Dalton de Araújo Honório

A two-stage AC/DC SST based on modular multilevel converterfeasible to AC railway systems

This paper proposes the use of the modular multilevel converter (MMC) for ac-dc conversion using medium frequency transformers in a two-stage topology with unidirectional switches. The losses analysis of the propose converter are presented with a comparative study among others two topology well know in the literature for traction applications. The basic description of the topology and some simulation results are presented, followed by a comparative losses result.

Comparison between sliding model control and vector control for a DSP-based position control applied to squirrel-cage induction motor

The principle of vector control of AC machine enables the dynamic control of AC motors, and induction motors in particular to a level comparable to that of a DC machine. The vector control of currents and voltages results in control of spatial orientation of the electromagnetic fields in the machine and has led to term field orientation [1]. Field oriented control schemes provide significant improvement to the dynamic performance of ac motors. The usual method of induction motor position and torque control, which is becoming an industrial standard [2], uses the indirect field orientation principle in which the rotor speed is sensed or estimated by rotor position and slip frequency is added to form the stator impressed frequency. Sliding-mode control has gained wide attention because of its simple design and implementation, fast dynamic response, and robustness to parameters variations and load disturbances. This paper proposes a performance comparison between sliding mode-control and field oriented control using synchronous reference applied to a small squirrel-cage induction motor using space vector pulse width modulation(SVPWM) for position and torque control and a digital signal processor and relay feedback method to evaluate the controller parameters.

An AC-DC Multilevel Converter Feasible to Traction Application

This paper proposes an ac-dc bidirectional power converter topology consisting of an arrangement of full-bridge converters based on the three-state switching cell using a medium-frequency isolation transformer. The topology description and simulation results for the dynamic conditions are presented and discussed on detail.

Hybrid Control Robust Using Logic Fuzzy Applied to the Position Loop for Vector Control to Induction Motors

Abstract This article presents the study and implementation of position control for an induction motor drive using the vector control strategy to improve tracking of the motor shaft. Thus, a novel hybrid control technique is proposed in contrast to the proportional-integral-derivative controller with a fixed gain traditionally used in this type of application. The hybrid control relies on error techniques based on fuzzy rules systems weighting the control action of proportional-integral-derivative and generalized predictive controllers previously adjusted. The simulation and experimental results to check the performance and robustness of the control strategy demonstrate the merit of the proposed approach.

An Interleaved-Stage AC–DC Modular Cascaded Multilevel Converter as a Solution for MV Railway Applications

This paper proposes an interleaved-stage ac–dc bidirectional power converter topology feasible to medium-voltage railway systems. It is based on an arrangement that uses input-series-output-parallel configuration with identical power modules. Each module consists of two interleaved legs employing coupled windings so that it is possible to connect a medium-frequency transformer. The topology conception is presented, followed by the adopted control and modulation technique. An estimation of semiconductor losses is also discussed, while a comparative analysis by means of simulation results validates the improved performance of the introduced approach if compared with similar solutions. The topology results are obtainedt through a medium-voltage high-power railway application, demonstrating the converter functionalities and performance under both steady-state and dynamic conditions. It is then possible to state that good performance in terms of efficiency is achieved even though the power stage presents higher component count if compared with the topology that presents the best result, thus making it suitable to high-power ac–dc machine drive applications.

A solid state transformer based on a single-stage AC-DC modular cascaded multilevel converter

This paper proposes a single-stage ac-dc bidirectional power converter which provides power conditioning capability and insulation for solid-state transformers. The topology conception is presented, as well as its operation principles and the employed modulation technique. Some results are also discussed to validate the proposed modulation algorithm and the claimed advantages.

A Space Vector PWM scheme for a Single-stage Ac-Dc Modular Cascaded Multilevel Converter

Multilevel power converters have been intensively studied in the power electronics field. However, approaches involving the evaluations and proposals of novel modulation techniques, topologies and applications of semiconductor technologies keep this path as an open research area. This paper proposes a Space Vector Pulse-Width Modulation (SVPWM) approach applied to a Single-stage Ac-Dc Modular Cascaded Multilevel Converter (SMCM). The analysis of the switching vectors is performed in order to design optimal sequences for the improvement of key characteristics, such as multilevel voltage Total Harmonic Distortion (THD), input current THD, magnetizing current level, as well as efficiency. A modulation algorithm is proposed through a step-by-step code and a proper vector sequence from all possible switching states is shown. Simulation results validate the proposed modulation algorithm and its operation, with significant advantages over the classical Phase-Shifted Pulse-Width Modulation (PSPWM) technique.

Hybrid position controller for an indirect field-oriented induction motor drive

This paper presents a conception and implementation of a hybrid controller technique applied in an indirect field-oriented (FOC) induction motor drive. The main goal is to improve the position tracking performance with a hybrid controller based on the classical proportional (P) controller and the generalized predictive control (GPC) approach. It has shown through experimental results, the effectiveness of the proposed hybrid controller. Indeed, the controller has the fast tracking capability as a P controller and the robustness as a GPC controller.

A two-stage AC/DC SST based on modular multilevel converter

This paper proposes the use of the modular multilevel converter (MMC) in ac-dc conversion using medium frequency transformers in a two-stage topology with unidirectional switches. The medium frequency link provided by each module of the MMC is used to supply the windings of the transformer. A full-bridge rectifier connected to the dc side supplies the secondary side as the power flow is controlled by the phase-shift angle between the primary and secondary voltages. The resulting topology is fault tolerant since a short-circuit in the dc side causes low additional stress in the semiconductors. The basic description and some simulation results are presented in order to valid the proposal.