L. Martinez-Salamero

Interleaved converters operation based on CMC

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.

A Fast-Response Sliding-Mode Controller for Boost-Type Converters With a Wide Range of Operating Conditions

This paper proposes a fast-response sliding-mode controller for controlling boost-type converters requiring a fast dynamical response over a wide range of operating conditions. The various aspects of the controller, which include the method of generating the reference-current profile, the choice of sliding surface, the existence and stability properties, and the selection of the control parameters, are discussed. Experimental results are presented to validate the theoretical design and to illustrate the strength of the proposed controller. It is demonstrated that, with the proposed controller, the boost converter has a faster response and a lower voltage overshoot over a wide range of operating conditions as compared to that under the widely used peak current-mode controller. Moreover, it is easily realized with simple analog circuitries.

The Mathematical Foundation of Distributed Interleaved Systems

The distribution and interleaving (D&I) of signals is a common method for ripple attenuation in various engineering applications in such areas as control, communication, and power electronics. Similarities to this technique may also been found in nonengineering fields such as biology and medicine. This paper presents a mathematical exploration of distributed interleaved systems along with a simple frequency-domain model of interleaving. We are hoping that the insights provided by this mathematical framework and the newly proposed model for interleaved systems will lead to enhanced techniques for evaluating D&I processes, and facilitate the design of better systems. In particular, we hope this work results in new approaches to low-pass filtering that will exhibit fast dynamics and very efficient ripple attenuation (in theory, this can produce complete ripple removal in some cases)

Why is sliding mode control methodology needed for power converters

A review of the state of the art in the sliding-mode control of DC-to-DC switching converters is presented. The method of the equivalent control is illustrated in the design of a two-loop control for the voltage regulation of a buck-boost converter. The theoretical predictions are validated by means of PSIM simulations. Prospective applications of the method reported are also discussed.

Inherent DCM operation of the asymmetrical interleaved dual buck-boost

A fifth order DC/DC converter based on the asymmetric connection of two buck-boost cells with complementary activation of their switches is presented. In steady state, the new converter inherently operates in discontinuous conduction mode (DCM). With a duty cycle greater than 38%, the asymmetrical interleaved dual buck-boost (AIDBB) behaves like an inverting boost converter. The AIDBB exhibits some benefits of interleaving cells without the need for specific control strategies to distribute the input current between the buck-boost cells. Mainly, the converter input current and output voltage ripples are significantly smaller than their average values. Due to the DCM operation, the system presents three operation intervals whose duration is independent of the converter parameters.

Modular Realization of Capacitive Converters Based on General Transposed Series–Parallel and Derived Topologies

The realization of capacitive converters based on a modular approach is presented and analyzed in this paper. The converters are based on topologies with identical capacitors. First, the switching network (SN) of a basic series-parallel topology is presented. The analysis reveals the assembly and growth rules for expanding the topology to any number of capacitors. Subsequently, the SN for the more versatile and complex general transposed series-parallel (GTSP) topology is presented. The topology is expanded by defining a basic cell comprising a capacitor and five peripheral switches. The expansion of this converter improves its performance by ameliorating accuracy and regulation in the dc/dc voltage ratio. The control schemes of these converters are also presented with emphasis on the GTSP topology, whose switches are not assigned in advance. The control scheme for achieving the desired voltage ratio is described. A five-capacitor converter with its control is built to illustrate the theory in open-loop mode, which provides experimental results that are in full agreement with the analytical predictions.

Interleaved Digital Power Factor Correction Based on the Sliding-Mode Approach

This study describes a digitally controlled power factor correction (PFC) system based on two interleaved boost converters operating with pulsewidth modulation (PWM). Both converters are independently controlled by an inner control loop based on a discrete-time sliding-mode (SM) approach that imposes loss-free resistor (LFR) behavior on each cell. The switching surface implements an average current-mode controller so that the power factor (PF) is high. The SM-based digital controller is designed to operate at a constant switching frequency so that the interleaving technique, which is recommended for ac-dc power conversion systems higher than 1 kW, can be readily applied. An outer loop regulates the output voltage by means of a discrete-time proportional-integral (PI) compensator directly obtained from a discrete-time small-signal model of the ideal sliding dynamics. The control law proposed has been validated using numerical simulations and experimental results in a 2-kW prototype.

Adapting a low voltage PEM fuel-cell to domestic grid-connected PV system

In this work, we present an electronic system that simplify the incorporation of additional sources to a previously existent small PV system. Particularly, we investigate how to proceed with a low voltage, high-current PEM fuel-cell. The proposed system is developed from the concept of loss-free resistor, and can be easily adapted to any type of energy source and storage elements. Among the advantages of the proposed system, the PV array keeps its maximum power point (MPP), with independence of the power delivered by the new source. In addition, the proposed system allows also a particular MPPT for the new source if required. Finally, as additional benefits, sources can the incorporated or extracted with hot-swapping, and the energy production profile can be smoothed, predictable, and even constant, as wanted by the utility grid regulators.

Modular-based PFC for low power three-phase wind generator

Hybrid Distributed systems include many sources, storage elements, and various local loads, connected to a common distribution bus. In this work, different matching methods to adapt a 3-phase wind alternator to a variable DC-bus are reviewed, and finally a modular solution based on single-phase Boost-based PFCs is proposed. Nevertheless, Boost modules must be adapted to operate with non-isolated sources, like 3–4 wire, 3-phase generators. Magnetic coupling is introduced here to enhance the isolation among phases, reducing also converter losses and size. Sliding mode approach has been applied to the whole converter as a single unit, to verify that independent regulation of all phase modules was possible, even sharing a common output capacitor. To verify the theoretical analysis, a 1.5 kW prototype has been built confirming independent phase control and good sinusoidal input waveforms.

High-voltage LED-based efficient lighting using a hysteretic controlled boost converter

Car industries are especially interested on decreasing the power rating of the electrical sub-system to reduce wire weight and fuel consumption. Using LED devices, a typical 50W halogen-based car spot-light, could be replaced by a LED array of 8–12W. To improve the array life-time and simplify light dimming, all LED devices are series-connected to a high-voltage current-source driver. This driver, based on a single-stage boost converter has a very high voltage gain. Supplied from a 12 V car-battery, and limited only by the commercially-available switching devices, our prototype reaches 900V. Hysteretic control is decisive to achieve the required extremely high duty ratios, circa 98%, as well as to guarantee DCM-CCM border converter operation to reduce switching losses.