Showing papers on "Buck converter published in 1998"

Variable supply-voltage scheme for low-power high-speed CMOS digital design

Abstract: This paper describes a variable supply-voltage (VS) scheme. From an external supply, the VS scheme automatically generates minimum internal supply voltages by feedback control of a buck converter, a speed detector, and a timing controller so that they meet the demand on its operation frequency. A 32-b RISC core processor is developed in a 0.4-/spl mu/m CMOS technology which optimally controls the internal supple voltages with the VS scheme and the threshold voltages through substrate bias control. Performance in MIPS/W is improved by a factor of more than two compared with its conventional CMOS design.

Switchings, bifurcations, and chaos in DC/DC converters

Abstract: Nonlinear phenomena in closed-loop pulsewidth modulated (PWM) DC/DC converters are analyzed. We introduce a new discrete time nonlinear map-the A-switching map-which is related to the asynchronous switchings, i.e., the changes of converter configuration occurring within the modulating period. This map is compared with the stroboscopic map, which is typically used in the study of DC/DC converters. Analytical conditions for the occurrence of periodic orbits and flip bifurcations are obtained. Moreover, necessary conditions for infinite local stretching on the phase space are derived. Finally, a possible explanation of the sudden jump to chaos exhibited by DC/DC converters is proposed. Analytical and numerical results can be applied to all fundamental DC/DC converter topologies. The case of the voltage-controlled buck converter is treated in detail.

Border-collision bifurcations in the buck converter

Abstract: Interesting bifurcation phenomena are observed for the current feedback-controlled buck converter. We demonstrate that most of these bifurcations can be categorized as "border-collision bifurcations." A method of predicting the local bifurcation structure through the construction of a normal form is applied. This method applies to many power electronic circuits as well as other piecewise smooth systems.

Comparison of basic converter topologies for power factor correction

Abstract: Basic types of DC-DC converters, when operating in discontinuous conduction mode, have self power factor correction (PFC) property, that is, if these converters are connected to the rectified AC line, they have the capability to give higher power factor by the nature of their topologies. Input current feedback is unnecessary when these converters are employed to improve power factor. In this paper, basic types of DC-DC converter topologies are studied to investigate their self-PFC capabilities. Their input characteristics are compared and their input line current waveforms are predicted.

Study of bi-directional buck-boost converter topologies for application in electrical vehicle motor drives

Abstract: The use of a bi-directional DC-DC converter in motor drives devoted to EVs allows a suitable control of both motoring and regenerative braking operations. In particular, during motoring operations of a battery-fed DC motor drive, a DC-DC converter is to be used to adjust the motor current in order to follow the torque reference signal. On the other hand, a bi-directional arrangement of the converter is needed for the reversal of the power flow, in order to recover the vehicle kinetic energy in the battery by means of motor drive regenerative braking operations. This paper deals with the study and comparison of two bi-directional buck-boost converter topologies. Each of them allows stepping the battery voltage level either up or down, according to motor drive modes of operation. For each converter topology computer simulations of modes of operation are presented together with experimental test results.

Optimizing the load transient response of the buck converter

Abstract: The optimized gain of the voltage-error amplifier and current-mode control provide instantaneous transient response and small DC shift of the output voltage for step changes in the load current. This paper analyzes the system, determines the best compensation, provides design guidelines for buck converters powering Pentium(R) II processors and presents results of simulations and experiments.

