Showing papers on "Buck converter published in 1991"

Switching Power Supply Design

Abstract: Using this book as a guide, Pressman promises, even a novice can immediately design a complete switching power supply circuit. No other book has such complete instruction in one volume. Using a tutorial, how-to approach, Pressman covers every aspect of this new technology, including circuit and transformer design, using higher switching frequencies, new topologies, and integrated PWM chips. For this latest edition, Pressman has added in-depth discussion of power factor correction, high-frequency ballasts for fluorescent lamps, and low-input voltage power supplies for laptop computers. Table of contents Part I:Fundamental Switching Regulators Buck, Boost, and Investor Topologies.Push-Pull and Forward Converter Topologies.Half- and Full-Bridge Converter Topologies.Flyback Converter Topologies.Current-Mode and Current-Fed Topologies.Miscellaneous Topologies.Part II: Magnetics and Circuits Designs.Transformer and Magnetic Design.Bipolar Power Translator Base Drives.MOSFET Power Transistors and Input Drive Circuits.Magnetic-Amplifier Postregulators.Turnon, Turnoff Switching Losses and Snubbers.Feedback-Loop Stabilization.Resonant Converters.Part III: Typical Switching Power Supply Warehouse.Part IV: Newer Applications for Switching Power Supply Technique.Power Factor, Power Factor Correction.High-Frequency Power Sources for Fluorescent Lamps.Low-Input-Voltage Regulators for Laptop Computers and Portable Electronics.

A new, continuous-time model for current-mode control (power convertors)

Abstract: A current-mode control power convertor model that is accurate at frequencies from DC to half the switching frequency is described for constant-frequency operation. Using a simple pole-zero transfer function, the model is able to predict subharmonic oscillation without the need for discrete-time z-transform models. The accuracy of sampled-data modeling is incorporated into the model by a second-order representation of the sampled-data transfer function which is valid up to half the switching frequency. Predictions of current loop gain; control-to-output; output impedance; and audio susceptibility transfer functions were confirmed with measurements on a buck converter. The audio susceptibility of the buck converter can be nulled with the appropriate value of external ramp. The modeling concentrates on constant-frequency pulse-width modulation (PWM) converters, but the methods can be applied to variable-frequency control and discontinuous conduction mode. >

One-cycle control of switching converters

Abstract: A new large-signal nonlinear control technique is proposed to control the duty-ratio d of a switch such that in each cycle the average value of a switched variable of the switching converter is exactly equal to or proportional to the control reference in the steady-state or in a transient. One-cycle control rejects power source perturbations in one switching cycle; the average value of the switched variable follows the dynamic reference in one switching cycle; and the controller corrects switching errors in one switching cycle. There is no steady-state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with a constant frequency buck converter have demonstrated the robustness of the control method and verified the theoretical predictions. This new control method is very general and applicable to all types of pulse-width-modulated, resonant-based, or soft-switched switching converters for either voltage or current control in continuous or discontinuous conduction mode. Furthermore, it can be used to control any physical variable or abstract signal that is in the form of a switched variable or can be converted to the form of a switched variable. >

Switching converters with wide DC conversion range

Abstract: Compared to basic converter topologies (buck, boost, buck-boost, Cuk, etc.), pulse-width modulation (PWM) converters with quadratic DC conversion ratios, M(D)=D/sup 2/, M(D)=D/sup 2//(1-D) or M(D)=D/sup 2//(1-D)/sup 2/, offer a significantly wider conversion range. For a given minimum ON-time and, consequently, for a given minimum duty ratio D/sub min/, D/sup 2/ in the numerator of M(D) yields a much lower limit on the minimum attainable conversion ratio. By applying a systematic synthesis procedure, six novel single-transistor converter configurations with quadratic DC conversion ratios are found. The simpler, single-transistor realization is the most important advantage over the straightforward cascade of two basic converters. As far as conversion efficiency is concerned, it is clear that a single-stage converter is usually a better choice than a two-stage converter. The quadratic converters proposed are intended for applications where conventional single-stage converters are inadequate-for high-frequency applications where the specified range of input voltages and the specified range of output voltages call for an extremely large range of conversion ratios. >

