Analysis and simulation of a novel Load-Commutated Inverter drive based on a symmetrical five-phase synchronous motor

In today's electrical drives, the use of more than three-phases to implement the electrical machine stator winding is a frequently adopted provision to enhance system power rating and fault tolerance. In VSI-fed electrical machines, multi-phase windings are adopted in both their symmetrical structures (with n equally distributed phases, supplied by a single n-phase inverter) and in their multiple three-phase arrangements (with two or more displaced three-phase windings, each supplied by an inverter). On the other hand, in CSI drives, based on synchronous motors and load commutated inverters (LCIs), the only multi-phase topology practically used consists of two three-phase windings, displaced by 30 electrical degrees, each fed by an LCI. This paper investigates an alternative, symmetrical multiphase LCI drive topology based on a five-phase motor supplied by a five-phase inverter. Both the motor and the inverter are accurately modeled in the Matlab/Simulink environment to study their combined behavior through numeric simulations, both in normal and faulty operating conditions. Simulation results are presented in order to highlight the pros and contras of the proposed topology with respect to the existing ones, taking performance and fault-tolerance features into account.