Introduction to modern power electronics

Abstract: Preface. 1 Principles and Methods of Electric PowerConversion. 1.1 What Is Power Electronics? 1.2 Generic Power Converter. 1.3 Waveform Components and Figures of Merit. 1.4 Phase Control. 1.5 Pulse Width Modulation. 1.6 Calculation of Current Waveforms. 1.6.1 Analytical Solution. 1.6.2 Numerical Solution. 1.6.3 Practical Examples: Single-Phase Diode Rectifiers. 1.7 Summary. Example. Problems. Computer Assignments. Literature. 2 Semiconductor Power Switches. 2.1 General Properties of Semiconductor Power Switches. 2.2 Power Diodes. 2.3 Semicontrolled Switches. 2.3.1 SCRs. 2.3.2 Triacs. 2.4 Fully Controlled Switches. 2.4.1 GTOs. 2.4.2 IGCTs. 2.4.3 Power BJTs. 2.4.4 Power MOSFETs. 2.4.5 IGBTs. 2.5 Comparison of Semiconductor Power Switches. 2.6 Power Modules. 2.7 Summary. Literature. 3 Supplementary Components and Systems. 3.1 What Are Supplementary Components and Systems? 3.2 Drivers. 3.2.1 Drivers for SCRs, Triacs, and BCTs. 3.2.2 Drivers for GTOs and IGCTs. 3.2.3 Drivers for BJTs. 3.2.4 Drivers for Power MOSFETs and IGBTs. 3.3 Overcurrent Protection Schemes. 3.4 Snubbers. 3.4.1 Snubbers for Power Diodes, SCRs, and Triacs. 3.4.2 Snubbers for GTOs and IGCTs. 3.4.3 Snubbers for Transistors. 3.4.4 Energy Recovery from Snubbers. 3.5 Filters. 3.6 Cooling. 3.7 Control. 3.8 Summary. Literature. 4 AC-to-DC Converters. 4.1 Diode Rectifiers. 4.1.1 Three-Pulse Diode Rectifier. 4.1.2 Six-Pulse Diode Rectifier. 4.2 Phase-Controlled Rectifiers. 4.2.1 Phase-Controlled Six-Pulse Rectifier. 4.2.2 Dual Converters. 4.3 PWM Rectifiers. 4.3.1 Impact of Input Filter. 4.3.2 Principles of Pulse Width Modulation. 4.3.3 Current-Type PWM Rectifier. 4.3.4 Voltage-Type PWM Rectifier. 4.4 Device Selection for Rectifiers. 4.5 Common Applications of Rectifiers. 4.6 Summary. Examples. Problems. Computer Assignments. Literature. 5 AC-to-AC Converters. 5.1 AC Voltage Controllers. 5.1.1 Phase-Controlled Single-Phase AC Voltage Controller. 5.1.2 Phase-Controlled Three-Phase AC Voltage Controllers. 5.1.3 PWM AC Voltage Controllers. 5.2 Cycloconverters. 5.3 Matrix Converters. 5.4 Device Selection for AC-to-AC Converters. 5.5 Common Applications of AC-to-AC Converters. 5.6 Summary. Examples. Problems. Computer Assignments. Literature. 6 DC-to-DC Converters. 6.1 Static DC Switches. 6.2 Step-Down Choppers. 6.2.1 First-Quadrant Chopper. 6.2.2 Second-Quadrant Chopper. 6.2.3 First-and-Second-Quadrant Chopper. 6.2.4 First-and-Fourth-Quadrant Chopper. 6.2.5 Four-Quadrant Chopper. 6.3 Step-Up Chopper. 6.4 Current Control in Choppers. 6.5 Device Selection for Choppers. 6.6 Common Applications of Choppers. 6.7 Summary. Example. Problems. Computer Assignments. Literature. 7 DC-to-AC Converters. 7.1 Voltage-Source Inverters. 7.1.1 Single-Phase Voltage-Source Inverter. 7.1.2 Three-Phase Voltage-Source Inverter. 7.1.3 Voltage Control Techniques for Voltage-SourceInverters. 7.1.4 Current Control Techniques for Voltage-SourceInverters. 7.2 Current-Source Inverters. 7.2.1 Three-Phase Square-Wave Current-Source Inverter. 7.2.2 Three-Phase PWM Current-Source Inverter. 7.3 Multilevel Inverters. 7.4 Soft-Switching Inverters. 7.5 Device Selection for Inverters. 7.6 Common Applications of Inverters. 7.7 Summary. Examples. Problems. Computer Assignments. Literature. 8 Switching Power Supplies. 8.1 Basic Types of Switching Power Supplies. 8.2 Nonisolated Switched-Mode DC-to-DC Converters. 8.2.1 Buck Converter. 8.2.2 Boost Converter. 8.2.3 Buck Boost Converter. 8.2.4 uk Converter. 8.2.5 SEPIC and Zeta Converters. 8.2.6 Comparison of Nonisolated Switched-Mode DC-to-DCConverters. 8.3 Isolated Switched-Mode DC-to-DC Converters. 8.3.1 Single-Switch Isolated DC-to-DC Converters. 8.3.2 Multiple-Switch Isolated DC-to-DC Converters. 8.3.3 Comparison of Isolated Switched-Mode DC-to-DCConverters. 8.4 Resonant DC-to-DC Converters. 8.4.1 Quasi-Resonant Converters. 8.4.2 Load-Resonant Converters. 8.4.3 Comparison of Resonant DC-to-DC Converters. 8.5 Summary. Examples. Problems. Computer Assignments. Literature. 9 Power Electronics and Clean Energy. 9.1 Why Is Power Electronics Indispensable in Clean EnergySystems? 9.2 Solar and Wind Renewable Energy Systems. 9.2.1 Solar Energy Systems. 9.2.2 Wind Energy Systems. 9.3 Fuel Cell Energy Systems. 9.4 Electric and Hybrid Cars. 9.5 Power Electronics and Energy Conservation. 9.6 Summary. Literature. Appendix A PSpice Simulations. Appendix B Fourier Series. Appendix C Three-Phase Systems. Index.

