Carlos M. R. Oliveira

Evaluation of surface mounted PM machine's parameters on load conditions using frozen permeability method. Part. II

This work deals with the influence of magnetic saturation on machine parameters of a surface mounted permanent magnet synchronous machine driven by an ideal six-step three-phase inverter. In this second part, a special attention is given to back-EMF calculation since the linkage flux of each phase has an abrupt change every sixty electrical degree due to the phase commutation.

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.

Integral sliding mode controller with anti-windup method analysis in the vector control of induction motor

This work presents an integral sliding mode controller, applied to the three-phase induction motor IM using indirect field oriented control technique. Besides seeking high dynamic performance using the slinding mode controller, it is discussed the necessity of a parametric action control (known as equivalent control) to turn the system stable. To do so, it is used an integral sliding mode controller with anti-windup method. The motor performance is verified by means of numeric simulations and experimental tests with load disturbances.

Electric vehicle hardware-in-the-loop simulation with differentiator optimised by genetic algorithm

Study of electric vehicles uses Hardware-In-the-Loop (HIL) simulation to improve its project. This work develops a system of mechanical HIL simulation, in order to simulate the behaviour of an electric vehicle. An induction motor with torque control is used to emulate vehicular dynamics, which is mechanically coupled to another induction motor acting as traction motor. The inclusion of vehicle inertia in HIL setup without a flywheel, for the sake of avoiding mechanical stress and lost of generality, is a challenge. Thus, this work applies a genetic algorithm to optimise a second order differentiator used to calculate system acceleration from motor measured system speed. This system allows to verify the performance of electric vehicles with different control strategies in the traction motor, optimizing the project. Results in Matlab/Simulink, compared to vehicle forward reference model, showed that HIL simulation was able to reproduce the electric vehicle dynamic performance.

Sliding mode control of brushless DC motor speed with chattering reduction

This paper proposes the use of an analog switching function in sliding mode control for a brushless DC motor speed, with the objective of input chattering reduction. The sliding mode control topology is used in the mechanical speed loop control as well as in the stator current loop control. The results show a good chattering reduction, a good machine performance and a good robustness of the controller due to disturbances, without the need of fine tunneling of the controller parameters, as in other kinds of control. The parameters of a real machine where used in the simulations. This kind of function in the used sliding mode controllers turned to be a very good alternative depending on the application.

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.

Improved finite control-set model-based direct power control of BLDC motor with reduced torque ripple

Brushless DC (BLDC) motor is used in a wide range of applications due to its high efficiency and high power density. However, as its main drawback, it develops significant torque ripple during phase commutation in conventional 120° conducting mode operation. To reduce torque undulations, this paper presents a simple approach for BLDC motor drive by applying a model-based predictive direct power control (MPDPC) with duty cycle concept. As a result of controlling active and reactive power exchanged between stator and rotor, low torque ripple can be achieved. Compared to priors works, this paper introduces the duty cycle concept with lower complexity and number of calculations to improve the conventional MPDPC steady-state performance. The effectiveness of proposed approach is demonstrated by simulation results.

Pseudo sliding mode control with integrative action applied to brushless DC motor speed control

Although sliding mode control has many drawbacks when applied to electrical drives due to real limitations of switches, as limited frequency of operation, turn on and turn off delays, some of its theory can be succesfully used in order to project a high performance controller, robust and with a reduced design effort. This paper shows the use of sigmoidal function, hyperbolic tangent, instead of the signal function. So, it actually consists not in a pure but in a pseudo (or quasi) sliding mode, combined to an integrative controller action and with an anti-windup effect, so the result is a high performance controller, robust to machine parameters and disturbances, and light in its design. Results shows its high performance and robustness. The chosen sliding surface has integrative control action combined to an anti-windup feature, which zeroes the steady state error and minimizes the output system overshoot.

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.

Evaluation of surface mounted PM machine's parameters on load conditions using frozen permeability method. Part. III

This work deals with the influence of magnetic saturation on machine parameters of a surface mounted permanent magnet synchronous machine driven by an ideal six-step three-phase inverter. In this third part, a special attention is given to each torque component on load condition, i.e., mutual torque, reluctance torque, cogging torque and a comparison between the electromagnetic torque and the summation of these components.