A double stator flux reversal PM machine with halbach consequent pole in slot opening

As one kind of stator-PM machines, flux reversal machine (FRM) has attached lots of attentions for its robust structure and cost effectively [1]. In regular FRMs, the permanent magnets were normally mounted on the stator teeth, which adds a large magnetic resistance to the magnetic circuit of coil winding. It causes reduction of the fundamental airgap permeance, weakening the working flux density and back-EMF, and restricting the electromotive force ultimately [2]. To increase the torque density of FRM, double stators were employed to utilize the inner space of machines [3], [4]. However, this structure introduces additional air-gap and more flux leakage to the magnetic circuit, therefore influencing the utilization of magnets. To reduce the flux leakage between N and S pole and improve the utilization of PM, consequent-pole PM was employed in FRM [5]. Instead of placing the PMs on the stator teeth, a novel FRM with Halbach consequent-pole magnets embedded in the slot opening is proposed in [6]. By moving the surface-mounted PM into the slot opening, the resistance of PMs no longer influences the permeance of coil windings, therefore the back-EMF of machine can be markedly increased. Moreover, the slot area is increased and the flux leakage is limited, hence improving the torque density and power factor. To further increase the torque density of FRM, a novel Halbach consequent pole double-stator flux reversal machine (HCP-DS FRM) is proposed in this digest. In proposed machine, a pole-piece rotor was placed between two identical stators with Halbach consequent-pole magnets in the stator opening. The performance of proposed machine with two configurations was then compared. At last, torque density, power factor and other properties of proposed HCP-DS FRM were compared with a regular 12/17 FRM shown in Fig.