This paper presents a technical overview for low-noise switched reluctance motor (SRM) drives in electric vehicle (EV) applications. With ever-increasing concerns over environmental and cost issues associated with permanent magnet machines, there is a technical trend to utilize SRMs in some mass production markets. The SRM is gaining much interest for EVs due to its rare-earth-free characteristic and excellent performance. In spite of many advantages compared with conventional adjustable-speed drives, SRMs suffer from torque ripple and radial distortion (and thus noise and vibration) by their nature. Therefore, for high-performance vehicle applications, it is important and urgent to optimize the SRM system to overcome the drawbacks of the noise and vibration. In order to present clear solutions to the acoustic noise in SRMs, this paper starts by analyzing the mechanism of the radial vibration and torque ripples inherent in the motors, and then focuses on the state-of-the-art technologies to mitigate the radial force and torque ripples. It highlights two categories for low-noise SRMs, including the machine topology improvement and control strategy design for radial vibration mitigation and torque ripple reduction. Advanced technologies are reviewed, classified, and compared accordingly. In addition to these methodologies, the schemes that have been developed by authors are also presented and discussed. Finally, the research status on this topic is summarized and forecast research hotspots are presented. It is our intention that this paper provides the guidance on performance improvements for low-noise SRM drives in EV applications.

A Review on Machine Topologies and Control Techniques for Low-Noise Switched Reluctance Motors in Electric Vehicle Applications

This paper presents a multiphysics modeling of a switched reluctance motor (SRM) to simulate the acoustic radiation of the electrical machine. The proposed method uses a 2-D finite-element model of the motor to simulate its magnetic properties and a multiphysics mechatronic model of the motor and controls to simulate operating conditions. Magnetic forces on the stator are calculated using finite-element analysis and are used as the excitation on a forced response analysis that contains a finite-element model of the motor stator structure. Finally, sound power levels are calculated using the boundary element method. Simulation results of the model are shown and compared with experimental measurements for a four-phase 8/6 SRM.

Multiphysics NVH Modeling: Simulation of a Switched Reluctance Motor for an Electric Vehicle

A thermal model for the determination of the temperatures of interior permanent magnets and stator windings is presented in this paper. The innovation of the model relies on one temperature sensor being located in the stator core of the machine. Such sensor is simple to implement in many applications such as traction or EV, where reliability is critical. The estimated stator winding and permanent magnet temperatures are determined by a simplified thermal lumped element network model with only two time constants. It is shown that the proposed thermal model is very robust due to the structure of the model and the measured stator core temperature. The distortion of the temperature estimates caused by the cooling circuit is inherently accounted for such that the model can be used for robust online prediction of temperatures. Experimental results based on a forced water-cooled interior permanent magnet synchronous machine setup are presented to validate the effectiveness of the presented model.

A Practical Thermal Model for the Estimation of Permanent Magnet and Stator Winding Temperatures

Loss Minimization Control of Permanent Magnet Synchronous Motor Drives

This paper proposes an effective and scientific method for the construction of a representative driving cycle for electric vehicles (EV) and takes it as a foundation for studying the energy consumption and equivalent emissions for EV. First, a test route is developed through the analysis of the topology of the Xi'an road structure and traffic flow. Second, the vehicle driving pattern data is gathered through an integrated method of chase car method and on-board method. The velocity-acceleration (V-A) grid method is used to divide speed and acceleration data into micro-states. Third, the proposed driving cycle construction method incorporates the Markov chain and Monte Carlo (MCMC) simulation method. Then, a filter process is designed to screen out the most representative driving cycle. Finally, the comparison of the simulation result and test results shows the constructed EV driving cycle is in line with reality, and estimating the EV's energy consumption per kilometer, driving range, and equivalent emissions under official driving cycles results in large relative errors. Therefore, the construction of a real-world driving cycle for specific cities or areas is necessary to evaluate energy consumption, driving range, and equivalent emissions of EV.

Construction of electric vehicle driving cycle for studying electric vehicle energy consumption and equivalent emissions

This paper describes the modeling of a permanent magnet synchronous machine (PMSM) by using lumped models (LMs). Designing electrical machines necessarily involves several fields of physics, such as electromagnetics, thermics, mechanics, and acoustics. Magnetic, electrical, electronic, and thermal parts are represented by LMs, whereas vibro-acoustic and mechanical parts are represented by analytical models. The aim of this study is to build a design model of a PMSM for traction applications. Each model is parameterized to optimize the machine. The method of taking into account saturation and movement is described. These fast, LMs make it possible to couple the software used with optimization tools. Simulation results are presented and compared with the finite-element method and the experiments performed.

