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Showing papers on "Boost converter published in 1996"


Proceedings ArticleDOI
06 Oct 1996
TL;DR: In this paper, the authors proposed a novel power control strategy for a PWM converter with no power-source voltage sensors, which has two main features to improve a total power factor and efficiency.
Abstract: This paper proposes a novel control strategy of a pulsewidth modulation (PWM) converter with no power-source voltage sensors. The strategy has two main features to improve a total power factor and efficiency, taking harmonic components into account without detecting the voltage waveforms. One feature is a direct instantaneous power control technique for the converter, which has been developed to control the instantaneous active and reactive power directly by selecting the optimum switching state of the converter. The other feature is an estimation technique of the power-source voltages, which can be performed by calculating the active and reactive power for each switching state of the converter from the line currents. A digital-signal-processor-based experimental system was developed, and experimental tests were conducted to examine the controllability. As a result, it was confirmed that the total power factor and efficiency were more than 97% and 93% over the load power range from 200 to 1400 W, respectively. These results have proven the excellent performance of the proposed system.

847 citations


Patent
28 May 1996
TL;DR: In this article, a load leveling scheme for load leveling of a battery in an electrical power system includes a power regulator coupled to transfer power between a load and a DC link, a battery coupled to the DC link through a first DC-to-DC converter and an auxiliary passive energy storage device coupled to a DC-link through a second DC toDC converter.
Abstract: A method and apparatus for load leveling of a battery in an electrical power system includes a power regulator coupled to transfer power between a load and a DC link, a battery coupled to the DC link through a first DC-to-DC converter and an auxiliary passive energy storage device coupled to the DC link through a second DC-to-DC converter. The battery is coupled to the passive energy storage device through a unidirectional conducting device whereby the battery can supply power to the DC link through each of the first and second converters when battery voltage exceeds voltage on the passive storage device. When the load comprises a motor capable of operating in a regenerative mode, the converters are adapted for transferring power to the battery and passive storage device. In this form, resistance can be coupled in circuit with the second DC-to-DC converter to dissipate excess regenerative power.

230 citations


Proceedings ArticleDOI
R. Watson, Fred C. Lee1
23 Jun 1996
TL;DR: In this paper, a full-bridge, active-clamp boost converter is proposed for single-phase high power PFC applications and applications requiring transformer isolation, which serves to limit bridge switch turn-off voltage overshoot and enable the energy stored in the transformer leakage inductance to be used for zero-voltage switching.
Abstract: A new full-bridge, active-clamp boost converter is proposed for single-phase high power PFC applications and applications requiring transformer isolation. The active-clamp network serves to limit bridge switch turn-off voltage overshoot and enable the energy stored in the transformer leakage inductance to be used for zero-voltage switching. PWM phase-shift control of the bridge switches is utilized to obtain zero-current switching for two of the four bridge switches. Simulation results are presented which verify the principle of operation.

188 citations


Journal ArticleDOI
23 Jun 1996
TL;DR: In this article, a reference modification part is incorporated with the generally used synchronous-frame proportional-integral (PI) controller for the fast transient response for the DC-link regulator.
Abstract: In this paper, a new simple current controller with both satisfactory steady-state characteristics and fast transient response is proposed. In this scheme, a reference modification part is incorporated with the generally used synchronous-frame proportional-integral (PI) controller for the fast transient response. Simulation and experimental results are presented and show the effectiveness of the proposed current controller. In the simulation and experimental results, both the current controller and DC-link regulator show conspicuous performance improvement. It is also observed in the simulation and experiment that the proposed current controller has a similar characteristic as the synchronous-frame PI controller in the steady state and as the minimum-time current controller in the transient state.

142 citations


Patent
03 Jun 1996
TL;DR: In this article, a bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels.
Abstract: A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

141 citations


Proceedings ArticleDOI
M.S. Elmore1
03 Mar 1996
TL;DR: In high power factor AC-to-DC applications, boost power converters operating on the boundary of continuous mode and discontinuous mode switch with variable frequency and draw high peak input currents.
Abstract: In high power factor AC-to-DC applications, boost power converters operating on the boundary of continuous mode and discontinuous mode switch with variable frequency and draw high peak input currents. A method is presented to parallel two or more of these power converters to reduce the high peak input currents. Each power converter continues to operate on the boundary of continuous mode and discontinuous mode and maintains the benefits of zero-voltage switching.

