Showing papers on "Boost converter published in 1995"

Uninterruptible power system

Abstract: An uninterruptible power system has a transformer with a primary connected to input terminals, a secondary connected to output terminals, a static switch connected between the input terminals and the primary, and an auxiliary primary connected to an inverter which is supplied by a battery to provide output voltage to the output terminals when a main AC power system connected to the input terminals has failed. The primary has multiple taps at different voltage levels and a buck-boost winding. The taps of the transformer are switched and the buck-boost winding is controlled to provide either buck, boost, or pass-by to allow control of the output voltage from the transformer to within a few percent of a desired voltage level despite large changes in the input voltage. A battery charger coupled to the auxiliary primary operates as a boost converter to provide current to charge the battery at a current level which tracks the input voltage from the AC power system, thereby providing a substantially unity power factor to the AC power system. The voltage control of the output voltage also controls the voltage at the output of the auxiliary primary to which the battery charger is connected, whereby the voltage applied to the charger is substantially regulated and the output power of the charger itself is substantially regulated. The charger can be operated in programmable modes to provide a desired charge configuration for the battery. Detection of faults in the AC power system is enhanced by accurate detection of the zero crossings of the input voltage from the AC power system, and by comparison of the AC input power waveform with an adaptive reference.

Single-phase three-level boost power factor correction converter

Abstract: In many single-phase power factor correction (PFC) applications, the power level can reach several kilowatts; and in some situations, the input voltage can be quite high too. For high power and/or high voltage applications, the major concerns of the conventional boost PFC converter are the inductor volume and weight, and losses on the power devices, which will affect converter cost, efficiency, and power density. In this paper, a three-level boost converter is adopted for single-phase PFC, which uses a much smaller inductor and lower voltage devices than the conventional boost PFC converter does, yielding high power density, high efficiency, and low cost. >

Integrated cranking inverter and boost converter for a series hybrid drive system

Abstract: An electric continuously variable drive system includes an ac motor, an alternator for supplying electrical power to the ac motor via a rectifier and an inverter, a heat engine for driving the alternator, an energy storage device for providing electrical energy to the electric continuously variable drive system, and a combination cranking inverter and boost converter. The combination cranking inverter and boost converter is coupled in series between the alternator and the energy storage device and coupled substantially in parallel with the rectifier in a series hybrid drive.

On lossless switched-capacitor power converters

Abstract: This paper addresses the design of efficient switched-capacitor power converters. The discussion starts with a review of the fundamental limitation of switched-capacitor circuits which shows that the topology of such circuits and the "forced" step changes of capacitor voltages are the inherent attributes of power loss. Although the argument follows from a rather trivial result from basic circuit theory, it addresses an important issue on the maximum efficiency achievable in a switched-capacitor power converter circuit. Based on the observed topological constraint of switched-capacitor power converter circuits, the simplest lossless topology for AC/DC power conversion is deduced. Also discussed is a simple version of lossless topology that achieves isolation between the source and the load. Finally, an experimental AC/DC switched-capacitor power converter, based on the proposed idea, is presented which demonstrates an improved efficiency over other existing switched-capacitor power converters. The proposed AC/DC power converter contains no inductors and thus is suitable for custom IC implementation for very low power applications. >

Design of the half-bridge, series resonant converter for induction cooking

Abstract: The forced commutated, half-bridge, series resonant power converter is well suited for induction cooking. A detailed analysis is made of the operation of this power converter to obtain the information needed for a complete design procedure. The values of the reactive components and the voltage and current requirements for all the power components can be calculated with this procedure for a given cooking vessel (experimental measurement of parameters needed), grid voltage and maximum output power. Experimental results are presented. >

Feed-forward pulse-width modulators for switching power converters

Abstract: This paper describes pulse width modulators (PWMs) that employ feedforward compensation to improve the steady-state and dynamic responses of power converters. It is shown how ideal feedforward PWMs (FF-PWMs) can be constructed for all duty-ratio controlled switch-mode power converters operating in the continuous conduction mode. A power converter with FF-PWM behaves at low frequencies as a linear power amplifier with constant gain independent of operating conditions. The proposed FF-PWM can be easily implemented using the same building blocks found in conventional PWM controllers. Experimental and simulation examples are included to illustrate applications of the FF-PWM.

