Introduction 1

Electric actuators, at least the most traditional ones (direct-current machine and alternating-current machines working under Park’s assumptions), have been the subject of a very large number of scientific studies and industrial realizations, and we can consider that they are currently well understood. The control structures use the machine’s decoupling properties in both axes (direct axis for the flux and quadrature axis for the torque), and the performance and robustness of the regulators are well adapted to the system specifications.

The implementation of overlapped regulations makes it possible to control the dynamics of the main variables, magnetic flux and rotation speed (via the torque), and to create “active safety features” (instant limitations of power amplitudes for example). These controls are even more efficient as long as the designer has precise models with known parameters. In fact, controllers most often use the innermost properties of actuators. The “direct model” is derived from the physical equations of the machine. From this model a reverse model is then obtained enabling direct access to the control architecture and allowing the selection of the control algorithms, the regulators or the controller best adapted to the original specifications. Knowledge of the physical laws and parameter values is therefore a requirement.

In addition, these controls involve variables whose direct measurements cannot always be achieved such as the magnetic flux ...

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