Israel’s consul-general reluctant to leave

'Chengdu has sufficient strength to attract an increasing number of international trend-setters.I have already become a genuine Chengdu trend-setter.'—Amir Lati,Israel consulgeneral in Chengdu Amir Lati,Israel’s consul-general in Chengdu,has worked and lived in the city for three and a half years.From his perspective,Chengdu,which is situated at the

Analysis and Research on Mechanical Stress and Multiobjective Optimization of Synchronous Reluctance Motor

The mechanical strength of the synchronous reluctance motor(SynRM)has always been a great challenge.This paper presents an analysis method for assessing stress equivalence and magnetic bridge stress interaction,along with a multiobjective optimization approach.Considering the complex flux barrier structure and inevitable stress concentration at the bridge,the finite element model suitable for SynRM is established.Initially,a neural network structure with two inputs,one output,and three layers is established.Continuous functions are constructed to enhance accuracy.Additionally,the equivalent stress can be converted into a contour distribution of a three-dimensional stress graph.The contour line distribution illustrates the matching scheme for magnetic bridge lengths under equivalent stress.Moreover,the paper explores the analysis of magnetic bridge interaction stress.The optimization levels corresponding to the length of each magnetic bridge are defined,and each level is analyzed by the finite element method.The Taguchi method is used to determine the specific gravity of the stress source on each magnetic bridge.Based on this,a multiobjective optimization employing the Multiobjective Particle Swarm Optimization(MOPSO)technique is introduced.By taking the rotor magnetic bridge as the design parameter,ten optimization objectives including air-gap flux density,sinusoidal property,average torque,torque ripple,and mechanical stress are optimized.The relationship between the optimization objectives and the design parameters can be obtained based on the response surface method(RSM)to avoid too many experimental samples.The optimized model is compared with the initial model,and the optimized effect is verified.Finally,the temperature distribution of under rated working conditions is analyzed,providing support for addressing thermal stress as mentioned earlier.

Five-phase Synchronous Reluctance Machines Equipped with a Novel Type of Fractional Slot Winding

Multi-phase machines are so attractive for electrical machine designers because of their valuable advantages such as high reliability and fault tolerant ability.Meanwhile,fractional slot concentrated windings(FSCW)are well known because of short end winding length,simple structure,field weakening sufficiency,fault tolerant capability and higher slot fill factor.The five-phase machines equipped with FSCW,are very good candidates for the purpose of designing motors for high reliable applications,like electric cars,major transporting buses,high speed trains and massive trucks.But,in comparison to the general distributed windings,the FSCWs contain high magnetomotive force(MMF)space harmonic contents,which cause unwanted effects on the machine ability,such as localized iron saturation and core losses.This manuscript introduces several new five-phase fractional slot winding layouts,by the means of slot shifting concept in order to design the new types of synchronous reluctance motors(SynRels).In order to examine the proposed winding’s performances,three sample machines are designed as case studies,and analytical study and finite element analysis(FEA)is used for validation.

A CONTROL STRATEGY OF SWITCHED RELUCTANCE MOTOR FOR ELECTRIC VEHICLE APPLICATION

A control strategy of switched reluctance motor (SRM)for electric vehicle applications is proposed. In electric vehicle application, the switched reluctance motor is a good choice with its flexible control method, compactness, robustness, high efficiency and high starting torque. In this paper, the control strategy of motoring and regenerative braking for electric vehicle application is presented. Computer simulations are employed to analyze the steady state behavior of SRM propulsion system. Experimental results in electric motorcycle are provided to demonstrate the validity of SRM propulsion system.

