios of the boost choke windings and the main transformer windings, and its effects on the operation of the converter, are studied. The two proposed start-up schemes are experimentally verified on a 1.6 kW, 12 V/288 V prototype.

On the generalized PI sliding mode control of DC-to-DC power converters: a tutorial

Abstract: A tutorial revisiting of the traditional sliding mode control of DC-to-DC power supplies, or power converters, of the 'buck','boost' and 'buck-boost' types is presented. The limitations of the traditional indirect sliding mode controller schemes are critically evaluated. These refer to the availability of the converter inductor current variable and a lack of robustness with respect to unmodelled load resistance variations. These limitations are overcome thanks to recent developments addressed as 'Generalized PI controllers' which are based on integral reconstructors of the unmeasured observable state variables and utilize only available input and output signals.

Maximum power point tracking of coupled inductor interleaved boost converter supplied PV system

Abstract: A photovoltaic generator exhibits nonlinear voltage-current characteristics and its maximum power point varies with solar radiation. A two-cell interleaved boost converter with coupled inductors is used to match the photovoltaic system to the load and to operate the solar cell array at maximum power point. A maximum power point tracking algorithm is developed using only load voltage information, eliminating the array current detection. The present converter system has the advantages of low ripple content, both on the load and source side, improved efficiency and reduced switch stress, as compared to noncoupled two-cell interleaved converters. As a result, a lower value of array capacitance is sufficient for smoothing the array voltage and current. Analytical expressions for the photovoltaic source and interleaved boost converter, corresponding to maximum power point operation of the SCA, are derived. Experimental results are presented to demonstrate the suitability of this converter system. Few experimental observations are also presented for partial shading conditions. Further, a comparative study of coupled and noncoupled interleaved boost converters for photovoltaic applications is made. These studies reveal that, by introducing coupling among the parallel branch inductors, it is possible to improve steady-state performance while maintaining the dynamic performance of the photovoltaic system.

A 3-D space vector modulation generalized algorithm for multilevel converters

Abstract: A three-dimensional (3-D) space vector algorithm of multilevel converters for compensating harmonics and zero sequence in three-phase four-wire systems with neutral is presented. The low computational cost of the proposed method is always the same and it is independent of the number of levels of the converter. The conventional two-dimensional (2-D) space vector algorithms are particular cases of the proposed generalized modulation algorithm. In general, the presented algorithm is useful in systems with or without neutral, unbalanced load, triple harmonics and for generating 3-D control vectors.

New zero-current-transition PWM DC/DC converters without current stress

Abstract: This paper presents novel zero-current-transition (ZCT) PWM DC/DC converters without additional current stress and conduction loss on the main switch during the resonance period of the auxiliary cell. The auxiliary cell consists of a resonant inductor, a resonant capacitor, an auxiliary switch and an auxiliary diode in parallel with the main switch and the zero-current-switching (ZCS) ranges of the main and the auxiliary switch of the proposed converters are entirely achieved by operating the auxiliary cell. In addition, the resonant inductor of the proposed ZCT cell helps soft turn-on of the main switch. The theoretical analysis and the operation principle of the new ZCT technique are described in detail using a boost converter as an example. To verify the validity of the proposed ZCT technique, the simulation and the experiment were performed on the nonisolated and the isolated converter, respectively. Here, the nonisolated converter is a boost converter having 100 kHz switching frequency, 1 kW rating power, and the isolated converter is a full-bridge (FB) converter having 50 kHz switching frequency, 1 kW rating power.