Pseudo-resonant full bridge DC/DC converter

Abstract: A DC-DC power converter topology that combines the ease of control and wide range of conventional DC-DC converters, with low switching losses, low dv/dt and low electromagnetic interference that is typical of zero voltage switched resonant converters is proposed. Consequently, the ratings of these components are substantially lower than for similarly rated resonant topologies. While resonant elements are used to ensure zero voltage switching of all devices, they have little or no role in the actual power transfer and can thus be reasonably sized. As the resonant elements are not involved in the primary power transfer, the converter is referred to as a pseudo-resonant converter. It is shown that the converter offers significantly higher levels of performance than either the pulse width-modulated (PWM) or typical resonant converters. Operation at very high frequencies is possible and is shown with the fabrication of a 200 W 1 MHz DC-DC converter. >

Dynamic analysis of switching-mode DC/DC converters

Abstract: 1. Survey of the Existing Analysis Methods.- 1. Introduction to the Injected-Absorbed-Current Method of Analysis.- 1-1 Theoretical Foundation.- 1-2 General, Low-Frequency, Small-Signal Model of a Switching Cell.- 1-3 Cell Transfer Functions.- 1-4 General Formulas for the Derivation of the Characteristic Coefficients.- 1-5 Summary and Conclusions.- References.- 2. Elementary Converters Operating at Constant Frequency with Duty Ratio as Controlled Quantity.- 2-1 Introduction.- 2-2 Buck Cell.- 2-3 Buck-Boost Cell.- 2-4 Boost Cell.- 2-5 Tabulation of Derived Transfer Functions, Comments.- 2-6 Influence of Capacitor Series Resistance.- 2-7 Characteristic Coefficients.- 2-8 Influence of the Inductor Resistance.- 2-9 Summary-1. Survey of the Existing Analysis Methods.- 1. Introduction to the Injected-Absorbed-Current Method of Analysis.- 1-1 Theoretical Foundation.- 1-2 General, Low-Frequency, Small-Signal Model of a Switching Cell.- 1-3 Cell Transfer Functions.- 1-4 General Formulas for the Derivation of the Characteristic Coefficients.- 1-5 Summary and Conclusions.- References.- 2. Elementary Converters Operating at Constant Frequency with Duty Ratio as Controlled Quantity.- 2-1 Introduction.- 2-2 Buck Cell.- 2-3 Buck-Boost Cell.- 2-4 Boost Cell.- 2-5 Tabulation of Derived Transfer Functions, Comments.- 2-6 Influence of Capacitor Series Resistance.- 2-7 Characteristic Coefficients.- 2-8 Influence of the Inductor Resistance.- 2-9 Summary-General Expression of Regulator Input Impedance.- 2-10 Correspondence Between the Cell Model Using Characteristic Coefficients and Other Known Models.- 3. General Small-Signal, Low-Frequency Analysis of Switching Regulators.- 3-1 Introduction.- 3-2 Modulator Transfer Functions.- 3-3 Essential Parameters of a Closed-Loop Regulator: Input Impedance, Output Impedance, Input-to-Output Voltage Transfer Function.- References.- 4. State-Variables-Averaging Method.- 4-1 Introduction.- 4-2 Continuous-Conduction Mode.- 4-3 Discontinuous-Conduction Mode.- References.- 2. Multiple-Loop Switching Power Cells.- 5. Elementary Switching Power Cells with Inductor Current as Controlled Quantity.- 5-1 Introduction.- 5-2 Open-Loop Instability of Power Cells Using Constant-Frequency Peak-Current-Commanding Control.- 5-3 Characteristic Coefficients of Elementary Power Cells Using Constant-Frequency Peak-Current-Commanding Control and Linear Compensating Ramp.- 5-4 Output Characteristic Coefficients of the Buck Cell in Heavy Mode with Hysteretic, Constant Off Time, and PWM-Conductance Control.- 5-5 Practical Evaluation of Different Current-Mode Control Techniques.- References.- 6. Multiple-Loop Switching Cells Using Inductor Voltage in a Minor Feedback Loop.- 6-1 Introduction.- 6-2 Pole-Zero Cancellation in a Buck Cell in Heavy Mode Using an IVI Configuration.- 6-3 Transfer Functions of Different Functional Blocks.- 6-4 Complete Small-Signal, Low-Frequency Model of a Switching Regulator Using the IVI Configuration.