Showing papers on "Boost converter published in 1992"

Novel zero-voltage-transition PWM converters

Abstract: A class of zero voltage transition (ZVT) power converters is proposed in which both the transistor and the rectifier operate with zero voltage switching and are subjected to minimum voltage and current stresses. The boost ZVT-PWM converter is used as an example to illustrate the operation of these converters. A 300 kHz, 600 W ZVT-PWM boost, DC-DC converter, and a 100 kHz, 600 W power factor correction circuit using the ZVT-PWM technique and an insulated gate bipolar transistor (IGBT) device were breadboarded to show the operation of the proposed converters. It is shown that the circuit technology greatly improves the converter performance in terms of efficiency, switching noise, and circuit reliability. >

Small-signal analysis of the phase-shifted PWM converter

Abstract: The specific circuit effects in the phase-shifted PWM (PS-PWM) converter and their impact on the converter dynamics are analyzed. The small-signal model is derived incorporating the effects of phase-shift control and the utilization of transformer leakage inductance and power FET junction capacitances to achieve zero-voltage resonant switching. The differences in the dynamic characteristics of the PS-PWM converter and its PWM counterpart are explained. Model predictions are confirmed by experimental measurements. >

Chaos in a current-mode controlled boost DC-DC converter

Abstract: A mapping is derived in closed form, without approximations, for an idealized current-mode controlled boost converter. This circuit is known experimentally to behave chaotically for certain values of the reference current, and to produce subharmonics of the clock frequency at others. Numerical iteration of the mapping indicates chaotic operation and the presence of subharmonics. Two mechanisms of bifurcation are explained. >

A high-power-factor buck converter

Abstract: A high-power-factor buck converter is proposed. The converter is composed of rectifier diodes, a small input capacitor, and a buck converter. It supplies low output voltages and uses low voltage semiconductor devices and ceramic capacitors. Two operation modes exist in the converter: discontinuous and continuous inductor current modes. Analysis and experimentation show that the converter's power factor is over 0.9 in discontinuous mode by constant duty ratio operation. It is clarified that the power factor decreases to about 0.7 in continuous mode by constant duty ratio operation, and it can be improved to over 0.9 by a new input current control system. >

Small-signal modeling of the single-phase boost high power factor converter with constant frequency control

Abstract: A simple and accurate small-signal model for the high-power-factor converter with constant switching frequency is developed and verified. The model is applicable to all frequencies below half the switching frequency. The model is useful in the design and analysis of the voltage and current loops, and of the input and the output impedances of the converter. The use of the model is demonstrated in the analysis and design of a power factor boost converter with average current control. >

Characteristics of load resonant converters operated in a high-power factor mode

Abstract: The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained. >

Optimized modulation techniques for the generalized N-level converter

Abstract: A balancing control strategy that allows the voltage differences among the DC link capacitors of the generalized n-level power converter to be minimized is presented. The case n=3 is treated, but the technique can be generalized to larger n values. The balancing algorithm does not achieve correct voltage sharing of the capacitors under all operating conditions, but it provides a great improvement. This strategy appears to be very promising in single-phase applications, for which nonredundant switching configurations do not affect the capacitor voltage balance. >

Steady-state analysis and design of a switched-capacitor DC-DC converter

Abstract: A switched capacitor DC-DC power converter topology which consists of n stages of semiconductor switches and capacitors is described The switches connect the capacitors across the input source during the charging phase and then across the load during the discharge phase to step down the input voltage by a nominal ratio n Further control of the output voltage is possible via current, resistive, or duty-ratio control Based on the observation that the ripple on the capacitor voltages is generally linear in practice, state-space averaging is used to derive the average state-space equations for a generalized n-stage switched capacitor converter circuit Both exact and approximate equations which are useful for design are derived for the practical performance parameters A design procedure based on these equations is described The analytical results have been verified by extensive simulation by PSPICE >

Pulse width modulated DC/DC converter with reduced ripple current coponent stress and zero voltage switching capability

Abstract: An improved DC to DC converter is provided in particular for converters with high power density requirements. The converter comprises an input voltage source and a capacitor connected in series to the voltage source. A switching transistor configuration connects the voltage source and the capacitor alternatively to the primary windings of a transformer. The secondary windings of the transformer are connected to a full-wave rectifier and a filter. The output voltage provided at the output of the filter is modulated by a controlling means.

