DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

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Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

New recommendations and future standards have increased the interest in power factor correction circuits. There are multiple solutions in which line current is sinusoidal. In addition, a great number of circuits have been proposed with nonsinusoidal line current. In this paper, a review of the most interesting solutions for single phase and low power applications is carried out. They are classified attending to the line current waveform, energy processing, number of switches, control loops, etc. The major advantages and disadvantages are highlighted and the field of application is found.

Single phase power factor correction: a survey

This paper explores predictive digital current programmed control for valley, peak or average current. The control laws are derived for the three basic converters: buck, boost, and buck-boost. It is found that for each variable of interest (valley, peak or average current) there is a choice of the appropriate pulse-width modulation method to achieve predictive digital current control without oscillation problems. The proposed digital control techniques can be used in a range of power conversion applications, including rectifiers with power factor correction (PFC). Very low current distortion meeting strict avionics requirements (400-800 Hz line frequency) is experimentally demonstrated on a digitally controlled boost PFC employing predictive average current programmed control.

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Predictive digital current programmed control

A nonlinear least-squares optimization algorithm based on the Newton model modified with Levenberg parameter, is described for the extraction of the five illuminated solar cell parameters from the experimental data. An initialization routine based on the reduced nonlinear least-squares technique in which only two parameters have to be initialized, is introduced to overcome the difficulty in initializing the cell parameters. The program when incorporated into a microcomputer-based data acquisition software, allows an in-situ theoretical modelling of solar cells in laboratories. Results obtained for a commercial solar cell and a module are given.

Nonlinear Minimization Algorithm for Determining the Solar Cell Parameters with Microcomputers

A major challenge for implantable medical systems is the inclusion or reliable delivery of electrical power. We use ultrasound to deliver mechanical energy through skin and liquids and demonstrate a thin implantable vibrating triboelectric generator able to effectively harvest it. The ultrasound can induce micrometer-scale displacement of a polymer thin membrane to generate electrical energy through contact electrification. We recharge a lithium-ion battery at a rate of 166 microcoulombs per second in water. The voltage and current generated ex vivo by ultrasound energy transfer reached 2.4 volts and 156 microamps under porcine tissue. These findings show that a capacitive triboelectric electret is the first technology able to compete with piezoelectricity to harvest ultrasound in vivo and to power medical implants.

Transcutaneous ultrasound energy harvesting using capacitive triboelectric technology

An equivalent circuit model for the discontinuous conduction mode flyback converter based on the loss-free resistor concept is presented. This simple model correctly describes the basic power processing properties of the converter, including input port resistor emulation, output port power source characteristics, and control characteristics. Based on this model, steady-state design equations are described and are used in a design example. Design of the slow output voltage feedback loop is also considered. A small-signal AC model is developed for both the resistive load and the DC-DC converter-voltage regulator load cases. In addition, a simple first-order approximation for the line current distortion and phase shift caused by 120 Hz duty cycle variations is derived. >

Design of a simple high-power-factor rectifier based on the flyback converter

A new family of low-ripple DC-to-DC switching converters based on a parallel connection of N-identical boost converters with current-mode control (CMC) is presented. The CMC strategy ensures that all the converters operate at the same duty cycle, sharing an equal amount of input current and forcing the output voltage to be an integer multiple (N) of the input voltage. As a result, the total input current and output voltage ripples are extremely low. The generation of control signals from inductor currents feedback without using external triangular or sawtooth signals is another characteristic of the new converter family.

Interleaved converters operation based on CMC

The fundamental power-processing properties of switching converter circuits are modeled using generalized power-conservative (POPI) networks. Depending on the application, it may be most appropriate to model the first-order converter properties as those of an ideal transformer, gyrator, loss-free resistor, or other POPI network. These basic functions can be obtained either through selection of a topology that naturally possesses the desired characteristics or by addition of a suitable control network. Some well-known converter topologies are shown to behave naturally as gyrators, loss-free resistors, and constant power networks. The application of the gyrator to network two voltage sources and the use of the loss-free resistor as a unity power factor rectifier are described. >

Canonical modeling of power processing circuits based on the POPI concept

A family of “Two-Switch Boosting Switched-Capacitor Converters (TBSC)” is introduced, which distinguishes itself from the prior arts by symmetrically interleaved operation, reduced output ripple, low yet even voltage stress on components, and systematic expandability. Along with the topologies, a modeling method is formulated, which provokes the converter regulation method through duty cycle and frequency adjustment. In addition, the paper also provides guidance for circuit components and parameter selection. A 1-kW 3X TBSC was built to demonstrate the converter feasibility, regulation capability via duty cycle and frequency, which achieved a peak efficiency of 97.5% at the rated power.

Sigmond Singer

Papers

Design of a simple high-power-factor rectifier based on the flyback converter

Interleaved converters operation based on CMC

Canonical modeling of power processing circuits based on the POPI concept

A Family of Two-Switch Boosting Switched-Capacitor Converters

Characterization of PV array output using a small number of measured parameters