Maximum torque per ampere control strategy of a 5-phase PM generator in healthy and faulty modes for tidal marine turbine application

The work presented in this paper aims to propose a control strategy being able to extract efficiently energy from a fixed-pitch marine current turbine associated with a 5-phase Permanent Magnet Synchronous Generator (PMSG) in healthy mode and in faulty mode. The considered faults are opened phases. For each tidal current speed, the control strategy aims to extract the maximum power with respect of the maximum values of currents and voltages related to the converter. The maximum power is directly related to the Maximum Torque per Ampere (MTPA) control strategy characteristics (all the points which are below the MTPA torque VS rotating speed characteristic can be reached by the converter/generator set). This paper proposes a methodology to establish MTPA characteristics and calculate the corresponding current references in healthy mode and in faulty mode (one or two opened phases) for a 5-phase generator. The studied strategy includes flux weakening operations in the both modes.