Unified approach to developing single-stage power converters

Abstract: A unified approach to developing single-stage power converters which can fulfil multiple functions is presented. Four synchronous switches corresponding to the four common node types of two active switches are introduced. The approach is then to replace the active switches in multistage converters (in cascade or cascode connection) with one or several of the synchronous switches and their degenerated versions to form a single-stage converter. Illustrations of using these switches to develop single-stage converters are presented. These are started with the development of the well-known single-stage switch-mode converters (SMCs), buck-boost, Cuk, sepic, and Zeta (also named dual sepic), from the basic converters, buck and boost. Then, synthesis and applications of other single-stage converters are addressed. Due to increased component stresses, the developed single-stage converters are primarily suitable for applications with moderate power levels.

A three-phase multilevel converter for high-power induction motors

Abstract: A new converter topology for drives is presented in this paper: a three-phase multilevel converter with separately regulated DC power supplies. The DC voltages are provided by medium-frequency DC-DC converters. The applications for the converter are especially high-power traction systems, where the voltage applied to the induction motor is bigger than 1 kV. The motor current is of a very high quality, compared to a classical three-phase converter. This allows keeping the switching frequency low by using phase-shifted pulsewidth modulation (PWM) carriers. Different modulation methods have been developed and simulated. Experimental tests have been made on a 12 kW prototype.

Reduction of power converter EMI emission using soft-switching technique

Abstract: Measurements of conducted and radiated electromagnetic interference (EMI) emission from hard-switched and soft-switched buck, boost, and flyback converters of similar power ratings are presented. Results indicate that EMI emission can be substantially reduced by using a soft-switching technique in power converters. Thus, the soft-switching technique provides a practical and useful solution to reduce EMI emission from switched-mode power circuits. A comparison of EMI emission on the three classes of converters is also included. The flyback converter is found to be the least EMC friendly among the converters tested.

Grazing, skipping and sliding: Analysis of the non-smooth dynamics of the DC/DC buck converter

Abstract: This paper provides an analytical insight into the observed nonlinear behaviour of a simple widely used power electronic circuit (the buck converter) and draws parallels with a wider class of piecewise-smooth systems. After introducing the buck converter model and background, the most fascinating features of its dynamical behaviour are reviewed. So-called grazing and sliding solutions are discussed and their role in determining many of the buck converter's dynamical oddities is demonstrated. In particular, a local map is studied which explains how grazing bifurcations cause sharp turning points in the bifurcation diagram of periodic orbits. Moreover, these orbits are shown to accumulate onto a sliding trajectory through a `spiralling' impact adding scenario. The structure of such a diagram is derived analytically and is shown to be closely related to the analysis of homoclinic bifurcations. The results are shown to match perfectly with numerical simulations. The sudden jump to large-scale chaos and the fingered structure of the resulting attractor are also explained.

