Investigation on brushless DC appropriateness to direct-drive generator wind turbine

Abstract

The paper studies the posibility to increase the power capability of direct-drive application. The system consists in a trapezoidal waveform PM brushless generator connected to the grid via a back-to-back concerter. Numerical model of the the system from the shaft of the generator until the DC bus circuit is setup. The studied parameters of the system are the electromagnetic torque ripple and the quality of the energy supplied to the grid. DC bus voltage adaption is proposed to avoid torque oscilltions and polyphased systems are proposed to reduce the low frequency harmonics of the power transferred to the grid.