João Batista Vieira Júnior

Design of an Internal Model Control strategy for single-phase grid-connected PWM inverters and its performance analysis with a non-linear local load and weak grid

This paper presents the design of a controller based on Internal Model Control (IMC) applied to a grid-connected single-phase PWM inverter. The mathematical modeling of the inverter and the LCL output filter, used to project the 1-DOF IMC controller, is presented and the decoupling of grid voltage by a Feedforward strategy is analyzed. A Proportional - Resonant Controller (P+Res) was used for the control of the same plant in the running of experimental results, thus moving towards the discussion of differences regarding IMC and P+Res performances, which arrived at the evaluation of the proposed control strategy. The results are presented for typical conditions, for weak-grid and for non-linear local load, in order to verify the behavior of the controller against such situations.

Simulated Annealing ‑ MPPT in Partially Shaded PV Systems

This paper is about simulated annealing (SA) algorithm used to tracking the maximum power point (MPP) applied to photovoltaic array. The present method adjusted the SA algorithm to variables analysed on photovoltaic systems (PV). Therefore, the power is the objective function and it depends on duty cycle, which is the independent variable. Initially, the SA algorithm is at random. However, the convergence methods lead the system to a global optimal point. Hence, the SA would avoid the ineffective exploration on the local optimal solutions like MPPT classic algorithms, mostly when the photovoltaic array is under partial shading conditions. The simulations have been done by PSIM software and the code could have been implemented in a digital signal controller (DSC).

Single-stage fuel-cell inverter with new control strategy

Renewable energy sources has been attracting great interest due to well known environment issues and, hence, the development of power electronics converters to deal with the transformation of these sources into conventional energy forms has been the main challenge faced by many researches working in this area of expertise. Within this subject, this paper focuses the establishment of a simple power structure that based on a new control strategy can provide an amplified sinusoidal output voltage from a fuel cell. The single-stage inverter works based on imposed waveforms of a CSI inductor current and output voltage. The proposed control strategy provides high voltage gain without using high frequency transformer, which contributes to weigh and size reduction of the proposed DC-AC converter structure. Theoretical analysis are presented and corroborated by experimental results of a 180W laboratory prototype.

A single switch double forward converter without commutation losses

This paper introduces a new forward converter topology that uses the full hysterisis cycle with two symmetric forward converters coupled in a single magnetic core. It also presents lossless commutation when turning on and off managed by an LC circuit and auxiliary switches. As a result, high frequency switching can be achieved not increasing the switching losses

Novel proposal of multilevel inverter using Buck EIE converter

A novel proposal of multilevel inverter is presented in this paper. The concept of the proposed topology is based on the association of Buck EIE converters in order to constitute a multilevel inverter and to provide an ac output voltage with low harmonic distortion and low voltage stress over the power semiconductor devices. The output voltage provided by the proposed multilevel is totally controlled and follows a reference signal, which assures low harmonic distortion without the necessity of using passive filters. Detailed circuit description is given and simulation results are also presented in order to confirm the operation of the proposed topology.

New control strategy applied to a CSI inverter with amplified sinusoidal output voltage: Analysis, simulation and experimental results

Renewable energy sources has been attracting great interest due to well known environment issues and, hence, the development of power electronics converters to deal with the transformation of these sources into conventional energy forms has been the main challenge faced by many researches working in this area of expertise. Within this subject, this paper focuses the establishment of a new control strategy applied to a step-down/step-up single-stage inverter with imposed waveforms of CSI inductor current and output voltage. The proposed control strategy provides high voltage gain without using high frequency transformer, which contributes to weigh and size reduction of the proposed DC-AC converter structure. Theoretical analysis are presented and corroborated by experimental results of a 180W laboratory prototype.

New approach on multilevel cascaded inverters using EIE commutation cells

A novel approach for cascaded multilevel inverters is presented in this paper. The proposed topology is based on the association of cc/cc pwm converters, developed from an active commutation cell, called EIE cell. The multilevel Buck eIE inverter provides an ac output and low voltage stress levels over the power semiconductor devices. The output voltage is totally controlled and follows a reference signal, which assures low harmonic distortion without the necessity of using passive filters. Detailed circuit description is given as well as simulation and experimental results, in order to confirm the operation of the proposed topology.

Amplificador classe d para subwoofer

This paper proposal presents a high power Class-D audio amplifier for subwoofer applications with efficiency above 90%. A regulated dc voltage supply is not needed as well as a low pass output filter overcoming the disadvantages of ordinary Class-D audio amplifiers structures. A 1 kW laboratory prototype was implemented and it was found that efficiency above 90 % and THD below 1 % could be achieved. Detailed design guide lines, principle of operation analysis and control strategy are also included in this paper proposal.