Modelling and Analysis of Multi-Three-Phase Drives for Radial Force Control

In the field of electrical machines for radial force control, several solutions have been proposed, all of which are able to simultaneously generate a magnetic flux distribution at the airgap required to produce torque and radial force. It is possible to divide the solutions into two main categories based on the arrangement of the windings. The first makes use of two separate sets of windings: one to generate the torque and the other to produce the radial force. The second is based on a combined winding, typically multiphase, that contributes simultaneously to the production of torque and radial force. The study presented in this thesis focuses on multiphase solutions. Multiphase electrical machines have a better fault-tolerance capability and the utilization of the entire winding for both torque and force production is considered potentially more efficient, due to the higher exploitation of the copper in the slots. The radial force control is proposed in order to reduce bearing stress since bearings are one of the most critical parts of an electric machine in terms of the probability of failure. Therefore, improving the fault-tolerance capability through radial force control is a promising research topic in the field of multiphase electrical machines. The purpose of the thesis activity is to obtain a mechanical model of the electric motor and incorporate it with the electromagnetic model of a multiphase electric machine, simulate the behavior of the motor through a numerical model (in Matlab/Simulink environment) and evaluate a control algorithm that allows improving the motor's performance by active compensation of rotor vibration. The multiphysics model of the multiphase drive and the control are based on a prototype and available in the laboratory of the PEMC (Power Electronics, Machines and Control) group at the University of Nottingham, UK. Preliminary experimental tests have been carried out to validate the models.