Soft-switching full-bridge dc/dc converting

Abstract: The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM full-bridge dc/dc converter substantially reduces the switching losses of the transistors and the rectifier diodes, under all loading conditions. We give analyses, practical design considerations, and experimental results for a 1.5-kW converter with 60-V, 25-A output, operating at 100-kHz clock frequency and 95% efficiency.

Power system for parallel operation of AC/DC converters

Abstract: A plurality of AC/DC converters (11) connected in parallel, are provided in which any one of the power converters can fail with-out affecting the operation of the machine which the plurality of converters are providing power. The failed AC/DC converter can be removed and replaced by another converter without shutting down the system. The output voltage of each converter is sensed on the power supply side of a decoupling diode (17, 19, 21). This allows each one of the converters to operate with its own sense loop (25, 27, 31, 33, 35, 41, 43) and, therefore, the feedback loop does not open when a converter is removed and another used in its place. Via power limit circuit (45) each of the parallel connected AC/DC converters (11) is designed to provide a preset maximum power which is independent of AC line voltage variation. To limit the power, the control voltage is made inversely proportional to the average input AC line voltage. The output voltage of the AC/DC converter is made to vary as a function of the load. This allows all the converters in parallel to provide power to the load all the time.

Steady-state performance of DC motors supplied from photovoltaic generators with step-up converter

Abstract: A simple step-up converter circuit consisting of a single power transistor and an inductor is used as an interface between a PV (photovoltaic) generator and a shunt DC motor driving a centrifugal water pump. The step-up converter allows maximum power output from the PV generator to the motor at all insolation levels. Steady-state performance of the motor is vastly improved as its input voltage and current are stabilized by the regenerative action of the converter. The PV generator operates at maximum power regardless of insolation variations. The converter duty ratio can be set at a fixed optimal value which is valid for all insolation levels. This remarkable property makes this device economically attractive since it is easy to build and does not require any insolation-dependent control as compared to other peak-power tracking devices. >

Polyphase AC/DC converter

Abstract: A power converter for converting input AC power comprising N phase-to-phase input AC waveforms at a first frequency into overall output DC power, where N is an integer greater than two, includes N phase-to-phase AC/DC converters each receiving a phase-to-phase waveform and having outputs connected in series whereby the converter outputs are combined to develop the overall output DC power. The AC/DC converters are operated such that a parameter of the input AC power and a parameter of the overall output DC power are controlled.

On time control and gain circuit

Abstract: A voltage regulating control loop for a boost converter having a gain stabilizing stage is provided. The gain stabilizing stage makes the open-loop AC gain independent of the DC output of the boost converter and of the root mean square value of the 50/60 Hz line input voltage. The gain stabilizing stage generates an error voltage that is proportional to the square root of a voltage that is a function of the DC output current divided by the root mean square value of the 50/60 Hz line voltage. The error voltage is compared to the integrated value of a signal inversely proportional to the error voltage to the on time of the power stage FET.

DC-DC power converter including sensing means for providing an output when the reserve power of the converter falls below a predetermined amount for a given input voltage

Abstract: A DC to DC power converter in the form of a pulse-width modulator is shown which can sense via an indication of duty cycle how much reserve power is available for loads using the present input voltage. The device is for use at the end of a telephone line where the input voltage power supply impedance can be appreciable. When the reserve power, as detected in the power converter, reaches a minimum critical level, a signal is sent out requesting the voltage supply to increase the available voltage to the power converter.

Development of power electronics converters based on switched-capacitor circuits

Abstract: A new DC-to-DC converter is proposed that uses only switched capacitors. The energy conversion is based on controlled cyclical switching between two phases. The DC gain can be fixed by choosing an appropriate steady-state value of the duty ratio. The output voltage can be kept constant over a large range of loads. The output voltage ripple was less than 5% for most of the load range interval. By avoiding the use of magnetic elements, a small-size and lightweight converter can be built. The circuit is analyzed by using the state-space averaging method. The theoretical results have been confirmed by experimental data. >

Tapped inductor slave regulating circuit

Abstract: A tapped inductor slave regulating circuit provides a second slave output voltage derived from a tapped connection to the filter storage inductor of a first output voltage of a switching power supply converter. In the converter, an unregulated voltage is provided through a switching circuit to a storage inductor to develop a first output. The switching circuit is turned off and a synchronous rectifier is turned on to freewheel the current through the storage inductor and the load. The storage inductor is center-tapped and coupled to a switching circuit to provide a second slaved output. The location of the center tap is chosen to provide the proper voltage of the second output. In one embodiment, the switching circuit for the slaved output is turned on during the freewheel portion of each cycle to provide a proper voltage level for the second output. In another embodiment, a separate local feedback circuit is provided to further regulate the second output voltage level.

