Switched reluctance machines (SRMs) are witnessing increased interests and applications in the industry and scientific communities thanks to the advantages of rigid structures, high reliability and robustness, the absence of permanent magnets, fast dynamic response, and low manufacturing cost. SRMs have become a feasible and popular alternative to conventional electric machines, such as induction machines and permanent magnet machines, with variable speed drives in many applications. Since improving the electromagnetic and thermal performances of an SRM at the design stage is of significant value, this paper presents an in-depth literature review on the status and potential trends of the technology pertinent to the design and optimization of SRMs in the following aspects: the mathematical modeling of the electromagnetic and thermal fields in SRMs, the enhancement of the performances in terms of the torque ripple, acoustic noise, efficiency, and torque density, and the multiobjective design optimization incorporating all the above factors. Finally, the presence of SRMs and their design considerations for specific applications in electric vehicles, aircraft and aerospace systems, wind generators, high speed, and energy storage systems are extensively discussed in this paper. The existing approaches advancing the SRM technologies are systematically and comprehensively summarized and compared for each category.

Modeling, Design Optimization, and Applications of Switched Reluctance Machines—A Review

Theory of Plasticity

The author describes a generalization of the theory of hysteresis to cover asymmetric or minor hysteresis loop excursions The original description of the model was found to be particularly useful because it enabled hysteresis loops of magnetic materials to be successfully modeled with a limited set of only five physically based parameters The extension of the model presented is completely self-consistent with the original formulation and requires no additional parameters to describe the minor loops Results of the model calculations are shown with the objective of demonstrating the morphology of the solutions These display the expected behavior and also include the phenomena of minor loop crossing the partial coincidence of minor loops under certain conditions >

A self consistent generalized model for the calculation of minor loop excursions in the theory of hysteresis

Permanent magnet synchronous motor (PMSM) drive has emerged as one of the most preferred motor drives for industrial applications owing to its distinguished advantages, such as high torque density, high efficiency, and wide speed range operation. However, accurately updated knowledge about the PMSM parameters is crucial to designing a high-performance trajectory tracking controller. This article presents a state-of-the-art comprehensive review and up-to-date progress of the offline and online parameter estimation techniques of the PMSM drives. First, the problems associated with parameter estimation of the PMSM are systematically summarized to identify the parameters having fast and accurate convergence. Second, the offline parameter estimation techniques are categorized based on the frequency and time responses. Third, the recent advances and developments of the online parameter estimation techniques for PMSMs are assessed. Finally, there is a discussion of extensive industrial applications and future research trends for the parameter estimation techniques.

A Comprehensive Review of State-of-the-Art Parameter Estimation Techniques for Permanent Magnet Synchronous Motors in Wide Speed Range

This paper presents a linearized demagnetization model taking into account temperature dependence of the hard magnetic material. At the same time, an efficient searching algorithm is proposed to properly identify the new worst working point and update the recoil line during the entire transient solution process if a working point is discovered below the knee point of the current recoil line. This model is further extended to take into account the temperature dependence of irreversible demagnetization behaviors.

Temperature-Dependent Demagnetization Model of Permanent Magnets for Finite Element Analysis

We present an approach for directly coupling transient magnetic fields and electric circuits. The circuit can contain arbitrarily connected solid conductors located in the magnetic field region. A systematic procedure suitable for both nodal method and loop method is used to couple fields and circuits. The structures of the system equations of the two methods are analogous. The formulations allow the equations in stranded windings and solid conductors to be unified and the coefficient matrix of the system equations to be symmetrical. In order to reduce the solution domain, the periodic boundary conditions are still applicable when the solid conductors are involved. Our approach has been applied to the simulation of electric machines. We give four examples: 1) calculation of the input phase current and output torque when a single-phase induction motor with shaded rings is in locked-rotor operation; 2) simulation of the sudden short circuit of a synchronous generator with starting cage; 3) study of the phase current waveform of an induction motor when the rotor bars are broken; and 4) investigation of the parasitic capacitive impact of the surge voltage on a winding due to drive switching and cable ring.

Modeling of solid conductors in two-dimensional transient finite-element analysis and its application to electric machines

We present a general approach to directly couple finite-element models with arbitrary electric circuits for application to electromagnetic devices. We describe both two-dimensional (2-D) and three-dimensional (3-D) transient finite-element models, with emphasis on 3-D using a T-/spl Omega/ formulation. For 3-D transient and circuit coupling, the derivation of the induced voltage is an integral part of the coupling approach, and the induced voltage links the magnetic field and the electrical circuit together. The system of electric circuits is created automatically. Then graph theory is used to deduce the circuit by tree/cotree and loop analysis. The resulting field equations and circuit equations are coupled together and solved simultaneously at each time step in the time domain. We give three examples of applications: a brushless dc motor drive, a permanent-magnet synchronous motor drive, and a three-phase power transformer with rectifier and load circuit.

Numerical modeling of magnetic devices

This book combines the knowledge of experts from both academia and the software industry to present theories of multiphysics simulation by design for electrical machines, power electronics, and drives. The comprehensive design approach described within supports new applications required by technologies sustaining high drive efficiency. The highlighted framework considers the electric machine at the heart of the entire electric drive. The book also emphasizes the simulation by design concept—a concept that frames the entire highlighted design methodology, which is described and illustrated by various advanced simulation technologies.

Multiphysics Simulation by Design for Electrical Machines, Power Electronics and Drives

An improved vector play model for magnetic hysteresis materials is proposed, and its required parameters are identified from the input major hysteresis loop. Validation results show that this new vector hysteresis model improves the accuracy of core loss computation not only for rotating fields but also for alternating fields compared with the ordinary vector play models. The presented model has been successfully implemented in 2-D and 3-D transient finite element analysis (FEA). Some application results from the 2-D and 3-D transient FEAs are presented.

D. Lin

Papers

Temperature-Dependent Demagnetization Model of Permanent Magnets for Finite Element Analysis

Modeling of solid conductors in two-dimensional transient finite-element analysis and its application to electric machines

Numerical modeling of magnetic devices

Multiphysics Simulation by Design for Electrical Machines, Power Electronics and Drives

Improved Vector Play Model and Parameter Identification for Magnetic Hysteresis Materials