Torque Ripple Reduction of Synchronous Reluctance Machine by Using Asymmetrical Barriers and Hybrid Magnetic Core

As there is no need of permanent magnet(PM)material and only silicon steel sheet required on the rotor,synchronous reluctance machine(SynRM)can be used for many applications and draws a great research interest.For the SynRM,the torque ripple is a big issue and a great of work could been done on reducing it.In this paper,asymmetrical magnetic flux barriers in the SynRM rotor were studied comprehensively,including angle and width of each layer and each side of the magnetic barrier.The SynRMb with asymmetrical and parallel magnetic flux barrier was found as the best way to design SynRM based on the multi-objective design optimization method.Moreover,each parameter was studied to show the design rule of the asymmetrical magnetic flux barrier.As the average torque will be reduced with the asymmetrical barrier is used,the grain-oriented silicon steel is used on stator teeth of the SynRMb(SynRMbG)was proposed and studied.The analysis results show that the proposed new method can make the SynRM have better performance.

Square-Wave Drive for Synchronous Reluctance Machine and its Torque Ripple Analysis

Synchronous reluctance machine(SynRM)can be perceived as a special type of permanent magnet synchronous machine(PMSM),and shares similar control method,i.e.the sine-wave current drive with sinusoidal phase currents.In this paper,square-wave drive,which is employed for permanent magnet brushless(BLDC)motors,is employed for the SynRM,in order to economically reduce the cost of rotor position sensor.It is revealed that the torque density and efficiency are slightly sacrificed,whereas torque ripple is deteriorated,proving the SynRM with square-wave drive still promising for the cost-sensitive application if torque ripple is not considered as a critical issue.To further investigate the additional pulsating torque under square-wave drive,mathematical model based on a-b-c phase inductance and d-q axis inductance are established,together with the time-stepping FE calculated currents.It is concluded that the harmonics in the currents tend to cause non-sinusoidal variation of the magnetic reluctance,which can be represented as additional inductance harmonics.The harmonics of the current and inductance interact with each other,thus undesirable torque ripple components are produced.

Design Methods of Transversally Laminated Synchronous Reluctance Machines

Transversally laminated synchronous reluctance machine(SynRM)are usually designed with multiple-layer flux barriers to achieve high electromagnetic performance.This paper summarizes three design methods to optimize the machine.Related implementation procedures are detailed.Besides,advantages and disadvantages of these methods are discussed.Based on these conventional techniques,a comprehensive optimization method is proposed,with which a prototype SynRM is designed.The performances of this prototype are discussed to verify the optimal design method.

Review of Parameter Identification and Sensorless Control Methods for Synchronous Reluctance Machines

Synchronous reluctance machines(SynRMs)have drawn increasing attention in recent years owing to their advantages such as low cost,simple structure,ease of manufacture,and high robustness.The main obstacle to the promotion of SynRMs is severe parameter nonlinearity,which deteriorates drive performance.Sensorless control methods for SynRMs are critical technologies that can broaden the industrial applications of SynRMs.Various methods of parameter identification and sensorless control strategies are reviewed and discussed,including self-commissioning,which is analyzed in detail.Furthermore,sensorless control strategies that can improve the industrial application of SynRMs are described.Finally,future research trends concerning SynRMs are analyzed and discussed.

Recent Development of Reluctance Machines with Different Winding Configurations,Excitation Methods,and Machine Structures

This paper reviews the performances of some newly developed reluctance machines with different winding configurations,excitation methods,stator and rotor structures,and slot/pole number combinations.Both the double layer conventional(DLC-),double layer mutually-coupled(DLMC),single layer conventional(SLC-),and single layer mutually-coupled(SLMC-),as well as fully-pitched(FP)winding configurations have been considered for both rectangular wave and sinewave excitations.Different conduction angles such as unipolar􀫚120°elec.,unipolar/bipolar􀫚180°elec.,bipolar􀫛240°elec.and bipolar􀫜360°elec.have been adopted and the most appropriate conduction angles have been obtained for the SRMs with different winding configurations.In addition,with appropriate conduction angles,the 12-slot/14-pole SRMs with modular stator structure is found to produce similar average torque,but lower torque ripple and iron loss when compared to non-modular 12-slot/8-pole SRMs.With sinewave excitation,the doubly salient synchronous reluctance machines with the DLMC winding can produce the highest average torque at high currents and achieve the highest peak efficiency as well.In order to compare with the conventional synchronous reluctance machines(SynRMs)having flux barriers inside the rotor,the appropriate rotor topologies to obtain the maximum average torque have been investigated for different winding configurations and slot/pole number combinations.Furthermore,some prototypes have been built with different winding configurations,stator structures,and slot/pole combinations to validate the predictions.

Quantitative Comparison of Electromagnetic Performance of Electrical Machines for HEVs/EVs

In this paper,various types of sinusoidal-fed electrical machines,i.e.induction machines(IMs),permanent magnet(PM)machines,synchronous reluctance machines,variable flux machines,wound field machines,are comprehensively reviewed in terms of basic features,merits and demerits,and compared for HEV/EV traction applications.Their latest developments are highlighted while their electromagnetic performance are quantitatively compared based on the same specification as the Prius 2010 interior PM(IPM)machine,including the torque/power-speed characteristics,power factor,efficiency map,and drive cycle based overall efficiency.It is found that PM-assisted synchronous reluctance machines are the most promising alternatives to IPM machines with lower cost and potentially higher overall efficiency.Although IMs are cheaper and have better overload capability,they exhibit lower efficiency and power factor.Other electrical machines,such as synchronous reluctance machines,wound field machines,as well as many other newly developed machines,are currently less attractive due to lower torque density and efficiency.

Advanced Computer-aided Design and Analysis for Synchronous Reluctance-Permanent Magnet Machines

This paper presents an advanced computer aided design (CAD) package for the synthesis, analysis, and optimization of synchronous reluctance combined with permanent magnet (SR PM) machines. The distinguishing features of the CAD package are that it allows a wide range of design options and parameter variations for the new type of machines, calculations of optimization for maximum efficiency and higher power density, and various performance. The package as described in the main text permits the integration of the machine design with an electronic controller, along with the simulation of the whole system. Through the optimal design, characteristic calculations, and system simulations, the CAD package offers a superior design for the SR PM machines, and presents a feasibility frontier outlined by the design.