Passivity-based controllers for the stabilization of DC-to-DC power converters

Abstract: Average models of PWM regulated DC-to-DC power supplies are shown to be Euler-Lagrange systems. As such, passivity-based dynamical feedback controllers can be derived for the indirect stabilization of the average output voltage. The derived controllers are based on a suitable stabilizing "damping injection" scheme. The approach is applied to regulate DC-to-DC power converters of the "boost" and "buck-boost" types. The effectivity and robustness of the proposed duty ratio synthesis policies are tested, via computer simulations, on a stochastically perturbed model of a switched "boost" converter.

Full range soft-switching DC-DC converter

Abstract: A soft-switching DC to DC power converter which minimizes switching losses from a no load condition to a full load condition while operating at fixed frequency. Output voltage control is achieved by controlling the phase angle between the two switching networks. High frequency transformer primaries are always excited with a square wave input voltage equal to ##EQU1## The power converter can be implemented with a single transformer. Moreover, the switch voltage never increases the input DC voltage from no load to full load. The power converter can be used in both low voltage high current applications and high voltage low current applications.

Modular power supply system

Abstract: A modular power supply system (10) is provided for providing a multiplicity of output voltages from a plurality of respective converter modules (70a - 70n). Each of the converter modules (70a - 70n) has an input coupled to a DC high voltage bus (22) from which a respective output voltage is generated. The voltage supplied on DC bus (22) is generated by a power factor corrected boost converter circuit (20) which is coupled to an AC input source (12). Further, a battery backup module (40) is coupled to the high voltage DC bus (22) for supplying backup power whenever the bus voltage drops below a predetermined level.

A boost DC-AC converter: operation, analysis, control and experimentation

Abstract: This paper proposes a new voltage source inverter referred to as a boost inverter or boost DC-AC converter The main attribute of the new inverter topology is the fact that it generates an AC output voltage larger than the DC input one, depending on the instantaneous duty-cycle This property is not found in the classical voltage source inverter which produces an AC output instantaneous voltage always lower than the DC input voltage Operation, analysis, modulation, control strategy and experimental results are included in this paper The new inverter is intended to be used in UPS design, whenever an AC voltage larger than the DC link voltage is needed, with no need of a second power conversion stage

20 kW water-cooled prototype of a buck-boost bidirectional DC-DC converter topology for electrical vehicle motor drives

Abstract: In brushless DC motor drives devoted to electric vehicles (EVs) a bi-directional DC-DC power converter can be used to control suitably both motoring and regenerative braking operations in order to improve the motor drive performance. In consideration of such an application, this paper deals with the experimental study of a buck-boost bi-directional DC-DC power converter topology which has been conceived for the use in EVs propelled by means of wheel-direct-coupling axial-flux PM motor drives. The paper discusses the power converter modes of operation and reports experimental results taken from a 20 kW water-cooled prototype of the proposed power converter topology. >

A novel zero-voltage switched PWM boost converter

Abstract: A novel, zero-voltage switched (ZVS) PWM boost converter that combines soft-switching with constant frequency operation is proposed in this paper. This converter can be operated with PWM control at a fixed frequency because ZVS operation is achieved with a simple auxiliary resonant circuit that is activated for only a small fraction of the switching period and handles much less power than the main power circuit. In the paper, the modes of operation of the converter are explained and analyzed, and a set of design guidelines is developed. The feasibility of the converter is shown with results obtained from an experimental prototype. >

