Showing papers on "Buck converter published in 1979"

General topological properties of switching structures

Abstract: Investigation of a wide variety of switching converter toplogies culminates in the establishment of the most general correlation between the converter topologies--the duality relationships. The recognition of this general law leads to a number of new results: new converter topologies generated by the application of the duality transformation to the existing converter configurations, the discovery of the new mode of converter operation (discontinuous capacitance voltage mode) as well as significantly improved understanding of the existing converters and their equivalent circuit models.

Power Factor Improvement with a Modified Phase-Controlled Converter

Abstract: A modified phase-commutated converter with an improved power factor (PF) is presented and is analyzed for both rectifying and inverting modes. The optimal power factor firing control is formulated while taking into account commutation overlaps. Different modes of converter operation are identified and are analyzed in terms of reactive power requirements, power factor, and harmonic distortion on both ac and dc sides. The results are used to compare critically the new converter with a conventional six-pulse bridge.

Frequency converter and its controlling method

Abstract: PURPOSE: To enhance the power factor of a power supply by regenerative control employing a voltage-type pulse-width modulation converting means as a converter on the power-supply side with converts AC voltages to DC and as an inverter on the motor side which supplies variable-voltage variable-frequency voltage to a motor. CONSTITUTION: A DC input current of an inverter 2 flows from a converter 5 to an inverter 2 in the case of a reverse-conversion operation, and from the inverter 2 to the converter 5 in the case of forward-conversion operation. In both cases, the voltage of a capacitor 15 is controlled at a constant value, and the DC output current from the converter 5 is always balanced with the DC input current of the inverter 2. That is, the operation of the inverter 2 and that of the converter 5 are opposite each other. Since both the converter and the inverter are sonstituted by a PWM converting means, the motor current forms a sinusoidal wave, torque ripples are not generated, and the harmonic waves of the power supply are not generated either. COPYRIGHT: (C)1980,JPO&Japio

Current limiter for switched DC-to-DC converter

Abstract: A switched DC-to-DC converter in a power supply is powered by input line current from an external power source and driven by voltage pulses from a variable duty cycle pulse width modulator for converting a DC input voltage to a DC supply voltage of a different value that is applied to a load impedance. A comparator monitors the supply voltage for producing an error voltage that biases the modulator for adjusting the width of the voltage pulses, and thus the duty cycle of the converter, for maintaining the supply voltage relatively constant. An RC circuit integrates the voltage pulses for producing an indication of the average value thereof, which is directly related to the value of line current drawn by the converter. When the average value of voltage pulses exceeds a reference voltage, the value of bias voltage is limited for establishing the maximum width of voltage pulses and duty cycle of the converter, and thereby limit the maximum line current drawn by the power supply.

Process of pulse duration modulation of a multi-phase converter

Abstract: A process of pulse duration modulation for improved voltage and frequency efficiency of a multi-phase converter. The sum of the time dependent voltage of a load phase and of an auxiliary time dependent voltage is formed, wherein the auxiliary time dependent voltage is the same for all converter phases. The pulse duration of the output voltage of each converter phase is modulated with said voltage sum.

Modeling and analysis of switching dc-to-dc converter in constant-frequency current-programmed mode

Abstract: An analysis of dc-to-dc switching converters in constant-frequency current-programmed continous conduction mode is performed, and leads to two significant resuslts. The first is that a ramp function, used to eliminate a potential instability, can be chosen uniquely to assure both stability and the fastest possible transient response of the programmed current. The second is the development of an extension of the state-space averaging technique by means of which both the input and output small-signal properties of any such converter may be accurately represented by a linear small-signal equivalent-circuit model. The model is presented and experimentally verified for the cuk converter and for the conventional buck, boost, and buck-boost converters. All models exhibit basically a one-pole control-to-output transfer fuction response.

Analysis and Design of an Adaptive Multi-Loop Controlled Two Winding Buck/Boost Regulator

Abstract: Small signal low frequency linear average model is derived for a multi-loop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multi-loop control can provide a second-order zero adaptive to output filter parameter changes due to component tolerances, temperature changes, aging, and the effect of duty cycle modulation. It also can provide stabilization effect by shifting the positive zero to the left-half S-plane. Design quidelines are formulated to optimize regulator-loop dependent characteristics.

A new three-phase to single-phase AC to AC frequency converter

Abstract: A new ac to ac frequency converter which uses two six-pulse fully controlled bridge rectifiers and converts three-phase power frequency to a single-phase higher frequency is introduced in this paper. The power elements in the bridge rectifiers may be power transistors or thyristors provided with external means of commutation. The basic operation of the system with variable frequency and variable voltage is described for a resistive load. Analytical expressions for the frequency converter with a resistive load are presented and the results are compared with the existing three-pulse frequency converter. The operation of the system with a series RLC load is described and experimental results are presented from which pertinent characteristics of the frequency converter are discussed. Compared with the existing three-pulse frequency converter, the six-pulse frequency converter provides the advantages of improved input power factor and hence reduced input filter size and a wider range of power control without an increase in the KVA per unit output power rating of the power devices.

