Identification and Restoration of IPMSM Nonlinear EM Characteristics for Motion Control Dynamic Simulation

This paper is about identifying electromagnetic (EM) nonlinearities of IPMSM using FEM process; specifically, the extracted nonlinear EM elements are restored into dynamic model for variable speed control simulation. And, for the requirement of being closer to actual IPMSM dynamical behavior, non-ideal aspects such as iron-core saturation and cross-saturation between d-/q- magnetic circuits as well as slot-effects should all be included. The former reveals the temporal harmonics, while the later shows the spatial harmonics. Then, the iron loss resistance (Ri) is introduced by correcting the d-/q- equivalent circuit, so as to account for the magnetic losses associated with the above EM nonlinear elements. In this study, data of these nonlinear elements, such as d-/q- inductances (Ld, Lq), BEMF coefficients (Ke) and cogging torque were extracted through FEM software, which are transformed into Look-Up Table (LUT) blocks and setup in the dynamic circuit-control model. This nonlinearized model (as Model-III) can be verified by coupling simulation between FEM (2D) and relevant dynamic model (as Model-IV) with current output/voltage input method. Besides, through the implementation of this identification and restoration process, the simulation time can be greatly reduced from about 24 hours required by Model-IV to only less than 5 minutes for Model-III, and it still keeps close simulation results between the two models.