A study of the residue-to-binary converters for the three-moduli sets

Abstract: In this paper, a detailed study on the four three-moduli sets reported in the literature is carried out from the point of view of the hardware complexity and speed of their residue-to-binary (R/B) converters. First, a new formulation of the Chinese remainder theorem is proposed that reduces the size of the modulo operation. Then, the proposed formulation is applied to derive, in a simple and unified manner, R/B conversion algorithms for three of the sets. Further, using this formulation, a new algorithm along with two corresponding R/B converters for the fourth set is proposed; one of these converters is area efficient while the other is speed efficient. Next, the best R/B converter(s) for each of the sets is chosen based on the hardware complexity and/or speed. These converters are implemented for 8, 16, 32, and 64-bit dynamic ranges, using CMOS VLSI technology. Based on a post-layout performance evaluation for the VLSI implementations of the chosen converters, it is shown that in order to represent 8-, 16-, 32-, and 64-bit binary numbers, the moduli set {2/sup n/,2/sup n/+1,2/sup n/-1} provides the fastest R/B converter and requires the smallest area.

Negative output super-lift converters

Abstract: The voltage lift technique has been successfully employed in design of DC/DC converters, e.g., four series Luo-converters. However, the output voltage increases in arithmetic progression. Negative output super lift technique in this paper implements the output voltage increasing in geometric progression. It effectively enhances the voltage transfer gain in power-law.

An evaluation of the spectral characteristics of switching converters with chaotic carrier-frequency modulation

Abstract: This paper presents an evaluation of the spectral characteristics of switching converters with a chaotic carrier-frequency modulation scheme (CCFMS). By incorporating a Chua's circuit (CC) into the pulsewidth modulator for driving the switches, three modulation schemes, including the standard pulsewidth modulation scheme, periodic carrier-frequency modulation scheme, and CCFMS, can be realized with the CC in equilibrium, limit cycle, and chaos, respectively. The property of frequency spreading in CCFMS is studied by using a statistical analysis method. The developed model is applied to formulate the power spectral densities of the input current and the output voltage of the three basic DC/DC converters under CCFMS. Theoretical predictions are verified with experimental measurements.

High Performance Coupled-Inductor DC-DC Converters

Abstract: Many emerging applications call for high- efficiency, high-step-up DC-DC converters. Basic DC-DC topologies encounter extreme duty ratio and severe rectifier reverse-recovery problems. Cascade DC-DC converters can meet the requirements with the drawbacks of extra complexity and higher cost. Coupled-inductor DC-DC converters can provide high step-up voltage gain without the penalty of extreme duty ratio, but the stress and the loss related to the leakage energy are severe concerns. In this paper, high performance coupled-inductor DC-DC converters which can effectively handle the leakage energy are proposed. Not only the extreme duty ratios are eliminated but also the rectifier reverse-recovery problem is alleviated. Theoretical analysis and experimental results verify the proposed solutions.

VSC transmission model for analytical studies

Abstract: This paper presents a model of voltage source converters (VSC) based transmission that can be used for wide range of stability studies and controller design with MATLAB software. The model is intended for analytical studies in the frequency domain above 5 Hz. The system model has modular structure and includes three separate units in state-space form: AC rectifier model, AC inverter and DC system model. The converters, controllers and phased locked loop (PLL) units are included in the DC model and the model is linked with other units using input-output matrices in the state-space models. The converter non-linear model is linearized assuming small deviations around the steady-state. The model is tested against the PSCAD/EMTDC non-linear model and the results show satisfactory accuracy. The tests also confirm that the analytical model well represents multivariable system properties. An example of the model used is given showing the eigenvalue study of the influence of PLL gains on the system stability. It is concluded that increased PLL gains deteriorate system stability.

A novel discrete control strategy for independent stabilization of parallel three-phase boost converters by combining space-vector modulation with variable-structure control

Abstract: We propose a discrete nonlinear controller, developed in a synchronous frame, for a parallel three-phase boost converter consisting of two modules. The basic idea, however, can be extended to a system with N modules. Each of the closed-loop power-converter modules operates asynchronously without any communication with the other modules. The controller stabilizes the currents on the dq-axes and limits the flow of the pure-zero sequence current. It combines the space-vector modulation scheme with a variable-structure control, thereby keeping the switching frequency constant and achieving satisfactory dynamic performance.