Switched Reluctance Machines (SRMs) are gaining more attention due to their simple and rugged construction, low manufacturing cost, and high-speed operation capability. An electromagnetic model of the machine is needed in the design and analysis processes. The required accuracy level of the model depends mainly on the application. A high-fidelity model is required to achieve a good design and predict the performance accurately. However, it requires high computational cost and longer simulation time. Other fast and less-comprehensive models with less computational burden could be utilized in the design and analysis of the motor drives. This paper extensively analyzes various electromagnetic modeling techniques of SRMs. Analytical, numerical, and hybrid models are considered. The paper investigates analytical models that are based on Maxwell's equations in addition to interpolation and curve fitting techniques. Numerical techniques such as Finite Element Method (FEM) and Boundary Element Method (BEM) are presented. Moreover, Magnetic Equivalent Circuit (MEC) method is discussed. Finally, potential research areas are proposed for the electromagnetic modeling of SRMs.

Designing a switched reluctance machine (SRM) is an iterative process. Sizing of the motor is one of the fundamental steps where the main geometry parameters are determined to achieve the performance requirements. Usually, finite element method (FEM) is employed in all design stages, which might require extensive computational burden. The magnetic equivalent circuit (MEC) method is an alternative for typical FEM. There are two approaches for the MEC method: conventional MEC method and reluctance mesh-based MEC method. The conventional MEC method can be challenging when modifying the motor geometry while conducting dynamic analysis with current control. This article presents a reluctance mesh-based MEC model for SRMs that can overcome those challenges. Reluctance mesh-based MEC models are developed for three-phase 6/4, 6/16, 12/8 SRMs and four-phase 8/6, 8/10, and 16/12 SRMs. The models calculate the static and dynamic characteristics of the considered SRMs. The static and dynamic characteristics are compared with the results obtained from FEM and experimental tests.

Operating capabilities of a dual-inverter open-winding interior permanent magnet synchronous motor (IPMSM) drive are investigated and compared with those of a conventional single-inverter drive in maximum torque per ampere (MTPA) and field-weakening (FW) regions. To predict the performance and operating limits of the drive systems with improved accuracy, the impact of saturation on inductances and permanent magnet (PM) flux linkage values are taken into account, and core, copper, friction and windage, and solid losses are considered in a wide speed range. Performance prediction is conducted using machine's electromagnetic parameters and losses that are obtained via finite element analysis, coupled with an optimization algorithm to find optimal operating points in MTPA and FW regions. The analytical findings are further validated against experimental results obtained from a 1-kW dual-inverter IPMSM motor drive.

Acoustic noise and vibration is one of the shortcomings of a switched reluctance machine (SRM). Harmonics of the radial force waveform in the airgap excite the stator structure at different vibration modes with specific frequencies. The radial force density in the airgap should be calculated before analyzing and mitigating acoustic noise and vibration. This paper proposes a reluctance mesh-based magnetic equivalent circuit (MEC) model to calculate the airgap radial force density. Reluctance mesh-based MEC models are developed for 3-phase 6/4, 6/16, 12/8 and 4-phase 8/6, 8/10, and 16/12 SRMs. A technique for the dynamic modeling of SRMs is proposed using the reluctance mesh-based MEC method. Dynamic currents are calculated using the proposed technique and, then, the radial and tangential flux density in the airgap are calculated. The radial force density in the airgap is calculated by applying the Maxwell Stress Tensor method. Fourier series is used to calculate the harmonics of the radial force density. The results obtained from the MEC model are verified using finite element method (FEM) models. The implemented MEC-based dynamic modeling method is validated using experimental results.

The switched reluctance motor (SRM) is a promising candidate for electric propulsion systems. In the design process of an SRM, the motor geometry needs to be determined. Using the finite element method (FEM) might be time-consuming for the sizing of the motor geometry. As an alternative, electromagnetic models based on a magnetic equivalent circuit (MEC) can be utilized for the sizing of an SRM. MEC models require fewer computational resources and can help determine the electromagnetic performance with reasonable accuracy. Using the conventional MEC method for SRM sizing might be challenging since the flux pattern inside the motor should be changed for different motor dimensions. In order to address this challenge, this paper applies a reluctance mesh-based MEC technique to determine the geometry of a three-phase 12/16 SRM for a high-lift motor in the NASA Maxwell X-57 electric aircraft. A comprehensive reluctance mesh-based MEC model is developed for this purpose. Both the static and dynamic characteristics of the SRM geometry are evaluated using the reluctance mesh-based MEC method. The determined geometry is verified using the results computed from FEM.