- 6-5 IVI Configuration in Applications.- References.- 3. Special Configurations.- 7. ?uk and SEPIC Switching Cells.- 7-1 Introduction.- 7-2 Characteristic Coefficients of the ?uk Converter in Heavy Mode.- 7-3 Extensions of the ?uk Converter.- 7-4 Comments.- 7-5 The SEPIC Converter as a Derivative of the ?uk Converter.- References.- 8. Analysis of Power Cells with Duty-Ratio Control at Variable Frequency.- 8-1 Introduction.- 8-2 Porter Switching Cell.- 8-3 Switching Cells with Constant Off Time or Constant On Time Control.- 8-4 Buck Cell in Heavy Mode with Frequency Control and Feedforward of Input Voltage.- References.- 9. Free-Running Hysteretic Regulator.- 9-1 Introduction.- 9-2 Exact Steady-State Analysis.- 9-3 Approximate Steady-State Analysis.- 9-4 Design Example.- 9-5 Transient Analysis.- References.- 4. Applications of Linear Analysis Method.- 10. Interconnection of a Power Source and a Switching Regulator.- 10-1 Introduction.- 10-2 Switching Regulator with Capacitive Input Filter.- 10-3 Analysis of the Switching Regulator with General Input Filter.- 10-4 Influence of Input Filter on Regulator Parameters.- 10-5 Simplified Approach.- 10-6 Regulator Employing a Buck Cell Operating at Constant Frequency, in Heavy Mode, with Duty Ratio Control, Preceded by an Input LC Filter.- 10-7 Final Remarks.- References.- 11. Feedforward in Switching Regulators.- 11-1 Introduction.- 11-2 A Combined Input Voltage and Output Current Feedforward in Regulators Using Switching Cells with Inductor Current as the Controlled Quantity.- 11-3 Feedforward Concept in Configurations with an Input Filter.- 11-4 Feedforward of Major Perturbations.- References.- 12. Parallel Operation of Switching Regulators.- 12-1 Introduction.- 12-2 Paralleled Autonomous Sources with Feedback-Controlled Current-Sharing.- 12-3 Conclusions.- References.- 5. Selected Analytic Approaches and Applications and Future Advances in Analysis Methods.- 13. Selected Analysis Examples.- 13-1 Introduction.- 13-2 Small-Signal Analysis of a Regulator Using a Buck Cell at Constant Frequency, in Heavy Mode, and with a Fast Voltage-Feedback Path.- 13-3 Small-Signal Analysis of a Regulator Using a Buck Cell at Constant Frequency, in Heavy Mode, and with Combined Fast Voltage and Output-Current Feedback.- 13-4 State-Plane Analysis of a Boost Cell.- References.- 14. High-Frequency Extension of the Linear Cell Model.- 14-1 Introduction.- 14-2 Inclusion of the Discrete (Sampled) Injected-Current Waveform into the Cell Model.- 14-3 Derivation of the Discrete Characteristic Coefficients of a Boost Cell in Heavy Mode, at Constant Switching Frequency, and with Duty Ratio as Controlled Quantity.- 14-4 Comparison of the Transfer Functions Obtained by Different Approaches.- 14-5 Discrete Characteristic Coefficients of the Elementary Switching Cells in Heavy and Light Modes, at Constant Switching Frequency, and with Duty Ratio as Controlled Quantity.- 14-6 Discrete Characteristic Coefficients of the Elementary Switching Cells in Heavy Mode, at Constant Switching Frequency, with Maximum Inductor Current as Controlled Quantity, and with Linear Compensating Ramp.- 14-7 Conclusions.- References.- Appendixes.- Appendix 1. Additional Information for Chapter 5.- A1-1 Derivation of Time Delay Between Control and Injected Current for Constant Off Time Current-Mode Control.- A1-2 Control-to-Output Voltage Functions of CurrentMode-Controlled Buck Converter with Three Different Control Methods.- Appendix 2. Graphical-Analytical Representation of Transfer Functions.- A2-1 Introduction.- A2-2 Transfer Functions of Passive Networks.- References.- Appendix 3. Examples and Problems.- A3-1 Introduction.- A3-2 Appendix to Chapter 2-Regulators Employing Elementary Cells, Operating at Constant Switching Frequency, and with Duty Ratio as the Controlled Quantity.- A3-3 Appendix to Chapter 14-Successive Approximations of the Cell Controlled-Quantity-to-Output-Voltage Transfer Function.- Appendix 4. Sources of Technical Information.- A4-1 Conferences.- A4-2 Periodicals.- A4-3 Compendia.- A4-4 Textbooks.

