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.

Analysis and Comparison of Power Electronic Converters for Conventional and Toroidal Switched Reluctance Machines

Different power electronic converter topologies are introduced in this paper for both Conventional Switched Reluctance Machine (CSRM) and Toroidal Switched Reluctance Machine (TSRM) drive systems. Their commutation, switch and diode currents, power losses, and efficiencies under over modulation operation are analyzed and compared for converter characteristics study, performance evaluation and topology selection for CSRM and TSRM drive systems. The switch and diode silicon volumes required for each CSRM and TSRM drives are also compared according to their corresponding currents at the equivalent machine torque versus speed operating points.

Torque Sharing Function Control of Switched Reluctance Machines with Reduced Current Sensors

This paper presents a Torque Sharing Function(TSF)control of Switched Reluctance Machines(SRMs)with different current sensor placements to reconstruct the phase currents.TSF requires precise phase current information to ensure accurate torque control.Two proposed methods with different chopping transistors or a new PWM implementation require four or two current sensors to replace the current sensors on each phase regardless of the phase number.For both approaches,the actual phase current can be easily extracted during the single phase conducting region.However,how to separate the incoming and outgoing phase current values during the commutation region is the difficult issue to deal with.In order to derive these two adjacent currents,the explanations and comparisons of two proposed methods are described.Their effectiveness is verified by experimental results on a four-phase 8/6 SRM.Finally,the approach with a new PWM implementation is selected,which requires only two current sensors for reducing the number of sensors.The control system can be more compact and cheaper.

Generic meminductive characteristics of switched reluctance machines

The meminductive system can be regarded as the generalization of the meminductor. This paper focuses on exploring the generic meminductive characteristics of the switched reluctance machine （SRM）. The dynamical equations of SRM sys- tems are derived and discussed in comparison with the typical constitutive relation equations of the meminductive system. Memory ability and pinched hysteresis loop （PHL） are taken as the indicative fingerprints to draw forth the theoretically comparative analysis. Based on the theoretical analysis, in addition to simulation and experimental confirmation, it can be concluded that from the viewpoint of circuit, SRM can be considered as a generic meminductive system.

Performance Evaluation and Comparison of Multi - Objective Optimization Algorithms for the Analytical Design of Switched Reluctance Machines

This paper systematically evaluates and compares three well-engineered and popular multi-objective optimization algorithms for the design of switched reluctance machines.The multi-physics and multi-objective nature of electric machine design problems are discussed,followed by benchmark studies comparing generic algorithms(GA),differential evolution(DE)algorithms and particle swarm optimizations(PSO)on a 6/4 switched reluctance machine design with seven independent variables and a strong nonlinear multi-objective Pareto front.To better quantify the quality of the Pareto fronts,five primary quality indicators are employed to serve as the algorithm testing metrics.The results show that the three algorithms have similar performances when the optimization employs only a small number of candidate designs or ultimately,a significant amount of candidate designs.However,DE tends to perform better in terms of convergence speed and the quality of Pareto front when a relatively modest amount of candidates are considered.

Electromagnetic Design of a Switched Reluctance Motor With Segmental Rotors and Full-pitch Windings

整距绕组分块转子开关磁阻电机具有高速运行时低风（油）阻和低铁心损耗等优点，特别适合用于航天航空驱动系统。根据整距绕组分块转子开关磁阻电机的基本工作原理，结合输出功率与平均转矩的关系，将绕组电流等效为方波，推导出了整距绕组分块转子开关磁阻电机的主体尺寸计算公式；基于电机定转子未对齐位置和对齐位置的电磁特性，以及整距绕组分块转子开关磁阻电机的电磁特点，确定了定、转子极弧系数选取的规则；同时分析了绕组匝数等主要尺寸的选取的规则；最后，基于上述方法优化设计了一台实验样机，并通过有限元仿真及实验验证了整距绕组分块转子开关磁阻电机的电磁设计方法的正确性。

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.

基于特征位置区间电感阈值约束的SRM中高速无位置传感器容错控制

针对开通角提前、磁路饱和造成的位置估算扰动问题,该文提出一种基于特征位置区间电感阈值约束的开关磁阻电机中高速无位置传感器容错控制方案,有效提高定转子对齐位置估计的准确性与可靠性。考虑到电流水平较低时难以提取对齐位置信息,在辅助电流斩波的基础上提出自适应启停控制策略,既保证控制系统在电机轻载、参考转速突降时能够准确完成特征位置的估计,又避免了产生不必要的开关损耗及负转矩。仿真和实验结果验证了该文所提无位置控制方案在电机轻载、重载、参考转速及负载突变等多种工况下的有效性。

Switched Reluctance Motor: Research Trends and Overview

There has been a growing interest in switched reluctance motor(SRM)ever since the development of thyristor in 1956.The most appealing feature of SRM which attracts researchers over these years is its simple structure that incorporates concentrated windings on the stator poles and plain laminations of ferromagnetic material as a rotor.Due to this attributes,advances are being made rapidly with the consideration that SRM can be used as an alternative to DC motors and permanent magnet motors.The objective of this paper is to present an overview of the recent developments and a prediction of possible future advancements in SR Drives.Brief history,importance,innovations in structure and control,along with practical application examples are all discussed here to give a more in-depth comprehension of the motor.

