Claudinor B. Nascimento

Nonlinear State Estimation and Control for Chaos Suppression in MEMS Resonator

During the last decade the chaotic behavior in MEMS resonators have been reported in a number of works. Here, the chaotic behavior of a micro-mechanical resonator is suppressed. The aim is to control the system forcing it to an orbit of the analytical solution obtained by the multiple scales method. The State Dependent Riccati Equation (SDRE) and the Optimal Linear Feedback Control (OLFC) strategies are used for controlling the trajectory of the system. Additionally, the SDRE technique is used in the state estimator design. The state estimation and the control techniques proved to be effective in controlling the trajectory of the system. Additionally, the robustness of the control strategies are tested considering parametric errors and measurement noise in the control loop.

Single-stage high power factor converter without electrolytic capacitors to drive power LEDs

This paper proposes the use of a single-stage high-power-factor converter for power LEDs, without electrolytic DC bus capacitor. The power factor correction is obtained through direct connection of the Boost inductor between inverter stage and two input capacitor. A rectifier with output capacitor filter connected between the inverter stage and DC bus capacitors is used to obtain DC current in power LEDs. Experimental results are presented to prove proposed design methodology.

Single-Stage High Power Factor Converters Requiring Low DC-Link Capacitance to Drive Power LEDs

This paper proposes two nonisolated single-stage high power factor converters requiring low dc-link capacitance for power LEDs systems. Both converters result from the integration of the power factor correction and the LEDs driver stages, and require a relatively low dc-link capacitance value. A high power factor is demonstrated to be an inherent property of the proposed topologies and no input current control is necessary. The LEDs current is regulated by a symmetrical soft-switching half-bridge converter associated with a capacitive output filter. An accurate mathematical analysis valid for the two converters is detailed, yielding the elaboration of a step-by-step design procedure. In order to verify the analyses carried out, experimental results for two 90xa0W, 50xa0kHz, and 220xa0V converters are also presented.

A Tri-State Bidirectional Buck-Boost Converter for a Battery/Supercapacitor Hybrid Energy Storage System in Electric Vehicle Applications

Hybrid Energy Storage System (HESS) are commonly used when a combination of features and advantages from different energy storage devices are needed. Due to their characteristics, when batteries and Supercapacitors (SC) are implemented in HESS they become a good option for Electric Vehicle (EV) applications. This paper presents a bidirectional DC-DC converter as an interface between the battery and the SC, this will allow the control of the power flow. A tri-state operation for a bidirectional Buck-Boost converter is proposed in order to improve the performance of the control and reduce losses in the HESS.

A SEPIC-energy-regenerative-snubber with linear current regulator for power LEDs

This paper presents an AC electronic lighting system using a non-isolated SEPIC PFC rectifier to drive and control power LEDs currents. One energy regenerative snubber for reducing the converter switching losses and improve the system efficiency is proposed. To reduce ripple current in the LEDs array a linear current regulator is placed in the SEPICs output terminals. In order to reduce the efficiency impairment, the conditions for achieving minimum energy loss in the current regulator are also detailed. The main equations of the proposed energy regenerative snubber as well as the experimental results of a prototype that feeds 35 LEDs / 42 W are presented. In this paper, the system operates with 127 Volts of input voltage and the point of minimum energy loss in the linear regulator is adjusted in open loop to validate the converter operation.

Performance comparison between nonlinear and linear controllers with weighted adaptive control applied to a buck converter using poles placement design

This work presents a comparative study between four control strategies applied to a buck converter: Linear PID, Adaptive nonlinear PID with Gaussian Gain Functions (ANLPID-GGF), Linear Quadratic Regulator (LQR) and (State-dependent Riccati Equation) SDRE. In the case of the buck converter application, SDRE exhibited a better overall performance, but lacks a null error characteristic, typical of a control with an integral component. Taken the converter transfer function, the designs of the four controllers are set so the operating point of the closed loop system presents the same natural frequency. Based on the fore mentioned study, weighted combinations of the controls are proposed and analyzed. In the case, the weighted combination aims to gather the best of a particular control technique in order to achieve better results when compared to a single control technique. The weights are dependent on the error range. Some performance enhancements have been observed. Simulation results of the proposed control schemes are presented.

Single-Stage Integrated Bridgeless-Boost Nonresonant Half-Bridge Converter for LED Driver Applications

A nonisolated single-stage electronic lighting system with a high power factor for driving power light-emitting diodes (LEDs) is proposed in this paper. The presented topology is based on the integration of a bridgeless boost rectifier with a nonresonant half-bridge converter. Accurate steady-state analyses of the nonresonant- and resonant-based circuits are reported, serving as the basis for designing the lighting systems. The LEDs current is adjusted by means of frequency modulation, being the converter switches driven by complementary symmetrical signals. A small-signal analysis is detailed for the proposed nonresonant scheme, providing fundamental information regarding its dynamic behavior. Also, a step-by-step design procedure based on the performed mathematical analysis is elaborated, allowing the adequate design of the proposed lighting system. In order to confirm the validity and the feasibility of the proposed converter, experimental results for a 42-W, 127-

A bidirectional DC-DC converter For Supercapacitors in Hybrid Energy Storage Systems

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Analysis and simulation of a buck-boost operation in a bidirectional ZVS DC-DC converter

, 50-kHz, 94.2% peak efficiency prototype are presented.

ON DC TO AC CONVERSION IN A BOOST SELF-OSCILLATING STRUCTURE BASED ON NON-LINEAR CONTROL TECHNIQUES

The high power density of Supercapacitors (SCs) make them good elements for Hybrid Energy Storage Systems (HESSs). In order to increase the amount of energy of their high power bursts, they should operate with large voltage variations. This paper presents the design equations of a 3-switch bidirectional DC-DC converter with a tapped inductor that can be used for interfacing SCs to DC buses. Some of its key features are possible operation with V1>V2 and V1<V2, high voltage ratios (V1/V2) and also the choice of operating in three modes (Buck, Boost and Buck-Boost), which offers the potential for switch power loss balancing. Experimental results obtained with a 1-kW prototype are presented.