Multi-sectioned power converter having current-sharing controller

Abstract: An interleaved power converter is constructed so as to substantially equalize the power output of individual converter slices or phases. In an embodiment of the invention an interleaved power control system (110) includes a power bus (114) having a battery (116) coupled thereto and a plurality of slices (112) operating in a phased relationship with one another for causing the battery to source current to the power bus or to sink current from the power bus. Each of the slices includes an inductor (L) that is switchably coupled to the power bus and a controller (146) for controlling the switching of the inductor. The switching of the inductor is controlled as a function of (a) a difference between a magnitude of a voltage potential (VB) of the power bus and a predetermined voltage potential magnitude (Voltage Setpoint); (b) a difference between a magnitude of a current flowing through the power bus (IT) and a predetermined current magnitude (Charge Current Setpoint); and (c) a signal that indicates both of (i) a predetermined proportion of a total amount of current that the power converter system is supplying and, (ii) a magnitude of a peak current flowing through the inductor.

E-beam high voltage switching power supply

Abstract: A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360°/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.

An overall study of the half-bridge complementary-control DC-to-DC converter

Abstract: The half-bridge complementary-control power converter has been recently proposed as a low-output voltage DC-to-DC power converter due to its excellent features (efficiency around 90% at as low an output voltage as 33 volts) A study of the statics and dynamics of this power converter is proposed in this paper Thus, DC voltage conversion ratio both in continuous and discontinuous conduction mode, the boundary between both modes, the DC current level in the transformer and a small-signal average model have all been obtained From the latter, transfer functions between duty cycle and output voltage and between input and output voltages have been also obtained, and some simplifications and design rules have been proposed to facilitate the design of the feedback loop >

New, zero voltage switching, high frequency boost converter topology for power factor correction

Abstract: This paper introduces a technique for combining zero-voltage-switching with boost converter technology to enable high frequency, high efficiency operation of the converter. The combination creates a new topology which is effective to meet the power factor correction and harmonic reduction requirements of new EMC standards. The unique topology provides limitation of the recovery current of the boost diode and uses the energy recovered from the reverse current to discharge the intrinsic and stray capacitance of the boost switch while transferring this recovered energy to the output. With the main switching losses removed, the frequency can be increased to reduce the size of the boost inductor while maintaining continuous conduction mode operation for improved input noise filtering.

DC operated electronic ballast for fluorescent light

Abstract: A device for operating lamps, such as fluorescent lamps includes an input protection circuit, a filter, a DC to DC converter, a power output stage, a lamp connecting circuit and a control circuit. The control circuit includes a pulse width modulator, a multivibrator and a start/stop controller. The pulse width modulator varies the duty cycle of a control signal supplied to the DC to DC converter based on a feedback signal from the DC to DC converter. The multivibrator assists in the control of the DC to DC converter. The start/stop controller initiates the operation of the power output stage when an output of the DC to DC converter reaches a predetermined level and halts the operation of the power output stage if a failure is detected.

Transient voltage protection circuit for electrical power converters

Abstract: A transient over-voltage protection circuit includes a normally closed switch connected between a rectifier circuit and a DC to DC converter. This switch is caused to partially open when the voltage input to the DC to DC converter exceeds a predetermined value, thereby protecting the DC to DC converter from input voltages that exceed the converter's operational limits. The switch is returned to its normally closed state when the level of voltage input to the converter drops below a predetermined lower value. A capacitor connected across the input terminals of the converter is charged up when the switch is closed and functions to supply power to the DC to DC converter when the switch is in its partially opened or current limit state.