Constant-frequency control of quasi-resonant converters

Abstract: An additional independent control needed to eliminate the undesirable variable switching frequency of quasi-resonant (QR) converters is obtained by replacing the output rectifier by an active switch. The concept is applicable to all classes of converters. Compared to QR converters with conventional switch realization, constant-frequency quasi-resonant (CF-QR) converters exhibit the same type of switching transitions and similar switch voltage and current stresses. Advantages of CF-QR converters are not restricted to the constant-frequency control. In all classes, operation at zero load is possible, so that the available load range is unlimited. The range of attainable, conversion ratios is significantly extended in the classes of zero-voltage quasi-square-wave (CF-ZV-QSW) and zero-voltage multiresonant (CF-ZV-MR) topologies. A practical design example of a 25 W CF-ZV-MR buck converter is constructed and evaluated. The converter operates at 2 MHz from zero load to full load, with a full-load efficiency of 83%. Simple duty ratio control is used to maintain the output voltage constant for all loads. The circuit is inherently immune to the short-circuit condition at the output. Disadvantages of CF-QR converters are the increased gate-drive losses and increased complexity of the power stage and the control circuitry. >

A high frequency AC/DC converter with unity power factor and minimum harmonic distortion

Abstract: A novel forced commutated AC/DC converter and control strategy is proposed that is able to draw nearly sinusoidal currents at unity power factor from three-phase power lines. The power factor is controlled by adjusting the relative position of the fundamental component of an optimized pulse-width-modulation (PWM) type voltage with respect to the supply voltage. Current harmonic distortion is minimized by the use of optimized firing angles for the converter at a frequency where gate turn-off thyristors (GTOs) can be used. This feature makes this approach attractive at power levels of 100 kW to 600 kW. An 8096 microcontroller is used to minimize the interface hardware requirements. The theoretical analysis of the converter, the control energy, and experimental results for a low-power prototype are presented. >

An improved zero-voltage-switched PWM converter using a saturable inductor

Abstract: The saturable inductor is employed in the full-bridge (FB) zero-voltage-switched (ZVS) pulsewidth-modulated (PWM) converter to improve its performance. The current and voltage stresses of the switches as well as parasitic oscillations are significantly reduced compared to those of the conventional FB-ZVS-PWM converter. The theoretical analysis is presented and is verified on a 500 kHz, 5 V/40 A converter. >

Apparatus for controlling the input impedance of a power converter

Abstract: A DC-DC power converter, which can be adapted for use with a single- or multiple-phase AC input, uses energy control because it transcends the modulators and is linear. The use of feed back control is minimized by the use of feed forward control, and in particular the feed forward of the output power to control the input power. The dynamic resistance of the input is controlled, ensuring high power factor in the AC input embodiments of the converter. A multiple-input buck derived converter can have parallel or series inputs, and one or more of the inputs can be lower than the output, even zero or negative. A multiple output boost derived converter can have parallel or series outputs, and one or more of the outputs can be lower than the input, even zero.

High power-factor converter for motor drives and power supplies

Abstract: A high power-factor converter (50) for use with motor drives and power supplies. A first and "buck"-type converter section (62) is connected to an a.c. voltage source. This section provides an output voltage having preselected voltage characteristics. This section is operational during that portion of an input voltage cycle in which the input voltage level exceeds that of the output voltage level. A second and "boost"-type converter section (70) is also connected to the voltage source. This second section also provides the output voltage, and is operational during that portion of the input voltage cycle in which the output voltage level exceeds that of the input voltage level. A control circuit (66) is responsive to the relative levels of the input and output voltages to operate the first and second converter sections on a time sharing basis in which converter operation is switched between the two converter sections as a function of the sensed actual output voltage characteristics compared to the preselected characteristics. This permits the converter to maintain a nearly full conduction angle, and therefore a high power factor, for any level of output voltage in a range from zero volts to voltage levels higher than the peak input voltage level.