开关磁阻电机的模糊自适应简化控制

为解决开关磁阻电机运行中存在的强耦合、非线性等问题,将模糊自适应控制技术应用到开关磁阻电机调速控制中。通过分析运行中速度误差和误差增量对模糊控制输出量的影响,同时考虑到开关磁阻电机自身的特性,建立了带有校正因子的输出量与误差、误差变量之间的关系,在兼顾计算量和性能的基础上,提出了一种简化的校正因子选择方法,从而实现了根据运行条件在线改变模糊规则。同时,在一台8/6四相开关磁阻电机上分别采用传统PI控制和简化模糊自适应方法进行了试验验证。对比研究结果证明,简化的模糊自适应方法能够有效提高开关磁阻电机调速的鲁棒性。通过使用Matlab仿真,验证了校正因子对模糊控制的影响,简化的模糊自适应方法能够应用于不同的情况,具有较好的动静态性能。

基于单片机和CPLD的SRM调速系统设计

针对开关磁阻电机SRM(Switched Reluctante Motor)非线性程度高,调速控制难度大等特点,设计提出了以单片机和CPLD为构架的开关磁阻电机(SRM)调速系统,系统采用双闭环结构,电机位置信息与电流信号通过传感器采集反馈回控制器,控制方法采用系统控制指令和电机控制策略分离协同执行的方法,与传统SRM控制不同,将控制策略的执行全部交给CPLD,利用CPLD控制精度高的优点,生成PWM控制波形,实现电机调速,有效提高了系统效率并降低了开发成本。另外,在控制策略方面,由于SRM非线性程度高、变参数等特点,如果采用传统的PID控制则控制性能较差,文中设计了基于模糊控制的控制策略,利用模糊控制,建立模糊自适应PID控制器,提高了系统的鲁棒性。文中对调速系统的设计方案进行了详细阐述与分析。

Influence of Magnetic Reluctances of Magnetic Elements on Servo Valve Torque Motors

The current research of electro-hydraulic servo valves mainly focuses on the vibration, pressure oscillating and source of noise. Unfortunately, literatures relating to the study of the influence of the magnetic reluctances of the magnetic elements are rarely available. This paper aims to analyze the influence of the magnetic reluctances of the magnetic elements on torque motor. Considering these magnetic reluctances ignored in previous literatures, a new mathematical model of servo valve torque motor is developed and proposed based on the fundamental laws of electromagnetism. By using this new mathematical model and the previous models, electromagnetic torque constant and magnetic spring stiffness are evaluated for a given set of torque motor parameters. A computer simulation by using AMESim software is also performed for the same set of torque motor parameters to verify the proposed model. The theoretical results of electromagnetic torque constant and magnetic spring stiffness evaluated by the proposed model render closer agreement with the simulation results than those evaluated by the previous models. In addition, an experimental measurement of the magnetic flux densities in the air-gaps is carried out by using SFL218 servo valve torque motor. Compared with the theoretical results of the magnetic flux densities in the air-gaps evaluated by the previous models, the theoretical results evaluated by the proposed model also show better agreement with the experimental data. The proposed model shows the influence of the magnetic reluctances of the magnetic elements on the servo valve torque motor, and offers modified and analytical expressions to electromagnetic torque constant and magnetic spring stiffness. These modified and analytical expressions could provide guidance more accurately for a linear control design approach and sensitivity analysis on electro-hydraulic servo valves than the previous expressions.

Large power analysis of switched reluctance machine system for coal mine

The conventional structures in the Switched Reluctance machines are introduced, such as three-phase 12/8 structure Switched Reluctance machine, three-phase 6/4 structure Switched Reluctance machine, four-phase 16/12 structure Switched Reluctance machine, and four-phase 8/6 structure Switched Reluctance machine. Three-phase 12/8 structure Switched Reluctance machine is the best choice for the large power Switched Reluctance machine system in coal mines. The asymmetric bridge power converter main circuit and the bifilar winding power converter main circuit are also introduced. Three-phase asymmetric bridge power converter main circuit is the best choice for the large power Switched Reluctance machine system in coal mines. The magnetic paths of the designed large power motor are given with one phase excitation and double phases excitation. The phase current waveforms are also given.

Optimization of reluctance accelerator efficiency by an improved discharging circuit

In this paper,an improved discharging circuit was proposed to quicken the decay of the current in the drive coil in a reluctance accelerator when the armature reaches the center of the coil.The aim of this is to prevent the suck-back effect caused by the residual current in drive coil.The method is adding a reverse charging branch with a small capacitor in the traditional pulsed discharging circuit.The results under the traditional circuit and the improved circuit were compared in a simulation.The experiment then verified the simulations and they had good agreement.Simulation and experiment both demonstrated the improved circuit can effectively prevent the suck-back effect and increase the efficiency.At the voltage of 800 V,an efficiency increase of 36.34% was obtained.

