Direct Eigen Control for Induction Machines and Synchronous Motors

Introduction

The applications of control theory for controlling electromechanical actuators (Grellet and Clerc, 1999) have always tried to simultaneously follow, in spite of disturbances, one or several physical variable set-points, and to do so with accuracy, without overshoot or lagging, and with the maximal velocity, compatible with the controlled processes, physical limits resulting from sizing, and the energy cost of the control.

This work proposes a method to develop control laws, to drive electrical actuators, which fulfills these aims as well as possible. The application of this method to electric motors makes it possible to consider its generalization.

1 Formulation of the Motor Control Problem

When one starts designing the process kinematics and the motor control, several important characteristics must be analyzed:

• the required electromagnetic torque rating
• the response time in set-point tracking mode, as well as the response time to any foreseeable disturbances
• physical variable limits.

1.1 Electromagnetic Torque

The robot or the table of a machine tool are controlled by position, the automatic subway is controlled by torque and speed, the locomotive is controlled by torque and speed, the rolling mill is controlled by speed or torque according to its position in the roll train.

The kinematic law of mechanics leads to controlling a motor by the torque C_c to overcome a load moment C_r and to accelerate or to slow down an inertia J, thus making it possible to vary its mechanical angular ...