125 citations


Proceedings ArticleDOI
12 May 1996
TL;DR: In this article, a steady-state analysis of a step-up DC-DC switched-capacitor power converter is performed and trade-offs between the efficiency requirement and good regulation capability are discussed.
Abstract: A comprehensive and accurate steady-state analysis of a step-up DC-DC switched-capacitor power converter is performed. No approximations, such as average techniques, are invoked. Parasitic elements such as diode forward voltages, on-resistances of transistors and equivalent-series resistances of capacitors are included into the model. The converter performance functions, i.e. DC voltage ratio, efficiency, output voltage ripple, are expressed in terms of the number of switched-capacitor stages, number of capacitors per stage, values of the capacitors and parasitic elements, switching frequency and load. Design criteria aiming at high efficiency, low ripple and achievable output voltage are formulated. Trade-offs between the efficiency requirement and good regulation capability are discussed.

123 citations


Proceedings ArticleDOI
06 Oct 1996
TL;DR: In this paper, the authors compared two current-fed push-pull DC-DC power converters: the isolated boost and an alternative topology named as the dual inductor pushpull power converter (DIC).
Abstract: This paper compares two current-fed push-pull DC-DC power converters: the current-fed push-pull power converter or isolated boost and an alternative topology named here as the dual inductor push-pull power converter (DIC). Since this latter converter has just one primary winding, the voltage across the main switches is reduced to the half of that in the isolated boost topology; the average current in the input inductors is also halved and the RMS current in the output capacitor is smaller. The overall efficiency is increased and the power converter's volume is reduced in the DIC converter. These and other improved design characteristics make this alternative topology more attractive than the isolated boost for equivalent applications. Analytical equations, output characteristic curves and computer simulations of both power converters are compared. An experimental breadboard of 480 W power has been assembled in order to verify the performance of the DIC power converter. The main results are provided.

122 citations


Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the feasibility of using chaos to depress the spectral peaks of the interference from a switched mode power supply and show that the spectrum of the input current is spread, its peaks are reduced and EMC is improved compared to the case when the circuit is operating periodically.
Abstract: The authors demonstrate the feasibility of using chaos to depress the spectral peaks of the interference from a switched mode power supply. A boost converter is used to show experimentally that the spectrum of the input current is spread, its peaks are reduced and EMC is improved, compared to the case when the circuit is operating periodically.

119 citations


Journal ArticleDOI
01 Jul 1996
TL;DR: In this article, the authors proposed a new topology for pulse-width modulated (PWM) AC choppers for single-phase and three-phase systems for buck, boost and buck-boost types.
Abstract: Novel topologies of pulse-width modulated (PWM) AC choppers for single-phase and three-phase systems are proposed for buck, boost and buck-boost types. A PWM AC chopper has important advantages compared with the phase-controlled AC controller using thyristors. The AC chopper has sinusoidal current waveforms, better power factor, faster dynamics, and smaller input/output filter. In an improved topology for AC choppers, an RC bypass snubber is used for minimising high-voltage spikes during the dead time in the gating signals of complementary switches. In the proposed topologies the commutation problem causing high-voltage spikes is resolved by intelligent gate-switching patterns using information from the input/output voltage. These switching patterns provide a current path for all operation modes without any RC bypass snubbers. Since RC bypass snubbers causing power loss are eliminated, the efficiency of the chopper is increased. Thus, advantages of the proposed topologies include increased power factor, low harmonic input current, fast dynamics, high efficiency, high reliability, high power capacity, and small size of the passive filter. The paper describes the operational principle and analysis of the proposed topologies. Experimental results show that the proposed topologies give good performance for AC choppers.

