A Brushless Dual-Mechanical-Port Dual-Electrical-Port Machine With Spoke Array Magnets in Flux Modulator

Brushless dual-mechanical-port dual-electrical-port (BLDD) permanent magnet (PM) machines have been gaining more and more attentions in recent years, with the merits of two decoupled rotors and contactless torque transmission. However, existing BLDD machines tend to suffer from low torque density due to low working flux density. In this paper, a BLDD machine with spoke array PMs in flux modular is proposed, which improves the torque density significantly. The structure and operation principle of the proposed machine is introduced. Detailed performance comparison between three different BLDD machine topologies, i.e., surface-mounted PM BLDD machine, flux-bidirectional modulation BLDD machine, and the proposed BLDD machine, is presented through finite-element analysis. The analyzing results show that although the modulated magnetic field coupled with the modulation winding is slightly reduced, the torque transmission capability of the regular winding in the proposed BLDD machine is significantly enhanced when compared with that of its two counterparts.