DC voltage control and stability analysis of PWM-voltage-type reversible rectifiers

Abstract: A PWM voltage rectifier has useful characteristics on its DC and AC sides. On its DC side, a DC-link unidirectional voltage is obtained and bidirectional power transfer capability is possible by reversing the flow direction of the DC-link current. On its AC side, near sinusoidal current waveforms and AC four-quadrant operation can be obtained, leading to high-quality power being exchanged between the power converter and the mains. The use of AC filters becomes unnecessary. The rectifier DC voltage must be regulated to a constant value. In this paper, three solutions for the DC voltage control are presented. In the first solution, the DC voltage is controlled by acting upon the quadrature component of the power converter fundamental Park's voltages with relation to the mains voltages. Slow responses are necessary because of stability reasons. Also, load power variations produce both active and reactive power variations in the power converter AC side. To improve the DC voltage response, a second control solution is presented. The power converter currents in Park's coordinates must be controlled. The DC voltage is controlled by controlling the direct Park's current component and, thus, acting only on the active power of the converter AC side. Faster responses are achieved. In this case, load power variations do not produce reactive power variations in the converter AC side. The third control solution is a simplified version of this last one. Experimental results from a 2 kVA IGBT-based prototype showing good system dynamic performance are presented.

Dynamics of a buck converter with a constant power load

Abstract: The dynamic properties of the buck converter with a constant power load are studied in this paper. The line-to-output and control-to-output transfer functions are derived, for voltage mode control and current mode control, in continuous conduction mode and discontinuous conduction mode. A comparison with the case of a resistive load is made in each case.

Modeling PWM DC/DC converters out of basic converter units

Abstract: 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.

Novel solar cell power supply system using the multiple-input DC-DC converter

Abstract: Recently, clean electric power generation systems have attracted a great deal of social attention to exploit clean energy resources such as solar arrays, wind generators, fuel cells, etc. In this case, the multiple-input DC-DC power converter is useful to combine the several input power sources and to supply the regulated output voltage for the load. The novel solar cell power supply system using the buck-boost type two-input DC-DC converter is proposed, in which the solar array and the commercial AC line are exploited as power sources and they are combined by the two input windings of the energy-storage reactor. Also, its operation principle and performance characteristics are discussed. Furthermore, the solar cell optimum operating point tracker is proposed and examined. It is confirmed by the experiment that the proposed solar cell power supply system has the excellent performance characteristics.

High frequency synchronous buck converter for low voltage applications

Abstract: The effect of dead time delays on the efficiency of a constant frequency, 1 MHz low voltage, synchronous buck power converter is investigated. The overall efficiency is calculated as a function of the load current and the switching frequency with the dead time as a parameter. It was calculated, and subsequently experimentally verified, that the efficiency can be improved by over 3.5% by eliminating unnecessary body diode conduction.

High-efficiency and wide-bandwidth performance obtainable from a two-input buck converter

Abstract: A study of the two-input post-regulators is carried out in this paper. In these post-regulators, only a part of the total power undergoes a switching conversion process, whereas the remainder of the power comes up to the load directly, with no power conversion process. Due to this fact, very high efficiency is achieved. Moreover, the stress in the semiconductors and the filter size are both much lower than in standard post-regulators. Two-input post-regulators require two-output main converters. However, many converter topologies can be easily adapted to supply two-output voltages with no efficiency penalty. Two-input postregulators can be used in many power converters. Multiple-output DC-to-DC converters and AC-to-DC power factor correctors are two good examples.