Optimal feed-forward compensation for PWM DC/DC converters with 'linear' and 'quadratic' conversion ratio

Abstract: An analytical procedure to optimize the feedforward compensation for any PWM DC/DC power converters is described. Achieving zero DC audiosusceptibility was found to be possible for the buck, buck-boost, Cuk, and SEPIC cells; for the boost converter, however, only nonoptimal compensation is feasible. Rules for the design of PWM controllers and procedures for the evaluation of the hardware-introduced errors are discussed. A PWM controller implementing the optimal feedforward compensation for buck-boost, Cuk, and SEPIC cells is described and fully experimentally characterized. >

A unity power factor forward converter

Abstract: A novel means of obtaining sinusoidal, unity power factor input currents in switched mode power supplies using minimum additional components is presented. The converter is topologically equivalent to a boost converter cascaded by a forward power converter, but is realized using only a single power stage. A detailed analysis of the operation is presented. A constant frequency current mode control provides excellent transient performance at the output and sinusoidal input currents at the input. Various tradeoffs involved in the design of the converter elements and control parameters are discussed in depth. All the results are backed up by experimental waveforms from a laboratory converter. >

PWM control and input characteristics of three-phase multi-level AC/DC converter

Abstract: The authors discuss the current control and pulse width modulation (PWM) pattern generation of a multilevel power converter which is capable of producing three levels of phase voltage. In the proposed current control, fast response is realized by introducing a converter model in the control algorithm and the effect of parameter difference between the model and an actual system is compensated for through proportional-plus-integral control of current difference. In PWM pattern generation, the balance of two capacitor voltages is taken into account. For the same sampling period, the current distortion factor of the proposed system can be approximately reduced to 60% of that of a conventional two-level power converter. The prototype was made using a digital signal processor, and simulation and experimental results were compared. >

Harmonic noise isolation and power factor correction network

Abstract: A network for connection between an AC power line and a DC power supply to isolate harmonic currents generated by the DC power supply from the AC power supply, the network employing at least one "resonator", which is connected across the input of a DC power supply, and at least one "reflector", which is connected to couple the input of the DC power supply to an AC power line. Each "resonator," includes the series combination of an inductor and a capacitor. At least some of the "reflectors" include the parallel combination of an inductor and a capacitor.

Power converter with plural regulated outputs

Abstract: A power converter comprises a power stage including a transformer, a pulse width modulator (PWM) for controlling the power stage, multiple output circuits providing individually regulated voltages, including switches for coupling the output circuits sequentially and cyclically to the power stage, and feedback circuitry for supplying respective feedback signals, each for a respective output circuit, as a control signal to the PWM synchronously with the coupling of the output circuits to the power stage, so that a single PWM and power stage serve for multiple output circuits. The converter can be a dc to dc converter or a four-quadrant switching amplifier. The PWM operates in current mode in conjunction with a current sensing resistor or transformer.

Combination static/dynamic inverter

Abstract: A power converter provides an AC output selectively using power from either a battery source or an alternator. The power converter includes a static converter (100) that is connected to receive DC from a battery (30), converting the DC to a relatively high frequency AC using a pulse width modulator (200). The high frequency AC is transformed to a higher voltage AC that is rectified and is used to charge a capacitor bank (104). The DC on the capacitor bank is converted to 120 (or 240) volts AC at 50/60 Hz by an inverter comprising an inverter (106) to provide power for an AC load. As the requirement for power by the AC load increases above a predefined level, a dynamic converter (24a) is energized to supply power to charge the capacitor bank in place of the static converter. The dynamic converter draws its power from a three-phase alternator (12) that includes three-phase AC output terminals connected to three-phase primary windings (140) of a transformer having a plurality of secondary windings. Secondary windings (168) produce a substantially higher voltage than the voltage from the alternator, and their output signal is rectified to charge the capacitor bank. The battery is charged with current supplied (after rectification) by secondary windings (148). Rectified DC supplied from the output of secondary windings (146) is supplied to the field winding of the alternator and controlled in response to the voltage developed across the battery terminals by rectified signal output from secondary windings (148). As the AC load draws power from the capacitor bank (through the H-bridge), the voltage of the battery charging current supplied by secondary windings (148) drops, causing a voltage regulator circuit (34) to increase the field winding current, and thereby increasing the power supplied by the alternator to compensate the greater load.

