Design of look up tables for a hybrid dynamic model of an IPM machine

Accurate, computationally-efficient modelling is necessary for the study of interior permanent magnet (IPM) machines’ dynamic performance considering their widespread industrial use. Hybrid models combining look up tables (LUT) and dynamic dq-models are a common method of incorporating non-linear effects whilst limiting computational cost. LUT construction for a dynamic hybrid dq-finite element analysis (FEA) model of an interior permanent magnet (IPM) machine is carried out to reduce computational demand. Minimising computation time for LUT construction by selecting uneven current steps when generating FEA data points is investigated. Furthermore, the effects of model fitting and interpolation (F&I) techniques on the accuracy of the LUT are studied with the number of FEA simulated data points being adjusted based on the results. The effects of LUT grid size on LUT construction time and accuracy are determined, and interpolation methods applied to the final implementation of the LUT within Simulink are compared. Significant variation in accuracy of F&I techniques was found, with different techniques performing best for each LUT. The LUT computational time could be further reduced through careful selection of FEA generated points with potential to optimise point selection in future work.