Standby boost converter

Abstract: A boost voltage converter is combined with any DC-DC converter to provide a power system with significant overall power efficiency improvement in applications requiring continuous operation through low line transient levels. The boost converter is normally in a standby mode and only operates when the input DC voltage drops below a predetermined minimum steady state voltage. During steady state operation, a simple, efficient feedthrough of the DC current directly to the DC-DC converter is provided. Efficiency improvements in the combination of boost converter and DC-DC converter result from the reduction of the effective transient range seen by the DC-DC converter, allowing the DC-DC converter components to be designed and selected to significantly reduce their power dissipation during nontransient input steady-state operation.

Method and apparatus for controlling the input impedance of a power converter

Abstract: A DC-DC power converter adaptable for use with an AC input, uses feed forward control of the output power to control the input power and the dynamic resistance of the input to ensure a high power factor in the AC input embodiments of the converter. The dynamic response of the power converter is controlled by feed forward, either through scheduling the energy content of a storage capacitor as an explicit function of the output power, the input voltage and the time constant, or through energy deficit feed forward in which the energy deficit caused by a transient is fed forward as an increment of power under feed forward control. Line frequency ripple feed forward compensates the feed forward in the embodiments having an AC input for any half frequency harmonics present in full wave rectified input due to a DC offset or asymmetry in the AC input. With load anticipation feed forward control, input power transitions smoothly without overshoot for a step change of output load from no load to full load and back.

Asymmetrical duty cycle power converter

Abstract: Operating a bridge type PWM switch mode power converter with asymmetrical duty ratios can eliminate switching losses with no increase in conduction loss. Included are three circuits, a full bridge buck converter, a half bridge buck converter, and a full bridge boost converter. These converters are an improvement over existing zero switching loss converter circuits in that they eliminate the large peak switch currents and voltages typical of existing circuits. The peak switch voltages found in these circuits are as low as those seen in standard PWM switch mode converters, and allow the use of efficient low voltage switches. The low peak and rms current delivered by the switches further improves efficiency, and the elimination of switching losses increases efficiency and allows operation at higher frequencies with the resultant benefit of smaller component size.

A 540-MHz 10-b polar-to-Cartesian converter

Abstract: A 10-b polar-to-Cartesian converter for generating digital sine and cosine waveforms simultaneously with a maximum sample rate of 540 MHz is presented. The converter is derived from a coordinate rotation digital computer (CORDIC) processor. Implementation details and the chip layout are given. The converter is implemented in a 1- mu m 13-GHz triple-level interconnect bipolar process, requiring 1000 mW from a single 5-V supply. The die size is 25 mm/sup 2/. >

Analysis and design of a saturable reactor assisted soft-switching full-bridge DC-DC converter

Abstract: The analysis and design of a saturable reactor-assisted soft-switching full-bridge DC-DC converter are presented. The converter has advantages such as low switching losses (with no substantial increase in conduction losses), wide load range, and constant switching frequency. In order to show how to utilize the analysis results in designing, a 350 W 500 kHz converter is chosen as an example. The results are verified experimentally on a prototype converter. >

Power factor correction device provided with a frequency and amplitude modulated boost converter

Abstract: A power factor correction circuit used to improve the ratio of real power to apparent power in an electric power distribution line containing a source of AC sinusoidal voltage and a load. The circuit includes a frequency and amplitude modulated boost converter forcing the input current to have the same wave shape as that of the input voltage.

Regulated bi-directional DC-to-DC voltage converter which maintains a continuous input current during step-up conversion

Abstract: A pulse-width modulated, bi-directional DC-to-DC voltage converter having a regulated output, and capable of converting between a high-potential direct current voltage and a low-potential direct current voltage. The converter's magnetic components, as well as several of its semiconductor rectifiers, perform dual functions (one in the step-up mode, and another in the step-down mode), which serves to minimize the total component count, and allows the converter to be both compact and lightweight. Additionally, as the converter maintains a continuous input current during voltage step-up conversion, the generation of signals which might cause electromagnetic interference is reduced.