Design and Initial Testing of An Integrated Switched Reluctance Starter/Generator System for Unmanned Aerial Vehicle

According to specific performance requirements,an integrated switched reluctance starter/generator system,which can start the engine and supply electrical energy to the loads,is designed and manufactured for the unmanned aerial vehicle.Considering the required starting torque and speed range,the geometrical dimensions of the switched reluctance machine are calculated based on the output equation and further optimized with finite element analysis,and the flux-linkage,inductance and static torque characteristics are illustrated.To verify the performances of the designed system,detailed simulation with the model considering piston engine and experiment using the test bench are carried out.

Improved Model of Radial Vibration in Switched Reluctance Motor Including Magnetic Saturation

This paper proposes an improved method for the prediction of radial vibration in switched reluctance motor(SRM)considering magnetic saturation.In this paper,the basic modeling principle is briefly introduced,it is based on the derivation that the peak acceleration is dependent on the product of phase current and current gradient idi/dt.However,the derivation may cause errors due to saturation effect.Thus in this paper,the discrete sample data are firstly acquired based on DC pulse measurement method,by which electromagnetic,torque and peak acceleration characteristics can all be acquired.Then the entire peak acceleration characteristics are obtained by improved Least Square Support Vector Machine(LSSVM).Based on the obtained static peak acceleration characteristics,the time-varied radial vibration model is established based on superposition of natural oscillations of dominant vibration modes.Finally,a simulation model is built up using MATLAB/Simulink.The good agreement between simulation and experiment shows that the proposed method for modeling is feasible and accurate,even under saturation.In addition,since LSSVM does not need any prior knowledge,it is much easier for modeling compared with other existing literatures.

Evaluation of Switched-Reluctance Machine through Generalized Sizing Equations

With the evolution of converter fed machines (CFMs), it becomes important to evaluate the power potential of such machines of vastly different topologies with a variety of waveforms of back emf and current. It is based on the generalized sizing equations and permits the evaluation of the main dimensions with respect to the power of those machines. In this paper, a general approach is presented to extend the evaluation method of machine power density to the switched reluctance (SR) machine, and furthermore to compare the power production capability between the SR machine and the well known squirrel cage induction machine.

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.

Static Simulation of a 12/8 Switched Reluctance Machine (Application: Starter-Generator)

Because its high efficiency, its simple stator and rotor structures, the low cost and high reliability, speed operation combined with robust and low cost construction, the switched reluctance machines have represented. In recent years, an interesting alternative to other machine types has been chosen for traction applications especially starter-generator. Their rotors do not generate significant heat, resulting in easy cooling. Their unidirectional flux and current may generate lower core losses and require a simple converter design. Moreover, the switched reluctance machines are known for their high reliability and capability of operating in four quadrants for a variable speed drive. Despite those merits, switched reluctance machine has not been extensively used until recently because of its problems of torque ripples and noise. Additionally, researchers have faced many difficulties to build a SRM model because it is inherently multivariable. It has strong coupling and especially a high nonlinearity. In this paper, we deal with many modeling methods. Numerical, analytical and intelligent approaches are studied. The important aim in this research is to use static results from FEMM simulation as flux-linkage, co-energy, static torque to form a dynamic model of a switched reluctance machine used next as a starter-generator of a hybrid vehicle.

High Frequency Charging Techniques—Grid Connected Power Generation Using Switched Reluctance Generator

Power generation becomes the need of developed, developing and under developed countries to meet their increasing power requirements. When affordability increases their requirement of power increases, this happens when increased per capita consumption. The existing power scenario states that highest power is produced using firing of coals called thermal energy. A high efficiency Switched Reluctance Generator (SRG) based high frequency switching scheme to enhance the output for grid connectivity is designed, fabricated and evaluated. This proposed method generates the output for the low wind speed. It provides output at low speed because of multi-level DC-DC converter and storage system. It is an efficient solution for low wind power generation. The real time readings and results are discussed.

