Dante Casini

SLIDING MODE SPEED CONTROLLER FOR TRAPEZOIDAL BRUSHLESS MOTORS

ABSTRACT This paper describes the application of a variable structure speed controller for a non sinusoidal brushless permanent magnets motor drive. Our trapezoidal brushless motor model changes the working conditions for every phase commutation and moreover it allows to simulate the different structural motor configurations. Controller synthesis is carried out using sliding mode theory with a pole assignment technique. During the sliding motion the state point is forced to reach a prescribed surface due to an active change of the control action. The order of the system is therefore reduced and moreover the dynamic behaviour of the closed-loop system is imposed. Results by digital computer simulation prove parametric variation insensitivity, disturbance rejection, fast transient responses, no overshoot and absence of speed ripples during phase commutations.

Field oriented adaptive controller using EKF for asynchronous drives

ABSTRACT This paper presents a high dynamic induction motor drive system utilizing a fully digital direct field oriented controller. The drive is characterized by a sliding mode controller and by a stochastic filtering technique, the latter obtained by an extended Kalman filter (EKF), in the feedback loop. The EKF, in addition to supplying a reliable estimation of state variables, is able to identify and to correct in real-time the values of rotor resistance and of rotor constant time, in effect, becoming an adaptive state observer. The system can work both with or without a speed sensor. Some computer simulations are reported.

Passive MAGLEV armature stabilization

In this paper a passive, Permanent Magnets (PMs) based Magnetic Levitation (MAGLEV) system is presented and its stability is discussed. The suspension is assured by the repulsive force of properly shaped PMs placed on both the guideway and the vehicle. The interaction between the motional induced currents on conductors on the guideway and the PMs on the armature produces a stabilization force. The performance of the system has been evaluated by a research code developed at the DESTEC.

Experimental testing of a high-power-quality modulator for A.C. resistive heaters

A.C. resistive heaters represent a widely diffused typology of loads. An effective power regulation may improve the overall energetic efficiency, the exploitation of the available peak power, the thermal load regulation and the power quality in their line-side operation. This paper focuses on the experimental testing of unconventional power modulators for mono- and 3-phase resistive heaters, previously proposed and analyzed under the theoretical and simulation points of view. Such modulators ideally permit a linear regulation of the heating power with an almost unity power factor and a low distortion of the line currents.