117 citations


Patent
Hwan-Ho Seong1
26 Dec 1996
TL;DR: In this article, a power factor correction circuit with a boost converter and a sense-FET was proposed, which enables an external pin count to be reduced by having a builtin boost converter controller and a built-in sense-fET in a single package.
Abstract: A power factor correction circuit includes a boost converter, a zero-current detector for detecting a period in which an inductor current is zero, a half-wave rectifier for supplying a power voltage proportional to an output voltage of the boost converter, a control voltage generator for generating a control voltage to control the turn-on time timing of a sense-FET, a turn-on controller for making constant a turn-on duration of the sense-FET, an over current detector for generating a signal when a mirror terminal current of the sense-FET is greater than a predetermined current, an OR gate for performing a logic OR operation of the output signals of the turn-on controller and the over current detector, an output current controller for generating a gate drive signal of the sense-FET, and an under voltage lock out for turning off the power voltage when the power voltage is less than a predetermined voltage. This circuit enables an external pin count to be reduced by having a built-in boost converter controller and a built-in sense-FET in a single package.

Patent
06 Nov 1996
TL;DR: In this paper, a controlled inductor with a magnetic core having one or more power windings and a control winding wound on the core is used to change the capacitor impedance and thus influence the converter output.
Abstract: An LC resonant circuit for a resonant converter includes a resonant capacitor and an inductor coupled to a fixed frequency AC supply. A controlled inductor in parallel with the resonant capacitor is controlled by a DC current to vary its inductance. The controlled inductor comprises a magnetic core having one or more power windings, and a control winding wound on the core. The DC current in the control winding produces core flux which effects core permeability. The controlled inductor has the effect of changing the capacitor impedance and thus influences the converter output. Multiple, independently controlled and regulated outputs may be driven by one power switching stage.

Patent
11 Dec 1996
TL;DR: In this article, a voltage related to the input voltage is compared to a periodic waveform for forming a switch control signal, which is controlled in an open loop, rather than in a closed loop.
Abstract: A controlled output voltage is provided for a switching mode power converter operating in the continuous conduction mode without requiring a feedback path coupled to monitor the output voltage. Instead, a voltage related to the input voltage is monitored. The monitored voltage is compared to a periodic waveform for forming a switch control signal. In the case of a buck converter operating as a voltage regulator, over each period of the periodic waveform, the periodic waveform is representative of the inverse function. In the case of a boost converter operating as a voltage regulator or buck converter operating as a bus terminator or power amplifier, over each period of the periodic waveform, the periodic waveform has a linear slope. The switch control signal controls a duty cycle of the power switches. Therefore, switching is controlled in an open loop, rather than in a closed loop. By monitoring a voltage related to the input voltage, rather than the output voltage, an integrated circuit for controlling the buck converter or boost converter requires few pins and can sink or source current.

Patent
30 Jul 1996
TL;DR: In this article, the switch controller is always energized with a sufficient level of the power supply regardless of the residual storage of the low-voltage battery 5, regardless of a low voltage from the battery.
Abstract: A backup power supply 11 is not loaded by peripheral equipment 9 and a low-voltage battery 5. A switch controller 12 is energized by any of the backup power supply 11, the DC/DC converter 7, and the low-voltage battery 5 for controlling the energization of a relay 3L. When the power supply from the DC/DC converter 7 and the low-voltage battery 5 to the switch controller 12 is declined, it is complemented by the backup power of a low voltage from the backup power supply 11. Accordingly, the switch controller 12 is always energized with a sufficient level of the power supply regardless of the residual storage of the low-voltage battery 5.