A passive lossless snubber cell for nonisolated PWM DC/DC converters

Abstract: A passive lossless snubber cell is proposed to improve the turn-on and turnoff transients of the MOSFETs in nonisolated pulsewidth modulated (PWM) DC/DC converters. Switching losses and EMI noise are reduced by restricting di/dt of the reverse-recovery current and dv/dt of the drain-source voltage. The MOSFET operates at zero-voltage-switching (ZVS) turnoff and near zero-current-switching (ZCS) turn-on. The freewheeling diode is also commutated under ZVS. As an example, operation principles, theoretical analysis, relevant equations, and experimental results of a boost converter equipped with the proposed snubber cell are presented in detail. Efficiency of 96% has also been measured in the experimental results reported for a 1 kW 100 kHz prototype in the laboratory, Six basic nonisolated PWM DC/DC converters (buck, boost, buck-boost, Cuk, Sepic, and Zeta) equipped with the proposed general snubber cells are also shown in this paper.

A unified averaging technique for the modeling of quasi-resonant converters

Abstract: A unified averaging technique, here called the generalized state-space averaging (GSSA) technique, for the analysis of a class of periodically switched networks is proposed in the present paper. The basic assumption of GSSA is that the switching frequency must be much higher than the highest natural frequency of the networks, while the input variables can be bounded fast time-varying functions. It is shown in this paper that the GSSA approach generalizes the idea of the averaging technique to overcome the limitations of the conventional state-space averaging method, which prevents us from applying it to quasi-resonant converters (QRCs). The application of GSSA to the analysis of QRCs has been illustrated via examples of the zero-current switching QRC buck converter and zero-voltage switching QRC boost converter. Its accuracy has been verified by numerical simulation and experimental results.

Electric arc welder and plasma cutter

Abstract: A single phase power supply module for electric arc welders and plasma arc cutters comprising: a single phase input stage; positive and negative output terminals; a full wave rectifier connected to the input stage for rectifying the single phase voltage at the input stage; a buck converter type power factor correcting circuit for controlling current flow from the input stage to the rectifier, which buck converter has an output capacitor regulated to an intermediate voltage in the range of 100-150 volts; and, a high speed DC to DC converter having an internal transformer coupling applying voltage across the output terminals and means for regulating the applied voltage to an output voltage in the range of 0-113 volts. The module is universal and several can be connected in parallel, in series or to switch networks to construct several welders or cutters.

DC-DC switching regulator with switching rate control

Abstract: A DC--DC switching regulator which converts a supplied DC voltage V DD to a DC output voltage V OUT for driving a load using a DC--DC buck converter operated with fixed-width pulses V X at an instantaneous switching rate n i . The regulator has a feedback for computing a subsequent switching rate n i+1 based on the instantaneous switching rate n i , an output frequency f OUT derived from output voltage V OUT by a ring oscillator and a desired frequency f DES provided by a frequency signaling device or a frequency signaling port of the load. By altering the desired frequency f DES the load communicates its power needs. The regulator can be used in the low-power regime and at high power levels.

Control of chaos in DC-DC converters

Abstract: It has been demonstrated previously that DC-DC buck and boost converters with current or voltage feedback exhibit chaos for significantly large ranges of parameter values. In this paper, we present two methods for controlling chaos particularly suitable for switching circuits. The results of numerical investigation and experimental implementation are presented with reference to the duty cycle controlled buck converter.

Re-lift converter: design, test, simulation and stability analysis

Abstract: The 're-lift' power converter is derived from the self-lift power converter and performs a positive-to-positive DC-DC step-up voltage conversion with high efficiency, high power density and cheap topology in a simple structure. The output voltage and current of this power converter are smooth. Two capacitors are applied to lift the output voltage by twice of the input voltage. The output voltage of the re-lift power converter is double that of the self-lift converter.

Single-switch two-output flyback-forward converter operation

Abstract: A double power converter with fully independent regulated outputs is introduced. The proposed topology results from magnetic integration of flyback and forward power converters. The derived converter shares a single power switch having a single magnetic component. Also, only one standard pulsewidth modulation (PWM) integrated modulator is needed in order to keep independent closed-loop control of both output voltages. The double regulation may be sustained over a wide spread of current loads. Boundaries of full regulation and experimental results are presented.

