Modeling and Analysis of Short-Circuit Current for a Novel Dual Three-Phase Electric Machine With Mixed Iron-Pole Halbach Magnet Pattern.

A key challenge for the design of dual three-phase electric machine is how to increase its electromagnetic torque and reduce short-circuit current simultaneously. In this paper, a novel mixed iron-pole Halbach (MIH) magnet pattern is proposed for the electric machine. It can offer a variety of advantages. First, it improves the air gap flux density, which help to increase the torque output of the electric machine. Second, it increases the inductance of phase winding, which help to reduce the short-circuit current significantly. Third, it improves the self-shielding effect, which help to reduce the back iron and rotor mass. Analytical, numerical and experimental investigations are performed to validate the proposed design concept. Firstly, the schematic structures of the electric machine and proposed MIH magnet pattern are presented. Then the magnetic field, torque output, inductance and short-circuit current are formulated analytically through sub-domain models. Following that, the numerical computation is performed to validate those analytical models. The flux density, torque output, inductance and short-circuit current of the MIH magnet pattern are compared with those of other traditional magnet arrays. Subsequently, a dual three-phase research prototype and experimental test platform are developed. The experimental results on the magnetic field, torque output and short-circuit current are provided for verify the analytical models and the proposed MIH magnet pattern well.