A three-switch high-voltage converter

Abstract: A novel three-switch HV converter derived from the Cuk converter is presented. This converter can operate into a capacitor-diode voltage multiplier, which offers simpler structure and control, higher efficiency, reduced EMI, size and weight savings than traditional switched-mode regulated voltage multipliers. Two significant advantages are the continuous input current and easy isolation extension. The new converter is experimentally verified. Both the steady state and dynamic theoretical models are correlated well with the experimental data. >

Small-signal modeling of soft-switched asymmetrical half-bridge DC/DC converter

Abstract: A small-signal model of soft-switched asymmetrical half-bridge DC/DC converter operating in a continuous inductor conduction mode is proposed. The analysis of this model is applicable to converters with any type of output rectifier (full-wave or half-wave). Based on the proposed model, the feedback compensation network for a prototype converter was designed. An open loop frequency response and voltage ripple attenuation of the converter with closed feedback loop were calculated. The experimental results validated all theoretical predictions. >

Series compensator inserting real and reactive impedance into electric power system for damping power oscillations

Abstract: A series compensator (11) for damping power oscillations in an electric power transmission system (1) includes a switching power converter (13) which injects a voltage into the transmission line (5) having a phase angle relative to transmission line current which is controlled to provide reactive compensation and to inject virtual real impedance into the line. The switching power converter (13) is a dc to ac converter which is capable of injecting virtual real impedance into the transmission line by virtue of the fact that it has a power exchange device (27) connected to its dc terminals (29). Where the power exchange device (27') is a resistor (37), the switching power converter (13) is capable of absorbing real power during surges in power on the line (5). Alternatively, the power exchange device (27) is a storage device (31) such as a battery bank or a super conducting magnet, in which case the switching power converter (13) can provide both virtual positive and negative real impedance.

Switch mode power converter and method

Abstract: A switch mode power converter (10) is provided. Converter (10) includes a switching cell (12) that transforms an input voltage at input port (22) to an output voltage at output port (24). Switching cell (12) is controlled by a fixed-period, variable on-time control signal from summing comparator (14). The period of the control signal is set by a driving circuit (20). The on time is set by first and second feedback circuits (16) and (18). First feedback circuit (16) provides a fast transient response. Second feedback circuit (18) provides an stable dc steady-state operating point.

Solar power supply unit for battery operated devices

Abstract: This invention uses low levels of light energy as found within dwellings, or other enclosed but lit spaces, to power a device such as a smoke alarm in place of conventional replaceable batteries. Light incident upon a solar cell array (2) attached to a smoke alarm or other battery powered device is collected and converted to a voltage which is multiplied by the action of one or more DC-DC converter circuits (3, 4 and/or 5) to give rise to a resulting output voltage (6). This voltage is applied via resistor (7) and series device (8) to a rechargeable cell or cells (10) and is limited to a maximum voltage by zener diode (9). If desired, a DC-DC converter can be added at the output of the cell (10) in addition to or in place of the DC-DC converter connected to the solar cell. The converter or converters, the regulating circuits and the cell (10) are all housed in a container which is the same size and shape as a conventional dry cell.

Control of power factor correcting boost converter without instantaneous measurement of input current

Abstract: This paper proposes a new control method for the constant-frequency control of power factor correcting boost power converter using a sinewave template modulated PWM signal which eliminates the need for instantaneous measurement of the line current for the switching control of the boost converter. The control strategy is based on the notion that the line current can be forced to trace a deterministic waveform such as a sinusoid by considering the implicit model of the sinewave in the boost converter controller structure. The modulating sinewave template is generated using the line voltage, the boost converter output voltage and the load current. The paper provides the analysis and the design of the controller and presents simulation and implementation results to demonstrate its effectiveness. >

Externally dimmable electronic ballast

Abstract: An electronic ballast includes a converter coupled to a variable frequency inverter and a series resonant, parallel loaded output coupled to the inverter. The frequency of the inverter increases when the supply voltage from the converter decreases. The converter includes a full wave rectifier (17) producing a first voltage and an unregulated boost circuit (Q1, Q2) producing a second voltage which is combined with the first voltage to produce the supply voltage. The amount of boost, and therefore the magnitude of the supply voltage, is varied to provide dimming. Dimming is controlled mechanically, via a potentiometer (126), or electrically, via a control input (132). Dimming also occurs in response to changes in the first voltage, i.e. from changes in the voltage on an AC power line or from changes in the voltage provided by a capacitive dimmer coupled between the ballast and an AC power line.