Small-signal high-frequency analysis of the free-running current-mode-controlled converter

Abstract: The small-signal high-frequency model of the free-running current-mode-controlled converter is determined using the analysis method of injected-absorbed currents and introducing high-frequency correction terms. The model is valid up to one-half of the switching frequency. The model parameters (the characteristic coefficients of the switching cell) can be obtained with a few lines of calculation while retaining the insight into the physical operation of the converter. The technique is applied for the buck, boost, and buck-boost cells, using hysteretic, constant off-time, or constant on-time control. A general procedure is recommended for determining the coefficients. The possible approximations for the high-frequency correction terms are discussed. Tables of characteristic coefficients are provided. Experimental data that are in excellent agreement with theoretical prediction are presented. >

Linear programming circuit for adjustable output voltage power converters

Abstract: An adjustable power converter which allows the output voltage of the power converter to be controlled linearly by a programming resistor or a programming voltage is provided. The adjustable power converter includes a linear programming circuit which generates a current as a linear function of the programming voltage or the resistance of the programming resistor. The current is connected to the feedback loop of a conventional power converter such that the output voltage of the power converter is a linear function of the current. As a result, the output voltage of the power converter can be linearly adjusted by adjusting the programming voltage or the programming resistor.

A multiple PWM GTO line-side converter for unity power factor and reduced harmonics

Abstract: A multiple PWM GTO line-side converter with low switching frequency has been developed for industrial uses needing both higher capacity and higher performance. The multiple converter is composed of two GTO converter units connected in parallel through an interphase reactor. The switching frequency of the GTO thyristors in the multiple converter can be reduced to a quarter of that in the single converter. It is verified by simulations and experiments with a 2750 kVA GTO converter and inverter system with a 500 Hz switching frequency that the system has: (1) a unity power factor, (2) reduced harmonics, (3) bidirectional power flow, and (4) speed regulatory performance equal to that of an advanced cycloconverter drive system. Analogies between inverter control and converter control are also studied for the development of the converter control. >

Control art of switching converters

Abstract: Switching Flow-Graph Model: The Switching Flow-Graph is a unified graphical model of large-signal, small-signal and steady-state behavior of pulse-width-modulated (PWM) switching converters. Switching branches are introduced into the flow-graph to represent the switches of the PWM switching converters. The Switching Flow-Graph model is easy to derive, and it provides a visual physical understanding of switching converter systems. The small-signal Switching Flow-Graph generates analytical transfer functions and the large-signal Switching Flow-Graph is compatible with the TUTSIM simulation program. The Switching Flow-Graphs of PWM switching converters reveal a regular pattern, and they predict right-half-plane (RHP) zeros, caused by the imbalanced effects of the duty-ratio control signal on the output of the switching converters. Criteria are found for the design of damping circuits that are capable of eliminating RHP zeros. General models are derived for current-mode controlled switching converters. In addition, the large-signal model and the small-signal model are verified by experiments. One-Cycle Control Technique: The One-Cycle Control technique is conceived to control the duty-ratio d of the switch in real time such that in each cycle the average of the chopped waveform at the switch output is exactly equal to the control reference. Implementation circuits are found for any type of switch, constant frequency, constant ON-time, constant OFF-time, and variable. One-Cycle Control fully rejects the input signal, and linearly all passes the control signal. This technique turns a nonlinear switch into a linear one. Experiments were conducted using the One-Cycle Control technique on the buck converter and the Cuk converter. One-Cycle Control was found to reject input perturbations and input filter dynamics. The diode voltage of One-Cycle Controlled converters follows the control reference instantaneously in one cycle. One-Cycle Control takes advantage of the pulsed and nonlinear nature of switching converters to achieve instantaneous control of the average value of the diode voltage. This technique is suitable for large-signal control of PWM switching converters and quasi-resonant converters.

VCO having voltage-to-current converter and PLL using same

Abstract: The voltage controlled oscillator in a phase-locked loop comprises a voltage-current converter (62) and a current frequency converter (34). The voltage-current converter (62) comprises a voltage differential-current converter (64), a current-current converter (66) and a current adder-subtracter (68). In the voltage differential-current converter (64), only the voltage fluctuation or difference ΔV CN with respect to one half a power supply voltage V DD /2, and not the absolute value of a control voltage V CN , undergoes current conversion as a control current I CN . Therefore, the center frequency of the oscillation frequency is not a factor of control voltage V CN and is controlled only by an offset voltage V B2 . Accordingly, the center frequency can be independently set by changing offset voltage VB 2 . This is particularly significant in zone bit recording, which requires a wide frequency band.

