An Enhanced Field Reconstruction Method for Design of Permanent Magnet Synchronous Machines

Knowledge of forces within permanent magnet synchronous machines (PMSMs) is of interest in numerous applications. To compute the forces, many analysts utilize the finite element (FE) method to compute the vector fields followed by the Maxwell stress tensor (MST) approach to calculate forces from the fields. Although the FE/MST approach has been used for decades, it does have a shortcoming in the computational requirement of the FE method, which limits the approach to a tool for analysis rather than for comprehensive machine design. To address this, a new so-called Enhanced Field Reconstruction Technique (EFRT) has been developed. Using the EFRT, the fields inside a machine are computed using a minimum number of FE evaluations. Using the results, a set of basis functions are established that enable the calculation of forces inside the machine under arbitrary excitation and rotor position. The EFRT greatly reduces the computational effort required to compute the vector forces inside machines with an accuracy similar to the FE method.