Torque control strategy for fault –tolerant “five-phase PMSG-PWM rectifier” set for marine current turbine applications

Abstract

Increasing the phase number of the generators improve the fault tolerance of the electrical energy production system in marine current applications. This paper deals with torque control strategy of five phase PMSG-PWM rectifier set. Based on Fortescue transformation a dynamical model of “five phase PMSG non sinusoidal EMF” in natural basis is established. In order to maximize the average torque, to minimize the copper losses and to reduce the torque ripples all harmonics of EMF are exploited not only for the normal operation mode but also under open phase conditions. Thus, an adequate stator phase current waveforms are synthesized in natural basis (abcde). To ensure an effective tracking of these currents waveforms a robust nonlinear model-free controller with a large bandwidth is proposed. Simulation and experimental results highlight the performances of the control strategy and confirm the efficiency and the robustness of the proposed controller.