High Order Sliding mode optimal current control of five phase permanent magnet motor under open circuited phase fault conditions

Electrical marine propulsion systems are characterized by very high level requirements in terms of compactness, acoustic behavior and reliability. In this particular context, the use of multiphase PM machines associated with VSI drives appears to be a very efficient solution. Presented work focus on the use of such a system in open circuited phase fault conditions. With this kind of system it is possible to determine optimal current references which maximize the torque density of the system when one or two phases are open circuited. Classical linear controllers (as PID for example) cannot provide a correct tracking of these optimal current references because they have a highly dynamical behavior. We propose in this paper to combine this optimal current reference generation with High Order Sliding Mode (HOSM) control. This kind of solution allows a good tracking of these unconventional current references with a fixed switching frequency for the VSI. This method is validated experimentally using a low power experimental set-up which associates a 5-phase PM machine with a DSP controlled IGBT 5-leg VSI drive.