MP-A9 a high-speed superconducting A/D converter

Abstract: device has been shown to have high charge e f f i~ i ency .~ This device differs from a conventional buried-channel CCD in yet another significant aspect. Instead of the p-substrate, n-active layer arrangement typically used in buried-channel CCD technology, this device employs a semi-insulating substrate and ntype active layer. The semi-insulating substrate has important implications for high-speed applications since stray capacitance is reduced substantially with the consequence that power dissipation jn the clock drivers (Pd = cv2f) is reduced accordingly. Also, the semi-insulating substrate eliminated the need for a separate channel stop. The first device described by Deyhimi e t aL2y4 was a 30-gate device and served to prove the concept of the Schottkybarrier gate, buriedchannel CCD, and to characterize it with respect t o transfer efficiency, linearity, and floating gate capability. A new device has been fabricated and very recently operated and transfer efficency has been verified to be >0.999 per transfer. ~ This device employs 4.5 pm X 100 pm transfer gates (separated by I-vm gaps), as well as an on-chip reset amplifier. A 131-gate and a 259-gate version of this device have been successfully operated. The CCD transfer gates are connected in a 4-phase configuration. The active layer of the device is n-type with ND = 1 X 10 l6 /cm3. The device channel is isolated with a mesa etch and the electrode interconnection patterns are printed directly on the semi-insulating substrate. The device employs two-level metallization isolated by a plasma-deposited silicon-nitride. The 13 1-gate version of this device has been operated at up to 500 MHz. The results of transfer efficiency measurements will be reported.

Bi-directional four quadrant (BDQ4) power converter development

Abstract: The feasibility for implementation of a concept for direct ac/dc multikilowatt power conversion with bidirectional transfer of energy was investigated. A 10 kHz current carrier was derived directly from a common 60 Hz three phase power system. This carrier was modulated to remove the 360 Hz ripple, inherent in the three phase power supply and then demodulated and processed by a high frequency filter. The resulting dc power was then supplied to a load. The process was implemented without the use of low frequency transformers and filters. This power conversion processes was reversible and can operate in the four quadrants as viewed from any of the two of the converter's ports. Areas of application include: power systems on air and spacecraft; terrestrial traction; integration of solar and wind powered systems with utility networks; HVDC; asynchronous coupling of polyphase networks; heat treatment; industrial machine drives; and power supplies for any use including instrumentation.

A new concept of thermionic converter

Abstract: The parameters of a new type of thermionic converter, which has a number of concentric electrodes, are computed. The obtained theoretical efficiency of this new type of converter is close to the efficiency of the ideal thermionic diode converter. The results obtained are explained by the reduction of the radiation loss from the emitter due to the electrode configuration. Efficiencies as high as 20% are expected from this type of converter, which is now being constructed.

An adaptive-control switching buck regulator-implementation, analysis and design

Abstract: Describing function techniques and average methods have been employed to characterize a multiloop switching buck regulator by three functional blocks: power stage, analog signal processor and pulse modulator. The model is employed to explore possible forms of pole-zero cancellation and the adaptive nature of the control to filter parameter changes. Analysis-based design guidelines are provided including a suggested additional RC compensation loop to optimize regulator performances such as stability, audiosusceptibility, output impedance and load transient response.

Application of 40 KW Power Darlington Transistors in Large DC to DC Converters and Motor Speed Control

Abstract: General Electric Company has developed the D67D (a high speed darlington) power transistor rated at 400 Volts (sustaining) and collector currents of 100 Amps continuous (160 Amps peak). The devices are monolithic and utilize a new power package which is available in the isolated (R ?JC = .4°C/W max.) and non-isolated (R ?JC = .25°C/W max.) collector configurations. Some typical applications for the device would be for motor control and switching power supplies. Some design considerations are detailed which show the D67D as the power switch for a (1) push-pull output stage, (2) buck converter, and (3) inverter for a 10 H.P. induction motor.

Energy-storage and transfer mechanism in the reactor of new multiple-output DC-DC converter

Abstract: The energy-storage and transfer mechanism in the reactor of new multiple-output dc-dc converter is examined to define the output characteristics of this converter. In this converter, only one output voltage is regulated directly by the feedback control, and all others are slave to it; the regulation of all the other outputs is performed by using the magnetic coupling among the windings of the reactor. The operation of this converter is divided broadly into two major modes. In one mode, this converter has advantages over the conventional ones in the steady-state and dynamic characteristics. But this converter, in the other mode, has a defect that extraordinary phenomena arise. With the increase in the sum of the slave output powers, the output voltage within the feedback loops tends to increase extraordinarily and also all the slave output voltages decrease inversely. Examining the energy-storage and transfer mechanism in the reactor of this converter, the critical condition is derived to define the boundary between the two operation modes, and the output characteristics is clarified in each mode.