Low-speed high-torque permanent magnet direct drive machine (LSPMDM) overcomes the shortcomings of traditional drive system, but its volume is large. In this paper, the numerical relationship between the motor
external diameter and the rated speed is deduced, and improvement of the torque density is qualitatively analyzed for a dual-stator motor. Owing to that semi-inserted magnetic circuit structure and auxiliary slots under
the poles can further increase the torque density of the motor, the effect of the shape, number and position of the auxiliary slots on the salient pole rate is also studied through comparative analysis. By incorporating the
merits of dual-stator motor and semi-inserted magnetic circuit structure with the auxiliary slots, a novel motor topology is proposed, which is verified by finite element analysis with good performance.