Journal ArticleDOI
23 Jun 1996
TL;DR: The proposed zero-voltage-switched pulsewidth-modulated boost converter with an energy feedforward auxiliary circuit is found to be about 2%-3% more efficient than the conventional PWM boost converter.
Abstract: A zero-voltage-switched (ZVS) pulsewidth-modulated (PWM) boost converter with an energy feedforward auxiliary circuit is proposed in this paper. The auxiliary circuit, which is a resonant circuit consisting of a switch and passive components, ensures that the converter's main switch and boost diode operate with soft switching. This converter can function with PWM control because the auxiliary resonant circuit operates for a small fraction of the switching cycle. Since the auxiliary circuit is a resonant circuit, the auxiliary switch itself has both a soft turn on and turn off, resulting in reduced switching losses and electromagnetic interference (EMI). This is unlike other proposed ZVS boost converters with auxiliary circuits where the auxiliary switch has a hard turn off. Peak switch stresses are only slightly higher than those found in a conventional PWM boost converter because part of the energy that would otherwise circulate in the auxiliary circuit and drastically increase peak switch stresses is fed to the load. In this paper, the operation of the converter is explained and analyzed, design guidelines are given, and experimental results obtained from a prototype are presented. The proposed converter is found to be about 2%-3% more efficient than the conventional PWM boost converter.

Patent
12 Apr 1996
TL;DR: In this article, a DC-to-DC converter topology is provided having switching devices that are switched under zero voltage switching conditions to minimize switching losses, which can be achieved over a wide load range by properly sizing the coupled inductors.
Abstract: A DC-to-DC converter topology is provided having switching devices that are switched under zero voltage switching conditions to minimize switching losses. The converter of the present invention includes two input side converter bridges, each based on a two switch forward converter topology. The input side converter bridges may be connected in series for high input voltage levels and in parallel for low voltage levels. The switching devices of each input side converter bridge are coupled together by coupling inductors. The turning-off of a switching device in one bridge causes part of the energy stored in the corresponding coupled inductor to discharge an output capacitance of an incoming switching device in the other bridge, causing an anti-parallel connected diode to conduct. The incoming switch can thus be turned on under zero voltage switching conditions. Zero voltage switching can be achieved over a wide load range by properly sizing the coupled inductors. The converter switching devices are preferably provided switching signals from a peak current control controller that controls the duty cycle of the converter to regulate the peak of the output currents to control the output power delivered to a load.

Patent
Rui Liu1, Wen-Jian Gu1
25 Jan 1996
TL;DR: In this article, a high frequency AC/AC converter with power factor correction is described, where a single control circuit controls both parts of the converter apparatus by controlling the switching of the first and second semiconductor switching devices.
Abstract: A high frequency AC/AC converter apparatus with power factor correction includes an AC/DC converter circuit part to provide power factor correction and a DC/AC inverter circuit part to produce a high frequency AC signal for operation of a load, for example, a discharge lamp. The AC/DC converter circuit part includes a diode and an inductor. The converter apparatus utilizes first and second semiconductor controlled switching devices, one of which is common to each part of the overall converter apparatus. A single control circuit controls both parts of the converter apparatus by controlling the switching of the first and second semiconductor switching devices. There are two possible control techniques, constant duty ratio control or duty ratio sweeping control. A voltage clamp circuit inhibits undesired oscillation of the diode voltage.

Journal ArticleDOI
Kwok-Wai Ma1, Yim-Shu Lee1
TL;DR: In this article, an integrated flyback power converter performing the combined functions of uninterruptible power supply (UPS) and switch-mode power supply is presented, which has a high voltage main power input and a low voltage backup battery input.
Abstract: An integrated flyback power converter performing the combined functions of uninterruptible power supply (UPS) and switch-mode power supply (SMPS) is presented. This power converter has a high voltage main power input and a low voltage backup battery input. DC output is obtained from the main input via a flyback power converter during normal operation and from the backup battery via another flyback power converter when input power fails. High conversion efficiency is achieved in normal, backup, and charging modes as there is only a single DC-DC conversion in each mode. The power converter circuit is very simple, with two switching transistors, a relay for mode switching, and a single magnetic structure only. This new design offers substantial improvement in efficiency, size, and cost over the conventional cascade of UPS and SMPS due to single voltage conversion, high frequency switching, and removal of design redundancy. The operation, design, analysis, and experimental results of the power converter are presented.

