Flux concentrating axial ferrite magnet motor

Two stator axial motors are studied over different magnetization methods. As the rotor magnets, a high energy product ferrite (NMF-12G) is used. It has a 20 pole, 24 slot structure, and concentrated pole windings. Each piece of tooth is made by stacking three different size of sheets, and can be assembled into the pan cake type back iron disk. The back iron is made by rolling a long thin steel strip. Throughout the paper, flux concentrating and axial magnetizations are compared in magnet usage and torque ripple. Proper magnet ratio is found by analyzing the simplified linear motor model. The flux concentrating method is more favorable in reducing the permanent magnet (PM) usage, but it has more torque ripple. The saving amount is more than 15%. Simulations were carried out by a commercial 3-D FEM tool.