A direct drive of multiple parallel-connected multi-pole synchronous generators for wind energy conversion systems

Abstract

To help cut investment cost and encourage the utilization of wind energy, a concept of tandem synchronous generators is proposed for wind energy conversion systems (WECS). Two multi-pole permanent-magnet synchronous generators are mechanically arranged in tandem and electrically connected in parallel and the direct drive can be achieved by using vector control. The drawback of parallel- connected generators is investigated; effects of mismatched parameters are analyzed. It is pointed out that the mismatched flux is considerable and can deteriorate torque controllability. The concept of tandem generators for WECS is verified by simulation and experimental results. The tandem generators are set up with two 350-W direct-drive machines and the maximum power point tracking (MPPT) scheme is additionally included in the developed WECS. The testing results demonstrate the success in gathering electrical power from each generator with tolerable current sharing.