High torque density low speed permanent magnet machine

This paper gives different solutions in order to increase torque density of permanent magnets machines. The study deals with low frequency machines and, in this case, iron losses are less important than copper losses, so that supplying the machines with square wave currents can be interesting. The authors identify an original structure in which the end winding parts are removed. The description of this topology and design comparison with machines having end winding emphasize the limits of this structure: it is difficult to keep a high efficiency system with this new topology due to the losses in the power electronics.