Commande vectorielle | EPFL Graph Search

vignette|upright=2.0|Exemple de commande vectorielle d'un moteur triphasé, où l'angle de Park (la position du rotor) est mesuré par un capteur à effet Hall La commande vectorielle, aussi appelée commande à flux orienté (field-oriented control en anglais), est une méthode de commande des variateurs de vitesse électrique dans laquelle les courants statoriques triphasés d'un moteur électrique à courants alternatifs sont transformés en deux composantes orthogonales qui peuvent être considérées comme étant des vecteurs. Le premier vecteur permet le réglage du flux magnétique du moteur, tandis que le second règle le couple. Ils sont alors décorrélés et le fonctionnement devient alors similaire à celui d'un moteur à courant continu. Il existe plusieurs variantes. Dans une variante, un premier régulateur PI dit 'de vitesse', permet d'estimer à partir de la consigne de vitesse, la consigne de couple (car le couple de charge est en général inconnu)(ce régulateur n'est pas représenté sur la fig

Analyse et conception de moteurs synchrones chemisés à commutation électronique

The number of brushless DC (BLDC) motor applications has increased significantly, essentially due to reduced costs of semiconductors and permanent magnets, but also because of the emergence of new control strategies, such as closed-loop and sensorless control. Among the different electric drives, the heating circulation pump is a typical application which could greatly benefits from new BLDC technologies. Nowadays, the majority of low power heating circulation pumps is driven by AC induction motors. Despite of its low efficiency (< 20% for a single phase motor and < 50% for a three phase motor), this kind of motor is still used widely, because of its inherent simplicity since no electronic driver is needed. When a regulation is necessary (for example pressure, flow regulation), this advantage disappears. The aim of this work is a systematic analysis of the circulating pump motor. One solution is investigated in particular: the pump with a sealed BLDC motor. The following points are analysed in details: An analytical method to calculate the flux density distribution is tailored for motors with an important gap, as the sealed motors or slotless motors. The analysis of the electromagnetic characteristics for brushless DC motors shows the similarity of the various brushless DC motors. The calculation of tube losses determines their influence on the energetic balance of the motor. The determination of the acoustical motor noise shows the influence of the different modes of phases switching. The thermal aspects which take into account the motor environment are examined from the theoretical and practical point of view. The synthesis of these points results in a concept for the design and optimisation of BLDC motors; a series of pump prototype have been designed. For the heating circulation pump, the replacement of the AC induction motor with a brushless DC motor makes it possible to double the global installation efficiency. This solution is very promising from an energising aspect as well as an economical one and contributes to electrical energy savings, essential in this end of century.

EPFL1998

Flux Observer-Based vector control for Induction Motor

Sébastien Allemand

The induction motor offers the best value for money and is therefore used in many different application fields where power requirements are higher than a few kilowatts. ln order to be able to reduce the priee and the motor's size, a control algorithm based on an estimation of the flux without speed sensor for a Brushless AC motor (BLAC) has been developed in the Professer Shen's lab. The objective of this project is to examine the possibility to adapt and then implement this sensorless control algorithm to the induction motor. The induction motor's specificities will have to be analysed carefully in order to be able to propose an adapted control solution which will be implemented and tested on an induction motor.

2013

Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty

Mahdieh Sadat Sad Abadi

This thesis focuses on the development of robust control solutions for linear time-invariant interconnected systems affected by polytopic-type uncertainty. The main issues involved in the control of such systems, e.g. sensor and actuator placement, control configuration selection, and robust fixed-structure control design are included. The problem of fixed-structure control is intrinsically nonconvex and hence computationally intractable. Nevertheless, the problem has attracted considerable attention due to the great importance of fixed-structure controllers in practice. In this thesis, necessary and sufficient conditions for fixed-structure H_inf control of polytopic systems with a single uncertain parameter in terms of a finite number of bilinear matrix inequalities (BMIs) are developed. Increasing the number of uncertain parameters leads to sufficient BMI conditions, where the number of decision variables grows polynomially. Convex approximations of robust fixed-order and fixed-structure controller design which rely on the concept of strictly positive realness (SPRness) of transfer functions in state space setting are presented. Such approximations are based on the use of slack matrices whose duty is to decouple the product of unknown matrices. Several algorithms for determination and update of the slack matrices are given. It is shown that the problem of sensor and actuator placement in the polytopic interconnected systems can be formulated as an optimization problem by minimizing cardinality of some pattern matrices, while satisfying a guaranteed level of H_inf performance. The control configuration design is achieved by solving a convex optimization problem whose solution delivers a trade-off curve that starts with a centralized controller and ends with a decentralized or a distributed controller. The proposed approaches are applied to inverter-interfaced microgrids which consist of distributed generation (DG) units. To this end, two important control problems associated with the microgrids are considered: (i) Current control of grid-connected voltage-source converters with L/LCL filters and (ii) Voltage control of islanded microgrids. The proposed control strategies are able to independently regulate the direct and quadrature (dq) components of the converter currents and voltages at the point of common couplings (PCC) in a fully decoupled manner and provide satisfactory dynamic responses. The important problem of plug-and-play (PnP) capability of DGs in the microgrids is also studied. It is shown that an inverter-interfaced microgrid consisting of multi DGs under PnP functionality can be cast as a system with polytopic-type uncertainty. By virtue of this novel description and use of the results from theory of robust control, the stability of the microgrid system under PnP operation of DGs is preserved. Extensive case studies, based on time-domain simulations in MATLAB/SimPowerSystems Toolbox, are carried out to evaluate the performance of the proposed controllers under various test scenarios, e.g., load change, voltage and current tracking. Real-time hardware-in-the-loop case studies, using RT-LAB real-time platform of OPAL-RT Technologies, are also conducted to validate the performance of the designed controllers and demonstrate their insensitivity to hardware implementation issues, e.g., noise and PWM non-idealities. The simulation and experimental results demonstrate satisfactory performance of the designed controllers.

EPFL2016

Analyse et conception de moteurs synchrones chemisés à commutation électronique

EPFL1998

Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty

Mahdieh Sadat Sad Abadi

EPFL2016