Marcelo Patrício de Santana

Anti-windup method for fuzzy PD+I, PI and PID controllers applied in brushless DC motor speed control

This paper proposes a new anti-windup method for integrative portion of many controllers: PI, PID and fuzzy PD+I. The proposed method does not require any coefficient for the anti-windup method, as other known anti-windup methods does. All the deduction and development of the proposed anti-windup method for PI, PID and fuzzy PD+I are presented here, resulting in two general and simple anti-windup equivalent methods. Following, the application of the proposed anti-windup method in a brushless DC motor speed control, employing a fuzzy PD+I controller, is shown and compared to a traditional anti-windup method, which achieves better results than that traditional method.

Improved Sensorless Vector Control of Induction motor Using Sliding Mode Observer

This work deals with a sensorless speed control for three-phase induction motor in order to improve its operation at low speed. Initially, a direct field oriented control employing space vector pulse with modulation based on sliding mode observer (SMO) is studied and evaluated due to its high accuracy in estimating the flux at low speed. The proposed current model based on SMO provides good speed estimation under low speed and parameter or load changes. Simulations and experimental tests with diferent operational conditions at low speed are carried out in order to test the sensorless control. The results show a good perfomance and agreed with the results shown in recent papers.

Vector control of induction motor using a sliding mode controller with chattering reduction

This work deals with vector control applied to the three phase induction motor (IM), using the indirect field oriented control (IFOC) technique. In the proposed topology, sliding mode controller with chattering reduction is applied, aiming high dynamic performance in a wide speed range and robust to load disturbances. Therefore, an approach with soft switching hyperbolic tangent function on the controllers is proposed. In order to analyze the control versatility, the usage of the controller in dq axes stator currents, rotor flux and mechanical speed is proposed. The performance of the motor is verified by means of numeric simulations and experimental tests, where good tracking results are obtained.

Investigation of Reluctance Torque in a BLDC Motor using Frozen Permeability Method and Equivalent Air-gap Analysis

This work investigates the reluctance torque in a surface mounted Brushless DC motor (BLDC) regarding the saturation effects due to the increase of electric load. At first, the reluctance torque is evaluated considering the line inductance waveforms for three different electromagnetic load conditions. Based on these results, which show an impressive change on the behavior of reluctance torque due to electromagnetic saturation, a further investigation is carried out in order to clarify the role played by each tooth in the reluctance torque, and of course, in the line inductance waveforms. These investigations are carried out with the aid of Frozen Permeability Method and the Equivalent Air-gap Analysis.

Low cost heading sensing system for an autonomous aquatic surface vehicle

This work describes the development of a heading reference system composed of low cost inertial sensors with MicroElectroMechanical Systems (MEMS) technology, which present high noise levels. Thus, filtering and sensors measurements fusion is done in order to achieve a reliable estimation, trough an extended Kalman filter. The system is used for navigation and control of an autonomous aquatic surface vehicle. In this work, the principles of inertial navigation, orientation representation as well as the coordinate frames involved are investigated, presenting the quaternion method, and the update procedure according to the heading changes. The developed system was tested in the lab and on a trimaran shaped vessel navigating on a dam.

Fuzzy logic for stator current harmonic control in Doubly Fed Induction Generator

This paper presents a new control topology to reduce the effect of the fifth negative and seventh positive voltages harmonic in the Doubly Fed Induction Generator (DFIG) in wind power systems. The proposed control is based on the concept of active power filters. A rotor current is delivered in the opposite direction of the harmonic content to reduces its effect. A incremental fuzzy controller is used within the principle of the traditional resonant control in which the frequency is tuned to six time the synchronous frequency. This method reduces both fifth and seventh harmonic at the same time. A 9MW wind farm is simulated to rate proposed control where some situations with different harmonic content are considered. Then the stator currents and the electromagnetic torque between those situations are compared to the traditional vector control.

Fault identification in doubly fed induction generator using FFT and neural networks

This paper presents a fault identification system for doubly fed induction generator (DFIG). It considers cases of single phase short-circuits and load switching. The system uses the fast fourier transform (FFT) to preprocessor data, which consist by the stator line currents. The principal component analysis (PCA) is employed to reduce the dimensionality of the output data of FFT and the fault identification is made by means of artificial neural network (ANN). Also, a post-processing (PP) is employed in order to increase the network reliability, which reduces the error of ANN. The system is simulated in the MATLAB simulation software using a database with different voltage, speed and load. The results show that the system with PCA, FFT and ANN has a good performance and accuracy with the PP to fault identification in the DFIG.