Passive adaptive control of chaos in synchronous reluctance motor

The performance of synchronous reluctance motor （SynRM） degrades due to chaos when its systemic parameters fall into a certain area. To control the undesirable chaos in SynRM, a passive control law is presented in this paper, which transforms the chaotic SynRM into an equivalent passive system. It is proved that the equivalent system can be asymptotically stabilized at the set equilibrium point, namely, chaos in SynRM can be controlled. Moreover, in order to eliminate the influence of undeterministic parameters, an adaptive law is introduced into the designed controller. Computer simulation results show that the proposed controller is very effective and robust against the uncertainties in systemic parameters. The present study may help to maintain the secure operation of industrial servo drive system.

Accurate Torque Modeling With PSO-Based Recursive Robust LSSVR for a Segmented-Rotor Switched Reluctance Motor

In order to improve the reliability in torque calculation of SRM,an accurate nonlinear torque model regresses by recursive robust least squares support vector regression(RR-LSSVR)is proposed in this paper.The model is in terms of a segmented-rotor switched reluctance motor(SSRM).The characteristics of the SSRM is introduced to show its nonlinear characteristics both in magnetic and torque.Then,its mathematic model is established,and an accurate inductance measurement method and a torque calculation method are presented.After this,the principle of the RR-LSSVR and why it can adjust weights according to errors are described.The model used the RR-LSSVR algorithm shows an outstanding capability in accuracy and quickness compared with other algorithms.Finally,to further validate the accuracy of the proposed model in practical application,simulation and experiment are designed based on a 16/10 SSRM.

Research of Reinforced Excitation Scheme for the Switched Reluctance Generator

This paper focuses on the reinforced excitation scheme for the switched reluctance generator (SRG) operating in a low voltage and wide speed range system. From the operational principle of SRG discussed, it can be seen that the key element to SRG generating is the reasonable and sufficient excitation. So the reinforced excitation scheme is addressed and proved by the tests of an SRG system.

RESEARCH OF THE SWITCHED RELUCTANCE STARTER/GENERATOR SYSTEMS

This paper focuses on the simulation and test of the switched reluctance starter/generator systems. Through the emulational analysis of the initial starting torque, the optimal turn-on section of the power switches is discovered. The fundamental theory of the generating operation is analyzed with the linearity model, and a new method is presented based on voltage pulse width modulation for the generating mode control. Through the steady-state and optimized emulation of the output power and system efficiency, the optimizational control approach for the generating mode over a wide speed range is introduced. At last, the test of the 3KW prototype system shows that the dynamic and static performance of this system is fine.

Study on the influence of armature on the efficiency of reluctance accelerator

The armature is an important part affecting the energy conversion efficiency of a reluctance accelerator.In this paper,six kinds of soft magnetic materials are chosen and four structures are designed for the armature.At first,the circuit and magnetic force are theoretically analyzed.Then the armatures with different materials and structures are used in the simulation,and the performances are compared and analyzed.At last,the experiment verifies the theory analysis and simulation design.It is concluded that the saturation flux density and conductivity of the material are the key factors affecting the armature force,and the optimization of armature structure can effectively restrain the eddy current,reduce negative force and improve efficiency.Compared with cutting slits in solid armatures,laminating the sheets radially can reduce the eddy current more efficiently.Although slitting can prevent the eddy current to a certain extent,meanwhile,it will decrease the magnetic force because of the losing of magnetized volume and the surface area.Hence,choosing the high saturation flux density material and making out the armature with radially_laminated sheets will improve the efficiency of the reluctance accelerator.In this paper,the silicon steel radially_laminated armature is a better choice for the armature design of the reluctance accelerator.