Two stage a/d converter utilizing dual multiplexed converters with a common converter

Abstract: A converter including an even and an odd digital-to-analog converter for converting digital signals from a successive approximation circuit and controlling the odd and even converters and the analog-to-digital converter device to alternate conversion by the even and odd converters. The odd and even converters operate in oppostie phases such that while one is in an acquisition phase the other is in a conversion phase. Each of the odd and even converters includes a separate coarse digital-to-analog converter and a common fine digital-to-analog converter. The control circuit resets the fine digital-to-analog converter during an initial portion of the conversion phase of each of the coarse digital-to-analog converters. In a two stage flash converter, the first stage includes a single analog-to-digital converter and the second stage includes a single digital-to-analog converter and alternatingly operating even and odd analog-to-digital converters.

Coupled inductor boost converter with input and output ripple cancellation

Abstract: The authors describe the HS601 spacecraft battery discharge controller (BDC), a fully redundant 100 kHz boost converter which provides up to 2 kW at 50.5 VDC from a 32 cell battery (32-45 VDC). The converter is designed to be connected in parallel with a second unit to provide up to 4 kW to the spacecraft to the spacecraft bus during an eclipse. Because a single design must accommodate many different spacecraft configurations, the unit must operate properly over a wide range of battery voltage (24 to 48 VDC), load current, and load impedance. The HS601 achieves ultra-low output ripple voltage ( 90%) using a unique coupled inductor boost converter topology. >

Process and device for operating as on-board charging set the inverse rectifier of the threephase current drive of an electric car

Abstract: A process and a device are disclosed for operating as on-board charging set the inverse rectifier (4) of the threephase current drive (2) of an electric car. In the charging mode of operation two bridge arms (18, 22) of the inverse rectifier (4) are set as boos regulator, so that a direct voltage (Ud) is supplied to an intermediate capacitor (16) of the inverse rectifier (4) depending on a mains-friendly supply, whereas a further bridge arm (20) of the inverse rectifier (4) is set as a buck regulator, so that a charging current from the intermediate capacitor (16) is supplied to the driving battery (10) of the electric car depending on a charging characteristic thereof. By adding simple elements, the inverse rectifier (4) of the threephase current drive (2) of an electric car can thus be used as an on-board charging set, saving volume and weight in relation to known electric cars.

A novel uninterruptible DC-DC converter for UPS applications

Abstract: The authors describes a novel DC-DC converter that integrates a Cuk converter and a buck converter to deliver uninterruptible DC output power. This converter has the desirable features of a simple circuit and high efficiency compared with a standalone uninterruptible power supply (UPS). The circuit operation and analysis of the converter, together with experimental results from a prototype circuit, are presented. >

Single conversion power factor correction using sepic converter

Abstract: A SEPIC converter powered off line is controlled to improve the input power factor by forcing the current in the input inductor to assume the same wave shape as the voltage across the inductor in series with the power switch to insure a sinewave input current. A switched capacitor is provided to provide brief holdover power to the converter should the input AC voltage fail.

Regenerative converter for PWM AC drives

Abstract: Since the PWM induction motor drive has become the industrial drive of choice, applications involving four-quadrant operation for AC drives have become more common. To satisfy such applications, a regenerative AC/DC converter that is robust is needed to allow bidirectional power flow between the load and power distribution system. A robust technology that is well understood is the 6 SCR converter operating in the inverting mode. However, the typical 6 SCR converter will either limit the maximum DC bus voltage or require a step-up transformer. The proposed regenerative converter allows the SCR power structure to operate as a synchronous line commutator, while a two-transistor series/shunt chopper, with a power resistor, controls the regenerative power flow, and offers an emergency braking capability. In addition, SCR commutation is accomplished by the line voltage and diversion of bus current. Both simulation and experimental results are given. >

Characterization and comparison of noise generation for quasi-resonant and pulse-width modulated converters

Abstract: A buck converter with a given output filter is operated with pulse-width modulated and quasi-resonant switching schemes at the same nominal load and switching frequency. Electromagnetic interference generated by the natural switching action of the converter is examined by spectral analysis. Interference caused by excitation of parasitic elements is examined experimentally. Quasi-resonant converters are found to have a lower switching frequency harmonic bandwidth than the equivalent pulse-width modulated converter, even with switching frequency control. The most significant parasitic responses are the turn-on current and turn-off voltage of the catch diode and the gate current of the MOSFET. A significant decrease in radiated and conducted noise occurs when the gate drive voltage rise and fall times are increased, which is possible without loss of efficiency using quasi-resonant switching. >