Patent
28 May 1996
TL;DR: In this paper, a high-power, switched-mode power conversion array having an input capacitance, an output capacitance and a multiple, reconfigurable converter cells is presented.
Abstract: A high-power, switched-mode power conversion array having an input capacitance, an output capacitance, and a multiple, reconfigurable converter cells. Each of the converter cells convert an input voltage to an output voltage using switched-mode power conversion. The converter cells operate at a conversion frequency and are phase-shifted across one conversion period, so that each converter is switched ON in a time-overlapping relationship with at least one other one of the plurality of converters. As a result, the input and output current and the voltage ripple are substantially reduced, the ripple frequency of the array is increased, and the power capacity is increased. The converter cells can have a selectable conversion frequency, and thus, a selectable period. The apparatus also can include a programmable interconnection network selectably and reconfigurably connecting each cell to at least one other cell, an input node, or an output node, using serial or parallel connections. The programmable interconnection network can consist of an interconnection switch array, that include programmable elements. Selected programmable elements are connected with respective ones of the plurality of converter cells. The array can be dynamically-adaptive and be reconfigured to adapt to the preselected criterion on-the-fly. The array can also be a thin-profile array having an array aspect ratio of greater than 30.

Patent
18 Mar 1996
TL;DR: In this paper, a customer side power management system includes a power transducer coupled to the electric lines from the utility (L1, L2, L3, AND N), and provides an output signal proportional thereto.
Abstract: A customer side power management system includes a power transducer (10) coupled to the electric lines (12) from the utility (L1, L2, L3, AND N). The power transducer (10) senses stochastic peak power demands from the electric utility (L1, L2, L3, AND N), and provides an output signal proportional thereto. The output signal is time averaged (14) and provided to a comparator circuit (21). A predetermined threshold signal (28 OR 32) is also provided to the comparator circuit (21), and the two signals are compared. An AC-to-DC converter (38) or power supply is coupled to the utility's electric line (L1, L2, L3, AND N) and provides a DC voltage on its ouput. The amplitude of the DC voltage is controlled by the output signal from the comparator circuit (21). A power isolation and ditribution circuit (48) and a storage battery (34) are also included. The power isolation and distribution circuit is connected between the AC-to-DC converter (38) and the storage battery (34). The power management system senses peak power demands for electricity, and switches a particular load (46) of the customer from being powered by the AC-to-DC converter (38) to the storage battery (34). When there is no peak power demand, the AC-to-DC converter (38) powers the particular load (46).

Proceedings ArticleDOI
12 May 1996
TL;DR: In this article, a DC-to-DC converter is proposed by using dual basic quasi-switched-capacitor (QSC) converter cells, which can reduce the electromagnetic interference due to conducted emissions as compared to the classical PWM type and SC-based converters.
Abstract: A new type of DC-to-DC converter is proposed by using dual basic quasi-switched-capacitor (QSC) converter cells. The prominent feature of this converter is its improved input current waveform, which can reduce the electromagnetic interference due to the conducted emissions as compared to the classical PWM-type and SC-based converters. The concept of energy transfer is realized by two symmetrical converter cells, operating in two cyclical phases. The d.c. voltage conversion ratio is determined by the voltage applied to the quasi-switch in each cell for controlling the charging trajectory of the capacitors in order to maintain a constant output voltage for a wide range of load and supply voltage. As the converter does not contain any inductive element, it makes the converter of small size, light weight, high power density and possible in IC form. The small-signal frequency response shows that the designed converter has good operation stability. A prototype of 36 W, 12 V/9 V, step-down DC-to-DC converter has been built, giving an overall efficiency of 73% with power density of 20 W/in/sup 3/.

Journal ArticleDOI
TL;DR: In this article, a technique for shaping the input current to a three-phase diode rectifier using a two-switch series-connected dual boost converter and a threephase bidirectional switch circuit is described.
Abstract: This paper describes a technique for shaping the input current to a three-phase diode rectifier using a two-switch series-connected dual boost converter and a three-phase bidirectional switch circuit. Circuits are described for generating a single voltage DC output, "single DC-rail", or a dual output DC voltage using center-tapped capacitors, "split DC-rail". Both rectifier types can be operated with the boost inductors located either on the DC or the AC side of the rectifier. The resultant rectifier circuit configurations have an excellent immunity to the "shoot-through" fault condition and use active switching elements with low per-unit current ratings and low switching losses. These features increase the reliability factor and lower the cost penalty associated with unity fundamental power factor three-phase rectifiers. Test results are presented for the rectifiers using simulation and experimental results.