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Multiphysics Modeling of a Permanent Magnet Synchronous Machine by Using Lumped Models

In this paper, the design optimization of a nonsalient high-speed permanent magnet synchronous machine (PMSM) for electric vehicle applications is presented. It will be shown how, with a new approach, it is possible to find a deterministic solution to solve the sizing of the machine from a given driving cycle. The optimal geometry and the optimal control strategy over the cycle minimizing both the energy losses and the volume of the machine will be calculated. At first, the one-dimensional analytical model used is presented and validated for the most significant point of the driving cycle using a finite element method. Then, the design methodology and the results through a specific application are detailed. Particularly, it will be shown how the flux weakening, directly given by the design process via the optimization of the control strategy, allows reducing both the energy losses and the constraints on the power converter. At last, in order to validate the solution considering the whole cycle while keeping a reduced computation time, a reluctance network model of the PMSM is used. This model validate the energy losses and the flux densities in the steel parts over the cycle. The study will be done considering the urban dynamometer driving schedule.

Design Optimization with Flux Weakening of High-Speed PMSM for Electrical Vehicle Considering the Driving Cycle

A novel transverse-flux permanent magnet linear motor (TFPMLM) named as double-sided double-excited one is proposed in this paper. First, the operational principle and structural advantages of the TFPMLM are presented. Then, the 3-D magnetic circuit structure of the TFPMLM is simplified equivalently into a 2-D one in order that Schwarz–Christoffel (SC) mapping method can be adopted to analyze the motor’s magnetic field and characteristics. Then, the air-gap flux density distribution, back voltage and force waveforms when at no-load and at load are calculated by the SC mapping method and 3-D finite-element method, respectively, for a prototype linear motor, The results from the two methods coincide much better with each other. At last, influences of magnet shape on the cogging force are studied by the SC method.

Presentation of a Novel Transverse-Flux Permanent Magnet Linear Motor and Its Magnetic Field Analysis Based on Schwarz–Christoffel Mapping Method

Afin de definir une conception optimale d’un systeme electromecanique, celui-ci doit integrer des contraintes toujours plus drastiques et de nombreux phenomenes physiques issus de : l’electromagnetique, l’aerothermique, l’electronique, la mecanique et l’acoustique. L’originalite de cette these est de proposer une modelisation multi-physique pour la conception reposant sur des modeles a constantes localisees : solution intermediaire entre la modelisation analytique et numerique. Ces differents modeles permettront l’etude et la conception sous contraintes d’une machine synchrone a aimants permanents dediee pour la traction ferroviaire. Les resultats de simulations seront compares a des resultats elements finis mais aussi a des essais experimentaux. Ce modele multi-physique est entierement parametre afin d’etre associe a des outils d’optimisation. On utilisera ici une optimisation par essaim de particules pour chercher des compromis entre differents objectifs sous forme de Front de Pareto. Dans ce papier, nous ciblerons les objectifs suivants : le couple d’origine electromagnetique et le bruit d’origine electromagnetique. Finalement une etude de sensibilite valide la robustesse de la conception retenue quand celle-ci est soumise aux contraintes de fabrication. L’objectif etant de poser les bases d’un outil d’aide a la decision pour le choix d’une machine electrique

Modélisation multi-physique par modèles à constantes localisées ; application à une machine synchrone à aimants permanents en vue de son dimensionnement.

The aim of this paper is to simulate a large power brushless synchronous generator (BLSG) used for large turbo-alternator brushless excitation systems, under conditions of saturation and rotating rectifier diode failures. A reluctance network coupled with electric circuits and power electronic components integrating the movement and nonlinearities of materials has been developed. The approach achieves good compromise between accuracy and computing time for the complete analysis of a 39 phase machine with 117 teeth and 22 poles, and 78 diodes in the associated rectifier bridge. Our model is validated by comparison with experimental measurements and numerical simulation by a finite element package. For the simulations presented, a gain in computation time of 800 can be obtained compared with a finite element model. Different results are calculated for healthy and faulty states to study the impact of open diode block failure. Simulation results show that open diode failures have little effect on the rectified output voltage but the current through diodes and protection fuses increases. The currents in armature phase coil are very affected due to failures. A flux sensor coil can be placed on the stator pole to capture the impact of failures. The harmonic content of the pole flux can be used to monitor and detect diode failures.

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Nicolas Bracikowski

Papers

Multiphysics Modeling of a Permanent Magnet Synchronous Machine by Using Lumped Models

Design Optimization with Flux Weakening of High-Speed PMSM for Electrical Vehicle Considering the Driving Cycle

Presentation of a Novel Transverse-Flux Permanent Magnet Linear Motor and Its Magnetic Field Analysis Based on Schwarz–Christoffel Mapping Method

Modélisation multi-physique par modèles à constantes localisées ; application à une machine synchrone à aimants permanents en vue de son dimensionnement.

Simulation of a large power Brushless Synchronous Generator (BLSG) with a rotating rectifier by a reluctance network for fault analysis and diagnosis