A comparison of machine modeling methods for real-time applications

Abstract

Electrical systems utilizing electromagnetic devices, namely power systems of all electric ships, are subject to nonlinearities from regenerative loads, distributed energy storage systems, and onboard loads such as air handling and fluid pumps. Thus, accurate and timely electromagnetic device models are required in order to fully assess the impact of such transient and/or nonlinear activity. Specifically, by exploiting an often overlooked technique, i.e. the Magnetic Equivalent Circuit (MEC) technique, a solution of adequate granularity for the electromagnetic device may be attained while still obeying a faster time commitment when compared to the simulation standard for electromagnetic devices, the finite element analysis (FEA) technique. This paper proposes a benchmarking study considering MEC, FEA, and Fourier series based inductance approximation differential equation modeling methods. A switched reluctance machine (SRM) is used as the case study device due to its inherent nonlinearity and since it provides an ideal foundation for incorporating various characteristics of the MEC modeling technique. In order to highlight the potential accuracy and computational benefits attainable via MEC when compared to FEA and differential equation models of the same machine and system a notional Hardware-in-the-Loop (HIL) applications study is proposed. Such a study simulates the SRM MEC model driven via power electronics and loaded via a mathematical load profile. Ultimately, this work aims to motivate to the development of real-time MEC modeling (RT-MEC).