Analytical armature reaction field calculation of permanent magnet pseudo direct drive machines

Purpose The purpose of this paper is to propose an exact and effective method for calculating the armature reaction field distribution of slotted permanent magnet pseudo direct drive (PDD) machines with surface mounted magnets. Design/methodology/approach Based on the Helmholtz’s theorem and using the Maxwell’s equations, two-dimensional analytical expressions are used to calculate the radial and tangential components of the inner and outer air-gap magnetic flux density. Neumann and continuous boundary condition between adjacent regions are used to calculate integration constants. Findings Comparing the results obtained from the proposed method with the results of the finite element method shows that despite the geometrical complexities due to the presence of the modulator openings and slots, the boundary value problem formulation is well implemented with negligible assumptions. Originality/value Effectiveness and accuracy of the proposed approach is assessed on two different sizes slotted PDD machines. Combining the presented analytical method with meta-heuristic methods can be simply used for the optimal design of PDD machines.