Analysis of subharmonic oscillation of fixed-frequency current-programming switch mode power converters

Abstract: Subharmonic oscillation of a generic fixed-frequency current-programming switch mode power converter (SMPC) operating in the continuous-conduction mode (CCM) is analyzed. The conditions for oscillation are derived by the geometric approach as well as by analyzing the converter in the discrete time domain and are shown to be equivalent. In obtaining the state-space averaged differential equation, the forward Euler approximation is invoked. This z/spl rarr/s transformation maps a z-domain pole outside the unit circle that causes the oscillation to a s-domain pole in the left-half plane (LHP), which has previously been overlooked. The analysis is then applied to a current-programming buck converter, which suggests the two correct control equations for both converters employing either trailing- or leading-edge modulation.

Temperature protection circuit for power converter and method of operation thereof

Abstract: A temperature protection circuit, a method of protecting a power converter and a power converter employing the circuit or the method. In one embodiment, the circuit includes: (1) a temperature sensor, located in thermal communication with the power converter, that produces a signal based on a temperature associated with the power converter and (2) a current controller, coupled to the temperature sensor, that reduces an output current of the power converter to an intermediate level based on the signal.

Power supply having means for extending the operating time of an implantable medical device

Abstract: A power supply comprising: a power source including a capacitive, nuclear or an electrochemical device for storing electrical energy; sensing circuitry for sensing when the voltage on power source is above or below a certain level; a DC-DC converter coupled to the power source switching circuitry coupled to the sensing circuitry and operable to connect the DC-DC converter to an output load and disconnect the power source from the output load when the voltage on the power source falls below a certain level and for connecting the power source to the output load and disconnecting the DC-DC converter from the output load when the voltage on the power source rises above a certain level; circuitry for activating the DC to DC Converter when the voltage on the power source falls below a certain level; and circuitry means for shutting down the DC to DC Converter when the voltage on the power source rises above a certain level. The method for extending the operating time of a capacitive, nuclear or electrochemical power source includes the steps of: sensing when the voltage level on the power source is below or above a certain level; producing a first logic signal when the voltage on the power source falls below a certain level and producing a second logic signal when the voltage on the power source is above a certain level; providing a DC-DC converter coupled to the output of the power source; switching the connections to an output load from the power source to the DC-DC converter when the first logic signal is produced; connecting the power source to an output load and disconnecting the DC-DC converter from the output load when the second logic signal is produced; activating the DC to DC Converter when the first logic signal is produced; and shutting down the DC to DC Converter when the second logic signal is produced.

New single-stage PFC regulator using the Sheppard-Taylor topology

Abstract: This paper describes a new usage of the DC/DC converter developed by D.I. Sheppard and B.E. Taylor in 1983 for achieving high power factor and output regulation. This converter may be viewed as a cascade of a modified boost stage and a buck stage, with the two stages sharing the same active switch. Two possible operation regimes are described. In the first regime, the converter's input part, which is a modified boost converter, operates in discontinuous mode, and the output part, which is a buck converter, operates in continuous mode. In this regime, high power factor is naturally achieved, and the output voltage is regulated by duty-cycle modulation via a simple output feedback. In the second regime, the input part operates in continuous mode, and the output part operates in discontinuous mode, with duty-cycle modulation maintaining a high power factor and frequency modulation regulating the output. Some comparisons between the Sheppard-Taylor converter and conventional boost and buck cascade are given in the paper.

Dual buck converter with coupled inductors

Abstract: This invention relates to a dual buck converter used to reduce an unregulated high input voltage without a ground reference to a regulated output voltage. This is accomplished by coupling the inductors of two independent buck converters. The input voltage is split across the dual buck converter and the mid point is balanced by coupling the inductors and switching the two switches at the same time. The inductors are wound on a single core, with the windings magnetically coupled, to form a new coupled inductor.