A new approach to the modeling of converters for SPICE simulation

Abstract: An approach to the modeling of DC-DC converters for SPICE simulation is developed in which the average current in the energy-storage inductor is first simulated in a SPICE subcircuit for both the continuous and discontinuous modes of operation. The inductor current is then weighted and redistributed to related branches of the circuit to simulate the average input and output currents of the converter. Based on this technique, various converter models, including that of the Cuk converter with coupled inductors, which are valid for both continuous and discontinuous modes of operation, are developed. >

DC to DC/DC to AC power conversion system

Abstract: A pulse width modulation DC to DC converter operates in an open loop mode to convert the DC output of the AC to DC converter (36) to a desired, predetermined DC level (221) using pulse width modulation techniques and a switching configuration (32) substantially similar to that of the AC to DC converter (36).

High power factor power supply

Abstract: An off-line switching power supply includes an ac rectifier and a dual-output switching converter having one output coupled between the ac rectifier and the input to the dual-output converter in order to provide a high power factor, the other output of the dual-output switching converter providing a dc voltage as the power supply output. The outputs of the dual-output converter are fully decoupled so as to allow independent control of the ac input current and the power supply output voltage. In a preferred embodiment, a full-wave ac rectifier bridge is coupled in series with the second output of the power converter via an input resonant boosting converter. A full-bridge dc-to-ac converter is coupled between the dc link and ground for providing an ac signal to excite the boosting converter and for providing another ac voltage through a transformer to an output rectifier to generate a regulated dc output voltage. The amplitude of the regulated output voltage is controlled by pulse width modulation, while active frequency control of the boosting converter is provided to control the amplitude of the ac input current. Alternatively, frequency control of the boosting converter is passive, i.e., depends on the gain characteristics of the boosting converter resonant circuit. As a result of the complete decoupling of the input boosting converter and the power supply output voltage, the off-line switching power supply is capable of drawing high quality current waveforms from the ac source while producing a regulated dc output voltage with fast transient response.

Soft switching boost and buck regulators

Abstract: A switching regulator for achieving soft switching comprises a pilot switch in series with a diode, and a pilot inductor connected from the junction between the pilot switch and the diode to a tap on the main inductor. A bidirectional circuit operating as a buck or a boost regulator can be achieved by replacing all of the diodes with active switches and selectively activating certain of the switches.

A high power, high frequency, DC to DC converter for space applications

Abstract: The authors describe a regulated, nonisolated Weinberg boost converter with the following advantages: breadboard efficiency from 95 to 97% at 500 W to 1 kW output power; continuous output current with small current ripple; a boost regulator without right-half plane zero effect giving a high bandwidth response; low switching losses (typically 1% at a switching frequency of 350 kHz); conductance control producing typical first order response: and a wide bandwidth voltage regulation loop (10 kHz, with 80 degrees phase margin), giving superior transient response and reduced output filtering. >

Analysis and design of a fixed frequency LCL-type series resonant converter

Abstract: A fixed-frequency LCL-type series resonant power converter which uses an inductive output filter is proposed. Steady-state analysis of the converter is presented using complex AC circuit analysis. Based on the analysis, a simple design procedure is given. Detailed experimental results obtained from a MOSFET-based 500 W converter are presented to verify the analysis. The proposed converter requires a narrow variation in pulse-width while maintaining a lagging power factor mode of operation for very wide variation in the load. >

A new high frequency, zero-voltage switched, PWM converter

Abstract: A high-efficiency, high-power-density converter operating at constant frequency and switching at zero voltage is presented. Zero voltage switching (ZVS) conditions are achieved over a broad input voltage and output current range. Continuous power transfer from the input to the output minimizes the output filter requirements, and, by using the integrated magnetics technique, high power density can be achieved. By employing the same configuration as classical pulse width modulation (PWM) topologies, a new family of ZVS-PWM converters can be derived. An experimental 5 V, 100 A converter was designed and built. The converter operates from an input voltage of 200 to 430 VDC, at a 400 kHz switching frequency. >