Circuit and method for achieving zero ripple current in the output of a converter

Abstract: A power converter and a method of operating a power converter. The power converter includes: (1) a transformer for receiving bipolar electrical input power from a power source, the power substantially free of dead time and (2) a hybridge rectifier coupled to the transformer and including first and second output inductors of independently selectable, differing inductance, the hybridge rectifier receiving the input power from the transformer and rectifying the input power to produce an output power substantially free of ripple current at a predetermined duty cycle operating point of the converter, the first and second output inductors being of independently selectable, differing inductance thereby to allow the predetermined duty cycle operating point to be adjustable.

Non-contact type electric power transmission device

Abstract: PROBLEM TO BE SOLVED: To reduce favorably the inductance value of a resonance means, by reducing the voltage of a rectification power through a DC/DC converter to feed it to the resonance means. SOLUTION: When feeding, e.g. a commercial power with signal-phase AC 100V from a commercial power supply 6 to a non-contract type electric power transmission device 1, rectifying this power by a rectification means comprising a diode D1 and a capacitor C1 to reduce its voltage to a predetermined one by a DC/DC converter 3, the reduced voltage is smoothed by a smoothing means comprising a capacitor C2 to be fed both to a resonance means comprising an inductor L1 and a capacitor C3 and to an oscillator 4. Thereby, from the oscillator 4, a pulse signal with a predetermined frequency is fed to the gate of a field effect transistor FET1 to switch on/off the FET1 at the predetermined frequency. Therefore, since the loss of the FET1 by switching is reduced, the switching frequency can be made high enough. As a result, the inductance value of the inductor L1 can be enough reduced. COPYRIGHT: (C)1997,JPO

High power factor electronic ballast based on a single power processing stage

Abstract: A new low cost high power factor electronic ballast is introduced in this paper. The proposed topology is based on a single power processing stage to provide high frequency voltage to fluorescent lamps and high power factor to the utility line. The power processing stage is formed by a half-bridge converter operating above the resonant frequency to provide zero voltage switching. The self-oscillating technique is employed, which increases the converter reliability with great simplicity and low cost. High power factor is achieved by using a nonconventional AC/DC boost converter operating in discontinuous current mode. Theoretical analysis and experimental results have been obtained for two 40 W fluorescent lamps operating at 50 kHz switching frequency and 127 V line voltage. >

Lightweight, compact, on-board, electric vehicle battery charger

Abstract: An onboard electric vehicle charger is provided which incorporates a forward converter with dynamic balancing of the primary drive currents of its ferrite core transformer to produce 5,000 watt charging power with a power density of 333 watts per kilogram and full safety isolation between the input power source and the batteries plus small size (approximately 15" by 9" by 6") and weight (less than 15 kilograms) and a power factor correcting boost preregulator with dynamic adjustment of its compensation networks which produces full correction to substantially unity (99.9+%) for power factor with current total haromonic distortion (THD) of 2% to 3% over the entire power range of 100 watts to 5,000 watts. The same boost preregulator circuit allows operation from power sources of 95 to 145 VAC or 200 to 275 VAC. The combination of the boost converter, (boost preregulator) and forward converters with the invention's control scheme enables constant throughput (in watts) during each step of the charging process and a constant pulse width modulation (PWM) duty cycle near maximum at all power levels by varying the output voltage of the boost preregulator in direct relation to the power level. A second forward converter, using the same dynamic balancing of primary currents utilized in the main forward converter described, works with the boost preregulator described to permit integration of a DC to DC converter function with 1 KW (75 A @ 14 VDC) capability plus full safety isolation between the high voltage propulsion batteries and the auxiliary (12 volt) electrical system of the vehicle.