Patent
03 Jul 1996
TL;DR: In this article, the authors proposed a boost converter for operating an array of light emitting diodes such as in an emergency exit sign in a non-emergency AC mode while concurrently charging and maintaining the charge of a low-voltage battery used to drive the array.
Abstract: Circuitry for operating an array of light emitting diodes such as in an emergency exit sign in a non-emergency AC mode while concurrently charging and maintaining the charge of a low-voltage battery used to drive the array in an emergency mode, the circuitry also allows operation of the same LED array in the emergency mode from the low-voltage battery. The advantages of the invention are realized in part through provision within the circuitry of a boost converter wherein the LED array and the battery are connected across the output of the usual boost circuit output capacitor, thereby allowing connection of the array and the battery in series to simplify operation from line power and to allow the same current limited source to operate the array and simultaneously charge the battery through the same current path. The functions so provided can be embodied in a form which allows all circuitry components including the battery to be mounted on a single, compact substrate such as a printed circuit board.

Proceedings ArticleDOI
11 Aug 1996
TL;DR: In this article, a series connected boost unit (SCBU) is proposed for low Earth orbit (LEO) satellite power management and distribution, which can help transition the aerospace industry towards an assembly line approach to building spacecraft.
Abstract: Current trends in satellite design are focused on developing small, reliable, and inexpensive spacecraft. To that end, a modular power management and distribution system is proposed which will help transition the aerospace industry towards an assembly line approach to building spacecraft. The modular system is based on an innovative DC voltage boost converter called the series connected boost unit (SCBU). The SCBU uses any isolating DC-DC power converter and adds a unique series connection. This simple modification provides the SCBU topology with many advantages over existing boost power converters. Efficiencies of 94-98%, power densities above 1,000 W/kg and inherent fault tolerance are just a few of the characteristics presented. Limitations of the SCBU technology are presented and it is shown that the SCBU makes an ideal photovoltaic array regulator. A set of photovoltaic power system requirements are presented that can be applied to almost any low Earth orbit satellite. Finally, a modular design based on the series connected boost unit is outlined and functional descriptions of the components are given.

Proceedings ArticleDOI
11 Aug 1996
TL;DR: This paper uses the boost converter as an example to show the details involved in deriving some novel averaged models and uses simplifications to highlight the accuracy of the models even when traditional small-ripple conditions are not satisfied.
Abstract: This paper presents some of the issues involved in applying frequency-selective averaging to modeling the dynamic behavior of PWM DC-DC converters. We use the boost converter as an example to show the details involved in deriving some novel averaged models and use simplifications to highlight the accuracy of the models even when traditional small-ripple conditions are not satisfied.

Patent
Hwan-Ho Seong1, Su-Gyeong Kim1
15 Nov 1996
TL;DR: In this article, an active power factor correction integrated circuit for a boost converter, comprising a bias voltage generator coupled to an external power source through a first pin, for generating internal bias voltages used for the integrated circuit, was presented.
Abstract: Disclosed is an active power factor correction integrated circuit for a boost converter, comprising a bias voltage generator coupled to an external power source through a first pin, for generating internal bias voltages used for the integrated circuit; a zero crossing detector coupled magnetically to the inductor through a second pin, for detecting a time at which a voltage across the inductor is zero to provide a zero crossing detection signal; an oscillator reset by the zero crossing detection signal for generating a pulse signal; a flip-flop for generating a first control signal in response to the zero crossing detection signal or the pulse signal; a switching element responsive to the first control signal for enabling a boosted voltage to be provided to the load; an over-current detector for generating an over-current signal when a current flowing through the switching element is over a predetermined value; and a voltage variation detector for detecting variation of a load voltage to generate a variation detection signal and generating a second control signal enabling the boosted voltage to flow through the switching element to a ground in response to both the variation detection signal and the over-current signal With the integrated circuit, the number of the IC pin and the number of the peripheral components thereof may be considerably reduced