Optimal design of linear switched reluctance motor for sea wave power generation

The switchless reluctance motor’s non-permanent magnet structure design ensures its high reliability in the marine environment;thus,it is a feasible solution for the generator of a sea wave power generation system.However,the corresponding thrust density and efficiency remain insufficient.This study focused on a new type of flat linear switched reluctance motor(LSRM),using the finite element software to establish a structural model,and optimized the design with the goal of improving the efficiency and energy density.The entropy method was adopted for sensitivity stratification to objectively select weights to avoid the influence of subjectively selected different proportional weights on the optimization results.Based on the entropy method,the sensitivity of different structural parameters was stratified,and the simulated annealing algorithm,response surface method,and single parameter scanning method were combined for optimization.Finally,the optimal structural size parameters of the motor were determined.Based on the two-dimensional finite element method,to simulate the electromagnetic performance of the reluctance motor under different operating conditions,such as thrust,loss,and efficiency,changes in motor performance before and after optimization were compared to verify the high power generation efficiency and energy density of the optimized linear motor.

High Speed SRM Using Vector Control for Electric Vehicle

The high speed motor is effective to realize downsizing motor in an electric vehicle(EV).Switched Reluctance Motor(SRM)is possible to the high speed drive because the rotor structure has simple and robust.However,the vibration and the acoustic noise are large from the drive principle.Moreover,the conventional complicated current excitation results in the difficulty of the torque controller design.To overcome these problems,the vector control has been proposed for SRM drive.However,the vector control has not been applied to the SRM in the high speed drive.In this paper,the drive conditions such as switching frequency,bus voltage for driving the SRM in the high speed region are clarified.It is shown that the proposed SRM can be driven by the vector control in the high speed region and can realize low vibration.

Four-quadrant Force Control with Minimal Ripple for Linear Switched Reluctance Machines

Linear switch reluctance machine(LSRM)has been tried to act as an alternative generator for direct drive linear wave energy converter(WEC).Many researchers have proposed new topologies of LSRM to improve the power density,efficiency and reliability.However,the control methods for LSRM applied in direct drive WEC have been paid little attention,especially control methods considering the wave energy generator operating characteristics.In this paper,according to the generator control requirements of the direct drive WEC,force control algorithm for LSRM operating in four quadrants without a speed closed loop is put forward.The force ripple of LSRM is suppressed using force sharing function method.The four-quadrant control is easy to realize requiring only phase currents information.Simulation results validate the proposed method and indicate that LSRM is able to be used as the generator for direct drive WEC.

Improvement Torque Performances of Interior Permanent-Magnet Machines

Due to their excellent efficiency,power density and constant power speed region,interior permanent-magnet(IPM)machines are very suitable for electric vehicles(EVs).This paper proposed a new IPM rotor topology,which can offer high reluctance torque,wide constant power speed range and excellent overload capability.Besides,five rotor topologies with integral-slot distributed-windings IPM machines,including four existing IPM topologies and the proposed IPM topology,are designed optimally.Their characteristics,which include d-q axis inductances,saliency ratios,electromagnetic torques,corresponding torque ripples,back-electromotive forces(EMFs),overload capabilities and flux weakening performances are evaluated quantitatively.Finally,a three phase 48s8p hybrid rotor PM machine is built to verify the performances of the proposed IPM machine.This work provides some general concepts for machine developers who are willing to build IPM machines for high-performance EV applications.

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.

Study on Magnetic Shielding for Performance Improvement of Axial-Field Dual-Rotor Segmented Switched Reluctance Machine

A category of permanent-magnet-shield(PM-shield)axial-field dual-rotor segmented switched reluctance machines(ADS-SRMs)are presented in this paper.These topologies are featured by using the magnetic material to shield the flux leakage in the stator and rotor parts.Besides,the deployed magnets weaken the magnetic saturation in the iron core,thus increasing the main flux.Hence,the torque-production capability can be increased effectively.All the PM-shield topologies are proposed and designed based on the magnetic equivalent circuit(MEC)model of ADS-SRM,which is the original design deploying no magnet.The features of all the PM-shield topologies are compared with the original design in terms of the magnetic field distributions,flux linkages,phase inductances,torque components,and followed by their motion-coupled analyses on the torque-production capabilities,copper losses,and efficiencies.Considering the cost reduction and the stable ferrite-magnet supply,an alternative proposal using the ferrite magnets is applied to the magnetic shielding.The magnet demagnetization analysis incorporated with the thermal behavior is performed for further verification of the motor performance.