Design and Analysis of a Novel Rotor-Segmented Axial-Field Switched Reluctance Machine

As excitation strategy is influenced by the parity of phase number,and serious end effect is caused by full pitch windings adopted by the conventional rotor-segmented switched reluctance machine(RS-SRM),a novel rotor-segmented axial-field switched reluctance machine(RS-AFSRM),which adopts concentrated windings,is proposed in this paper,whose control strategy is independent of the parity of phase number.The stator of the proposed RS-AFSRM consists of inner and outer flux-conductive ring,excitation poles,and stator yoke,while the rotor consists of fan-shape cylinder-type segments.The structure and principle of the proposed machine is introduced through the magnetic circuit model of the machine.The fringing effect on air-gap field is considered.The simplified magnetic circuit considering the fringing effect is presented and the fringing effect coefficient is introduced.The design procedure considering the fringing effect through iterative modification is presented in this paper and is validated through 3D finite-element method(3D-FEM).Results show that both magnetic field distribution and operation are reasonable and satisfy the requirements.

一种多模式双定子开关磁阻电机混合控制系统

开关磁阻电机(switched reluctance motor,SRM)具有可靠性高、成本低、结构简单和起动转矩大等优点,但同时存在功率密度低、转矩脉动大的问题。该文针对新型磁场解耦型双定子开关磁阻电机(double stator switched reluctance machine,DSSRM)具有内定子、外定子、双定子、内外定子串联和并联5种工作模式的特性,设计一种高效低转矩脉动的多模式双定子开关磁阻电机混合控制系统。首先,构建综合考虑电机工作效率和转矩脉动的优化函数;其次,提出一种混合控制方法,在电机低速和高速时分别采用直接瞬时转矩控制和自抗扰控制,提高电机的动态性能;此外,为降低模式间切换时产生较大的转矩峰值,提出以转矩负反馈补偿理念为中心的模式切换策略。通过仿真和实验验证该控制系统的优越性,为推广新型双定子开关磁阻电机的应用奠定一定基础。

一种电动车用开关磁阻电机四象限双极性转速环控制系统研究

开关磁阻电机(Switched reluctance motor,SRM)因结构简单坚固、起动转矩大和转速范围宽的特点,在电动车驱动系统有着广阔的应用前景。不同于异步电机和同步电机依靠调节器双极性输出量实现四象限工作,传统单极性SRM转速环控制系统需要依靠外部给定来切换工作象限,在四象限运行工况下存在切换过程平滑性难以控制的问题。针对此,本文提出一种将SRM转速环控制系统及其四象限控制方法相结合,以传统的角度位置控制(Angle position control,APC)理论为基础,将转速调节器双极性输出量与电机转速方向进行逻辑判断形成新的APC控制参数,配合传统电流斩波控制(Chopping current control,CCC)形成新型的四象限转速环控制系统。该系统优化了SRM频繁电制动切换的顿挫问题,为电动车坡道动态行驶安全提供了平滑切换的保障。仿真和实验结果均验证了该系统原理的可行性,较好地实现了电动车SRM驱动系统的四象限工况切换。

自适应三管导通机制下模块化开关磁阻电机系统转矩交叉补偿控制

模块化变换器驱动型开关磁阻电机(switched reluctance motor,SRM)系统在降低系统体积与开发成本、促进电机变换器系统统一的同时,受两相串联励磁和母线电压的限制,转矩脉动问题进一步加剧。文中提出一种基于自适应三管导通的转矩控制策略可有效避免换相区两相串联励磁导致的转矩跌落,并在此基础上建立一种三步换相机制,通过确定换相区的自适应分区原则,揭示各换相分区的转矩交叉补偿原理,有效抑制模块化SRM转矩控制系统的相电流峰值,提高转矩跟踪效果。最后,基于一台150 W、三相12/8极SRM搭建系统模型与实验平台,验证所提出控制方案的可行性和有效性。

基于遗传算法的SRM转矩分配函数优化

开关磁阻电机采用传统型转矩分配策略时,电流峰值过高、电流可控性下降导致其出现严重的转矩脉动。针对这一问题,提出了基于遗传算法的开关磁阻电机电流变化率和铜耗的综合优化方法。在直线型转矩分配函数的基础上,根据电流输出波形与转矩分配函数的关系提出了二次型补偿曲线。选择电流变化率和铜耗作为优化目标,利用遗传算法的全局寻优能力,对新型转矩分配函数的参数进行优化,得到最优的转矩分配函数曲线,从而降低了换向时的电流峰值。仿真和实验结果表明,新型转矩分配函数能够有效地改善各相给定电流波形,降低电流控制难度,从而抑制转矩脉动。