Journal ArticleDOI
TL;DR: Using the new configuration, sinusoidal line current in phase with the bus voltage is achieved, thanks to a new and simple to implement control strategy via a cascade buck-boost power converter.
Abstract: This work presents a detailed theoretical analysis and experimental results of a novel means of obtaining sinusoidal input current and unity power factor (UPF) via a cascade buck-boost power converter. Using the new configuration, sinusoidal line current in phase with the bus voltage is achieved, thanks to a new and simple to implement control strategy. Comparison between the input and output voltages is used to select the instantaneous operating mode of the converter. Offline references are calculated and stored in two EPROM circuits and then compared to measured currents to generate the gating signals of the appropriate switches. Complete theoretical analysis, simulation results and experimental data on a 500 W power converter are presented, to demonstrate the superiority of the new control strategy. Low order harmonics in the input current are eliminated and the input power factor is found to be over 0.99.

Patent
19 Dec 1996
TL;DR: In this article, a boost power converter for powering a load with an AC source is described, which consists of an AC to DC conversion circuit, a resonator, and a boost circuit.
Abstract: A boost power converter for powering a load with an AC source is disclosed. The boost power converter comprises an AC to DC conversion circuit, a resonator, and a boost circuit. The resonator includes an energy storage device and a resonant circuit, and alternately applies energy from the energy storage device to the resonant circuit for powering the load. The AC to DC conversion circuit generates a DC signal in response to the AC source. The boost circuit includes a choke for receiving the DC signal, a rectifier for electrically coupling the choke to the energy storage device, and a switching device for selectively coupling the choke to the resonant circuit for charging and discharging the choke. The resonator operates in full resonant mode with zero voltage switching. The boost power converter is well-suited for ballast applications that drive a fluorescent lamp.

Patent
27 Jun 1996
TL;DR: In this paper, the authors propose a circuit for extending the sustain time of a DC converter power supply in the event of interruption of AC power, where in the circuit includes a capacitor storage element, an associated charge path for controllably charging the capacitor bank and discharge and disconnect paths for discharging the energy stored in the capacitor to sustain operation of the DC power converter and for disconnecting the capacitor from the DC converter when the voltage across the capacitor has discharged below a threshold level.
Abstract: Circuitry for extending the sustain time of a DC converter power supply in the event of interruption of AC power. Where in the circuit includes a capacitor storage element, an associated charge path for controllably charging the capacitor bank and discharge and disconnect paths for discharging the energy stored in the capacitor to sustain operation of the DC power converter and for disconnecting the capacitor from the DC converter when the voltage across the capacitor has discharged below a threshold level and prevents the capacitor from creating and introducing periodic ringing transient oscillations into the same charging means, with the charging means and discharging means therefore being connected to said DC voltage source to provide a charging path to said raw DC voltage source during normal operation of the AC power source, and a discharging means to provide a discharging path for said capacitor means to sustain operation of a power converter means during momentary interruption of the AC power source and to disconnect said capacitor means from the DC source means and dc converter means wherein said capacitor means has been discharged to a minimum level required to insure proper operation of said power converter means.

Journal ArticleDOI
TL;DR: In this paper, a versatile AC-AC converter that can be used as a control device for custom power applications is presented, which has the ability to regulate bus voltage through voltage sags and overvoltages and act as a solid state circuit breaker.
Abstract: A versatile AC-AC converter that can be utilized as a control device for custom power applications is presented. The converter has the ability to regulate bus voltage through voltage sags and overvoltages, and act as a solid state circuit breaker. Performance characteristics under typical conditions are presented along with experimental verification of converter operation. Technical feasibility, protected efficiency and other practical implementation issues are discussed. Operation of the power converter is illustrated using EMTP simulations.