Impact of Structural Dimensions and Poles on the Torque Performance of Dual-stator Permanent Magnet Machines

Abstract

The impact of structural dimensions and rotor pole numbers on load and no-load torque of dual stator permanent magnet machine is investigated and presented in this work. Finite element analysis (FEA) is adopted in the prediction, since it exhibits higher computation accuracy compared to other methods such as analytical modelling and techniques, etc. Version 15.0 of MAXWELL/ANSYS-2D software is implemented in the entire computations. The considered structural dimensions include: rotor centrifugal size (Rth), aspect ratio (Sr), permanent magnet width (Mth), outer stator tooth width (Tth), rotor outer pole arc/pitch ratio (ϒ1) and rotor inner pole arc/pitch ratio (ϒ2). Also, model topologies having stator pole (S) and rotor pole (P) numbers are compared i.e. 6S/10P, 6S/11P, 6S/13P, and 6S/14P. The results show that the shaft torque and no-load torque would reasonably depend on the adopted machine’s structural dimensions; in addition to the impact of rotor pole number. More so, it is observed that the optimal output torque of a given machine may not necessarily occur at the same operating structural point with that of the required least no-load torque. Implementation of the optimum structural dimensions would result to largest average output electromagnetic torque from the machine. Moreover, practically all the most optimum results are obtained from the 6S/11P machine type. The useable average shaft torque from the simulated models is approximately: 2.33 Nm, 4.16 Nm, 3.75 Nm and 2.31 Nm, for the 6S/10P, 6S/11P, 6S/13P and 6S/14P categories, respectively. Similarly, least values of the no-load torque in the compared machine types are 1.2 Nm, 0.08 Nm, 0.04 Nm and 0.68 Nm i.e. for the 6S/10P, 6S/11P, 6S/13P and 6S/14P machine topologies.

Keywords

• dual stato
• no-load torque
• permanent magnet machine
• pole number
• shaft torque
• structural dimensions