Francois Baudart's PhD Thesis

Permanent magnet drives are more and more widely used in high performance actuation systems due to their high efficiency associated to the control possibilities nowadays given by digital and power electronics. However, in aerospace applications, their spread is limited by some risks of failure.
The first part of the thesis validates the fact that, with a proper choice of the motor technology and power electronics architecture, the main risk of failure is the loss of feeding of one phase of the motor. Hence the reliability can be substantially improved by making the drive able to palliate such a fault. A thorough analysis of the selected motor architecture (i.e. the segment motor with tooth-coil technology) is also performed.
The second part investigates the motor torque control. A general method, based on a Lagrangian formulation, is introduced for determining the optimal currents allowing generating the needed torque, both in normal operation mode and after the loss of one phase. Then, two new controller architectures for controlling the motor currents in the rotor frame are developed, aiming for a minimal reconfiguration when moving into fault-tolerant operation mode.
The third part deals with the optimal design of the motor for a given application: the thrust vector control of a launcher. For this application, the motor has to be designed according to a mission profile and the space environment. For that purpose, an optimization program based on a genetic algorithm is interfaced with an analytical model, coupling magnetic and thermal aspects. This analytical model has been validated by FEM analysis and tests on a prototype designed for that purpose.

Jury:
Professeur Bruno DEHEZ, promoteur (UCL)
Professeur Ernest MATAGNE, promoteur (UCL)
Professeur Grégoire WINCKELMANS, président (UCL)
Professeur Francis LABRIQUE, secrétaire (UCL)
Docteur Paul ALEXANDRE (S.A.B.C.A.)
Professeur Christophe ESPANET (UFC, France)
Professeur Eric MONMASSON (UTC, France)